IBM Distributed  
Computing Environment Version 3.2; (C) IBM Corporation

IBM(R) Distributed Computing Environment Version 3.2 for AIX(R) and Solaris: Introduction to DCE


Glossary

This Glossary defines terms used in this document and in the remainder of the DCE documentation set. Each term is defined for the audience of the document in which it is found. In some cases, a given term has a different meaning when used in the context of different technology components. This difference is indicated by the technology's abbreviation as a prefix to its definition. For example, the term server has a different meaning when used in conjunction with the RPC, CDS, DTS, and DFS technology components. The four definitions are listed in the entry for server in the Glossary. When no prefix is given, the definition applies to all DCE documentation.

absolute time

A point on a time scale. For DTS, absolute time refers to the UTC standard.

abstract class

GDS: An OM class of OM object of which instances are forbidden. An abstract class typically serves to document the similarities between instances of two or more concrete classes.

Abstract Syntax Notation One (ASN.1)

A notation that both enables complicated types to be defined and also enables values of these types to be specified.

access control list (ACL)
  1. Security: Data that controls access to a protected object. An ACL specifies the privilege attribute(s) needed to access the object and the permissions that can be granted, with respect to the protected object, to principals that possess such privilege attribute(s).
  2. DFS: The following ACL permissions are defined for file system objects: (1) read (abbreviated r): allows you to read a file or, with x, list a directory and the ACLs of its objects; (2) write (abbreviated w): allows you to modify a file or, with i, add a new object to a directory or, with d, remove an object from a directory; (3) execute (abbreviated x): allows you to execute a file or, with r, list a directory and the ACLs of its objects; (4) control (abbreviated c): allows you to modify a file's ACLs or a directory's ACLs; (5) insert (abbreviated i): with w, allows you to add a new object to a directory or, with w and d, rename an object in a directory; (6) delete (abbreviated d): with w, allows you to remove an object from a directory or, with w and i, rename an object in a directory.
  3. CDS: The following ACL permissions are defined for CDS: (1) read (abbreviated r): allows a principal to look up a name and view the attribute values associated with it; (2) write (abbreviated w): allows a principal to change the modifiable attributes associated with a name, except its ACLs; (3) insert (abbreviated i): (for use with directory entries only) allows a principal to create new names in a directory; (4) delete (abbreviated d): allows a principal to delete a name from the namespace; (5) test (abbreviated t): allows a principal to test whether an attribute of a name has a particular value without being able to actually see any of the values (that is, without having read permission to the name). Test permission provides application programs with a more efficient way to verify a CDS attribute value. Rather than reading an entire set of values, an application can test for the presence of a particular value; (6) control (abbreviated c): allows a principal to modify the ACL entries associated with a name. Control permission is automatically granted to the creator of a CDS name; (7) administer (abbreviated a): (for use with directory entries only) allows a principal to issue cdscp commands that control the replication of directories.
  4. GDS: A recurring attribute of an entry for specifying the access authorization for an object. The following ACL permissions are defined for GDS: (1) MODIFY PUBLIC: specifies the user, or subtree of users, that can modify attributes classified as public attributes; (2) READ STANDARD: specifies the user, or subtree of users, that can read attributes classified as standard attributes; (3) MODIFY STANDARD: specifies the user, or subtree of users, that can modify attributes classified as standard attributes; (4) READ SENSITIVE: specifies the user, or subtree of users, that can read attributes classified as sensitive attributes; (5) MODIFY SENSITIVE: specifies the user, or subtree of users, that can modify attributes classified as sensitive attributes.

access control list entry

Data in an ACL that specifies a set of permissions. In the case of a principal or group entry, the permission set is that which can be granted to a principal having the privilege attribute specified in the entry; in the case of a mask entry, the permission set is that which masks the permission set in a principal or group entry.

access control list facility

A DCE security facility that enables a principal's access to an object to be determined by a comparison of the principal's privileges to entries in an object's ACL.

access right

See permission.

accessible

Said of an object for which the client possesses a valid designator or handle.

account

An entry in the registry database that defines a principal's network identity by associating the principal with a group and optional organization, and with related account information such as the password used to authenticate a principal's identity.

ACF

See attribute configuration file.

ACL

See access control list.

active context handle

RPC: In RPC applications, a context handle that the remote procedure has set to a nonnull value and passed back to the calling program; the calling program supplies the active context handle in any future calls to procedures that share the same client context. See also client context, context handle.

address

An unambiguous name, label, or number that identifies the location of a particular entity or service. See also presentation address.

administration domain

GDS: A collection of several DSAs that share the same schema object (mastered by one of these DSAs and shadowed by all the others).

administrative domain
  1. DFS: A collection of machines configured as the server machines necessary to be administered as a single unit. The administration is typically handled by groups of administrative users.
  2. GDS: A collection of several DSAs that share the same schema object (mastered by one of these DSAs and shadowed by all the others).

administrative list

DFS: A file used to determine who can issue commands that affect filesets or DFS server processes. Administrative lists allow system administrators to control the security of the administrative domains in a cell. See also administrative domain, privilege required.

aggregate

DFS: A logical unit of disk storage that can contain multiple DCE LFS filesets or a single UFS fileset. An aggregate is physically equivalent to a standard UNIX disk partition, but a DCE LFS aggregate supports an optimized metadata structure and a number of specialized fileset-level operations not available on standard UNIX partitions. A UFS partition exported into the global namespace is referred to as an aggregate even though it does not support the optimizations and features of a DCE LFS aggregate.

aggregate identifier

DFS: The part of the fileset representation that identifies the aggregate on the file server machine on which the fileset is stored.

alias
  1. GDS: A name for a (directory) object, provided by the use of one or more alias entries in the DIT.
  2. Security: An optional alternate name for a primary name in the registry database. Aliases and the primary name for which they are an alternate share the same UUID and UNIX ID.

alias entry

GDS: A directory entry, of object class alias, containing information used to provide an alternative name for an object.

aliased object

The object to which an alias entry refers.

aliasing

RPC: Occurs when two pointers of the same operation point at the same storage.

anode

DFS: An abstraction for referring to an open-ended address space of storage. See also vnode.

anonymous user

A user who is not entered in the directory as an object and who logs into the directory service without giving a name and password.

API

See application programming interface.

application programming interface (API)

A set of runtime routines or system calls that allows an application program to use a particular service provided by either the operating system or another application program.

application thread

RPC: A thread of execution created and managed by application code. See also client application thread, local application thread, RPC thread, server application thread.

ASN.1

See Abstract Syntax Notation One.

asynchronous operation

An operation that does not of itself cause the process requesting the operation to be blocked from further use of the CPU. This implies that the process and the operation are running concurrently.

AT

See attribute table.

at-most-once semantics

RPC: A characteristic of a procedure that restricts it to executing once, partially, or not at all--never more than once. See also idempotent semantics, broadcast semantics, maybe semantics.

atomic transaction

DFS: A transaction that happens entirely or not at all; used when partial completion of a transaction is undesirable.

attention threshold

DFS: In the scout program, the value at which the program highlights a statistic in its graphical display. Separate attention thresholds can be set for most scout statistics. See also scout.

attribute
  1. Threads: The individual components of the attributes object. Attributes specify detailed properties about the objects to be created.
  2. RPC: (1) An IDL or ACF syntax element, occurring within [] (brackets), and conveying information about an interface, type, field, parameter, or operation. (2) An attribute of an entry in a name service database that stores binding, group, object, or profile information for an RPC application and identifies the entry as an RPC server entry; an NSI attribute.
  3. DTS: A piece of information associated with a DTS entity or command. DTS has four attribute categories: characteristics, counters, identifiers, and status.
  4. XDS: Information of a particular type concerning an object and appearing in an entry that describes the object in the DIB.
  5. XOM: A component of an object, comprising an integer that denotes the attribute's type and an ordered sequence of one or more attribute values, each accompanied by an integer denoting the value's syntax.

attribute configuration file (ACF)

RPC: A .acf file. An optional companion to an interface definition file (a .idl file) that modifies how the DCE IDL compiler locally interprets the interface definition. See also interface definition, Interface Definition Language.

attribute configuration language

RPC: A high-level declarative language that provides syntax for attribute configuration files. See also attribute configuration file.

attribute encoding type

A specifier of the data format (for example, integer, string, UUID) of an attribute value.

attribute instance

An attribute type UUID and value created according to the attribute type's semantics and attached to a registry object. (Also called attribute or ERA.)

attribute schema

A collection of attribute type definitions or schema entries. (Also called schema.)

attribute schema object

See schema object.

attribute set

An attribute instance with encoding type attr_set. Its value is a list of attribute type UUIDs that identify member attributes of this set. Attribute sets are created for the purpose of efficient queries for related attributes.

attribute syntax

GDS: A definition of the set of values that an attribute can assume. It includes the data type, in ASN.1, and usually one or more matching rules by which values can be compared.

attribute table (AT)

GDS: A recurring attribute of the directory schema with the description of the attribute types that are permitted.

attribute type
  1. XDS: The component of an attribute that indicates the class of information given by that attribute. It is an object identifier, so it is completely unique.
  2. XOM: Any of the various categories into which the client dynamically groups values on the basis of their semantics. It is an integer unique only within the package.
  3. Security: The description of the identifiers (such as name and UUID) and semantics (such as encoding type and access control parameters) of instances of this type.

attribute value
  1. XDS: A particular instance of the class of information indicated by an attribute type.
  2. XOM: An atomic information object.
  3. Security: The data in an attribute instance.

attribute value assertion (AVA)

GDS: A proposition, which may be true, false, or undefined, concerning the values (or perhaps only the distinguished values) of an entry.

attribute value syntax

See attribute syntax, syntax.

audit action

A component of the filter directive that specifies where the audit record is to be written: to the console or to an audit trail file.

audit client

Users of the DCE Audit Service. All DCE servers and user-written distributed applications can be audit clients.

audit condition

A component of the filter directive that specifies the required outcome of the event before an audit record is written to the audit trail file.

audit daemon

A DCE component. It maintains the audit filters and the central audit trail file.

audit event

An occurrence in the use of the application that requires logging of audit records. Generally, audit events involve the integrity of the system.

audit filter

Used to narrow down the conditions by which audit records are logged. A filter provides a means to specify these conditions.

audit record

Contains information pertaining to an audit event.

audit trail file

A set of audit records that provide evidence of the sequence of events that occurred on the system.

authentication

The verification of a principal's network identity.

authentication header

A record containing a ticket and an authenticator to be presented to a server as part of the authentication process.

authentication level

See protection level.

authentication path

The sequence of cells transited when a principal in one cell communicates with one in another cell. Also known as a trust path.

authentication protocol

A formal procedure for verifying a principal's network identity; Kerberos is an instance of a shared-secret authentication protocol.

authentication service

One of the services provided by DCE Security: the authentication service authenticates principals according to a specified authentication protocol. See also authentication protocol.

authentication surrogate

A type of principal represented by an entry in a cell's registry that specifies the same secret key as a corresponding entry in another cell's registry. The authentication services of the two cells use the secret key for the purpose of exchanging data about principals without either authentication service having to share its private key with the other. Authentication surrogates are necessary for intercell authentication. See also peer trust.

authenticator

A record containing information that can be shown to have been recently generated via a conversation key known only by two principals that are participating in an authenticated network exchange.

authorization
  1. The determination of a principal's permission(s) with respect to a protected object.
  2. The approval of a permission sought by a principal with respect to a protected object.

authorization data

That portion of a Kerberos ticket that contains data necessary for authorization decisions. Sometimes abbreviated Auth_Data or A_D.

authorization protocol

A formal procedure for establishing the authorization of principals with respect to protected objects. Authorization protocols supported by DCE Security include one based on PACs and EPACs (DCE authorization) and one based on names (name-based authorization) See also PAC, EPAC, name-based authorization.

automatic binding method

RPC: A method of managing the binding for a remote procedure call. The automatic method completely hides binding management from client application code. If the client makes a series of remote procedure calls, the stub passes the same binding handle with each call. See also binding handle, implicit binding method, explicit binding method.

