Topic: Ajax technology

I had to deal with AJAX once ... it was quite painful since there was not much support from the VuGen function library. Maybe this has changed with the Click+Script Vuser type, which I doubt. There is a function to evaluate JavaScript but as far as I can remember it doesn't really allow multiple return values, etc.

Here is basically what I did:
Since my load generators were running on Windows, I used the C system function (depending on your Vuser language; their are similar functions for every programming language) combined with the Scripting Host facility - wsf. I imported the JavaScript used in AJAX into the WSF and executed the functions necessary to generate the data which I need to have for the next step. From the VuGen network traces you can tell what these AJAX calls normally look like. Of course you are only interested in the call which data is actually needed for the next web_url or whatsoever call.

To reflect in code (informally):

    * Define web parameter size to very large (like 100k).
    * Catch full output of the AJAX call(s) into that parameter.
    * Extract XML data from the parameter.
    * Safe that XML data into a file (using a file name with the Vuser Id).
    * Process XML data in the file using the AJAX library over WSF locally.
    * Safe to an output file whatever you need to return to the Vuser for the next request.
    * Read that output from the file into the Vuser.
    * Make the next request using that data.



As you see, this has left the trails of record/corelate/parametrize quite a bit. Also this puts a lot of stress onto your load generators; you need to monitor their CPU and memory usage as well (which you should do anyway) to see that these aren't becoming a bottleneck themselves.

Also don't forget to add the .js files and the .wsf to your Vuser, otherwise they don't get loaded as part of the Vuser.