What are JMeter Test Plan Elements?

JMeter Test Plan Elements

A JMeter Test Plan is made up of the test elements listed below. A Test Plan must include at least one Thread Group. Within each Thread Group, we can mix and match one or more of the following elements: the Sampler, Logic Controller, Listener, Configuration Element, and Timer. Each Sampler can have one or more Pre-processor elements preceding it, followed by a Post-processor element and an Assertion element. Let us explore each of these elements in greater depth.

Before the detailed discussion, let's see a flowchart to help you understand the elements.

Below given are some major elements of JMeter:

• Test Plan
• Thread Group
• Controllers
• Listeners
• Timers
• Configuration Elements
• Pre-Processor Elements
• Post-Processor Elements

The above image shows what all Jmeter Test Plan elements can be added to the test plan.

Thread Group

Thread Group elements serve as the starting point for your test strategy. As the name implies, the thread group elements control the number of threads used by JMeter during the test. The Thread Group also allows us to control the following.

• Configuring the number of threads
   
• To set ramp-up time. Ramp-up is the period of time Apache JMeterTM will require to add all test users (threads) to a test operation. Or, to put it another way, how long it will take JMeter to begin running each thread.
   
• To set the number of test iterations to run.
   

The Thread Group Panel contains the following elements:

• Action to be taken in the event of a Sampler error: If an error occurs during test execution, you may allow the test to either
  1. Continue to the next test element.
  2. Stop Thread to terminate the current Thread.
  3. Stop Test entirely if you want to inspect the error before it continues to run.
   
• The Number of threads: It simulates the total number of connections to your server application.
• Ramp-Up Period: It specifies how long JMeter will take to start all threads.
• Loop Count: It specifies how many times the test should be run.
• Scheduler checkbox: When you select the Scheduler checkbox, the Scheduler Configuration section can be noticed at the bottom of the control panel.
• Scheduler Configuration: You can specify when the test should begin and end.
   

Let us see what the Thread Group Panel looks like in the image below:

Controllers

There are two types of Controllers in JMeter: Samplers and Logic Controllers.

Samplers

JMeter can send specific types of requests to a server using samplers. They simulate a user request for a page from the target server. For example, if you need to execute a POST, GET, or DELETE on an HTTP service, you can add an HTTP Request sampler.

Examples of some useful samplers are −

• HTTP Request
• JDBC Request
• Java Request
• FTP Request
• RPC Requests
• SOAP/XML Request
   

For example:

Logic Controllers

Logic Controllers allow you to control the order in which Samplers in a Thread are processed. Logic controllers can reorder requests coming from any of their child elements. 

A few examples of logic controllers are:

• ForEach Controller
• While Controller
• Loop Controller
• Run Time Controller
• IF Controller
• Interleave Controller
• Throughput Controller
• Run Once Controller
• Random Controller
• Switch Controller
• Transaction Controller
• Once only Controller
• Recording Controller
   

Let’s see the panel for while controller:

Test Fragments

The Test Fragment element is a type of controller that exists on the same level of the Test Plan tree as the Thread Group element. It differs from a Thread Group in the manner that it is not executed unless referred to by a Module Controller or an Include_Controller.

 The Test fragment panel in JMeter looks like this:

Listeners

Listeners allow you to view Sampler results in log files as tables, graphs, trees, or plain text. They show the data collected by JMeter about the test cases as the Sampler component of JMeter is executed.

Listeners can be added to the test at any point, including directly under the test plan. They will only collect data from elements at or below their level.

The list below includes all of the Listeners that JMeter offers:

• Sample Result Save Configuration
• Graph Full Results
• Aggregate Report
• Mailer Visualizer
• BeanShell Listener
• Summary Report
• View Results in Table
• Simple Data Writer
• Monitor Results
• Distribution Graph (alpha)
• Graph Results
• Spline Visualizer
• Assertion Results
• View Results Tree
• Aggregate Graph
   

Example of a Listener called Summary Report:

Timers

Assertions allow you to include a validation test on the response to a Sampler-based request. You can use assertions to demonstrate that your application is returning correct data. When an assertion fails, JMeter highlights it.

Below given is the list of Timers in JMeter:

• Constant Timer
• Gaussian Random Timer
• Uniform Random Timer
• Constant Throughput Timer
• Synchronizing Timer
• JSR223 Timer
• BeanShell Timer
• BSF Timer
• Poisson Random Timer
   

An example of a Timer called JSR223 Timer:

Assertions

In JMeter, the assertion is used to validate the response to the request you sent to the server. At run time, the assertion is a process in which you compare the expected result to the actual result of the request. If you need to apply assertion to a specific Sampler, make it a child of that Sampler.

