Delta Function Component

Introduction

The Delta Component provides lookup, add and delete access to the Delta services outside of the normal Connector modes. The Delta Function Component allows the Delta functionality to be placed anywhere in the AssemblyLine. This way entries read from the input source can be modified before computing the Delta changes and applying them to the Delta Store.

Configuration

The Delta Function Component has the following parameters:

Unique Attribute Name

The name of an attribute that holds a unique value in a given data source. Data sources with duplicate keys cannot be subjected to the delta function, except when Allow duplicate Delta keys is enabled.

Delta Store

The table in the System Store that holds the Delta information from previous runs for this Connector, so as to be able to detect differences on subsequent runs. When this parameter is empty a default name composed from the "AssemblyLines" literal string, the AssemblyLine name and the component name is used (for example, "AssemblyLines_AL1_DeltaFunc").

Read Deleted

If checked, the AssemblyLine will inject deleted entries into the AssemblyLine run when the Iterator has completed iterating, that is, finished input. The operation code will indicate that this Entry was deleted in the input source. Note that delete-tagged Entries are not removed from the Delta Store unless you also enable the Remove Deleted flag.

Remove Deleted

If checked, the deleted entries from the input source are deleted from the Delta Store, such that they will not be detected again in subsequent runs.

Return Unchanged

If checked, any unchanged entries in this run are injected into the AssemblyLine.

Commit

Selects when to commit changes to the Delta Store as a result of iterating through the input. Choices are:

• After every database operation
• On end of AL Cycle
• On Connector close
• No autocommit

The default is After every database operation.

Row Locking

Selects the transaction isolation level for the connection to the Delta Store. For more information refer to subsection "Row Locking" in section "Delta feature for Iterator mode" in IBM Tivoli Directory Integrator V7.1.1 Users Guide. Possible values are:

• READ_UNCOMMITTED
• READ_COMMITTED
• REPEATABLE_READ
• SERIALIZABLE

The default is READ_COMMITTED.

Faster algorithm

When checked, instructs the AssemblyLine to use a faster algorithm to compute changes, at the expense of more memory use. In essence, it does not write unchanged entries to the Delta store; instead it remembers keys in memory if Read Deleted is set to true.

Allow duplicate Delta keys

When the Delta feature is enabled for Changelog/Change Detection Connector in long running AssemblyLines, an Entry can be modified more than once. These modifications will result in receiving the Entry a second time and this will cause the Duplicate delta key exception to be thrown. Checking this parameter allows Entries with duplicate key attributes (specified in the Unique Attribute Name parameter) to be processed by Iterator Connectors with enabled Delta.

Attribute List

A comma-separated list of attributes whose changes will be detected or ignored during the compute changes process. The changes in listed attributes will be affected by the Change Detection Mode parameter that specifies whether to ignore or detect them. For more information about this parameter see subsection "Detect or ignore changes only in specific attributes" in section "Delta feature for Iterator mode" in IBM Tivoli Directory Integrator V7.1.1 Users Guide.

Change Detection Mode

Specifies changes in which attributes will be detected or ignored. For more information about this parameter see subsection "Detect or ignore changes only in specific attributes" in section "Delta feature for Iterator mode" in IBM Tivoli Directory Integrator V7.1.1 Users Guide.

Using the Function Component

The Delta Function Component provides the same functionality as an enabled Delta tab for connectors in Iterator mode; see section "Delta" in IBM Tivoli Directory Integrator V7.1.1 Users Guide. This function component allows Delta detection and applying logic to be placed anywhere in the AssemblyLine.

Since the Delta FC is a function component it requires an Entry on which to perform its Delta function. Therefore when the input source reaches end of data, the Delta component will have nothing to process. So when the Read Deleted parameter is selected the deleted entries will be returned by the Delta Function Component only if you feed the component with some dummy empty entries. These entries will signal the function component to start returning any deleted entries.

Similar to an Iterator connector with Delta enabled, the Delta Function Component displays delta statistic at the end of Assembly Line execution (for example, "Add:3, Modify:1, CallReply:5, Skip:2, Nochange:2").

Example

The following example demonstrates how to synchronize an input source with the TDI Delta Store using the Delta FC when the Read Deleted parameter is enabled. The deleted entries from the input source will be marked with a delete delta operation and returned to the AssemblyLine.

Steps to execute:

1. Add connector(s) in Iterator mode that will iterate over the input data source.
2. Add a Script Connector as the last connector in the Feed section.
3. Add this code in its getNextEntry() method:

   	r = task.getResult();									
   													
   	if (r != null){										
   		if (r.size() > 0){								
   			entry = system.newEntry();						
   			result.setStatus(1);        // OK					
   		} else {										
   			result.setStatus(0);        // end of input			
   		}											
         }	

4. Add some custom logic or components that modify the work entry.
5. Add Delta Function Component and configure it to iterate over deleted entries.
6. Start the AssemblyLine.
7. Delete some entries in the input data source.
8. Start the AssemblyLine again and receive the deleted entries tagged as delete.