AVA

See attribute value assertion.

background skulk time

An automatic timer that guarantees a maximum lapse of time between skulks of a CDS directory, regardless of other factors, such as namespace management activities and user-initiated skulks. Every 24 hours, a CDS server checks each master replica in its clearinghouse and initiates a skulk if changes were made in a replica since the last time a skulk of that replica completed successfully.

backup

DFS: The dump of a fileset to a permanent medium such as tape. To back up also means to clone a read/write fileset, which results in a backup fileset.

backup database

DFS: A database that records the dump schedule for backups, the backup system's tape coordinators, the fileset families that can be dumped, and other administrative information.

backup database machine

DFS: A server machine in a cell that houses the backup database. See also server machine.

backup fileset

DFS: A fileset created by cloning (copying) a read/write fileset (referred to as the source fileset). The backup version always resides on the same aggregate as its source and usually requires little disk space. It preserves the state of the read/write fileset at the time of the cloning. See also clone, read-only fileset, read/write fileset.

backup fileset ID

DFS: A unique fileset identification number (fileset ID) assigned to the backup version of a fileset.

backup server

DFS: A server process that runs on backup database machines (which house the backup database). It communicates with the backup database to back up and restore filesets and aggregates.

backup system

DFS: A system that allows you to copy fileset data to tape and restore it from tape if necessary. The DFS backup system consists of the backup server, the backup database, and one or more tape coordinator machines. See also dump, restore.

basename

DFS: In the scout program, the DCE pathname prefix common to the file server machines to be monitored. If specified on the command line, the basename is displayed in the program's banner line. See also scout.

Basic Encoding Rules (BER)

A set of rules used to encode ASN.1 values as strings of octets.

basic overseer server (BOS server)

DFS: A server process that runs on all DFS server machines. It monitors the other DFS server processes running on its machine; it can usually restart those that fail without requiring intervention from a human operator.

BER

See Basic Encoding Rules.

big endian

An attribute of data representation that reflects how multioctet data is stored in memory. In big endian representation, the lowest addressed octet of a multioctet data item is the most significant. See also endian, little endian.

binary distribution machine

DFS: A server machine that distributes DFS binaries to other file server machines of its machine type (same CPU/operating system). It runs the server portion of the update server for this purpose. There is one binary distribution machine of each machine type that the cell uses as a DFS server machine. See also server machine, update server, upserver.

binary timestamp

An opaque 128-bit (16-octet) binary number that represents a DTS time value.

binding

RPC: A relationship between a client and a server involved in a remote procedure call.

binding handle

RPC: A reference to binding information that defines one possible binding (a client/server relationship). See also binding, customized binding handle, primitive binding handle.

binding handle vector

RPC: A data structure that contains an array of binding handles and the size of the array. See also binding handle.

binding information

RPC: Information about one or more potential bindings, including an RPC protocol sequence, a network address, an endpoint, at least one transfer syntax, and an RPC protocol version number. See also binding, endpoint, network address, RPC protocol sequence, RPC protocol, transfer syntax.

binding management method

RPC: Any of the methods for managing the binding for a remote procedure call. See also automatic binding method, implicit binding method, explicit binding method.

blocking call

A call in which a caller is suspended until a called procedure completes.

bnode

DFS: A structure that describes common characteristics of the BOS server process. There are two types: simple and cron. Processes are created through bnodes. See also basic overseer server.

BOS server

See basic overseer server.

broadcast

Threads: To wake all threads waiting on a condition variable. See also signal.

broadcast semantics

RPC: A form of idempotent semantics that indicates that the operation is always broadcast to all host systems on the local network, rather than delivered to a specific system. An operation with broadcast semantics is implicitly idempotent. Broadcast semantics are supported only by connectionless protocols. See also at-most-once semantics, idempotent semantics, maybe semantics.

browser

A Motif-based program that lets users view the contents and structure of a cell namespace.

butc process

DFS: A process that runs on a tape coordinator machine to monitor the activity of a tape drive. One butc process must run for each tape drive on the machine. See also tape coordinator.

C interface

The interface, defined at a level that depends on the variant of C standardized by ANSI.

C-stub

The part of the DUA that implements the connection with the communications network.

cache
  1. CDS: The information that a CDS clerk stores locally to optimize name lookups. The cache contains attribute values resulting from previous lookups, as well as information about other clearinghouses and namespaces. The cache is written to disk periodically so that it can survive a system reboot. See also copy.
  2. DFS: A reserved amount of disk or memory space on a DFS client machine. The DFS cache manager uses the cache to temporarily store files or parts of files retrieved from DFS file server machines so that future access time and network load are reduced. DFS uses a cache-consistency mechanism (token-passing) to guarantee that the source and cached data are consistent. See also caching.

cache manager

DFS: The portion of a DFS client machine's kernel that communicates with DFS server processes by translating local file requests into RPCs (if needed). It stores the requested files in a local disk or memory cache, from which it makes the files available to users on that machine.

caching

DFS: The technique of copying a file from a file server machine (its central storage place) to a client machine's local disk or memory; users then access the copy locally. Caching reduces network load because a file does not have to be fetched across the network more than once (unless the central copy changes).

caching layer

DFS: The part of the DFS cache manager that manages the cached data, performing fetches and stores and answering status requests.

call chain

The chain of operations (RPC calls) leading from the delegation initiator to the final target.

call queue

RPC: A first-in, first-out queue used by an RPC server to hold incoming calls when the server is already executing its maximum number of concurrent calls.

call thread

RPC: A thread created by a server's RPC runtime to execute remote procedures. When engaged by a remote procedure call, a call thread temporarily forms part of the RPC thread of the call. See also application thread, RPC thread.

callback

DFS: A procedure that is registered with a token to be called automatically if the token is revoked. The act of revoking a token is also referred to as a callback.

cancel
  1. Threads: A mechanism by which a thread informs either itself or another thread to terminate as soon as possible. If a cancel arrives during an important operation, the canceled thread may continue until it can terminate in a controlled manner.
  2. RPC: A mechanism by which a client thread notifies a server thread (the canceled thread) to terminate as soon as possible. See also thread.

CDS

See DCE Cell Directory Service.

CDS Advertiser
See Cell Directory Service Advertiser.

CDS control program (cdscp)

A command interface that CDS managers use to control CDS servers and clerks and manage the namespace and its contents.

CDS-defined attribute

A standard attribute that CDS associates with names. A specific CDS-defined attribute has the same meaning no matter what type of entry (clearinghouse, directory, object) it is associated with. However, different types of entries can have different CDS-defined attributes. For example, every CDS name has the CDS-defined attributes of Creation Timestamp (CDS_CTS), Update Timestamp (CDS_UTS), and Access Control Set (CDS_ACS). In addition to those attributes, a soft link has unique CDS-defined attributes containing its expiration time and the name it points to.

cdscp

See CDS control program.

cell
  1. The basic unit of operation in DCE. A cell is a group of users, systems, and resources that are typically centered around a common purpose and that share common DCE services. At a minimum, a cell configuration includes one cell directory server, one security server, and one distributed time server. A cell can consist of from one system to as many as several thousand systems. Systems in the cell can be in the same geographic area (for example, on the same LAN), but geography does not necessarily determine a cell's boundaries. The boundaries of a cell are typically influenced by its purpose, as well as by security, administrative, and performance considerations. With respect to individual DCE technologies, a cell represents the following definitions.
  2. CDS: A unified naming environment consisting of CDS clerks and servers.
  3. DFS: An administratively independent installation of server and client machines.
  4. Security: The set of principals that share their secret keys with the same authentication service.

cell alias

DFS: An additional global name given to a cell.

Cell Directory Service (CDS) Advertiser
A daemon that starts a CDS clerk, when needed, to access the CDS name space. On the CDS server machine, the advertiser broadcasts the existence of the server every 10 minutes and each time a client is first started. On the client machine, the advertiser receives broadcasts from the CDS server which inform the clients of the existence of the CDS servers and their addresses.

cell module

DFS: The part of the DFS cache manager that maintains a list of cells that have been contacted.

cell-relative name

See local name.

central audit trail file

The audit trail file that is maintained by the audit daemon. This is created and used if the user does not specify an audit trail file when starting the audit daemon.

chaining

A mode of interaction optionally used by a DSA that cannot perform an operation itself. The DSA chains by invoking an operation of another DSA and then relaying the outcome to the original requester.

character set

A group of characters, such as the English alphabet, Japanese Kanji, and the European character set.

characteristic attribute

A type of attribute that reflects or affects the behavior of a software entity. You generally can set or change characteristic attributes.

child cell

A cell whose name is stored in the CDS server of another cell (its parent cell) and includes its parent cell's name as a prefix to its own name.

child directory

A CDS directory that has a directory above it is considered a child of the directory immediately above it.

child pointer

A pointer that connects a directory to a directory immediately below it in a namespace. You do not explicitly create child pointers; CDS creates them for you when you create a new directory. CDS stores the child pointer in the directory that is the parent of the new directory.

ciphertext

The output of an encryption function. Encryption transforms plaintext into ciphertext.

class

A category into which objects are placed on the basis of both their purpose and their internal structure. See also object class, OM class.

class-id

A component of the event class number, which identifies the event class within the set of event classes.

class-specific attribute

CDS: An attribute that has meaning only to a particular class of object and to the application using that object class. A CDS object's class can be defined in an attribute named CDS_Class. Programmers who write applications that use CDS can define their own object classes and class-specific attributes.

clearinghouse

A collection of directory replicas on one CDS server. A clearinghouse takes the form of a database file. It can exist only on a CDS server node; it cannot exist on a node running only CDS clerk software. Usually only one clearinghouse exists on a server node, but there may be special cases when more than one exists.

clearinghouse object entry

A special class of object entry that describes a clearinghouse. The clearinghouse object entry is a pointer to the network address of an actual clearinghouse. This pointer enables CDS to find a clearinghouse and use and manage its contents. A clearinghouse modifies and manages its own object entry when necessary; normally CDS managers do not need to maintain it. The clearinghouse object entry has the same name as the clearinghouse.

clerk
  1. CDS: The software that provides an interface between client applications and CDS servers. The clerk receives a request from an application, sends the request to a CDS server, and returns any resulting information to the application. The clerk saves (caches) the results of lookups so that it does not have to repeatedly go to a CDS server for the same information.
  2. DTS: A software component that synchronizes the clock for its client system by requesting time values from servers, computing a new time from the values, and supplying the computed time to client applications.

client
  1. CDS: Any application that interacts with a CDS server through the CDS clerk.
  2. DTS: Any application that interacts with a DTS server through the DTS clerk.
  3. RPC: The party that initiates a remote procedure call. Some applications act as both an RPC client and an RPC server. See also server.
  4. DFS: A consumer of resources or services. See also server.
  5. GDS: Consists of an application that links the DUA library, the C-stub that handles the connection over the communications network for accessing a remote server, and the DUA cache.

client application thread

RPC: A thread which is executing client application code that makes one or more remote procedure calls. See also application thread, local application thread, RPC thread, server application thread.

client binding information

RPC: Information about a calling client provided by the client runtime to the server runtime, including the address where the call originated, the RPC protocol used for the call, the requested object UUID, and any client authentication information. See also binding information, server binding information.

client context

RPC: The state in an RPC server's address space generated by a set of remote procedures (manager) and maintained across a series of calls for a particular client. See also manager, context handle.

client machine

DFS: A machine whose kernel includes the DFS cache manager. A client machine is capable of requesting data from remote file exporters and caching the data locally. See also server machine.

client portion of update server

See upclient.

client stub

RPC: The surrogate code for an RPC interface that is linked with and called by the client application code. In addition to general operations such as marshalling data, a client stub calls the RPC runtime to perform remote procedure calls and, optionally, manages bindings. See also server stub, stub.

clock

The combined hardware interrupt timer and software register that maintain the system time. In many systems, the hardware timer sends interrupts to the operating system; at each interrupt, the operating system adds an increment to a software register that contains the time value.

clock adjustment

DTS: Process of changing the system clock time by modifying the incremental value that is added to the clock's software register for a specified duration.

clone

DFS: A backup or read-only copy of a fileset created by copying only the read/write (source) fileset's header rather than the data it contains. The clone preserves pointers to fileset data that existed when the clone was made; it therefore must exist on the same aggregate as the source. Cloning a fileset also refers to making a copy of it with the proper fts commands for later use with the DFS backup system. See also replica.

clone ID number

DFS: The fileset ID number of the last clone made from the fileset's read/write source for the purpose of replication.

code point

Location in the distributed application code that designates the operations in the application where logging of audit records may be required. The DCE audit APIs are called in the application's code points.

code set

The mapping of the members of a character set to specific numeric code values. Examples of code sets include ASCII, JIS X0208, and ISO 8859-1.

code set registry

A per-host file that contains, for each code set supported on the host, a mapping between a string name for the code set (which is the name used on the host to refer to the code set) and the unique identifier that has been assigned (by OSF or by the site) to the code set.

collapse

To remove the contents of a directory from the display (close it) via the CDS browser. To collapse an open directory, you double-click on its icon. Double-clicking on a closed directory expands it.

command suite

DFS: The DFS command suites are bak, bos, cm, dfsgw, dfstrace, and fts.

