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Oracle® Fusion Middleware Configuring and Using the Diagnostics Framework for Oracle WebLogic Server
12c Release 1 (12.1.1)

Part Number E24426-02
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14 Deploying WLDF Application Modules

This chapter describes how to deploy WebLogic Diagnostics Framework (WLDF) application modules. The only WLDF component you can use with applications is Instrumentation (see Configuring Application-Scoped Instrumentation).

You configure and manage instrumentation for an application as a diagnostics application module, which is an application-scoped resource. The configuration is persisted in a descriptor file which you deploy with the application. A diagnostic module deployed in this way is available only to the enclosing application. Using application-scoped resources ensures that an application always has access to required resources and simplifies the process of deploying the application to new environments.

You can deploy an application using a deployment plan, which permits dynamic configuration updates.

Note:

For instrumentation to be available for an application, instrumentation must be enabled on the server to which the application is deployed. (Server-scoped instrumentation is enabled and disabled in the <instrumentation> element of the diagnostics descriptor for the server.)

This chapter includes the following sections:

Deploying a Diagnostic Module as an Application-Scoped Resource

To deploy a diagnostic module as an application-scoped resource, you configure the module in a descriptor file named weblogic-diagnostics.xml. You then package the descriptor file with the application archive in the ARCHIVE_PATH/META-INF directory for the deployed application. For example:

D:\bea\wlserver_12.1\samples\server\medrec\dist\standalone\exploded\medrec\META-INF\weblogic-diagnostics.xml 

You can deploy the diagnostic module in both exploded and unexploded archives.

Note:

If the EAR archive contains WAR, RAR or EJB modules that have the weblogic-diagnostics.xml descriptors in their META-INF directory, those descriptors are ignored.

You can use any of the standard WebLogic Server tools provided for controlling deployment, including the WebLogic Administrative Console or the WebLogic Scripting Tool (WLST).

For information about creating modules and deploying applications, see Deploying Applications to Oracle WebLogic Server.

Because of the different ways that diagnostic application modules and diagnostic system modules are deployed, there are some differences in how you can reconfigure them and when those changes take place, as shown in Table 14-1. The details of how to work with diagnostic application modules is described throughout this section. See Chapter 11, "Configuring Instrumentation," for information about working with diagnostic system modules.

Table 14-1 Comparing System and Application Modules

Monitor Type Add/Remove Objects Dynamically Add/Remove Objects with Console Modify with JMX Remotely Modify with JSR-88 (non-remote) Modify with Console

System Module

Yes

Yes

Yes

No

Yes - via JMX

Application Module

Yes, when HotSwapFoot 1  is enabled

No, when HotSwap is not enabled: module must be redeployed

Yes

No

Yes

Yes - via plan


Footnote 1 See Using Deployment Plans to Dynamically Control Instrumentation Configuration, for information about HotSwap.

Using Deployment Plans to Dynamically Control Instrumentation Configuration

WebLogic Server supports deployment plans, as specified in the Java EE Deployment Specification API (JSR-88). With deployment plans, you can modify an application's configuration after the application is built, without having to modify the application archives. For complete documentation on using deployment plans in WebLogic Server, see "Configuring Applications for Production Deployment" in Deploying Applications to Oracle WebLogic Server.

If you want to reconfigure an application that was deployed without a deployment plan, you must undeploy, unarchive, reconfigure, re-archive, and then redeploy the application. With a configuration plan, you can dynamically change many configuration options simply by updating the plan, without modifying the application archive.

If you enable a feature called Java HotSwap (see Enabling Java HotSwap) before deploying your application with a deployment plan, you can dynamically update all instrumentation settings without redeploying the application. If you do not enable HotSwap, or if you do not use a deployment plan, changes to some instrumentation settings require redeployment, as shown in Table 14-2.

Table 14-2 When Application Instrumentation Configuration Changes Take Effect

Scenario / Settings to Use => Add and remove monitors Attach and detach actions Enable and disable monitors

Application deployed with a deployment plan, HostSwap enabled

Dynamic

Dynamic

Dynamic

Application deployed with a deployment plan, HotSwap not enabled

Must redeploy applicationFoot 1 

Dynamic

Dynamic

Application deployed without a deployment plan

Must redeploy application

Must redeploy application

Must redeploy application


Footnote 1 If HotSwap is not enabled, you can "remove" a monitor, but that just disables it. The instrumentation code is still woven into the application code. You cannot re-enable it through a modified plan.

You can use a deployment plan to dynamically update configuration elements without redeploying the application.

Using a Deployment Plan: Overview

The general process for creating and using a deployment plan is as follows:

  1. Create a well-formed weblogic-diagnostics.xml descriptor file for the application.

    Oracle recommends that you create an empty descriptor. This provides full flexibility for dynamically modifying the configuration. It is possible to create monitors in the original descriptor file and then use a deployment plan to override the settings. However, you will be unable to completely remove monitors without redeploying. If you add monitors using a deployment plan to an empty descriptor, all such monitors can be removed. For information about configuring diagnostic application modules, see Configuring Application-Scoped Instrumentation.

    The schema for weblogic-diagnostics.xml is available at http://xmlns.oracle.com/weblogic/weblogic-diagnostics/1.0/weblogic-diagnostics.xsd.

  2. Place the descriptor file weblogic-diagnostics.xml, in the top-level META-INF directory of the appropriate archive.

  3. Create a deployment plan, for example by using weblogic.PlanGenerator. See Creating a Deployment Plan Using weblogic.PlanGenerator.

  4. Start the server, optionally enabling Java HostSwap. See Enabling Java HotSwap.

  5. Deploy the application using the deployment plan. See Deploying an Application with a Deployment Plan).

  6. When needed, edit the plan and update the application with the plan. See Updating an Application with a Modified Plan.

