TCAP:Adding component portion

The transaction component add (request/response) message is used to add components to TCAP messages. Each invoked component must have a unique invoke identifier assigned within the current transaction.

Upon receiving this request, TCAP builds the component in ASN.1 format and queues it until it gets the transaction data send message. The components are queued in the order in which they are added. The components that can be queued are limited to system memory. If any mandatory information is missing in the component structure (which is required to build the component) then an alarm or a reject component with general encoding failure problem code is generated (if the 'return on error' variable is set to 'True' as part of the general configuration).

An invoke request can be canceled by sending a transaction component add message (for both ITU and ANSI TCAP) with component type set to component type 'unknown' and a cancellation flag of component structure set to 'True'. If the invoke component was not sent then it is to be removed from the queue and the instance of the invoke context will be deleted. If the invoke component was already sent and the instance of the invoke context exists then it would be deleted.

In the case of ANSI TCAP, there is no invoke timer maintained in TCAP (the ANSI recommendation does not specify any timer). There is a possibility that a component is not received in response to an invoke component sent for operation class 2 (only failure is reported), 3 (only success is reported), and 4 (neither failure nor success is reported). The instance of the invoke context may remain allocated even after the operation is over. To resolve this situation, TCAP assumes that the TCAP user application maintains the operation timer, and upon expiry of this timer, application will generate a cancel request to TCAP (to delete the invoke instance).

The component portion contains the following parameters:

• TCAP userpart handle
• TCAP transaction identifier
• Component parameters
• Component specific parameters buffer