Description and example of the string

Strings that are included in API_MSG messages begin with the following fields, some of which are optional, depending on whether the API_MSG is a request, indication, response, or confirmation, as shown in Table 1.

Table 1. Destination and source fields in string headers
Type of CMIP message	src-type field	src field	dest-type field	dest field
Request	Optional for subtree managers, only. This is choice (2), if included. This is never included for application programs other than subtree managers.	Optional. This is the distinguished name, if included.	Optional. This can be any choice.	Optional. This can be any choice.
Indication	1	assoc-handle	Never included	Never included
Response	Optional for subtree managers, only. This is choice (2), if included. This is never included for application programs other than subtree managers.	Optional. This is the distinguished name, if included.	1	assoc-handle
Confirmation	1	assoc-handle	Never there	Never there

The message field is the only field that must be provided on requests. Responses and linked replies must be formatted with the association data that was provided on the indication. (The indication is the request being answered.) The caller of the MIBSendRequest function or MIBSendResponse function must build the string with all fields. Other API functions do not require the caller to build the string with all fields.

For API functions that build the string automatically, for example, the MIBSendCmipRequest function, separate fields are provided to pass individual fields that are placed in the string by the API function.

The syntax of the string header follows, in ASN.1 notation:

Header ::= SEQUENCE
  {
    src-type INTEGER                 -- source type
    {
      assoc-handle(1)                -- association handle
    } OPTIONAL,
    src GraphicString OPTIONAL,      -- source
    dest-type INTEGER                -- destination type
    {
      assoc-handle(1),               -- association handle
      full-dn(2),                    -- distinguished name
      ae-title(3                     -- AE title
    } OPTIONAL,
    dest GraphicString OPTIONAL,     -- destination
    msg GraphicString                -- the message itself
  }

The format of the required msg field in the string header is dictated by the syntax of the message sent or received by the application program. The following example shows a CMIP string, as received by an application program from CMIP services. This string immediately follows the localIds field of the APIhdr structure.

src-type 1, src a1,msg CMIP-1.ROIVapdu (invokeID 327686, operation-v
alue 3, argument (baseManagedObjectClass 1.3.18.0.0.1829, baseManage
dObjectInstance (distinguishedName (RelativeDistinguishedName (Attri
buteValueAssertion (attributeType 1.3.18.0.2.4.6, attributeValue "MY
NETID")), RelativeDistinguishedName (AttributeValueAssertion (attrib
uteType 1.3.18.0.0.2032, attributeValue "MYCPNAME")), RelativeDistin
guishedName (AttributeValueAssertion (attributeType 1.3.18.0.0.1984,
 attributeValue "APPL1")))), synchronization bestEffort, scope (basi
cScope 0), filter (and ())))