beginSample

beginSample(samplingHandle:          Integer;
            libraryName:             String;
            initializationParameter: String);

The beginSample method of the System class opens a new sampling context for each of the nodes in the sample definition group, begins the accumulation of sampling statistics for those nodes, and invokes the following entry points:

• NodeSampleInfoCallBack, passing it the initializationParameter string and setting the eventType parameter in the user library entry point to 1.

• NodeSampleNodeInfoCallBack, passing it information about the local node to the point and setting the eventType parameter in the user library entry point to 1.

• NodeSampleProcessInfoCallBack, invoked every time a process begins and once for every existing process at the time sampling begins.

The samplingHandle parameter identifies the context that is sampled.

When this method is called in your application, request statistics are stored in transient memory for every process in the nodes of the sample definition group until they are passed to corresponding entry point in the user library specified in the libraryName parameter. The JADE-supplied library writes a record type (6) to the statistics file.

For details about the node sampling entry points and the contents of the statistics sample files, see "JADE Sampling Libraries" and "Statistics File Format", later in this chapter.

If you are using the filesmpl or tcpsmpl JADE sampling library, you can set the initializationParameter parameter to "<null>" or to "" so that sample values will not be output. For filesmpl, the values will not be written to a file.

For tcpsmpl, the values will not be sent to a TCP/IP connection. Use this option in situations where node sampling needs to be enabled for the Process class getRequestStatistics method but no file or TCP/IP output is wanted. For more details, see "Direct Retrieval of Node Sampling Statistics", later in this chapter.