Creating a Deployment Plan Using weblogic.PlanGenerator

You can use the weblogic.PlanGenerator tool to create an initial deployment plan, and interactively override specific properties of the weblogic-diagnostics.xml descriptor.

The PlanGenerator tool inspects all Java EE deployment descriptors in the selected application, and creates a deployment plan with null variables for all relevant WebLogic Server deployment properties that configure external resources for the application.

To create the plan, use the following syntax:

java weblogic.PlanGenerator -plan output-plan.xml [options] 
      application-path

For example:

java weblogic.PlanGenerator -plan foo.plan -dynamics /test/apps/mywar

Note:

The -dynamics options specifies that the plan should be generated to include only those options that can be dynamically updated.

For more information about creating and using deployment plans, see "Configuring Applications for Production Deployment" in Deploying Applications to Oracle WebLogic Server.

For more information about using PlanGenerator, see weblogic.PlanGenerator Command Line Reference" and "Exporting an Application for Deployment to New Environments" in Deploying Applications to Oracle WebLogic Server

Sample Deployment Plan for Diagnostics

Example 14-1 shows a simple deployment plan generated using weblogic.PlanGenerator. (For readability, some information has been removed.) The plan enables the Servlet_Before_Service monitor and attaches to it the actions DisplayArgumentsAction and StackDumpAction.

Example 14-1 Sample Deployment Plan

<?xml version='1.0' encoding='UTF-8'?>
<deployment-plan xmlns="http://xmlns.oracle.com/weblogic/weblogic-diagnostics"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
global-variables="false">
  <application-name>jsp_expr_root</application-name>

  <variable-definition>
    <!-- Add two additional actions to Servlet_Before_Service monitor -->
    <variable>
      <name>WLDFInstrumentationMonitor_Servlet_Before_Service_Actions_113050559713922</name>
      <value>"DisplayArgumentsAction","StackDumpAction"</value>
    </variable>
    <-- Enable the Servlet_Before_Service monitor -->
    <variable>
      <name>WLDFInstrumentationMonitor_Servlet_Before_Service_Enabled_113050559713927</name>
      <value>true</value>
    </variable>
  </variable-definition>

  <module-override>
    <module-name>jspExpressionWar</module-name>
    <module-type>war</module-type>
    <module-descriptor external="false">
      <root-element>weblogic-web-app</root-element>
      <uri>WEB-INF/weblogic.xml</uri>
    </module-descriptor>
    <module-descriptor external="false">
    <root-element>web-app</root-element>
    <uri>WEB-INF/web.xml</uri>
    </module-descriptor>
    <module-descriptor external="false">
      <root-element>wldf-resource</root-element>
      <uri>META-INF/weblogic-diagnostics.xml</uri>
      <variable-assignment>
        <name>WLDFInstrumentationMonitor_Servlet_Before_Service_Actions_113050559713922</name>
        <xpath>/wldf-resource/instrumentation/wldf-instrumentation-monitor/[name="Servlet_Before_Service"]/action</xpath>
        </variable-assignment>
        <variable-assignment>
          <name>WLDFInstrumentationMonitor_Servlet_Before_Service_Enabled_113050559713927</name>
          <xpath>/wldf-resource/instrumentation/wldf-instrumentation-monitor/[name="Servlet_Before_Service"]/enabled</xpath>
        </variable-assignment>
      </module-descriptor>
    </module-override>
  <config-root xsi:nil="true"></config-root>
</deployment-plan>

For a list and documentation of diagnostic monitors and actions that you can specify in the deployment plan, see Appendix B, "WLDF Instrumentation Library."

Enabling Java HotSwap

To enable Java HotSwap, start the server with the following command line switch:

-javaagent:$WL_HOME/server/lib/diagnostics-agent.jar

Deploying an Application with a Deployment Plan

To take advantage of the dynamic control provided by a deployment plan, you must deploy the application with the plan.

You can use any of the standard WebLogic Server tools for controlling deployment, including the Administration Console or the WebLogic Scripting Tool (WLST). For example, the following WLST command deploys an application with a corresponding deployment plan.

wls:/mydomain/serverConfig> deploy('myApp', './myApp.ear', 'myserver',
          'nostage', './plan.xml')

After deployment, the effective diagnostic monitor configuration is a combination of the original descriptor, combined with the overridden attribute values from the plan. If the original descriptor did not include a monitor with the given name and the plan overrides an attribute of such a monitor, the monitor is added to the set of monitors to be used with the application. This way, if your application is built with an empty weblogic-diagnostics.xml descriptor, you can add diagnostic monitors to the application during or after the deployment process without having to modify the application archive.

Updating an Application with a Modified Plan

You change configuration settings by modifying the deployment plan and then updating or redeploying the application, depending on whether or not HotSwap is enabled. (See Table 14-2 to see when you can simply update the application and when you must redeploy it.) You can use any of the standard WebLogic Server tools for updating or redeploying, including the Administration Console or the WebLogic Scripting Tool (WLST).

If you enabled HotSwap, you can update the configuration for the application with the modified plan values by updating the application with the plan. For example, the following WLST command updates an application with a plan:

wls:/mydomain/serverConfig> updateApplication('BigApp', 
            'c:/myapps/BigApp/newPlan/plan.xml', stageMode='STAGE',
            testMode='false') 

If you did not enable HotSwap, you must redeploy the application for certain changes to take effect. For example, the following WLST command redeploys an application using a plan:

wls:/mydomain/serverConfig> redeploy('myApp' 'c:/myapps/plan.xml')