As you have seen we have added some basic elements to the Test Plan like Sampler and some listeners. Similarly you can add many other elements in your Test Plan as shown under Group heading.
|Samplers||The requests to the servers are being sent by these elements for the request types SOAP, JDBC,"Java", HTTP/HTTPS, FTP,|
|Listeners||The results of the run can be saved by these elements in the single request, tabular forms etc by saving the results in a named file.|
|Timers||To make the test more realistic we use Timers element to insert delays between the requests.|
|Logic||Logic controllers are used if you have defined the request to be executed on some logic like if-then-else and loop structures in Java etc.|
|Configuration Elements||common information about the requests is added to work with samplers using this element.|
|Assertions||This element is used to check whether you are getting the responses within a given amount of time containing the expected data or not.|
What does Apache JMeter do?
JMeter is not a browser
Errors and warnings are also depicted by the JMeter. These errors and warnings are reported to the jmeter.log file by the JMeter including some information which runs itself on the test. Some errors which are not depicted by the JMeter may appear on the command console. You need to check the log file for any errors being reported if in case the test performed by you is not going the way to be expected. For instance a syntax error in a function call might be reported in the log file.
The errors which are not trapped and logged by the JMeter get stored as attributes of the sample result. For instance sampling errors like HTTP 404 - file not found etc get stored as attributes of the sample result.
Recommend the tutorial