commit

DFS: An indication that all of the actions associated with a specific transaction have been written to the log. Once a transaction has committed, its actions are permanent. In the event of system problems, those actions are repeated when the system's recovery mechanism replays the log.

communications link

RPC: A network pathway between an RPC client and server that uses a valid combination of transport and network protocols that are available to both the client and server RPC runtimes.

compatible server

RPC: A server that offers the requested RPC interface and RPC object and that is available over a valid combination of network and transport protocols that are supported by both the client and server RPC runtimes.

computed time

The result of the synchronization process--the time value that the clerk or server process computes according to the values it receives from several servers.

concrete class

An OM class of which instances are permitted.

condition variable

A synchronization object used in conjunction with a mutex. A condition variable allows a thread to block until some event happens.

configuration of directory service

GDS can be configured as a client system or a client/server system. In a client system, a DUA either accesses the local DUA cache or a remote server over the communications network. In a client/server system, a DUA either accesses a local server or a remote server over the communications network. The local server is also accessible from a remote client or server.

conformant array

RPC: An array whose size is determined at runtime. A structure containing a conformant array as a field is a conformant structure.

connection-oriented protocol

A connection-based, reliable, virtual-circuit transport protocol, such as TCP; an RPC protocol that runs over a connection-based transport protocol.

connectionless

Not connected. For example, a connected datagram is a network protocol that is connected. A connectionless datagram network protocol is one that is not connected.

container

Containers are objects that hold other objects. The objects they hold can themselves be either simple objects or container objects. Simple objects do not hold other objects. Files are simple objects, and directories are containers. The directories can hold simple objects (files) and other containers (subdirectories). See also container object, simple object.

container object

An object that can hold another object. For example, a directory is a container object since it can hold files. See also simple object.

context handle

RPC: A reference to the state (client context) maintained across remote procedure calls by a server on behalf of a client. See also client context.

continuation reference

Describes how the performance of all or part of an operation can be continued at a different DSA or DSAs. See also referral.

control access

CDS: An access right that grants users the ability to change the access control on a name and do other powerful management tasks, such as replicate a directory or move a clearinghouse.

convergence

The degree to which CDS attempts to keep all replicas of a directory consistent. Two factors control the persistence and speed at which CDS keeps directory replicas up to date: the setting of a directory's CDS_Convergence attribute and the background skulk time. You can set the CDS_Convergence attribute to high, medium, or low. By default, every directory inherits the convergence setting of its parent. See also background skulk time.

conversation key

A short-lived encryption key provided by the authentication service to two principals for the purpose of ensuring secure communications between them.

Coordinated Universal Time (UTC)

An international time standard that DTS uses. The zero hour of Coordinated Universal Time is based on the zero hour of Greenwich (England) Mean Time.

copy

GDS: Either a copy of an entry stored in other DSAs or a locally and dynamically stored copy of an entry resulting from a request (a cache copy).

core leak

DFS: A situation that can develop as a process allocates virtual memory but does not free it again. When memory is completely exhausted, the machine crashes. The BOS server can be configured to restart all processes on a file server machine once a week to reduce the likelihood of core leaks.

courier

DTS: A local server that requests a time value from a randomly selected global server each time it synchronizes.

Creation Timestamp (CTS)

An attribute of all CDS clearinghouses, directories, soft links, child pointers, and object entries that contains a unique value reflecting the date and time the name was created. The timestamp actually consists of two parts: a time portion, and a portion containing the system identifier of the node on which the name was created. This guarantees uniqueness among timestamps generated on different nodes.

credentials

A general term for privilege attribute data that has been certified by a trusted privilege certification authority. The DCE authorization protocol implements credentials as Privilege Attribute Certificates (PACs).

cron bnode

DFS: A bnode that manages a single process that is to be run either exactly once or periodically. See also basic overseer server, bnode.

cron process

DFS: A type of process defined in a server machine's BosConfig file. It executes weekly or daily at a defined time rather than running continuously. See also cron bnode, simple process.

CTS

See Creation Timestamp.

customized binding handle

RPC: A user-defined data structure from which a primitive binding handle can be derived by user-defined routines in application code. See also primitive binding handle.

daemon
A program that runs unattended to perform a standard service. Some daemons are triggered automatically to perform their tasks; others operate periodically. An example is the cron daemon, which periodically performs the tasks listed in the crontab file.

DAP

See Directory Access Protocol.

Data Encryption Standard (DES)

A data encryption algorithm widely used in the United States.

data limit

RPC: A value that specifies which elements of an array are transmitted during a remote procedure call.

data token

DFS: A token that grants access to a range of bytes in a file. Read and write data tokens are available. See also token.

datagram

An unreliable network data packet that is independent of all other packets and lacks any guarantees of delivery or sequentiality.

datagram protocol

A connectionless, datagram-based transport protocol, such as UDP; an RPC protocol that runs over a connectionless transport protocol.

date-specific restore

DFS: In the DFS backup system, a restore that returns a fileset to its state when it was last dumped before a specified date. A date-specific restore differs from a full restore. See also full restore, restore.

DCE

See Distributed Computing Environment.

DCE Audit Service

That part of the DCE Security Service which detects and records the execution of DCE server operations that are relevant to the maintenance of a secure distributed computing environment. See also DCE Security Service.

DCE authorization

Provides a server with the client's PAC and EPAC. See also PAC, EPAC, name-based authorization, authorization protocol.

DCE Cell Directory Service (CDS)

The DCE Cell Directory Service stores names and attributes of resources located in a DCE cell. It is optimized for local access, since most directory service queries are for information about resources within the same cell as the originator of the query. It is replicated, in order to make it highly available. There must be at least one cell directory server in each DCE cell.

DCE control program (dcecp)

An administrative interface that provides consistent and uniform access to DCE administration functions, wherever they reside, from any and every point in the cell.

DCE daemon (dced)

A continuously running program on each host that provides access to the host services either locally on that host, or remotely from another host.

DCE Directory Service

The DCE Directory Service is a distributed, replicated database service consisting of a hierarchical set of names which have associated attributes. Given a name, its associated attributes can be looked up in the directory service.

DCE Distributed File Service (DFS)

In DCE, a file service that joins the local file systems of several file server machines, making the file systems equally available to all DFS client machines.

DCE Distributed Time Service (DTS)

A time service that provides fault-tolerant clock synchronization for systems in local area networks and wide area networks. The clock synchronization provided by DTS enables distributed computing applications to determine event sequencing, duration, and scheduling.

DCE Global Directory Service (GDS)

The DCE GDS component is a distributed, replicated directory service based on the CCITT X.500/ISO 9594 international standard. It provides a global namespace that connects the local DCE cells into one worldwide hierarchy.

DCE remote procedure call (RPC)

A call to a procedure in a different address space. In a traditional procedure call, the calling procedure and the called procedure are in the same address space on one machine. In a remote procedure call, the calling procedure invokes a procedure in a different address space, and usually on a different machine. See other glossary terms beginning with binding, interface, and RPC.

DCE Security Service

The DCE Security Service comprises several parts, including the authentication service, the privilege service, the registry service, the access control list facility, the login facility, and the audit service.

DCE Threads

A user-level (nonkernel) threads library based on the pthreads interface specified by POSIX in the 1003.4a standard (Draft 4). It consists of an API that gives programmers the ability to create and manipulate threads.

dcecp

See DCE control program.

dced

See DCE daemon.

default cell

Security: With the sec_admin and rgy_edit commands, the cell in which the replica being acted on by the sec_admin command is registered.

default DSA

The DSA generally used when the user does not specify any particular DSA when connecting to the directory system.

default element

RPC: An optional profile element that contains a nil interface identifier and object UUID and that specifies a default profile. Each profile can contain only one default element. See also default profile, profile, profile element.

default profile

RPC: A backup profile, referred to by the default element in another profile. The NSI import and lookup operations use the default profile, if present, whenever a search based on the current profile fails to find any useful binding information. See also default element, profile.

delegate restrictions

Restrictions that limit who can act as an intermediary for a particular identity in a call chain.

delegation token

A checksum over EPAC data, encrypted in the privilege server's key and placed in the A_D field of a PTGT. The token is placed in the A_D field by the privilege server when it enables delegation and when it generates a new delegation chain or impersonated identity.

DES

See Data Encryption Standard.

descriptor
  1. XOM: The means by which the client and service exchange an attribute value and the integers that denote its representation, type, and syntax.
  2. XDS: A defined data structure that is used to represent an OM attribute type and a single value.

descriptor list

GDS: An ordered sequence of descriptors that is used to represent several OM attribute types and values.

destructor

A user-supplied routine that is expected to finalize and then deallocate a per-thread context value.

DFS

See Distributed File Service.

dfsd

DFS: A program that initializes the cache manager and several daemons on a DFS client machine. It must run each time the client machine reboots for the machine to function as a DFS client.

DIB

See Directory Information Base.

directory
  1. CDS: A logical unit for storing entries under one name (the directory name) in a CDS namespace. In addition to object entries, a directory can contain soft links and child pointers. You can copy, delete, and control access to a directory. Each physical instance of a directory is called a replica.
  2. GDS: A collection of open systems that cooperate to hold a logical database of information about a set of objects in the real world.

Directory Access Protocol (DAP)

GDS: The protocol used by a DUA to access a remote DSA.

directory ID

See directory identifier.

directory identifier (directory ID)

An identifier for distinguishing several configurations of the directory service within an installation.

Directory Information Base (DIB)

GDS: The complete set of information to which the directory provides access, which includes all of the pieces of information that can be read or manipulated using the operations of the directory. It consists of entries.

Distributed File Service (DFS)

DFS: A file service that joins the local file systems of several file server machines, making the file systems equally available to all DFS client machines.

Directory Information Tree (DIT)

GDS: The DIB considered as a tree, whose vertices (other than the root) are the directory entries.

directory package

DFS: The part of the DFS cache manager that stores directory (rather than file) caching information.

directory schema

See schema.

directory service

GDS: A system using a directory. The directory service consists of the DUA and the directory system. The components of the directory service are connected by a communications network.

directory system

GDS: A system for managing a directory, consisting of one or more DSAs. Each DSA manages part of the DIB.

Directory System Agent (DSA)

GDS: An Open Systems Interconnection (OSI) application process that is part of the directory.

Directory System Protocol (DSP)

GDS: The protocol by a DSA to access another DSA.

Directory User Agent (DUA)

GDS: An OSI application process that represents a user accessing the directory.

discriminator

RPC: The data item that determines which union case is currently used.

disk usage

DFS: A statistic reported by the scout program that indicates space usage on a file server machine's aggregates and partitions. An administrator can use scout to highlight disk usage statistics that exceed specified values. See also scout.

dispatcher

XOM: The software that implements the service interface functions using workspace interface functions.

distinguished encoding

The restrictions to the Basic Encoding Rules designed to ensure a unique encoding of each ASN.1 value, defined in the X.500 Directory Standards (CCITT X.509).

Distinguished Name (DN)

GDS: One of the names of an object, formed from the sequence of RDNs of its object entry and each of its superior entries.

distinguished value

GDS: An entry's attribute value that has been designated to appear in the RDN of the entry.

Distributed Computing Environment (DCE)

Services and tools that support the creation, use, and maintenance of distributed applications in a heterogeneous computing environment.

DIT

See Directory Information Tree.

DN

See Distinguished Name.

Domain Name Service ( DNS)

A hierarchical, distributed naming service which, like the GDS, can act as a higher level connector of DCE cells. See also DCE Global Directory Service.

drift

DTS: The change in a clock's error rate over a specified period of time.

DSA

See Directory System Agent.

DSP

See Directory System Protocol.

DTS

See DCE Distributed Time Service.

DTS entity

DTS: The server or clerk software on a system.

DUA

See Directory User Agent.

