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Sync Point Attach Manager

Instead of issuing separate RECEIVE_ALLOCATE verbs for each possible transaction name, a Sync Point implementation may instead register as the Sync Point Attach Manager for Host Integration Server. It does so by issuing a RECEIVE_ALLOCATE verb specifying a TP name consisting of all 0x00s.

When a Sync Point Attach Manager is registered, the following changes are effected in server's incoming Attach support on Host Integration Server:

  • When an Attach message arrives for any TP name on a conversation with the syncpoint_rqd field of the VCB set to AP_YES, Host Integration Server matches it with the application that issued the special RECEIVE_ALLOCATE verb registering itself as the Sync Point Attach Manager.

  • Any Attach message arriving for the Resynchronization TP (0x06F2) will automatically be routed to the Sync Point Attach Manager.

  • If no RECEIVE_ALLOCATE has been issued for the Sync Point Attach Manager, or for the specific TP name, Host Integration Server will queue the Attach for a configured period of time. If no RECEIVE_ALLOCATE is issued in that time, the Attach will be rejected with a return code of TP_NOT_AVAILABLE_RETRY.

  • If a RECEIVE_ALLOCATE is matched with the Attach message, the verb is returned to the TP with the tp_name field of the VCB set to the TP name contained in the Attach message.

    Applications using this feature must adhere to two restrictions:

  • All verbs issued on conversations started in this manner must be issued by the same process, as Host Integration Server cannot pass tp_ids between processes.

  • Only a single process may register as the Sync Point Attach Manager on any server running Host Integration Server. If a second process attempts to register, its RECEIVE_ALLOCATE verb will return immediately with the primary return code set to AP_SYNCPOINT_MANAGER_ACTIVE.

    Sync Point Attach Manager applications must reside on a Host Integration Server server. They may not be distributed across Host Integration Server clients. This restriction is imposed to ensure that only a single instance of Sync Point Services (SPS) and Conversation-Protected Resource Manager (C-PRM) exists for each LU on the Host Integration Server (which might not be the case if Sync Point Attach Managers were visible from multiple servers in the Host Integration Server ___domain).

    The structure of the RECEIVE_ALLOCATE verb control block does not require modification to support this function.