For a list of protocols that support asynchronous communication, see Protocol support for 64-bit recording, Async, and IPv6.
For a list of the API functions that allow Vuser scripts to emulate asynchronous communication see:
The web_reg_async_attributes/web.regAsyncAttributes function should be called before the step that starts the asynchronous conversation. This function receives a number of arguments that define the asynchronous conversation. One of these arguments is the URL of the asynchronous conversation. As soon as the replay engine downloads this URL in the step that follows the web_reg_async_attributes/web.regAsyncAttributes function, the asynchronous conversation begins.
The callbacks that are registered in the web_reg_async_attributes/web.regAsyncAttributes function enable the script developer to control some of the characteristics of the asynchronous conversation (for example, to change the URL). The asynchronous conversation continues until the web_stop_async/web.stopAsync step, or until the end of the iteration. In a push-type conversation, the server may close the connection and thereby end the conversation.
Note: Async functionality is not supported when replaying a Vuser script in WinINet mode.
For details on how the asynchronous functions differ from synchronous functions, see How asynchronous functions differ from synchronous functions.