Asynchronous Behavior › Async Action Statements › CHECK ASYNC RESPONSE › Conditional Clauses (WHEN)

Conditional Clauses (WHEN)

When executing the CHECK ASYNC RESPONSE statement, the process flow gives control to an applicable WHEN clause, if it is present. When the block of code associated with the WHEN clause has completed, processing continues with the statement immediately after the CHECK ASYNC RESPONSE statement. All of the WHEN clauses are included in the code when the CHECK ASYNC RESPONSE statement is constructed by the PAD editor. You can delete any of the WHEN clauses, as required.

Control is passed to the associated WHEN clause under the following circumstances:

• WHEN available—Control is passed to the WHEN available block of code if the response associated with the specified ASYNC_REQUEST Work set view has been received by the runtime, and is available for the application to retrieve via a GET ASYNC RESPONSE statement. Note that the WHEN available clause does not imply the success or failure of the actual request, it only indicates that the response is available to be retrieved by the application.

  If this clause is not present, there is no way to know if the response is available using the CHECK ASYNC RESPONSE. Processing continues at the statement following the CHECK ASYNC RESPONSE statement, as in the case where the response is still pending.

• WHEN pending—If this clause is present, and the identified request has not yet completed execution, then control is passed to the WHEN pending block of code. The associate request is still considered outstanding.

  If this clause is not present, there is no way to know if the response is available using the CHECK ASYNC RESPONSE. Processing continues at the statement following the CHECK ASYNC RESPONSE statement, the same as if the response is still pending.

• WHEN invalid ASYNC_REQUEST ID—If the specified request identifier does not correspond to an outstanding request, control is passed to the first statement contained in the WHEN invalid ASYNC_REQUEST ID.

  If the WHEN invalid ASYNC_REQUEST ID is not present, processing continues at the default error handling code generated for this statement. Processing exits the currently executing code. This may be handled differently if within a GUI event or within an action block. For more information, see the appendix "User Exits" in the Distributed Processing – Overview Guide.