Rejecting Conversations

If necessary, your server can reject particular conversations by calling the Reject_Conversation service. A server might reject conversations for reasons such as:

After issuing Get_Attributes, the server determines that the inbound conversation has attributes the server does not support, such as a different synchronization level or data format.
The server determines that the output values from the Receive_Allocate service do not match values that the server is designed to expect.
When the server cannot satisfy inbound requests quickly enough to meet the installation's performance goals. For example, assume a database the server needs to access has become unavailable. In this situation, you might decide that it is better to require users to retry rather than wait for an unacceptably long period.

When rejecting a conversation, your server communicates the reason for the rejection to the client TP by specifying a sense code (as an input parameter to the Reject_Conversation service). The partner LU resolves the sense code to a return code that it passes to the client TP.

The Reject_Conversation service must be used early in a transaction; that is, before any communication activity has occurred (such as data being sent or received). Otherwise, APPC/MVS fails the call to the Reject_Conversation service. A limited set of services, however, can be used on a conversation without causing the conversation to be rendered ineligible for rejection. These services allow you to obtain the conversation ID, as well as conversation-related information that might help you in making rejection decisions.

Specifically, you can call the following services on a conversation and still retain the ability to reject it:

Receive_Allocate
Get_Conversation
Accept_Conversation
Get_Type
Get_Attributes
Extract_Conversation_Type
Extract_Mode_Name
Extract_Sync_Level
Extract_Partner_LU_Name.

The Reject_Conversation service is available to all TPs (including APPC/MVS servers). For more information about using the Reject_Conversation service, see z/OS MVS Programming: Writing Transaction Programs for APPC/MVS.