Performance and loading testing WCF services with JMeter - Part 2

A while ago I wrote a brief post about JMeter and performance / load testing WCF services. This post will list the steps I'm normally go through to set up JMeter from scratch to test a service, it also includes the steps for parameterising the request payload using a CSV file. 

• Add a new thread group to the test plan. The loop count when using a CSV data set means how many times to process the file.

• Under the thread group add a CSV Data Set Config element (available under Config Element). Typically I have the CSV file in the same location as the .jmx file which allows you to just specify the file name. In the below example RequestPayloads.csv contains a payload per line, request is the variable name that will be used as a placeholder to insert the sample into the soap envelope. This will become clearer in the next step. 

• Add a Loop Controller to the thread group (which is located under Logic Controller), and tick the Forever option.  This will ensure all entries in the CSV file will be processed (rather than having to configure the thread group to have the right amount of loops to completly process the file). Under the Loop Controller add a SOAP/XML-RPC Request element. Enter the appropriate endpoint (URL) and SOAP action (ensure that this is ticked). The request body is where it gets interesting. Here I have stripped out the entire body of the request (i.e. the elements between the SOAP Body element - <soapenv:Body>), and replaced it with ${request} - where request is the name of the variable we set in the CSV Data Set Config element. 

• Each line in the the CSV file contains the appropriate xml to replace ${request} - so for example, the service that JMeter is testing is expecting an body element called DoStuffRequest, so each line in my CSV file contains:

<DoStuffRequest><anotherElement><name>john</name></anotherElement></DoStuffRequest>

<DoStuffRequest><anotherElement><name>sam</name></anotherElement></DoStuffRequest>

<DoStuffRequest><anotherElement><name>peter</name></anotherElement></DoStuffRequest>

• To determine how successful our request are (and to prove that the the CSV file is being processed) we'll need to add some listeners. Add a View Results Tree element under the thread group. Start the test, you should see something similar to the below where the each individual request is logged. Select the Request tab and check that it's been formatted correctly using the CSV file etc. Select the Response data tab and check the it's the response that you're expecting. 

• A couple of other listeners that I normally use is the Summary Report, and a Spline Visualizer. Summary report is good for latency metrics, where the Spline visualizer is good to determine the behaviour of a service over time (e.g. does the latency slowly increase?). 

• To increase the load that the service is under, up the thread count in the Thread Group element, which will result in more threads processing the CSV data set.