DUA cache

GDS: The part of the DUA that stores frequently required information.

dump

DFS: Generally, the conversion of a fileset's contents into a format suitable for storage on a backup tape and the data object that results from this action. However, the operation need not involve dumping to other media such as tape. See also full dump, incremental dump, restore.

dump hierarchy

DFS: A logical structure in the DFS backup system that defines the parent/child relationship between full and incremental dump levels. See also full dump, incremental dump.

dump ID number

DFS: A unique identification number that the DFS backup system assigns to a dump set. It is distinct from the job ID number assigned to an operation in interactive mode. See also job ID number.

dump level

DFS: An entry in the dump hierarchy recorded in the DFS backup system's backup database. There are two types of dump levels: full and incremental. See also full dump, incremental dump.

dump set

In the DFS backup system, the fileset data that results from dumping a particular fileset family at a given dump level. By implication, all of the data in a dump set was dumped at the same time and in the same manner (fully or incrementally).

dynamic endpoint

RPC: An endpoint that is generated by the RPC runtime for an RPC server when the server registers its protocol sequences and that expires when the server stops running. See also well-known endpoint, endpoint.

effective permissions

The permissions granted to a principal as a result of a masking operation.

element

Any of the bits of a bit string, the octets of an octet string, or the octets by means of which the characters of a character string are represented.

encryption key

A secret value shared between two parties that enables them to communicate securely by using the key to encrypt and decrypt messages. Some servers store encryption keys in a keytab file. See also keytab file, password.

endian

An attribute of data representation that reflects how certain multioctet data is stored in memory. See also big endian, little endian.

endpoint

RPC: An address of a specific server instance on a host. See also dynamic endpoint, well-known endpoint.

endpoint map

RPC: A system-wide database where local RPC servers register binding information associated with their interface identifiers and object UUIDs. The endpoint map is maintained by the endpoint map service of the RPC daemon. See also endpoint map service, RPC daemon.

endpoint map service

RPC: A service provided by the RPC daemon that maintains a system's endpoint map for local RPC servers. When an RPC client makes a remote procedure call by using a partially bound binding handle, the endpoint map service looks up the endpoint of a compatible local server. See also endpoint map, partially bound binding handle, RPC daemon.

entity
  1. CDS: A component of CDS software that you can manage independently of any other component. The CDS control program commands are based on directives targeted for specific entities.
  2. DTS: A specific software implementation on a system.

entity type

DTS: An identifier of an entity that determines its relationship to other components: clerk or server.

entry

GDS: The part of the DIB that contains information relating to a single directory object. Each entry consists of directory attributes.

entry point vector (EPV)

RPC: A list of addresses for the entry points of a set of remote procedures that implements the operations declared in an interface definition. The addresses are listed in the same order as the corresponding operation declarations.

EPAC

See extended privilege attribute certificate.

epoch

A timestamp that identifies directory replicas as being part of the same set. CDS uses the epoch timestamp when it skulks a directory: it finds all replicas of the directory that are in the same epoch and makes their contents consistent. If not all replicas share the same epoch, the skulk aborts. The set directory to new epoch command updates the value of the CDS_Epoch attribute.

epoch number

DTS: An identifier that a server appends to the time values it sends to other servers. Servers only use time values from other servers with whom they share epoch numbers.

EPV

See entry point vector.

ERA

See extended registry attribute.

error

DTS: The difference between a system's clock value and the computed time.

error tolerance

DTS: The amount of system clock error to which DCE Distributed Time Service responds by abruptly setting the system clock to the computed time, rather than gradually adjusting the clock.

event class

Logical grouping of audit events, designated by a name that can be any character string up to 256 characters. Generally, an event class comprises audit events that have some form of commonality.

event class file

A file that contains the declaration of events that constitute an event class. The name of the event class is the same as the name of the event class file.

event name

Symbolic name assigned to an audit event, consisting of any character string up to 256 characters. It is used for documentation only, and is not used for any other administrative purpose.

event number

A 32-bit integer assigned to an audit event. An event number is a tuple made up of a set-id and the event-id. It is used in grouping audit events into event classes.

event-id

Component of the event number that identifies the audit event.

execution semantics

RPC: The rules of execution for a remote procedure call, including the effect of multiple invocations on the outcome of a procedure's operation. See also at-most-once semantics, broadcast semantics, maybe semantics, idempotent semantics.

expand

To display the contents of (open) a directory by using the CDS browser. You expand a directory that is closed by double-clicking on its icon. Double-clicking on an expanded directory collapses it.

expiration age

RPC: The amount of time that a local copy of name service data from an NSI attribute remains unchanged before a request from an RPC application for the attribute requires updating it. See also NSI attribute.

explicit binding method

RPC: The explicit method of managing the binding for a remote procedure call in which a remote procedure call passes a binding handle as its first parameter. The binding handle is initialized in the application code. See also automatic binding method, binding handle, implicit binding method.

export
  1. RPC: (1) To place the server binding information associated with an RPC interface or a list of object UUIDs or both into an entry in a name service database. (2) To provide access to an RPC interface.
  2. DFS: Offering data or making data available to another system. For example, hosts must export a local DCE LFS or non-LFS aggregate to make it available in the DCE namespace.

extended privilege attribute certificate (EPAC)

Contains authorization information specific to the user, such as groups to which the user belongs. EPACs are used to authorize users; that is, to help a server decide whether users should be granted access to resources that the server manages.

extended registry attribute (ERA)

An attribute attached to a registry object, created using the ERA API interfaces.

fault

RPC: An exception condition, occurring on a server, that is transmitted to a client.

file exporter

DFS: The part of a file server machine's kernel that responds to file or directory information requests from the client's cache manager.

file server machine

DFS: A system that maintains one or more local file systems on disk and makes them available (exports them) to other nodes through the file exporter. See also server machine.

file system

DFS: A mountable subtree of the directory hierarchy.

fileset

DFS: A hierarchical grouping of files managed as a single unit. DCE LFS supports multiple filesets within a single aggregate; in other file systems used with DFS, filesets are equivalent in size to a partition.

fileset database machine

DFS: A server machine in a cell that houses the FLDB. See also server machine.

fileset family

DFS: In the DFS backup system, a collection of one or more fileset entries. It defines a group of filesets to be backed up together (at the same time and in the same manner).

fileset family entry

DFS: A single definition in a DFS backup system fileset family. It defines a collection of filesets in terms of their common site, their prefix, or both. See also site.

fileset header

DFS: Part of the data structure that records information about a fileset. The fileset header records status information such as the the current size of the fileset, the quota of the fileset, and the ID number of the fileset. Information such as the fileset ID is also stored in the entry for the fileset in the FLDB.

fileset ID number

DFS: A number that uniquely identifies each fileset. The read/write and backup versions of a fileset each have their own fileset ID; all copies of the read-only version share the same fileset ID.

fileset label

DFS: A file containing information about a fileset, such as its name, fileset ID, unique identifier, type, and status.

fileset location database (FLDB)

DFS: A database that records the location and other status information about available DCE LFS and non-LFS filesets, allowing transparent data access. To be available, a fileset must be exported, registered in the FLDB, and mounted in DFS. The FLDB is maintained by the FL server.

fileset location server (FL server)

DFS: A server process that runs on fileset database machines and maintains the FLDB, which tracks the locations of all DCE LFS and non-LFS filesets.

fileset module

DFS: The part of the cache manager that maintains a list of accessed filesets, their mounted positions in the global file system tree, and their physical locations.

fileset name

DFS: A name that uniquely identifies each fileset. All versions of a fileset have the same name; the read-only and backup versions have .readonly and .backup extensions.

fileset quota

DFS: A disk space limit that a system administrator imposes on each read/write fileset.

fileset registry

DFS: The part of the file exporter that stores information about filesets residing on the local machine.

fileset server

DFS: A server process that runs on all file server machines. It provides the interface for system administrators to perform all tasks that treat a fileset as a unit, including creating, deleting, backing up, cloning, and moving.

filespace

DFS: The global file system made available to all cells in DCE by DFS. Every entry for a file or directory in DFS resides in the DFS filespace. See also Distributed File Service, DCE.

filter

An assertion about the presence or value of certain attributes of an entry in order to limit the scope of a search.

filter directives

Specifies the conditions that must be satisfied before audit records are written, and where to write these records: the audit trail file or the console.

filter rules

The prescribed procedure used to resolve overlapping directives from different filters.

filter subject

Denotes the principal, group, or cell to which the filter applies. The filter subject is the client of the distributed application program that caused the event to occur. A filter is always associated with one and only one filter subject.

first-level DSA

GDS: A DSA that holds the master entry of a first-level object. See also first-level object.

first-level object

GDS: A directory object that is an immediate subordinate to the root.

FL server

See fileset location server.

FLDB

See fileset location database.

flush

DFS: To force the cache manager to discard data from the local cache, so that the next time an application requests the data, the data must be fetched from the file exporter.

foreign cell

A cell other than the one to which the local machine belongs. See also local cell.

foreign cell surrogate

Principals (whose names are in the form krbtgt/ cell_name) that are maintained in the registry database for the purpose of intercell authentication. To accomplish intercell authentication, the foreign cell surrogates in each cell's registry share a secret key. This secret key is known to both the local and foreign cell's authentication service. It is through their surrogates that two instances of the authentication service are able to convey information about their respective principals to one another, thus enabling a principal from one cell to acquire a ticket to a principal in another cell. See also trust peer.

full dump

DFS: A dump set in the DFS backup system that includes all of the data from a fileset. A full dump is different from an incremental dump. See also dump, incremental dump.

full name

CDS: The complete specification of a CDS name, including all parent directories in the path from the cell root to the entry being named.

full pointer

RPC: A pointer without the restrictions of a reference pointer.

full restore

DFS: In the DFS backup system, a full restore returns a fileset to its state when last dumped. The resultant fileset includes data from the last full dump and all subsequent incremental dumps, if any. A full restore is different from a date-specific restore. See also date-specific restore, restore.

fully bound binding handle

RPC: A server binding handle that contains a complete server address including an endpoint. See also partially bound binding handle.

function

A programming language construct, modeled after the mathematical concept. A function encapsulates some behavior. It is given some arguments as input, performs some processing, and returns some results. Also known as procedures, subprograms or subroutines. See also operation.

GDA

See Global Directory Agent.

GDS

See DCE Global Directory Service.

generic interface

The interface, defined at a level that is independent of any particular programming language.

gigabyte (GB)

A unit of measurement for storage capacity equal to 1,073,741,824 (230) bytes.

Global Directory Agent (GDA)

A DCE component that makes it possible for the local CDS to access names in foreign cells. The GDA provides a connection to foreign cells through either GDS or DNS.

global name

A name that is universally meaningful and usable from anywhere in the DCE naming environment. The prefix /... indicates that a name is global.

global server

DTS: A server that frequently provides its clock value to courier servers on other LANs, or infrequently provides its clock value to systems that have failed to obtain the specified number of servers locally.

global set

DTS: The group of global servers in a network.

glue layer

DFS: The VFS+ functions that integrate the token and authentication requirements of the DCE environment with the standard VFS functions available to a file system.

group
  1. RPC: A name service entry that corresponds to one or more RPC servers that offer common RPC interface(s), RPC object(s), or both. A group contains the names of the server entries, other groups, or both that are members of the group. See also NSI group attribute.
  2. Security: Data that associates a named set of principals who can be granted common access rights. Also, the second field of a subject identifier.

group member

RPC: A name service entry whose name occurs in the group. See also group.

group name

A name that uniquely identifies a group of users to the system.

handle

RPC: An opaque reference to information. See also binding handle, context handle, interface handle, name service handle, thread handle.

high convergence

A setting that controls the degree to which CDS attempts to keep all replicas of a directory consistent. High convergence means CDS makes one attempt to immediately propagate an update to all replicas. If that attempt fails (for example, if one of the replicas is unavailable), the software schedules a skulk for within 1 hour. Under normal circumstances, a skulk occurs at least once every 12 hours on a directory with high convergence. High convergence is expensive, so constant use of it is not advisable. To control convergence, you modify a directory's CDS_Convergence attribute. See also low convergence, medium convergence.

home cell

See local cell.

host ID

See network address.

host module

DFS: The part of the file exporter that associates information with each cache manager's request. This information includes the state of the client that made the call and authentication information about the user who made the request.

idempotent semantics

RPC: A characteristic of a procedure in which executing it more than once with identical input always produces the same result, without any undesirable side effects; for example, a procedure that reads a particular block of an immutable file is idempotent. DCE RPC supports maybe and broadcast semantics as special forms of idempotent operations. See also at-most-once semantics, broadcast semantics, maybe semantics.

IDL

See Interface Definition Language.