Below given is the list of all the assertions JMeter provides −

• Compare Assertion
• Beanshell Assertion
• BSF Assertion
• JSR223 Assertion
• BeanShell Assertion
• MD5Hex Assertion
• HTML Assertion
• XPath Assertion
• Response Assertion
• Duration Assertion
• Size Assertion
• XML Assertion
• XML Schema Assertion

Configuration Elements

Configuration Elements allow you to define defaults and variables for Samplers to use. They are used to add or change Sampler requests.

They are implemented at the start of the scope in which they are located, before any Samplers in the same scope. As a result, a Configuration Element can only be accessed from within the branch in which it is placed.

Below given is the list:

• Counter
• CSV Data Set Config
• FTP Request Defaults
• HTTP Authorization Manager
• HTTP Cache Manager
• HTTP Cookie Manager
• HTTP Proxy Server
• HTTP Request Defaults
• HTTP Header Manager
• Java Request Defaults
• Keystore Configuration
• JDBC Connection Configuration
• Login Config Element
• LDAP Request Defaults
• LDAP Extended Request Defaults
• TCP Sampler Config
• User Defined Variables
• Simple Config Element
• Random Variable
   

Below is an example of JDBC Configuration panel:

Pre-processor Elements

A pre-processor element is something that runs before the execution of a sampler. Pre-Processor elements are frequently used to modify a Sample Request's settings just before it executes.

All of the pre-processor elements provided by JMeter are listed below.

• HTTP URL Re-writing Modifier
• HTML Link Parser
• HTTP User Parameter Modifier
• User Parameters
• RegEx User Parameters
• BeanShell PreProcessor
• BSF PreProcessor
• JDBC PreProcessor
• JSR223 PreProcessor
   

Below given is an example of a Pre-processor called the JSR223 Pre-Processor:

Post-processor Elements

Post-Processors are actions that occur after your sampler starts running. You can use them to perform actions on your response or to extract values from the response and save them in a variable for later use.

• Regular Expression Extractor
• XPath Extractor
• Result Status Action Handler
• JSR223 PostProcessor
• JDBC PostProcessor
• BSF PostProcessor
• CSS/JQuery Extractor
• BeanShell PostProcessor
• Debug PostProcessor
   

Below given is an example of a Post-processor called the XPath Extractor:

Order of Execution of Test Elements

The execution order of Test Plan Elements is as follows:

1. Configuration elements
2. Pre-Processors
3. Timers
4. Sampler
5. Post-Processors (unless SampleResult is null)
6. Assertions (unless SampleResult is null)
7. Listeners (unless SampleResult is null)

Frequently Asked Questions

In JMeter, how many threads can be executed at once?

JMeter allows you to run multiple processes in the same box, and it generates up to 200 threads per JMeter instance. If you require more, we recommend running multiple JMeter instances. With some tweaking, a modern machine can easily generate 500 to 1000 threads.

In JMeter, what is thread lifetime?

Each thread will begin 10 (100/10) seconds after the previous one. With 30 threads and a ramp-up time of 120 seconds, each subsequent thread will be delayed by 4 seconds.

JMeter employs which programming language?

JMeter uses the Groovy language as a scripting language. Groovy has proven to be a powerful yet lightweight language in terms of performance when it comes to improving JMeter's functionality.

In JMeter, what are non-test elements?

You can capture network traffic in JMeter by adding a Non-Test element to your test plan. Right-click on Test Plan > Add > Non-Test Elements > HTTP(S) Test Script Recorder and select HTTP(S) Test Script Recorder. JMeter will now have the ability to record. Understand the business flow and have your input data ready before you begin recording.

What exactly is a simple configuration element in JMeter?

The 'Simple Config Element' in JMeter adds or overrides arbitrary values in samplers. You can customize both the value's name and the value itself.

Conclusion

This article brought you a detailed discussion of the various JMeter Test Plan elements and their sub-components and types. We hope you now understand what a JMeter Test Plan is and what the JMeter Test Plan Elements are.

For more information on JMeter, Refer to our other articles-

• What is the Monitor test Plan in JMeter?
• Introduction to JMS test Plan in JMeter
• JMeter Interview Questions
   

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