Package org.apache.jmeter.visualizers.backend

Interface BackendListenerClient

All Known Implementing Classes:
AbstractBackendListenerClient, GraphiteBackendListenerClient, InfluxdbBackendListenerClient, InfluxDBRawBackendListenerClient
public interface BackendListenerClient
This interface defines the interactions between the BackendListener and external Java programs which can be executed by JMeter. Any Java class which wants to be executed using the BackendListener test element must implement this interface (either directly or through AbstractBackendListenerClient).

JMeter will create one instance of a BackendListenerClient implementation for each user/thread in the test. Additional instances may be created for internal use by JMeter (for example, to find out what parameters are supported by the client).

When the test is started, setupTest() will be called on each thread's BackendListenerClient instance to initialize the client. Then handleSampleResults(List, BackendListenerContext) will be called for each SampleResult notification. Finally, teardownTest(BackendListenerContext) will be called to allow the client to do any necessary clean-up.

The JMeter BackendListener GUI allows a list of parameters to be defined for the test. These are passed to the various test methods through the BackendListenerContext. A list of default parameters can be defined through the getDefaultParameters() method. These parameters and any default values associated with them will be shown in the GUI. Users can add other parameters as well.

Listeners should extend AbstractBackendListenerClient rather than implementing BackendListenerClient directly to protect your code from future changes to the interface.

While it may be necessary to make changes to the BackendListenerClient interface from time to time (therefore requiring changes to any implementations of this interface), we intend to make this abstract class provide reasonable default implementations of any new methods so that subclasses do not necessarily need to be updated for new versions. Implementing BackendListenerClient directly will continue to be supported for cases where extending this class is not possible (for example, when the client class is already a subclass of some other class).

Since:
2.13

  • Method Details

    • setupTest

      void setupTest(BackendListenerContext context) throws Exception
      Do any initialization required by this client. It is generally recommended to do any initialization such as getting parameter values here rather than handleSampleResults(List, BackendListenerContext) in order to add as little overhead as possible to the test.
      Parameters:
      context - provides access to initialization parameters.
      Throws:
      Exception - when setup fails

    • handleSampleResults

      void handleSampleResults(List<SampleResult> sampleResults, BackendListenerContext context)
      Handle sampleResults, this can be done in many ways:
      • Write to a file
      • Write to a remote server
      • ...
      Parameters:
      sampleResults - List of SampleResult
      context - provides access to initialization parameters.

    • teardownTest

      void teardownTest(BackendListenerContext context) throws Exception
      Do any clean-up required at the end of a test run.
      Parameters:
      context - provides access to initialization parameters.
      Throws:
      Exception - when tear down fails

    • getDefaultParameters

      default Arguments getDefaultParameters()
      Provide a list of parameters which this test supports. Any parameter names and associated values returned by this method will appear in the GUI by default so the user doesn't have to remember the exact names. The user can add other parameters which are not listed here. If this method returns null then no parameters will be listed. If the value for some parameter is null then that parameter will be listed in the GUI with an empty value.
      Returns:
      a specification of the parameters used by this test which should be listed in the GUI, or null if no parameters should be listed.

    • createSampleResult

      default SampleResult createSampleResult(BackendListenerContext context, SampleResult result)
      Create a copy of SampleResult, this method is here to allow customizing what is kept in the copy, for example copy could remove some useless fields. Note that if it returns null, the sample result is not put in the queue. Defaults to returning result.
      Parameters:
      context - BackendListenerContext
      result - SampleResult
      Returns:
      SampleResult