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Remotely Initiated Conversations

  • Article

Applications that want to receive remotely initiated conversations (incoming Attaches) issue a RECEIVE_ALLOCATE verb. To accommodate Sync Point support, the RECEIVE_ALLOCATE verb is modified in a number of ways as follows:

  • The returned sync_level parameter of the RECEIVE_ALLOCATE verb can take on a value of AP_SYNCPT, specifying that the conversation is a Sync Point conversation. The value of the sync_level parameter can also be determined by issuing a GET_ATTRIBUTES verb on the new conversation.

  • Support is added for the receipt of program initiation parameters (PIP) data by a new parameter to the RECEIVE_ALLOCATE verb:

    The pip_incoming parameter is set by the application to indicate whether it is willing to accept incoming PIP data, and is returned by Host Integration Server to indicate whether PIP data is available to be received. If the application does not want to receive PIP data, this member should be set to AP_NO, the default, before issuing the RECEIVE_ALLOCATE verb. If it is willing to accept PIP data, this member should be set to AP_YES. On completion of the RECEIVE_ALLOCATE verb, this member will be set to AP_YES if PIP data is available to be received by the application and to AP_NO otherwise.

  • If PIP data is available, the application can receive it by issuing one of the verbs for receiving data on completion of the RECEIVE_ALLOCATE verb. For basic conversations, these receive verbs include RECEIVE_AND_POST, RECEIVE_AND_WAIT, and RECEIVE_IMMEDIATE. On basic conversations the PIP data will be returned inclusive of the general data stream (GDS) header for PIP data (GDS identifier 0x12F5). For mapped conversations, these receive verbs include MC_RECEIVE_AND_POST, MC_RECEIVE_AND_WAIT, and MC_RECEIVE_IMMEDIATE. On mapped conversations, Host Integration Server removes the 4-byte GDS header, and returns the PIP data only.

  • For basic conversations, if the application issues a SEND_ERROR, DEALLOCATE, or TP_ENDED verb before the PIP data is received, the PIP data will be discarded. For mapped conversations, if the application issues an MC_SEND_ERROR, MC_DEALLOCATE, or TP_ENDED verb before the PIP data is received, the PIP data will be discarded.

  • If PIP data is received for a TP that cannot or does not want to receive it, the conversation is rejected with a primary return code of AP_ALLOCATION_ERROR, and a secondary return code of AP_PIP_NOT_ALLOWED.