Pre-Processors Elements in JMeters
A Pre-Processor element is a type of element that executes some action. But, this action is executed before making the Sampler Request.
Let's say there is a pre-processor element, and it is joined to a sampler element. In this case, the pre-processor element will run just before the sampler element.
You can use a pre-processor element to modify or change the settings of a sample request just before its execution. You can also use it to update the variables that are not retrieved from a response text.
Now, let's understand this by an example.
Assume you are testing a website. You want to "spider" (crawl) through this website that is under testing. Afterward, you want it to parse the links, which means checking all the links on that page. In the end, you want it to return an HTML file.
In this case, you can include some actions like "HTML Link Parser" to the controller. This can be done before creating the HTTP Request.
Following are all the Pre-processor elements that are already present in JMeter:
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JSR223 Pre-processor,
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JDBC Pre-processor,
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RegEx User Parameters,
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BSF Pre-processor,
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BeanShell Pre-processor,
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HTML Link Parser,
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HTTP URL Re-writing Modifier,
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User Parameters, and
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HTTP User Parameter Modifier.
Let's see an image that will help you to add Pre-processor elements to the test plan.
Post-Processors Elements in JMeters
A Post-Processor element is also a type of element that executes some action. But, in this case, the action is executed just after making the Sampler Request.
Let's say there is a post-processor element, and it is joined to a sampler element. In this case, the post-processor element will run just after the sampler element.
Now, let's understand this by an example.
Assume you are testing a Web Server. You are sending an HTTP request using JMeter. In return for the request, you will receive a response. Now, let's say you want JMeter to halt the test as soon as the server sends an error as a response.
In this case, you can make use of the post-processor. You can extract the values from the response post receiving the server.
Following are all the Post-processor elements that are already present in JMeter:
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CSS/JQuery Extractor,
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JSR223 Post-processor,
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BeanShell Post-processor,
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JDBC Post-processor,
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Regular Expression Extractor,
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Debug Post-processor,
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Result Status Action Handler,
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XPath Extractor, and
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BSF Post-processor.
Let's see an image that will help you to add Post-processor elements to the test plan.
Frequently Asked Questions
What is JMeter load time?
The load time is the period of time between sending the request and receiving the final part of the response.
What is the full form of KPI in JMeter?
KPI stands for Key Performance Indicator in JMeter.
How many threads can JMeter run?
You can use JMeter to run numerous processes simultaneously. Up to 200 threads can be produced by each JMeter instance, which is typically rather reliable.
What is keepalive in JMeter?
Keep-alive is an important HTTP feature. You can use it to keep a persistent connection between round trips. It makes sure that it does not initiate a new one on each request.
Does JMeter require JDK?
If you want to create the JMeter source or develop JMeter plugins, you will need a JDK 8 or higher.
Conclusion
In this article, we have studied the Pre-Processor and Post-Processor Elements in JMeter in detail.
We hope that this article has provided you with the help to enhance your knowledge regarding the Apache JMeter and if you would like to learn more, check out our articles on JMeter Functions and JMeter Timers.
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