Asynchronous example - push

The following example describes a Vuser script that is developed to emulate a browser displaying an application that utilizes push-type asynchronous conversations. The application is a demo of a “stock quote” page.

The browser shows the page with the stock values, and then sends a request and receives a response with updated stock values. The request remains open until it is closed by the user. For as long as the page is displayed, the server continues to send sub-messages as part of the response - whenever the server has an update for the displayed stocks. Whenever such a sub-message is received by the client, the client displays the updated stock values.

If you attempt to run a script that calls a push url - without first performing an asynchronous scan - the replay will halt while waiting for the response to the highlighted request. After two minutes, VuGen displays an error similar to the following, in the Replay log:

The error indicates that the response never finished.

Regenerating the script, with Async Scan enabled, creates a script similar to the following:

/* Added by Async CodeGen.
IO-Push_0
ScanType = Recording

The following urls are considered part of this conversation:
    http://push.example.com/sIREAMING_IN_PROGRESS?LS_sessionsS3437Id5eb8f9c6412253451&LS_phase=4903&LS_domain=lights",

T000 - The following callbacks have been added to AsyncCallbacks.c.
Add your code to the callback implementations as necessary.
    Push_0_RequestCB
    Push_0_ResponseBodyBufferCB
    Push_0_ResponseCB

*/

web_reg_async_attributes("ID-Push_0",
    "URL=http://push.example.com/sIREAMING_IN_PROGRESS?LS_sessions(CorrelationParameter)&LS_phase=4903&LS_domain",
    "Pattern=Push",
    "RequestCB=Push_0_RequestCB",
    "ResponseBodyBufferCB=Push_0_ResponseBodyBufferCB",
    "ResponseCB=Push_0_ResponseCB",
    LAST);

web_url("STREAMING_IN_PROGRESS",
    "URL=http://push.example.com/sIREAMING_IN_PROGRESS?LS_session(CorrelationParameter)&LS_phase=4903&LS_domain",
    "Resource=0",
    "RecContentType=text/html",
    "Referer=http://www.app.example.com/GNT_StockListDemo_Basic/lightstreamer/lsengine.html",
    "Snapshot=t13.inf",
    "Mode=HTML",
    LAST);

web_custom_request("control.js",
    "URL=http://push.example.com/lightstreamer/control.js",
    "Method=POST",
    "Resource=0",
    "RecContentType=text/plain",
    "Referer=http://push.example.com/ajax_frame.html?phase=594&domain=example.com&",
    "Snapshot=t14.inf",
    "Mode=HTML",
    "Body=LS_session(CorrelationParameter)&LS_table=1&LS_with_phase=19&LS_reg_phase=311&LS_op=add&LS_mode=NERGE&LS_id=itemI",
    LAST);
/* Added by Async CodeGen.
IO = Push_0
*/
    web_stop_async("IO-Push_0",
    LAST);

return 0

Notice that a web_reg_async_attributes function was added before the web_url function that starts the push conversation, and that a web_stop_async function has been added after the last action step in the script. The script will now run successfully. The push conversation will remain active – running in parallel with the other script functions – until the web_stop_async function, or until the end of the script is reached.

Note that during the Async scan, VuGen did not remove (comment-out) any of the generated code in the Vuser script.

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