Download Sun Java System Messaging Server 6 2005Q1 MTA Developer`s

Caller-Supplied Processing Routine
3.
For each queued message requiring processing, an execution thread created by
mtaDequeueStart() calls the routine whose address was provided in Step 2.
Threads created by mtaDequeueStart() each sequentially process multiple
messages. That is, mtaDequeueStart() does not create a distinct thread for each
and every queued message to be processed.
For a list of the tasks the processing routine should do, see “Caller-Supplied
Processing Routine” on page 51.
NOTE
The mtaDequeueStart() routine will use one or more threads, with
each thread calling the message processing routine. The maximum
number of threads allowed can be set when calling
mtaDequeueStart(). Consequently, a program that does not support
threading should specify a maximum of one thread when it calls
mtaDequeueStart().
For a list of the tasks the processing routine should do, see “Dequeue Message
Processing Routine Tasks.”
4.
After mtaDequeueStart() returns, deallocate SDK resources and data structures
with a call to mtaDone().
Caller-Supplied Processing Routine
Channel programs typically perform some form of processing on each message
they dequeue. For instance, virus scanning, MMS conversion, decryption, delivery
to a proprietary messaging system, and so forth. When using the MTA SDK,
channel programs must provide a routine which initiates this processing on a per
message basis. That is, programs must supply a routine that to be called to process
a single queued message. Throughout the rest of this text, this caller-supplied
routine will be referred to as “the caller-supplied processing routine,” or, for short,
“the processing routine.”
When called by one of the mtaDequeueStart() execution threads, the processing
routine uses the SDK to access the message’s envelope, header, and any content.
Upon completion of processing, the message is then either removed from the MTA
queues, or, in the event of a temporary error, left in its queue for a later processing
attempt.
Chapter 4
Dequeuing Messages
51