Discussion for all testing needs

As illustrated in Figure 3, several fields must be configured for the HTTP Proxy Server element:

• Port: The listening port used by the proxy server.
• Target Controller: The controller where the proxy stores the generated samples. By default, JMeter will look for a recording controller in the current test plan and store the samples there. Alternatively, you can select any controller element listed in the menu. Usually, the default is okay.
• Grouping: How you would like to group the generated elements in the test plan. Several options are available, and the most sensible one is probably “Store 1st sampler of each group only,” otherwise, URLs embedded in a page such as those for images and JavaScripts will be recorded as well. However, you may want to try the default “Do not group samples” option to find out what exactly JMeter creates for you in the test plan.
• Patterns to Include and Patterns to Exclude: Help you filter out some unwanted requests.

Figure 3. JMeter Proxy Server. Click on thumbnail to view full-sized image.

When you click the Start button, the proxy server starts and begins recording the HTTP requests it receives. Of course, before clicking Start, you must configure your browser’s proxy server setting.

You can add a timer as a child of the HTTP Proxy Server element, which will instruct JMeter to automatically add a timer as a child of the HTTP request it generates. JMeter automatically stores the actual time delay to a JMeter variable called T, so if you add a Gaussian random timer to the HTTP Proxy Server element, you should type ${T} in the Constant Delay field, as shown in Figure 4. This is another convenient feature that saves you a lot of time.

Figure 4. Add a Gaussian random timer to the HTTP Proxy Server element. Click on thumbnail to view full-sized image.

Note that a timer causes the affected samplers to be delayed. That is, the affected sampling requests are not sent before the specified delay time has passed since the last received response. Therefore, you should manually remove the first sampler’s generated timer since the first sampler usually does not need one.

Before starting the HTTP proxy server, you should add a thread group to the test plan and then, to the thread group, add a recording controller, where the generated elements will be stored. Otherwise, those elements will be added to WorkBench directly. In addition, it is important to add an HTTP Request Defaults element (a Configuration element) to the recording controller, so that JMeter will leave blank those fields specified by the HTTP request defaults.

After the recording, stop the HTTP proxy server; right-click the Recording Controller element to save the recorded elements in a separate file so you can retrieve them later. Don’t forget to resume your browser’s proxy server setting.

Specify response-time requirements and validate test results

Although not directly related to JMeter, specifying response-time requirements and validating test results are two critical tasks for load testing, with JMeter being the bridge that connects them.