This section describes API extensions to Windows APPC that allow asynchronous communication. Asynchronous communication occurs when a function returns before the request completes. The application is notified later when the request is completed.
Under Microsoft® Windows NT® and Windows® 95, two methods are available for asynchronous communication using the APPC API:
The first method uses messages posted to a window handle to notify an application of verb completion. This method using window handles and messages is also supported on Microsoft® Windows® 3.x with the exception of real mode Windows 3.0. There is one such window for each APPC application, independent of the number of conversations. Each APPC conversation can have one asynchronous verb outstanding at any time. When a verb completes, the posting to the window takes as parameters the asynchronous task handle returned by the original call and a pointer to the verb control block which has completed, containing the return codes of the verb.
The extensions using window handles and message posting described in this section (WinAsyncAPPC) have been designed for all implementations and versions of Microsoft Windows from version 3.0 through the latest versions of Windows NT and Windows 95. They provide compatibility for Windows programming and optimum application performance in the 16-bit operating environment.
A second method using Win32 events for notification is supported. The extensions using Win32 events described in this section (WinAsyncAPPCEx) operate only on Windows NT and Windows 95. and offer optimum application performance in the 32-bit operating environment. If an event has been registered with the conversation, then an application can call the Win32 WaitForSingleObject or WaitForMultipleObjects function to wait to be notified of the completion of the verb.
Windows APPC allows multithreaded Windows-based processes. A process contains one or more threads of execution. The 16-bit Windows environment is not multithreaded. In this instance, a task corresponds to a process with a single thread. All references to threads in this document refer to actual threads in multithreaded Windows environments.
This section provides, for each extension, a definition of the function, syntax, returns, and remarks for using the function.