Load testing AJAX with JMeter

Testing normal AJAX (using DWR) connections with JMeter is reasonably straight forward. Note that if you are using Spring’s CharacterEncodingFilter and force UTF-8 (since JMeter does not set the character encoding), POST parameters will not be read by the DWR servlet, in this case either disable your filter or use a GET for your AJAX requests and keep the parameter size in check.

Setup a POST to login to your application (or whatever is necessary to establish a session).

GET dwr/engine.js, parse the response and bind the HTTP Session ID and scriptSessionId to JMeter variables:

And now to make an actual AJAX request:

To inspect your existing AJAX calls I recommend using a proxy such as Charles, Firebug doesn’t show you (or at least me:) the request parameters. Parameters to note are:

page:

where the click happened

batchId:

DWR seems fairly unbothered by this but I click through a sequence of events, setup my test plan to match that sequence and then use those batchIds (Charles’s sequence view is very useful for this)

c0-paramX:

Be sure to pass the required parameters.

Coming in Pt II … how to load test reverse AJAX connections. Watch this space.