IDL compiler, DCE

RPC: A compiler that processes an RPC interface definition and optional ACF to generate client and server stubs, header files, and auxiliary files. See also Interface Definition Language, stub.

illegal

A violation of an architecture rule that an implementation is required to report. See also unpredictable.

immediate delegation target

An object on which a client directly performed an operation.

immediate subclass

A subclass, of a class C, having no superclasses that are themselves subclasses of C.

immediate subobject

One object that is a value of an attribute of another.

immediate subordinate

In the DIT, an entry is an immediate subordinate of another if its DN is formed by appending its RDN to the DN of the other entry.

immediate superclass

The superclass, of a class C, having no subclasses that are themselves superclasses of C.

immediate superior

In the DIT, an entry is the immediate superior of another if its DN, followed by the RDN of the other, forms the DN of the other entry.

immediate superobject

One object that contains another among its attribute values.

impersonation

Transmission of a delegation initiator's identity in a manner than does not preserve the identities of participants in the call chain.

implicit binding method

RPC: The implicit method of managing the binding for a remote procedure call in which a global variable in the client application holds a binding handle that the client stub passes to the RPC runtime. See also automatic binding method, binding handle, explicit binding method.

import
  1. RPC: To obtain binding information from a name service database about a server that offers a given RPC interface by calling the RPC NSI import operation.
  2. RPC: To incorporate constant, type, and import declarations from one RPC interface definition into another RPC interface definition by means of the IDL import statement.

inaccessible

XOM: Said of an object for which the client does not possess a valid designator or handle.

inaccuracy

DTS: The bounded uncertainty of a clock value as compared to a standard reference.

incremental dump

DFS: A dump set in the DFS backup system that includes only data from a fileset that changed since the previous dump. An incremental dump is different from a full dump. See also dump, full dump.

index priority

Priority of an attribute type in search queries.

index window

A navigation aid in the CDS browser. When the namespace is in the display window, dragging the slider up and down the vertical scroll bar produces a rectangular box called the index window. The index window displays the name where the slider is currently positioned; releasing mouse button 1 causes the browser to position that name at the top of the window.

information architecture

GDS: Describes the representation of the information stored in OM objects and the hierarchical relationships between different classes of OM objects.

initial DSA

GDS: The master DSA of the directory schema.

initiator

The initial client in a delegation call chain.

instance

XOM: An object in the category represented by a class.

instance UUID

RPC: An object UUID that is associated with a single server instance and is provided to clients to unambiguously identify that instance. See also object UUID, server instance.

integrity

A protection level that can be specified in secure RPC communications that ensures that data transferred between two principals has not been modified in transit.

interface

See also API, RPC interface, SPI.

interface definition

RPC: A description of an RPC interface written in the DCE Interface Definition Language (IDL). See also RPC interface.

Interface Definition Language (IDL)

RPC: A high-level declarative language that provides the syntax for interface definitions. The file syntax of the IDL interface definition is part of the NCA. See also IDL compiler, DCE.

interface handle

RPC: A reference in code to an interface specification. See also interface specification.

interface identifier

RPC: A string containing the interface's UUID and major and minor version numbers of a given RPC interface. See also RPC interface.

interface specification

RPC: An opaque data structure, generated by the DCE IDL compiler from an interface definition, that contains identifying and descriptive information about an RPC interface. See also interface definition, interface handle, RPC interface.

interface UUID

RPC: The UUID generated for an RPC interface definition via the UUID generator, uuidgen. See also interface definition, RPC interface, Universal Unique Identifier (UUID).

intermediary

A server acting on behalf of an initiator, via delegation or impersonation, making requests to another target server.

intermediate data type

Any of the basic data types in terms of which the other, substantive data types of the interface are defined.

international character

A character that is not a member of the DCE PCS character set and so is not guaranteed to be supported in a DCE environment. Programmers writing RPC applications that use international characters build support for them into their applications by using user-provided or DCE RPC features for international character support.

interval

DTS: The combination of a time value and the inaccuracy associated with it; the range of values represented by a combined time and inaccuracy notation. As an example, the interval 08:00.00I00:05:00 (8 o'clock, plus or minus 5 minutes) contains the time 07:57.00.

invoke ID

An integer used to distinguish one (directory) operation from all other outstanding ones.

job ID number

DFS: A number assigned to each operation by the DFS backup system when the backup system is used in interactive mode. It is distinct from the dump ID number assigned to a dump set. See also dump ID number.

junction

A specialized entry in the DCE namespace containing binding information to enable communications between different implementations of the directory service.

Kerberos

The authentication protocol implemented by DCE shared-secret authentication. Kerberos was developed at the Massachusetts Institute of Technology. In classical mythology, Kerberos was the three-headed dog that guarded the entrance to the underworld.

key

A value used to encrypt and decrypt data. See also encryption key.

key management facility

A DCE security facility that enables noninteractive principals to manage their secret keys.

keytab file

A security file that contains the encryption keys for server processes (for example, DFS processes) that run on the host machine. Typically, encryption keys for human principals are not stored in a keytab file. See also encryption key.

kilobyte (KB)

A unit of measurement for storage capacity equal to 1024 (210) bytes.

knowledge reference

Knowledge that associates, either directly or indirectly, a DIT entry with the DSA in which it is located.

LAN

See local area network.

leaf entry

A directory entry that has no subordinates. It can be an alias entry or an object entry.

leap seconds

An infrequent adjustment to UTC to account for the irregularity of the earth's rotation.

Legacy DCE

Any version of DCE that does not make use of the DCE Security Registry and LDAP Integration feature.

LFS, DCE

See local file system, DCE.

little endian

An attribute of data representation that reflects how multioctet data is stored in memory. In little endian representation, the lowest addressed octet of a multioctet data item is the least significant. See also big endian.

load balancing

DFS: Distributing system load evenly across file server machines by placing frequently accessed DCE LFS filesets among available file server machines.

local application thread

RPC: An application thread that executes within the confines of one address space on a local system and passes control exclusively among local code segments. See also application thread, RPC thread, client application thread, server application thread.

local area network (LAN)

A set of computers sharing a network that does not include bridges or WAN links.

local audit trail file

The audit trail file that is specified by the user, using any convenient pathname. This is specified when the audit daemon is started. If the file name is not an absolute pathname, the file is created in the <dcelocal>/var/audit/adm directory.

local cell

The cell to which the local machine belongs. See also foreign cell.

local DSA

GDS: A DSA that is resident on the same computer as the DUA.

local file system, DCE (DCE LFS)

DFS: The high-performance, log-based file system provided by DCE. DCE LFS supports multiple filesets within a single aggregate, fileset replication, fast system restarts, and DCE ACLs.

local name

A name that is meaningful and usable only from within the cell where the entry exists. The local name is a shortened form of a global name. Local names begin with the prefix /.: (or the prefix /: for names in the DFS filespace) and do not contain a cell name.

local server

DTS: A server that synchronizes with its peers and provides its clock value to other servers and clerks on the same LAN.

local set

DTS: All of the servers in a particular LAN.

local type

RPC: A type named in a [represent_as] clause and used by application code to manipulate data that is passed in a remote procedure call as a network type. See also network type.

lock token

DFS: A token that allows a client to place a lock on a range of bytes in a file. Read and write lock tokens are available.

log

DFS: A record of the actions of a program or system and any changes to data associated with those actions. DCE LFS also maintains a log of changes to metadata on each LFS aggregate.

log-based file system

DFS: A file system in which changes to metadata are recorded in a log associated with the aggregate on which that file system is located. DCE LFS is a log-based file system. See also log.

login facility

A DCE security facility that enables a principal to establish its identity and assume other identities.

low convergence

A setting that controls the degree to which CDS attempts to keep all replicas of a directory consistent. Low convergence means CDS does not immediately propagate an update; it simply waits for the next skulk to distribute all updates that occurred since the last skulk. Skulks occur at least once every 24 hours on directories with low convergence. Low convergence helps conserve resources by avoiding update propagations between skulks. To control convergence, you set a directory's CDS_Convergence attribute. See also high convergence, medium convergence.

manager

RPC: A set of remote procedures that implement the operations of an RPC interface and that can be dedicated to a given type of object. See also object, RPC interface.

manager entry point vector (manager EPV)

RPC: The runtime code on the server side uses this EPV to dispatch incoming remote procedure calls. See also entry point vector, manager.

marshalling

RPC: The process by which a stub converts local arguments into network data and packages the network data for transmission. See also network data, unmarshalling.

mask
  1. With respect to DCE ACLs, a set of permissions that may be intersected (logically ANDed) with another set of permissions associated with a specified privilege attribute in order to yield the effective permissions for principals that possess that privilege attribute.
  2. To apply a mask.
  3. DFS: A pattern of bits or characters used to control the retention or elimination of portions of another pattern of bits or characters, usually through an AND or OR operation.
  4. GDS: Refers to the administration screen interface menus.

mask_obj mask

When supported by an ACL manager type, the mask_obj mask represents the greatest set of security: an optional alternate name for a primary name in the registry database. Aliases and the primary name for which they are an alternate share the same UUID and UNIX ID permissions granted to principals other than those that match the user_obj or other_obj.

master DSA

GDS: The DSA that contains the master entry of an object.

master entry

GDS: The original entry of an object. This is the entry in the DSA that is specified in the master knowledge attribute of the entry.

master information

GDS: The information from the master entries.

master knowledge attribute

GDS: An attribute that designates the master DSA of an entry.

master replica
  1. The first instance of a specific directory in the namespace. Once copies of the directory have been made, it is possible to designate a different replica as the master if necessary, but only one master replica of a directory can exist at a time. CDS can create, update, and delete object entries and soft links in a master replica.
  2. Security: An instance of a security server that accepts queries and updates to its associated registry database. The master replica dynamically propagates its updates to slave replicas. Each cell has only one master replica. See also slave replica.

maybe semantics

RPC: A form of idempotent semantics that indicates that the caller neither requires nor receives any response or fault indication for an operation, even though there is no guarantee that the operation completed. An operation with maybe semantics is implicitly idempotent and lacks output parameters. See also at-most-once semantics, broadcast semantics, idempotent semantics.

medium convergence

A setting that controls the degree to which CDS attempts to keep all replicas of a directory consistent. Medium convergence means CDS makes one attempt to immediately propagate an update to all replicas of the directory in which a change was just made. If the attempt fails, the software lets the next scheduled skulk take care of making the replicas consistent. Skulks occur at least once every 12 hours on a directory with medium convergence. When you create a namespace, the default setting on the root directory is medium. To control convergence, you set a directory's CDS_Convergence attribute. See also high convergence, low convergence.

megabyte (MB)

A unit of measurement for storage capacity equal to 1,048,576 (220) bytes.

metadata

The structural data associated with the file system, such as the organization of directories, inode tables, and links. Metadata is not data supplied by a user; it is information about the structure of user data.

minimally consistent

Said of an object that satisfies various conditions set forth in the definition of its class.

monitoring window

DFS: A separate terminal session dedicated to tracking the activities of a tape coordinator on a tape coordinator machine. A monitoring window must run on the same machine as the tape coordinator and tape drive it is monitoring.

mount point

DFS: An access point to a fileset in the DFS file tree. Once a fileset has been mounted, the resulting mount point looks and acts like a directory in the file tree.

mount-level directory

DFS: The top-level directory of a mounted fileset. It becomes transparently equivalent to the mount point for that fileset after the fileset is mounted. See also mount point.

multivalued attribute

A collection of attribute instances of the same attribute type attached to a single registry object.

mutex

A synchronization object that provides mutual exclusion among threads. A mutex is often used to ensure that shared variables are always seen by other threads in a consistent state.

name

GDS: A construct that singles out a particular directory object from all other objects. A name must be unambiguous (that is, denote just one object); however it need not be unique (that is, be the only name that unambiguously denotes the object).

name service handle

RPC: An opaque reference to the context used by the series of next operations called during a specific NSI search or inquiry.

Name Service Interface (NSI)

RPC: A part of the application programming interface of the RPC runtime. NSI routines access a name service, such as CDS, for RPC applications.

name-based authorization

Provides a server with the client's principal name. See also DCE authorization.

namespace

A complete set of CDS names (these can include directories, object entries, and soft links) that one or more CDS servers look up, manage, and share. CDS names are stored in directory replicas in clearinghouses at each server. The logical picture of a namespace is a hierarchical tree of all of those directories, with the root directory at the top, and one or more levels of directories beneath the root directory. The physical implementation of the namespace consists of directories replicated in one or more clearinghouses in the network.

naming attribute

An attribute used to form the RDN of an entry.

NCA

See Network Computing Architecture.

NDR

See Network Data Representation.

network address

RPC: An address that identifies a specific host on a network.

Network Computing Architecture (NCA)

RPC: An architecture for distributing software applications across heterogeneous collections of networks, computers, and programming environments. NCA specifies the DCE RPC architecture.

network data

RPC: Data represented in a format defined by a transfer syntax. See also transfer syntax.

Network Data Representation (NDR)

RPC: The transfer syntax defined by the NEA. See also transfer syntax.

network descriptor

RPC: The identifier of a potential network channel, such as a UNIX socket.

network protocol

A communications protocol from the Network Layer of the OSI network architecture, such as the IP.

Network Time Protocol (NTP)

Internet-recommended time standard.

network type

RPC: A type defined in an interface definition and referenced in a [represent_as] clause that is converted into a local type for manipulation by application code. See also local type.

