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Oracle® Fusion Middleware Visualizer User's Guide for Oracle Complex Event Processing
11g Release 1 (11.1.1.6.3)

Part Number E14302-10
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3 Overview of Application Tasks

This chapter introduces the typical application tasks you can perform with Oracle CEP Visualizer, including managing event processing networks (EPNs), application lifecycle, Oracle Continuous Query Language (CQL) rules, and configuration history.

3.1 Event Processing Network (EPN) Management

The Oracle CEP Event Processing Network (EPN) represents the interconnections between the various Oracle CEP components of an Oracle CEP application. Using Oracle CEP Visualizer, you can manage the EPN, including viewing and changing the configuration of a stage, recording and playing back events, and monitoring the throughput and latency of a stage or path. Right-click a stage to select common stage-related functions from a convenient context menu.

For more information, see:

3.2 Application Lifecycle Management

You can manage the full application lifecycle including uploading an application, deploying it, suspending and resuming the application, and undeploying the application.

For more information, see:

3.3 Rules Management

You can create, replace, and delete the rules in the Oracle CQL and EPL processors of Oracle CEP applications you develop and deploy as well as applications that Oracle CEP server deploys.

It is important to note that Oracle CEP Visualizer will update your configuration file on the server with any queries that you create. However, you will not see this take effect in your application from within the Oracle CEP IDE for Eclipse, in order to make the change there you will need to copy and paste the query from Oracle CEP Visualizer into your application.

For more information, see:

3.4 Configuration History Management

Using the Oracle CEP Visualizer, you can manage the configuration changes you make to Oracle CEP components. You can review change history and you can undo (roll back) changes to an earlier version. You can perform these operations on a given resource or application in both standalone-server and multi-server domains.

Alternatively, you can manage configuration history using the wlevs.Admin command-line tool.

For more information, see:

3.4.1 Enabling and Disabling Configuration History Management

By default, Oracle CEP provides resource and application configuration history management.

Optionally, you can disable this feature by editing the CEP_SERVER/startwlevs.cmd/sh file and adding the com.oracle.ocep.config.version.enabled system property to the last line (in practice, the command should be on one line):

"$JAVA_HOME/bin/java" $JVM_ARGS $DEBUG_ARGS -Dwlevs.home="$USER_INSTALL_DIR"
    -Dcom.oracle.ocep.config.version.enabled=false -Dbea.home="$BEA_HOME"  
    -jar "${USER_INSTALL_DIR}/bin/wlevs.jar" $ARGS

If you disable this feature, Oracle CEP cannot propagate rules among the Oracle CEP servers in a multi-server domain. In this case, to propagate rule changes, you must manually update the rules in all the servers of a multi-server domain.

If you disable this feature and then wish to re-enable it, you must do so as follows:

  1. Undeploy your Oracle CEP application.

  2. Shut down the Oracle CEP server.

  3. Edit the startwlevs.cmd/sh file to either remove the -Dcom.oracle.ocep.config.version.enabled system property or set it to true.

  4. Start the Oracle CEP server.

  5. Deploy your Oracle CEP application.

    Failure to do so may cause rule propagation to fail in a multi-server domain and may prevent the Oracle CEP Visualizer from maintaining a consistent view of the Oracle CEP servers in a multi-server domain.

3.4.2 Configuring Change Record Purge Behavior

You can set how often change records in the configuration history are purged, along with how many records are retained on each purge (in other words, records not purged). You might use these settings for enhancing performance. Purging more often and retaining fewer records might improve performance in some cases, such as when your application makes a large number of configuration changes dynamically at run time.

You configure these settings with system properties that you pass when starting the Oracle CEP server. The system properties are as follows:

  • com.oracle.ocep.config.version.changeRecordsPurgeFrequency -- Amount of time, in seconds, between each purge. Default value is 3600 (one hour).

  • com.oracle.ocep.config.version.numSavedChangeRecords -- Number of change records that will be saved when purging old change records. Default value is 25.

To make these settings, edit the CEP_SERVER/startwlevs.cmd/sh file, adding the system property to the last line (in actual practice, the command should be on one line).

For example, to set the purge frequency to 10 minutes and retain 50 records, you could use a command such as the following:

"$JAVA_HOME/bin/java" $JVM_ARGS $DEBUG_ARGS -Dwlevs.home="$USER_INSTALL_DIR"
    -Dcom.oracle.ocep.config.version.changeRecordsPurgeFrequency=600
    -Dcom.oracle.ocep.config.version.numSaveChangeRecords=50
    -Dbea.home="$BEA_HOME"  
    -jar "${USER_INSTALL_DIR}/bin/wlevs.jar" $ARGS

You must restart the Oracle CEP server to have your changes take affect.

3.4.3 Resource Configuration History Management

You can manage the configuration history of the following Oracle CEP resources:

  • Oracle CEP high availability adapters

  • Oracle CQL rules

For more information, see Section 8.1, "Managing Resource Configuration History".

3.4.4 Application Configuration History Management

You can manage the configuration history for a given application. This allows you to see a summary of all the configuration changes made to all resources of a given application.

For more information, see Section 8.2, "Managing Application Configuration History".

3.4.5 Application Lifecycle and Configuration History Management

When you deploy an application, the Oracle CEP server creates a new configuration history for the application.

When you update an application, the Oracle CEP server erases the existing configuration history and creates a new configuration history for the application.

When you uninstall an application, the Oracle CEP server erases the configuration history for the application.

For more information, see Section 3.2, "Application Lifecycle Management".

3.4.6 Multi-Server Domains and Configuration History Management

When you deploy an application to a multi-server domain, consider the following configuration history management restrictions:

For more information, see Section 9.8, "Multi-Server Domain Management".

3.4.6.1 Rejoining a Multi-Server Domain

When an Oracle CEP server joins (or rejoins) a multi-server domain, the server's existing configuration history records (if any) are deleted and replaced with the current multi-server domain configuration history when the Oracle CEP server has synchronized with the primary.

3.4.6.2 Simultaneous Updates

Oracle CEP does not support simultaneous configuration updates from more than one Oracle CEP server in a multi-server domain.

Make configuration changes from one Oracle CEP Visualizer instance on one node in the multi-server domain.