Most servers will likely use IXCSEND to send a message containing the results of its processing back to the client. But for some applications, perhaps depending on the particular request,the reply could be an acknowledgment indicating whether or not the request was processed. You can use IXCSEND to explicitly send a simple acknowledgment. Using IXCSEND allows the acknowledgment to include a return and reason code. An alternative approach is to have the server exit routine update the SXPL to have XCF send the acknowledgment. Setting either the SXPL_ResultCode or the SXPL_RefusalCode to a nonzero value causes XCF to send an acknowledgment on behalf of the server. For a given request, the server exit can set either the result code or the refusal code, not both. XCF stops the server if both codes are set to a nonzero value.

If the server exit arranges for the request to be processed by some other work unit, it is the responsibility of that other work unit to invoke IXCSEND to send the result of the request back to the originating client. In this case, the SXPL "result code" and "refusal code" is not used. If the client expects either some sort of data in response to its request, or some sort of acknowledgment, it is up to the work unit that processes the request to send the response or acknowledgment by explicitly invoking IXCSEND.

Note that for any given request, you either use the technique of setting the result code or refusal code to have XCF send an acknowledgment, or you invoke IXCSEND to send the acknowledgment or results. If both techniques are used, there are race conditions to consider. The client receives at most one of the responses, either the XCF acknowledgment or the response sent using IXCSEND. In general, it is unpredictable which will be delivered to the originator.