NFS/DFS authenticating gateway

DFS: The NFS/DFS authenticating gateway provides authenticated access to DFS from NFS clients. Users who have DCE accounts can authenticate to DCE via a DFS client configured as a gateway server and access DFS data according to their DCE identities. Administrators can allow users to authenticate to DCE from NFS clients, or administrators can reserve the ability to grant authenticated access from a gateway server only.

node

A computer connected to a network.

nonspecific subordinate reference

A knowledge reference that holds information about the DSA that holds one or more unspecified subordinate entries.

NSI

See Name Service Interface.

NSI attribute

RPC: An RPC-defined attribute of a name service entry used by the DCE RPC name service interface. An NSI attribute stores one of the following: binding information, object UUIDs, a group, or a profile. See also NSI binding attribute, NSI group attribute, NSI object attribute, NSI profile attribute.

NSI binding attribute

RPC: An RPC-defined attribute (NSI attribute) of a name service entry; the binding attribute stores binding information for one or more interface identifiers offered by an RPC server and identifies the entry as an RPC server entry. See also binding information, NSI object attribute, server entry.

NSI group attribute

RPC: An RPC-defined attribute (NSI attribute) of a name service entry that stores the entry names of the members of an RPC group and identifies the entry as an RPC group. See also group.

NSI object attribute

RPC: An RPC-defined attribute (NSI attribute) of a name service entry that stores the object UUIDs of a set of RPC objects. See also object.

NSI profile attribute

RPC: An RPC-defined attribute (NSI attribute) of a name service entry that stores a collection of RPC profile elements and identifies the entry as an RPC profile. See also profile.

NTP

See Network Time Protocol.

NULL

The value of a pointer that indicates that the pointer does not point to data.

null binding handle

RPC: A binding handle containing the NULL value. See also binding handle.

object
  1. A data structure that implements some feature and has an associated set of operations.
  2. RPC: For RPC applications, an object can be anything that an RPC server defines and identifies to its clients (using an object UUID). Often, an RPC object is a physical computing resource such as a database, directory, device, or processor. Alternatively, an RPC object can be an abstraction that is meaningful to an application, such as a service or the location of a server. See also object UUID.
  3. XDS: Anything in some ``world,'' generally the world of telecommunications and information processing or some part thereof, that is identifiable (can be named) and for which the DIB contains some information.
  4. XOM: Any of the complex information objects created, examined, modified, or destroyed by means of the interface.
  5. DFS: A file or directory in a file system. Directories can be further classified as container objects.

object class

CDS, GDS: An identified family of objects that share certain characteristics. An object class can be specific to one application or shared among a group of applications. An application interprets and uses an entry's class-specific attributes based on the class of the object that the entry describes.

Object Class Table (OCT)

A recurring attribute of the directory schema with the description of the object classes permitted.

object entry

CDS: The name of a resource (such as a node, disk, or application) and its associated attributes, as stored by CDS. CDS managers, client application users, or the client applications themselves can give a resource an object name. CDS supplies some attribute information (such as a creation timestamp) to become part of the object, and the client application can supply more information for CDS to store as other attributes. See also entry.

object identifier

A value (distinguishable from all other such values) that is associated with an information object. (X.208)

object management

The creation, examination, modification, and deletion of potentially complex information objects.

object name

A CDS name for a network resource.

object UUID

RPC: The universal unique identifier that identifies a particular RPC object. A server specifies a distinct object UUID for each of its RPC objects; to access a particular RPC object, a client uses the object UUID to find the server that offers the object. See also object, Universal Unique Identifier.

OCT

See Object Class Table.

octet

An 8-bit quantity of data.

OM

See XOM.

OM attribute

An OM attribute comprises one or more values of a particular type (and therefore syntax).

OM class

A static grouping of OM objects, within a specification, based on both their semantics and their form.

opaque

A piece of data or a data type whose contents are not visible to the application routines that use it.

opaque structure

A data item or data type whose structure is hidden from the code that is handling it.

Open Systems Interconnection (OSI)

The interconnection of open systems in accordance with ISO standards.

open token

DFS: A token that grants the right to open a file. The types of tokens available are as follows: normal reading, normal writing, executing, shared reading, and exclusive writing. See also token.

operation
  1. A set of step-by-step actions specified by a procedure, function, or routine.
  2. RPC: The task performed by a given routine or procedure.
  3. GDS: Processing performed within the directory to provide a service, such as a read operation. It is given some arguments as input, performs some processing, and returns some results. An application process invokes an operation by calling an interface function.

organization

Data that associates a named set of users who can be granted common access rights that are usually associated with administrative policy. Also, the third field of a subject identifier.

orphaned call

RPC: A call executing in an RPC server after the client that started the call fails or loses communications with the server.

OSI

See Open Systems Interconnection.

PAC

See privilege attribute certificate.

package

A specified group of related OM classes, denoted by an object identifier.

package closure

The set of classes that need to be supported in order to be able to create all possible instances of all classes defined in the package.

PAG

See process activation group.

group name

A binding in which the first parameter is a handle parameter that determines the location of a server of the interface.

parent directory

Any directory that has one or more levels of directories beneath it in a cell namespace. A directory is the parent of any directory immediately beneath it in the hierarchy.

parent dump level

DFS: An entry in the dump hierarchy that is used as the reference point for dumps made at an incremental dump level. Both a full dump level and another incremental dump level can serve as a parent. See also dump, dump hierarchy, full dump, incremental dump.

parent ID number

DFS: A fileset ID number stored in a fileset header. If the fileset being examined is a read/write fileset, the parent ID is its fileset ID. If the fileset being examined is a read-only or backup copy of a read/write fileset, the parent ID is the fileset ID of the read/write fileset. See also fileset ID number.

password

A string presented by a principal to prove its identity. The login facility transforms this string to generate an encryption key that is used by the authentication service to authenticate the principal. Server principals usually bypass the string-to-key transformation and present an encryption key to the authentication service for authentication. See also encryption key.

PCS

See Portable Character Set.

peer trust

A type of trust relationship established between two cells by means of a secret key shared by mutual authentication surrogates maintained by the two cells. A peer trust relationship enables principals in the one cell to communicate securely with principals in the other.

permission
  1. The modes of access to a protected object. In DCE security, the number and meaning of permissions with respect to the object are defined by the ACL manager of the object. See also access control list.
  2. GDS: One of five groups that assigns modes of access to users: MODIFY PUBLIC, READ STANDARD, MODIFY STANDARD, READ SENSITIVE, or MODIFY SENSITIVE. See also access control list.

person

The name assigned to a DCE principal. The registry database contains the person objects with which accounts can be associated. Also, the first field of a subject identifier.

pickle

An encoding of a typed value in a byte stream. Pickles are useful for storing or transmitting typed values in typeless media. The type of value contained in a pickle may be understood from context or represented in the pickle itself.

pipe
  1. RPC: A mechanism for passing large amounts of data in a remote procedure call.
  2. RPC: The data structure that represents this mechanism.

PKSS

See private key storage server.

plaintext

The input to an encryption function or the output of a decryption function. Decryption transforms ciphertext into plaintext.

Portable Character Set (PCS)

The DCE PCS is the group of characters for which DCE guarantees support. The DCE RPC runtime requires that all DCE RPC clients and servers support the DCE PCS. The IDL base type specifiers char and idl_char identify DCE PCS characters.

position (within a string)

The ordinal position of one element of a string relative to another.

position (within an attribute)

The ordinal position of one value relative to another.

potential binding

RPC: A specific combination of an RPC protocol sequence, RPC protocol major version, network address, endpoint, and transfer syntax that an RPC client can use to establish a binding with an RPC server. See also binding, endpoint, network address, RPC protocol sequence, RPC protocol, transfer syntax.

predicate
  1. A Boolean logic term denoting a logical expression that determines the state of some variable(s). For example, a predicate can be an expression stating that "variable A must have the value 3." The control expression used in conjunction with condition variables is based upon a predicate. Use a condition variable to wait for some predicate to become true; for example, to wait for something to be in a queue.
  2. Audit Service: The criteria used to select audit records in an audit trail file. This is used in creating audit trail analysis and examination programs that read a select number of records from the audit trail file.

presentation address

An unambiguous name that is used to identify a set of presentation service access points. Loosely, it is the network address of an OSI service. See also address.

Presentation Service Access Point (PSAP)

Address of an OSI communications partner. It addresses an application in a computer.

presented type

RPC: For data types with the IDL transmit_as attribute, the data type that clients and servers manipulate. Stubs invoke conversion routines to convert the presented type to a transmitted type, which is passed over the network. See also transmitted type.

primary alias

The default name for a cell that has multiple cell aliases. This is the name of the cell that the system will return when asked. See also alias.

primary name

The string name of an object to which any aliases for that object refer. DCE refers to objects by their primary names, although DCE users can refer to them by their aliases.

primary representation

The form in which the service supplies an attribute value to the client.

primitive binding handle

RPC: A binding handle whose data type in IDL is handle_t and in application code is rpc_binding_handle_t. See also customized binding handle.

principal

An entity that is capable of believing that it can communicate securely with another entity. In DCE, principals are represented as entries in the registry database and include users, servers, computers, and authentication surrogates.

principal identifier

The name used to identify a principal uniquely. In DCE, principal identifiers are implemented as UUIDs.

privacy

A protection level that may be specified in secure RPC communications and that encrypts RPC argument values.

private key

The key needed by a principal in public key authentication. It is half of the key pair used in public key authentication. The other half is the public key. This method of public and private key pair usage constitutes the public key protocol.

private key storage server

A server that stores private keys in such a way that only their true owners can retrieve them.

private object
  1. XDS: An OM object created in a workspace by using the object management functions. The term is simply used for contrast with a public object.
  2. XOM: An object that is represented in an unspecified fashion.

privilege attribute

An attribute of a principal that can be associated with a set of permissions. DCE privilege attributes are identity based and include the principal's name, group memberships, and native cell.

privilege attribute certificate (PAC)

Data, describing a principal's privilege attributes, that has been certified by an authority. In DCE, the privilege service is the certifying authority and seals the privilege attribute data in a ticket. The authorization protocol, DCE authorization, determines the permissions granted to principals by comparing the privilege attributes in PACs with entries in an ACL.

privilege required

DFS: The administrative privilege required to issue a DFS command that affects filesets or DFS server processes. Administrative privilege for a DFS server process is granted to a user who is listed in the administrative list for that server process. See also administrative list.

privilege service

One of the services provided by DCE security; the privilege service certifies a principal's privileges.

procedure declaration

RPC: The syntax for an operation, including its name, the data type of the value it returns (if any), and the number, order, and data types of its parameters (if any).

process activation group (PAG)

DFS: A unique identifier that the DFS cache manager associates with a user's DCE credentials. The cache manager identifies the user's credentials by the associated PAG to allow the user authenticated access to DFS. Processes forked from the user's login process inherit the PAG to allow for authenticated access to DFS. The cache manager stores the PAG in the kernel of the DFS client.

process entry

DFS: A definition in the BosConfig file that determines a server process to run, the process's type, and any command parameters used by the process.

profile

RPC: An entry in a name service database that contains a collection of elements from which NSI search operations construct search paths for the database. Each search path is composed of one or more elements that refer to name service entries corresponding to a given RPC interface and, optionally, a given object. See also NSI profile attribute, profile element.

profile element

RPC: A record in an RPC profile that maps an RPC interface identifier to a profile member (a server entry, group, or profile in a name service database). See also group, interface identifier, profile, server entry.

profile member

RPC: A name service entry whose name occupies the member field of an element of the profile. See also profile.

project list

A list of all the groups in which a principal is a member. The project list is used to determine the principal's access rights to objects. See also principal.

protection level

The degree to which secure network communications are protected.

protocol sequence

See RPC protocol sequence.

protocol sequence vector

RPC: A data structure that contains an array-size count and an array of pointers to RPC protocol-sequence strings. See also RPC protocol sequence.

PSAP

See Presentation Service Access Point.

public key

An authentication protocol that works via public and private key pairs. The protocol is used by security clients and servers to obtain TGTs for users during login, and which is the first part of user-authentication process. This method of public and private key pair usage constitutes the public key protocol.

public object
  1. XOM: An object that is represented by a data structure whose format is part of the service's specification.
  2. XDS: A descriptor list that contains all of the OM attributes of an OM object.

purported name

A construct that is syntactically a name but that has not yet been shown to be a valid name.

