Obtaining Results from an Asynchronous Method Call

The waitForMethods method on the Process class returns a JadeMethodContext instance for an asynchronous method call that has completed or timed out. This object provides methods to report on:

• Whether the call completed, timed out, or failed

• The error information (if it failed)

• The return value from the call (if there was one)

The following code fragment shows the result of an asynchronous method call being examined.

vars
    context: JadeMethodContext;
    cust: Customer;
    date: Date;
    completedContext: JadeMethodContext;
begin
    ...
    // Obtain context of last asynchronous call to complete
    completedContext := process.waitForMethods(context);
    // Check how things went and obtain the result
    if completedContext = null then
        write "All calls completed";
    elseif completedContext.getErrorNumber <> 0 then
        write "Error info: " & completedContext.getErrorText;
    elseif completedContext.isTimedOut then
        write "Call timed out";
    else
        write "Return value: " & completedContext.getReturnValue.String;
    endif;
    ...

You can use the getTimestamps method to return the information listed in the following table.

Parameter	Description
invokeTS	The timestamp value when the asynchronous method call was invoked using the JadeMethodContext instance
beginTS	The timestamp value when the worker application began processing the asynchronous method call
finishTS	The timestamp value when the worker application completed processing the asynchronous method call
harvestTS	The timestamp when the receiver was returned by the waitForMethods method and reported as complete
qdepth	The number of requests already queued when the asynchronous method call request was added to the queue

If the getTimestamps method is called:

• Before the invoke method is called, none of the output parameters returns a value.

• After the invoke method is called but before the waitForMethods method is called, only the invokeTS and qdepth parameters return a value.

• After the waitForMethods method is called, all output parameters return a value.