What is Jmeter Elements?

• The different components of JMeter are called Elements. Each Element is designed for a specific purpose.
• The figure below gives the some common elements in JMeter.

• Studying all the componens at one go is an invitation to confusion and boredome. Here, we will discuss the must-know components before you can start Testing in JMeter. Remaining components will be discussed as when they are used in the succeeding tutorials. The elements discussed in this tutorial are:
• Thread Group
• Samplers
• Listeners
• Configuration

• Thread Groups is a collection of Threads. Each thread represents one user using the application under test. Basically each Thread simulates one real user request to the server.
• The controls for a thread group allow you to Set the number of threads for each group.
• For example, if you set the number of threads as 100; JMeter will create and simulate 100 user requests to the server under test.

• As we know already that JMeter supports testing HTTP, FTP , JDBC and many other protocols.
• We already know that Thread Groups simulate user request to the server
• But how does a Thread Group know which type of requests (HTTP, FTP etc.) it needs to make ?
• The user request could be FTP Request, HTTP Request, JDBC Request...Etc.

• Let imagine you want to performance test an FTP server. You can use FTP request sampler in JMeter to do this task.
• This controller lets you send an FTP "download file" or "upload file" request to an FTP server.

• For example, if you want to download a file "Test.txt" from a FTP server under test, you need to configure some parameters in JMeter as figure below

• JMeter will send FTP command to FTP server ftp.example.com, and then download a file Test.txt from that server.

• This sampler lets you send an HTTP/HTTPS request to a web server.
• Consider the example below. JMeter send a HTTP request to Google website and retrieve HTML files or image from this website.

• In the tutorial JMeter Performance Testing, we will explain more about this HTTP request.

• This sampler lets you execute Database Performance Testing. It sends a JDBC Request (an SQL query) to a database.

• For example, a database server has a field test_result stored in a table name test_tbl. You want to query this data from the database server; you can configure JMeter to send a SQL query to this server to retrieve data.

• This sampler allows you to write a sampler using a BSF scripting language.
• Here is an example of BSF Sampler in JMeter

• This sampler allows you to read access logs and generate http requests. The log could be image, html, css....

• If you want to test a mail server, you can use SMTP sampler. This sampler is used to send email messages using SMTP protocol.

• Listeners: shows the results of the test execution. They can show results in different format such as tree, table, graph or log file

• Graph result listeners display the server response times on a Graph.

• View Result Tree show results of user request in basic HTML format.

• Table Result show summary of test result in table format

• Log show summary of test result in the text file

• set up defaults and variables for later use by samplers.
• The figure below shows some commonly used configuration elements in JMeter

• Suppose you want to test a website for 100 users signing-in with different credentials.
• You do not need to record the script 100 times! You can parameterization the script to enter different login credentials. This login information (e.g. Username, password) could be stored in a text file.
• JMeter has an element that allows you to read different parameters from that text file.
• It is "CSV Data Set Config", which is used to read lines from a file, and split them into variables.

• This is an example of CSV Data. It's a text file which contains user and password to login your target website.

• Let's understand this with an example -
• You used your browser (Firefox, IE...Etc) to browse www.wikitechy.com
• You login with your user and password.
• Your username and password will be stored in your computer as cookies.
• Next time, when you visit www.wikitechy.com , you don't need to do login again because your browser will use your cookies as user data to login.
• HTTP Cookie Manager also has the same feature like a web browser. If you have an HTTP Request and the response contains a cookie, the Cookie Manager automatically stores that cookie and will use it for all future requests to that particular web site.

• This element lets you set default values that your HTTP Request controllers use.
• For example,
• You are sending 100 HTTP requests to the server wikitechy.com
• You would have to manually enter server name = google.com for all these 100 requests
• Instead, you could add a single HTTP request defaults with the "Server Name or IP" field = google.com
• No need to type 100 times!

• This element will be explained detail in JMeter Performance Testing

• The Login Config Element lets you add or override username and password settings in samplers.
• For example, you want to simulate one user login to website www.facebook.com with user and password.
• You can use Login Config Element to add these user and password setting in user request

• The Login Config Element vs. the CSV data Config