RDN

See Relative Distinguished Name.

read access

An access right that grants the ability to view CDS data.

read-only fileset

DFS: A fileset created by replicating a read/write fileset. A read-only fileset is also referred to as a read-only replica or a read-only version See also backup fileset, read/write fileset.

read-only replica

A copy of a CDS directory in which applications cannot make changes. Although applications can look up information (read) from it, they cannot create, modify, or delete entries in a read-only replica. Read-only replicas become consistent with other, modifiable replicas of the same directory during skulks and routine propagation of updates.

read/write fileset

DFS: The single version of a fileset that houses the modifiable versions of files and directories. The read/write fileset is the original version for which an FLDB entry is allocated. It serves as the source fileset for its associated read-only and backup filesets. It is also referred to as the read/write source or read/write version. See also backup fileset, read-only fileset.

read/write mount point

DFS: A type of mount point that instructs the cache manager to access only the exact fileset specified in the mount point, not its read-only version. See also mount point, regular mount point.

realm

A cell, considered exclusively from the point of view of security; this term is used in Kerberos specifications. In DCE documentation, the term ``cell'' designates the basic unit of DCE configuration and administration, and incorporates the notion of a realm.

recurring attribute

An attribute with several attribute values.

redirection

The act of changing the standard use of input and output to a user-specific method. For example, standard output can be redirected to a file.

reentrant service

A service that is safe to call from multiple threads in parallel. If a service is reentrant, there is no burden placed on calling routines to serialize their access or take other explicit precautions. See also thread-serial service, thread-synchronous service.

reference monitor

Code that controls access to an object. In DCE, servers control access to the objects they maintain; and for a given object, the ACL manager associated with that object makes authorization decisions concerning the object.

reference pointer

RPC: A non-null pointer whose value is invariant during a remote procedure call and cannot point at aliased storage.

referral

An outcome that can be returned by a DSA that cannot perform an operation itself. The referral identifies one or more other DSAs more able to perform the operation.

register
  1. RPC: To list an RPC interface with the RPC runtime.
  2. RPC: To place server-addressing information into the endpoint map.
  3. RPC: To insert authorization and authentication information into binding information. See also endpoint map, RPC interface.

registry database

A database of information about persons, groups, organizations, and accounts.

registry object

A data node in the registry database. Registry objects are of the following object types: principal, group, org, directory, policy, replist (replica list), and xattrschema. There are many nodes of the principal, group, org and directory types. There is only one node each for the policy, replist and xattrschema types.

registry replica

A read-only instance of a registry database.

registry service

One of three services provided by DCE security; the registry service manages account information for principals. The other services are the privilege service and the authentication service.

regular mount point

DFS: The most common type of mount point. If the fileset it names is a read/write fileset, the cache manager is free to access a read-only version of the fileset (if one exists). See also mount point, read/write mount point.

Relative Distinguished Name (RDN)

A set of Attribute Value Assertions (AVAs), each of which is true, concerning the distinguished values of a particular entry.

relative time

A discrete time interval that is usually added to or subtracted from an absolute time.

release replication

DFS: A method of updating read-only copies of filesets. Release replication is not automatic like scheduled replication; each update must be initiated by an administrator. See also replication, scheduled replication.

remote procedure

RPC: An application procedure located in a separate address space from the calling code. See also remote procedure call.

remote procedure call (RPC)

RPC: A procedure call executed by an application procedure located in a separate address space from the calling code. See also remote procedure.

replica
  1. CDS: a copy of a directory in the CDS namespace. The first instance of a directory in the namespace is the master replica. When CDS managers make copies of the master replica to store in other clearinghouses, all of the copies, including the master replica, become part of the directory's replica set. See also read-only replica.
  2. DFS: A read-only copy of a fileset that contains all the data of the source fileset. As a full copy of a fileset, a replica can exist on any aggregate. A replica is different from a clone, which can reside only on the same aggregate as the source fileset. See also clone.
  3. Security: An instance of the security server and its database. One replica, the master replica, can accept updates and queries to its database. The slave replica can accept only queries.

replica set

The set of all copies of a CDS directory. Information about a directory's replica set is contained in an attribute of directories and child pointers called CDS_Replicas. The attribute contains the type of each replica (master or read-only) and the clearinghouse where it is located. When skulking a directory, CDS refers to the directory's replica set to ensure that it finds all copies of that directory. During a lookup, CDS can refer to the replica set in a child pointer when trying to locate a directory that does not exist in the local clearinghouse.

replication
  1. CDS: Making a copy of a CDS directory in another clearinghouse. Replication can improve availability and load sharing. See also replica.
  2. GDS: The process by which copies of objects are created and maintained.
  3. DFS: The process of creating read-only copies of a fileset. In DFS, there are two types of replication: release replication and scheduled replication. Replication is supported only for DCE LFS filesets. See also release replication, scheduled replication.

replication server

DFS: A server process used in release replication and scheduled replication. The replication server tracks the currency of read-only replicas of filesets. It updates each replica to match its read/write source fileset as appropriate. See also replication.

request buffer

RPC: A first-in, first-out queue where an RPC system temporarily stores call requests that arrive at an endpoint of an RPC server, until the server can process them.

restore

DFS: The translation of a previously dumped fileset back into fileset format and its eventual replacement in the file system. The DFS Backup System allows several different types of restores, including full restores and date-specific restores. The operation need not involve recovery from other media such as tapes. See also date-specific restore, dump, full restore.

return value

A function result that is returned in addition to the values of any output or input/output arguments.

RPC

See also remote procedure call, DCE remote procedure call.

RPC control program

RPC: An interactive management facility for managing name service entries and endpoint maps for RPC applications. The program is started by the rpccp command.

RPC interface

RPC: A logical grouping of operation, data type, and constant declarations that serves as a network contract for calling a set of remote procedures. See also interface definition.

RPC protocol

RPC: An RPC-specific communications protocol that supports the semantics of the DCE RPC API and runs over either connectionless or connection-oriented communications protocols.

RPC protocol sequence

RPC: A valid combination of communications protocols represented by a character string. Each protocol sequence typically includes three protocols: a network protocol, a transport protocol, and an RPC protocol that works with those network and transport protocols. See also network protocol, RPC protocol, transport protocol.

RPC runtime

RPC: A set of operations that manages communications, provides access to the name service database, and performs other tasks, such as managing servers and accessing security information, for RPC applications. See also RPC runtime library.

RPC runtime library

RPC: Routines of the RPC runtime that support the RPC applications on a system. The runtime library provides a public interface to application programmers, the application programming interface (API), and a private interface to stubs, the stub programming interface (SPI). See also RPC runtime.

RPC thread

RPC: A logical thread within which a remote procedure call executes. See also thread.

rundown procedure

RPC: A procedure, typically used with a context handle, that is called following a communications failure to recover resources reserved by a server for servicing requests by a particular client. See also context handle.

S-stub

The part of the DSA that establishes the connection to the communications network.

salvager

DFS: A program that finds and attempts to repair inconsistencies in DCE LFS aggregates. The salvager is similar to the fsck program in other, non-LFS file systems.

scheduled replication

DFS: A method of updating read-only copies of filesets. Scheduled replication is automatically performed by the replication server at specified intervals. See also release replication, replication.

schema

The directory schema is the set of rules and constraints concerning the DIT structure, object class definitions, attribute types, and syntaxes that characterize the DIB. See also attribute schema.

schema entry

A record containing the identifiers and characteristics of an attribute type. A schema entry is essentially an attribute type definition.

schema object

The registry data node, with the well-known name xattrschema (under the security junction point, typically /.:/sec), containing the attribute schema information. (Also called attribute schema object.)

scout

DFS: A program that can be run on any machine configured as a DFS client. It monitors the file exporter running on designated file server machines by periodically collecting statistics and displaying them in a graphical format. See also attention threshold, basename, disk usage.

seal

To encrypt a record containing several fields in such a way that the fields cannot be modified without either knowledge of the encryption key or leaving evidence of tampering.

secondary representation

A second form, an alternative to the primary representation, in which the client can supply an attribute value to the service.

secondary site

DFS: A read-only site that receives updates to its copy of a DFS administrative database from the Ubik synchronization site. There can be more than one secondary site. If necessary, a secondary site can be elected to assume the role of synchronization site. See also synchronization site, Ubik.

secret key

A long-lived encryption key known to more than one principal, usually two. In DCE, each secret key is known to the Authentication Service and one other principal.

security

See DCE Security Service.

segment

Zero or more contiguous elements of a string.

self-pointing type

RPC: A data type containing a pointer member that can point directly or indirectly to another item of the same type.

SEP line

In an event class file, an entry that specifies the prefixes of the event numbers in the file. This is an optional entry and is used to speed up the search for events in event class files.

server
  1. RPC: The party that receives remote procedure calls. A given application can act as both an RPC server and an RPC client. See also client.
  2. CDS: A node running CDS server software. A CDS server handles name-lookup requests and maintains the contents of the clearinghouse or clearinghouses at its node.
  3. DTS: A system or process that synchronizes with its peers and provides its clock value to clerks and their client applications.
  4. DFS: A provider of resources or services. See also client.
  5. GDS: The server consists of a DSA, which accesses the database, and an S-stub, which handles the connection over the communications network for responding to remote clients and accessing remote servers.

server addressing information

RPC: An RPC protocol sequence, network address, and endpoint that represent one way to access an RPC server over a network; a part of server binding information. See also binding information, endpoint, network address, RPC protocol sequence.

server application thread

RPC: A thread executing the server application code that initializes the server and listens for incoming calls. See also application thread, client application thread, local application thread, RPC thread.

server binding information

RPC: Binding information for a particular RPC server. See also binding information, client binding information.

server entry
  1. RPC: A name service entry that stores the binding information associated with the RPC interfaces of a particular RPC server and also the object UUIDs for any objects offered by the server. See also binding information, NSI binding attribute, object, NSI object attribute, RPC interface.
  2. DFS: A unique identifier for a server machine in the FLDB.

server instance

RPC: A server executing in a specific address space; multiple server instances can coexist on a single system. See also server.

server machine

DFS: A machine that runs one or more DFS server processes. Depending on the process it runs, a server machine can be further classified as a file server machine, a system control machine, a binary distribution machine, a fileset database machine, or a backup database machine. See also client machine.

server module

DFS: The part of the DFS cache manager that provides information for tracking server activity.

server portion of update server

See upserver.

server process

DFS: A process that runs on server machines, providing services such as storing and transferring files or tracking fileset locations to clients. See also server machine.

server stub

RPC: The surrogate calling code for an RPC interface that is linked with server application code containing one or more sets of remote procedures (managers) that implement the interface. See also client stub, manager, stub.

service

RPC: An integral set of RPC interfaces offered together by a server to meet a specific goal. See also RPC interface.

service controls

A group of parameters, applied to all directory operations, that direct or constrain the provision of the service.

session

A sequence of directory operations requested by a particular user of a particular DUA. The operations use the same session OM object.

session key

Used in Kerberos specifications; acronym for ``conversation key.'' See also conversation key.

set-id

In event numbers, the component of the event number that identifies a set of events to which the audit event belongs. In event class numbers, the component of the event class number that identifies a set of event classes to which the event class belongs.

shadow entry

A copy entry of an object. This is an entry of an object in a DSA other than the master DSA.

signal

Threads: To wake only one thread waiting on a condition variable. See also broadcast.

signed

Information is digitally signed by appending to it an enciphered summary of the information. This is used to ensure the integrity of the data, the authenticity of the originator, and the unambiguous relationship between the originator and the data.

simple bnode

DFS: A bnode that manages a single process that is to be kept running at all times. See also bnode, basic overseer server.

simple name

One element in a CDS full name. Simple names are separated by / (slashes).

simple object

An object that does not hold other objects. For example, a file is a simple object. See also container object.

simple process

DFS: A type of process defined in a server machine's BosConfig file. It runs continuously and can be stopped and restarted independently of any other process on its machine. See also cron process, simple bnode.

site

DFS: The location of a fileset expressed as a specific file server machine and aggregate.

site count

DFS: A count of the number of sites where the read/write and read-only versions of a fileset reside.

site flags

DFS: A term for the flags associated with each site definition in an FLDB entry. The flags can indicate the fileset type (read/write or read-only) and other administrative information.

skew

The time difference between two clocks or clock values.

skulk

A process by which CDS makes the data consistent in all replicas of a particular directory. CDS collects all changes made to the master replica since the last skulk completed, and disseminates the changes from the up-to-date replica to all other existing replicas of the directory. All replicas of a directory must be available for a skulk to be considered successful. If a skulk fails, CDS informs you of the replicas that it could not reach.

slave replica

An instance of a security server that accepts only queries to its associated registry database. Slave replicas are updated by the master replica. Each cell can have many slave replicas. See also master replica.

soft link

A pointer that provides an alternate name for an object entry, directory, or other soft link in the namespace. A soft link can be permanent or it can expire after a period of time that you specify. The CDS server also can delete it automatically after the name that the link points to is deleted.

source fileset

See read/write fileset.

specific

The attribute types that can appear in an instance of a given class, but not in an instance of its superclasses.

