Sync Point Level 2 Confirm Support

The current SNA Server implementation supports conversations with synclevel of AP_NONE, AP_CONFIRM_SYNC_LEVEL, or AP_SYNCPT. The DEALLOCATE, MC_DEALLOCATE, PREPARE_TO_RECEIVE, and MC_PREPARE_TO_RECEIVE verbs specify a type member indicating the synchronization level required. This parameter is interpreted as follows:

Allocated synclevel	Type specified	Action performed
AP_NONE	AP_FLUSH	Action of FLUSH or MC_FLUSH verb before deallocation or change of direction.
AP_NONE	AP_SYNCLEVEL	Action of FLUSH or MC_FLUSH verb before deallocation or change of direction.
AP_SYNCPT	AP_FLUSH	Action of FLUSH or MC_FLUSH verb before deallocation or change of direction.
AP_SYNCPT or AP_CONFIRM_SYNC_LEVEL	AP_CONFIRM_TYPE	Action of CONFIRM or MC_CONFIRM verb before deallocation or change of direction.
AP_SYNCPT	AP_SYNCLEVEL	It is assumed that a Sync Point implementation built on the SNA Server APPC API implements the defer states appropriately. See the note below.

Note With an allocated synclevel of AP_SYNCPT and a specified type of AP_SYNCLEVEL, it is assumed that a vendor-supplied Sync Point component implements the defer states appropriately. A vendor-supplied Sync Point system must:

Intercept DEALLOCATE, MC_DEALLOCATE, PREPARE_TO_RECEIVE, and MC_PREPARE_TO_RECEIVE verbs on Sync Point Level 2 conversations when type AP_SYNCLEVEL is specified for synclevel.
Maintain the defer state until one of the verbs valid in that state completes.
On completion of the verb, issue the original DEALLOCATE, MC_DEALLOCATE, PREPARE_TO_RECEIVE, or MC_PREPARE_TO_RECEIVE verb to SNA Server.

SNA Server does not implement the defer states directly. In particular, when it receives a DEALLOCATE, MC_DEALLOCATE, PREPARE_TO_RECEIVE, or MC_PREPARE_TO_RECEIVE verb with a type specified as AP_SYNCLEVEL on a Sync Point conversation, it treats it as if the conversation has a synclevel of AP_NONE.

So that Sync Point Level 2 conversations can use confirm type synchronization, the DEALLOCATE, MC_DEALLOCATE, PREPARE_TO_RECEIVE, and MC_PREPARE_TO_RECEIVE verbs are modified to support a type member of AP_CONFIRM_TYPE.

Versions of SNA Server 2.x prior to SNA Server 3.0 support conversations with synclevel of AP_NONE or AP_CONFIRM_SYNC_LEVEL. The DEALLOCATE, MC_DEALLOCATE, PREPARE_TO_RECEIVE, and MC_PREPARE_TO_RECEIVE verbs specify a type member indicating the synchronization level required. This parameter is interpreted as follows:

Allocated synclevel	Type specified	Action performed
AP_NONE	AP_FLUSH	Action of FLUSH or MC_FLUSH verb before deallocation or change of direction.
AP_NONE	AP_SYNCLEVEL	Action of FLUSH or MC_FLUSH verb before deallocation or change of direction.
AP_CONFIRM_SYNC_LEVEL	AP_FLUSH	Action of FLUSH or MC_FLUSH verb before deallocation or change of direction.
AP_CONFIRM_SYNC_LEVEL	AP_SYNCLEVEL	Action of CONFIRM or MC_CONFIRM verb before deallocation or change of direction.