Using Synchronous and Asynchronous Modes

You can specify whether you want operations in a given module to function synchronously or asynchronously.

• Synchronous Mode. In the examples shown so far, the objects on the local workstation have been shown in synchronous mode. In synchronous mode, the requestor (in this case, the operation) waits for a reply from the server in the form of an output parameter. On the Workstation Objects window, synchronous services are shown with input and output parameters. Synchronous objects are the default view.

• Asynchronous Mode. When calling a TUXEDO service asynchronously, an asynchronous operation contains only input parameters but no output parameters-instead, the information comes back as output parameters of the operation reply. As shown on the Workstation Objects window, asynchronous operations are named differently (the suffix Async is attached to the operation name) and the output parameters are returned in the operation reply. Notice that the sample code for an asynchronous operation contains events that indicate the replies.

Naming Conventions for Operations to be Used in Asynchronous Mode

The naming conventions you use for operations (also known as services) can affect asynchronous mode. To ensure that your operation names map properly for async mode, do not use two operations in the same project whose names are distinguishable only because one has an underscore and one does not.

For example, you cannot have the following two operations in the same interface:

• myservice

• my_service

The reason for this is that having these two similarly named operations in async mode will result in having two different event methods with the same name.

When the Active Expert creates an ActiveX control, it creates events and corresponding methods. The Active Expert uses operation names as a basis for naming associated event methods, but ignores the underscores as a part of this process.

For a given interface with an operation called myservice, the Active Expert creates an event method called myserviceasyncdone. Similarly, for an operation called my_service, the Active Expert creates an event method with the exact same name (myserviceasyncdone).

Viewing Objects in Asynchronous Mode

To view objects in asynchronous mode:

1. Make sure the Workstation Objects window has the focus.

2. Choose View->Async from the menu bar

   Or

   Click on the async toolbar button.

   (The keyboard shortcut to show asynchronous mode is Alt V A.)

   This shows the workstation objects in asynchronous mode as shown in Figure 3-5.

   Figure 3-5 Workstation Objects in Asynchronous Mode

   

In the figure, the module BANKAPP is expanded to show the asynchronous operations contained in the TELLER interface. Note that the asynchronous operations are named in the form OperationNameAsync. The sample code shown returns the requested values as output parameters of the selected reply object operation.

Switching Back to Synchronous Mode

To view objects in synchronous mode:

1. Make sure the Workstation Objects window has the focus.

2. Choose View->Sync from the menu bar

   Or

   Click on the sync toolbar button.

   (The keyboard shortcut to show synchronous mode is Alt V Y.)

   This shows the workstation objects in synchronous mode.