SPI

See stub programming interface.

SRT

See Structure Rule Table.

status flag

DFS: In a BosConfig file, the flag that tells the BOS server whether a server process should be running. In an FLDB entry, the flag that indicates whether a fileset of each possible type (read/write, read-only, and backup) actually exists at a site. In a fileset header, a flag that indicates whether the contents of the fileset are accessible via the file server machine.

status token

DFS: A token that grants access to the status information associated with a file or directory. Read and write status tokens are available.

string

An ordered sequence of bits, octets, or characters, accompanied by the string's length.

Structure Rule Table (SRT)

A recurring attribute of the directory schema with the description of the permitted structures of distinguished names.

stub

RPC: A code module specific to an RPC interface that is generated by the DCE IDL compiler to support remote procedure calls for the interface. RPC stubs are linked with client and server application and hide the intricacies of remote procedure calls from the application code. See also client stub, server stub.

stub programming interface (SPI)

A private RPC runtime interface whose routines are unavailable to application code.

subclass

One of the classes, designated as such, whose attribute types are a superset of those of another class.

subobject

An object that is in a subordinate relationship to a given object.

subordinate

In the DIT, an entry is subordinate to another if its distinguished name includes that of the other as a prefix.

superclass

One of the classes, designated as such, whose attribute types are a subset of those of another class.

superior

In the DIT, an entry is superior to another if its distinguished name is included as a prefix of the distinguished name of the other. Each entry has exactly one immediate superior.

superobject

An object that is in a superior relationship to a given object.

synchronization

DTS: The process by which a DTS entity requests clock values from other systems, computes a new time from the values, and adjusts its system clock to the new time.

synchronization list

DTS: The list of servers that a DTS entity has discovered; the entity sends requests for clock values to the servers on the list.

synchronization site

DFS: The one Ubik site that accepts changes to its copy of a DFS administrative database and distributes them to the secondary sites. The synchronization site can change as necessary. See also secondary site, Ubik.

syntax

XOM: (1) An OM syntax is any of various categories into which the object management specification statically groups values on the basis of their form. These categories are additional to the OM type of the value. (2) A category into which an attribute value is placed on the basis of its form. See also attribute syntax.

syntax template

A lexical construct containing an asterisk from which several attribute syntaxes can be derived by substituting text for the asterisk.

system control machine

DFS: The machine that distributes common configuration files to other server machines in the cell or administrative domain. The system control machine runs the server portion of the update server for this purpose. See also server machine, update server, upserver.

system time

The time value that the operating system maintains according to its reading of the system's hardware clock.

tape coordinator

DFS: A process that runs on a tape coordinator machine and controls the behavior of one tape drive. There must be one tape coordinator running for each tape drive in use.

tape coordinator ID (TCID)

DFS: A number, assigned when a tape coordinator machine is configured, that uniquely identifies each tape coordinator and the associated tape drive. Backup operators use it to specify the tape coordinator that is to execute a command.

tape coordinator machine

DFS: A client machine on which backup and restore operations are performed with the DFS backup system. Each tape coordinator machine must have one tape drive attached and must run one instance of the butc process for each drive.

target restrictions

Restrictions on the targets to whom a client's delegated identity can be projected.

TCID

See tape coordinator ID.

TCP

See Transmission Control Protocol.

TDF

See Time Differential Factor.

thread

A single sequential flow of control within a process.

thread handle

RPC: A data item that enables threads to share a memory management environment.

thread-serial service

A reentrant system service is thread-serial if it blocks the current thread and all other threads that attempt to call the same service or other related services until the first call returns.

thread-synchronous service

A reentrant system service is thread-synchronous if it blocks only the current thread and allows other threads to execute the same operation during the block.

tick

DTS: The clock timer interrupt that causes the operating system to increment the system time.

ticket

An application-transparent mechanism that transmits the identity of an initiating principal to its target. A simple ticket contains the principal's identity, a session key, a timestamp, and other information, sealed using the target's secret key. A privilege ticket contains the same information as a simple ticket, and also includes a privilege attribute certificate. A ticket-granting ticket is ticket to the ticket-granting service; a service ticket is a ticket for a specified service other than the ticket-granting service.

Time Differential Factor (TDF)

DTS: The difference between UTC and the time in a particular time zone.

time-provider

DTS: A hardware device that monitors UTC time and forwards it to a DTS server.

Time-Provider Interface (TPI)

A software intermediary between the DTS server and external time-provider processes. The DTS server uses the interface to obtain UTC time values and to determine the associated inaccuracy of each value.

time-provider program

DTS: Software that enables a time-provider device to call the time-provider interface and supply time values to a DTS server.

timeslicing

A mechanism by which running threads are preempted at fixed intervals. This ensures that every thread is allowed time to execute.

token

DFS: A device sent along with requested data from a file server machine to a client machine to indicate the types of operations (for example, read or write) the client can perform on the data. It prevents simultaneous access while permitting cooperative access; for example, only one client can possess a write token for a single piece of data at any given time. A client must have the appropriate tokens to operate on a file exporter. See also data token.

token management layer

DFS: The part of the DFS cache manager that handles file and directory tokens. See also token manager.

token manager

DFS: A component that maintains the set of file and directory tokens that have been granted to existing clients of a file server machine. See also token management layer.

top-level pointer

RPC: A pointer parameter that, in a chain of pointers, is the only member that is not the referent of any other pointer.

tower

Physical address and protocol information for a particular server. CDS uses this information to locate the system on which a server resides and to determine which protocols are available at the server. Tower values are contained in the CDS_Towers attribute associated with the object entry that represents the server in the cell namespace.

TP server

DTS: A server system connected to a time-provider.

TPI

See Time-Provider Interface.

traced delegation

Transmission of a delegation initiator's identity in a manner that preserves the identities of each participant in a call chain.

transaction

A related set or unit of changes to metadata. The events in a transaction are atomic. No change takes effect unless all the changes that make up that transaction are performed. See also log.

transfer syntax

RPC: A set of encoding rules used for transmitting data over a network and for converting application data to and from different local data representations. See also Network Data Representation.

transmissible

Able to send a data type over the network by way of an RPC operation.

Transmission Control Protocol (TCP)

A protocol of the Internet Protocol (IP) family.

transmitted type

RPC: For data types with the IDL transmit_as attribute, the data type that stubs pass over the network. Stubs invoke conversion routines to convert the transmitted type to a presented type, which is manipulated by clients and servers. See also presented type.

transparent access

DFS: A feature that allows users to access files without needing to know which machine stores the files. The FLDB keeps track of fileset locations, so the user needs to know only a file's pathname. See also fileset location database.

transport independence

RPC: The capability, without changing application code, to use any transport protocol that both the client and server systems support, while guaranteeing the same call semantics. See also transport layer, transport protocol.

transport layer

A network service that provides end-to-end communications between two parties, while hiding the details of the communications network. The TCP and ISO TP4 transport protocols provide full-duplex virtual circuits on which delivery is reliable, error free, sequenced, and duplicate free. UDP provides no guarantees (the connectionless RPC protocol provides some guarantees on top of UDP).

transport protocol

A communications protocol from the transport layer of the OSI network architecture, such as the TCP or the UDP.

trigger

A remote operation, associated with an attribute type, that is executed when attributes of that type are either queried or updated.

trigger type

A classification, either query or update, on a trigger that identifies on which attribute operation the trigger will be invoked.

trust path

See authentication path.

trust peer

A characterization of one cell with respect to another with which the cell maintains a mutual authentication surrogate.

type

XOM: A category into which attribute values are placed on the basis of their purpose. See also attribute type.

type UUID

RPC: The universal unique identifier that identifies a particular type of object and an associated manager. See also manager, object, Universal Unique Identifier.

Ubik

DFS: A library of utilities that the DFS FL server and the DFS backup server use to keep individual copies of the FLDB and the backup database. See also secondary site, synchronization site.

UFS

See UNIX File System.

unauthenticated mask

The maximum set of permissions granted when access to the object is not authenticated. Unauthenticated access is granted only if the caller matches some ACL entry (frequently the any_other entry) and if the required permission is granted by both the entry and the mask.

unconfigure

To remove configuration data.

unexport

RPC: To remove binding information from a server entry in a name service database. See also export.

uniquifier

DFS: A piece of data that, in combination with a fileset ID, produces a globally unique identifier.

Universal Unique Identifier (UUID)

RPC: An identifier that is immutable and unique across time and space. A UUID can uniquely identify an entity such as an RPC interface or object. See also interface UUID, object UUID, type UUID.

UNIX File System (UFS)

A section of the UNIX file tree that is physically contained on a single device or disk partition and that can be separately mounted, dismounted, and administered.

unmarshalling

RPC: The process by which a stub disassembles incoming network data and converts it into local data in the appropriate local data representation. See also marshalling, network data.

unpickle

A decoding of a typed value in a byte stream.See also pickle.

unpredictable

A violation of an architecture rule that an implementation is not required to report. Results can include an error report from a threads call, the operating system, or the hardware; a hang or deadlock of the program; or an incorrect operation of the program without indication of error.

unreachable

At your current location in the network, you cannot get to your destination. For example, the network address may be in use or a physical network connection may not exist or be operational.

upclient

DFS: A process that runs on DFS server machines, taking copies of common configuration files and new DFS server process binary files from central sources. See also update server, upserver.

update propagation

An immediate attempt to apply a change to all replicas of the CDS directory in which the change was just made. An update propagation delivers changes in a more efficient and timely way than a skulk, which is the periodic distribution of a whole collection of changes.

update server

DFS: A process that guarantees that all DFS server machines in a cell have the same versions of common configuration files and the same versions of DFS binary files appropriate for their machine types. It has a server portion called the upserver and a client portion called the upclient. See also upclient, upserver.

Update Timestamp (UTS)

An attribute that identifies the time at which the most recent change was made to any attribute of a particular CDS name. For directories, the UTS reflects changes made only to attributes that apply to the directory as a whole (not one of its replicas).

upserver

DFS: A process that runs on DFS server machines, making local copies of common configuration files and new DFS server process binary files available to other DFS server machines. See also upclient, update server.

user

GDS: The end user of the directory; the entity or person that accesses the directory. A user can be an application program that is calling the directory interface on behalf of a human user.

user data

DFS: Data such as ASCII and binary files that resides in a fileset. The data is manipulated and accessed by users of the file system.

User Datagram Protocol (UDP)

A protocol of the Internet Protocol (IP) family.

user-to-user

A protocol used in the ticket-granting process of security authentication of an application.

UTC

See Coordinated Universal Time.

UTS

See Update Timestamp.

UUID

See Universal Unique Identifier.

V file

DFS: With disk caches, a file on the disk that, by default, can hold up to 64 kilobytes of cached data. A maximum of 32,000 V files can be used for one disk cache.

value

XOM: An arbitrarily complex information item that can be viewed as a characteristic or property of an object. See also attribute value.

varying array

RPC: An array whose elements do not all need to be transmitted during a remote procedure call.

vector

RPC: An array of other structures and the number of array items.

VFS

See Virtual File System.

VFS+

DFS: Extensions to the standard UNIX Virtual File System (VFS). See also Virtual File System.

Virtual File System (VFS)

DFS: A level of abstraction above the specific interfaces to various types of file systems. It is used to avoid having to change kernel code to handle low-level, system-specific differences.

vnode

DFS: The structure used to access the inode or anode structure associated with a specific file through a virtual file system interface. The term vnode stands for virtual node. See also anode.

WAN

See wide area network.

WAN links

Communications connections between groups of computers that are spread across a large geographical distance. Modem connections, T1 lines, and satellite hookups are some common examples. See also wide area network.

well-known endpoint

RPC: A preassigned, stable endpoint that a server can use every time it runs. Well-known endpoints typically are assigned by a central authority responsible for a transport protocol. An application declares a well-known endpoint either as an attribute in an RPC interface header or as a variable in the server application code. See also dynamic endpoint, endpoint.

wide area network (WAN)

A network that includes computers spread across a large geographical distance, usually involving several cities, states, or countries.

workspace

XDS: A space in which OM objects of certain OM classes can be created, together with an implementation of the object management functions that supports those OM classes.

workspace interface

The interface as realized, for the dispatcher's benefit, by each workspace individually.

X.500

A set of standards covering electronic directory services. Namespace identifications such as /.../C=US/O=IBM/OU=DCE (where c=country, o=organization, and ou=organizational unit) follow the X.500 standard.

XDS

X/Open Common Application Environment specification for Directory Services API.

XOM

X/Open Common Application Environment specification for OSI-Abstract-Data Manipulation API.


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