Deploying Applications to WebLogic Server

      

Preparing Applications and Modules for Deployment

The following sections provides information on key topics required to prepare applications for deployment:

 

Packaging Files for Deployment

WebLogic Server supports deployments that are packaged either as archive files using the jar utility or Ant's jar tool, or as exploded archive directories.

In general, using archived files is more efficient when deploying applications to managed servers. However, it makes updating the application, such as updating web content, more difficult as it requires a redeployment of the application.

 

Using Archived Files

An archive file is a single file that contains all of an application's or module's classes, static files, directories, and deployment descriptor files. In most production environments, the applications an Administrator receives for deployment are stored as archive files.

Deployment units that are packaged using the jar utility have a specific file extension depending on the type:

In addition to an archive file, you may also receive a deployment plan, which is a separate file that configures the application for a specific environment. Configuring Applications for Production Deployment describes deployment plans in more detail.

 

Using Exploded Archive Directories

An exploded archive directory contains the same files and directories as a JAR archive. If you choose to use an exploded archive directory, you may be required to manually unpack a previously-archived deployment. However, the files and directories reside directly in your file system and are not packaged into a single archive file with the jar utility.

You may choose to deploy from an exploded archive directory under the following circumstances:

Java EE Rules for Deploying Exploded EAR Directories without Deployment Descriptors

The Java EE specification recommends that archived EARs (Enterprise Application Archives) can be deployed to a Java EE-compliant server without any deployment descriptors. To achieve this, all containers assume reasonable defaults or use annotated classes. In addition to supporting this mandate, WebLogic Server also allows deploying exploded EAR directories without deployment descriptors.

Since this applies to directories, certain rules are used to identify EARs and their nested modules. Otherwise, the WebLogic Server Administration Console or deployment tools will not treat the directories as valid exploded Java EE directories.

 

Creating an Exploded Archive Directory from an Archive File

If you have an archive file that you want to deploy as an exploded archive directory, use the jar utility to unpack the archive file in a dedicated directory. For example: 

   mkdir /myapp

   cd /myapp

   jar xvf /dist/myapp.ear

If you are unpacking an archive file that contains other module archive files (for example, an Enterprise Application or Web Service that includes JAR or WAR files) and you want to perform partial updates of those modules, expand the embedded archive files as well. Make sure that you unpack each module into a subdirectory having the same name as the archive file. For example, unpack a module named myejb.jar into a /myejb.jar subdirectory of the exploded Enterprise Application directory.

If you want to use different subdirectory names for the archived modules in an exploded EAR file, modify any references to those modules in the application itself. For example, update the URI values specified in application.xml and CLASSPATH entries in the manifest.mf file.

 

Understanding Default Deployment Names

When you first deploy an application or stand-alone module to one or more WebLogic Server instances, you specify a deployment name to describe collectively the deployment files, target servers, and other configuration options you selected. You can later redeploy or stop the deployment unit on all target servers by simply using the deployment name. The deployment name saves you the trouble of re-identifying the deployment files and target servers when you want to work with the deployment unit across servers in a domain.

If you do not specify a deployment name at deployment time, the deployment tool selects a default name based on the deployment source file(s). For archive files, weblogic.Deployer uses the name of the archive file without the file extension. For example, the file myear.ear has a default deployment name of myear. For an exploded archive directory, weblogic.Deployer uses the name of the top-level directory you deploy.

For Java EE libraries and optional packages, weblogic.Deployer uses the name specified in the library's manifest file. If no name was specified in the library's manifest file, you can specify one with the -name option.

See the following section, Understanding Application Naming Requirements for information on application naming requirements; See Deploying Applications and Modules with weblogic.deployer to specify a non-default deployment name.

 

Understanding Application Naming Requirements

In order to successfully deploy an application to WebLogic Server, the application name must be valid. Application naming requirements are as follows:

 

Understanding Deployment Version Strings

In addition to a deployment name, an application or module can also have an associated version string. The version string distinguishes the initial deployment of the application from subsequent redeployed versions. For example, you may want to later update the application to fix problems or add new features. In production systems, it is critical to maintain a version string for both the initial and subsequent deployments of an application. Doing so allows you to update and redeploy an application version without interrupting service to existing clients. See Redeploying Applications in a Production Environment for more information.

The version string is specified in the manifest file for the application, and should be provided by your development team along with the other deployment files. Assigning Application Versions in Developing WebLogic Server Applications describes the conventions for specifying the version string.

 

Creating an Application Installation Directory

The application installation directory separates generated configuration files from the core application files, so that configuration files can be easily changed or replaced without disturbing the application itself. The directory structure also helps you to organize and maintain multiple versions of the same application deployment files.

The following figure shows the application installation directory hierarchy for storing a single version of a deployable application or module. Figure 3-1 Application Installation Directory

Application Installation Directory

Oracle recommends copying all new production deployments into an application installation directory before deploying to a WebLogic Server domain. Deploying from this directory structure helps you easily identify all of the files associated with a deployment unit—you simply deploy the installation root using the Administration Console, and the Console automatically locates associated files such as deployment plans and WebLogic Server deployment descriptors that were generated during configuration.

 

Steps for Creating an Application Installation Directory

To create an application installation directory:

  1. Choose a top-level directory where you want to store deployment files for applications and modules on your system. Follow these best practices:

    • Do not store deployment files within a WebLogic Server domain directory.

    • Use source control if available to maintain deployment source files.

    • If possible, store deployment files in a directory that is accessible by the Administration Server and Managed Servers in your domain.

      The instructions that follow use the sample deployment directory, c:\deployments\production.

  2. Create a dedicated subdirectory for the application or module you want to deploy: 
    mkdir c:\deployments\production\myApplication

  3. Create a subdirectory beneath the application directory to designate the version of the application you are deploying. Name the subdirectory using the exact version string of the application. For example: 
    mkdir c:\deployments\production\myApplication\91Beta

  4. The version subdirectory will become the installation root directory from which you deploy the directory. Create subdirectories named app and plan under the version subdirectory: 
    mkdir c:\deployments\production\myApplication\91Beta\app

    mkdir c:\deployments\production\myApplication\91Beta\plan

    If you have more than one deployment plan associated with the application, create one \plan subdirectory for each plan. For example, if you have two deployment plans associated with the 91Beta version of the application myApplication, you would create two \plan subdirectories. For instance: 

    mkdir c:\deployments\production\myApplication\91Beta\plan1

    mkdir c:\deployments\production\myApplication\91Beta\plan2

  5. Copy your application source deployment files into the \app subdirectory. If you are deploying from an archive file, simply copy the archive file, as in: 
    cp c:\downloads\myApplication.ear c:\deployments\production\myApplication\91Beta\app

    If you are deploying from an exploded archive directory, copy the complete exploded archive directory into \app: 

    cp -r c:\downloads\myApplication c:\deployments\production\myApplication\91Beta\app

    This results in the new directory, c:\deployments\production\myApplication\91Beta\app\myApplication.

  6. If you have one or more deployment plans for the application, copy them into the \plan subdirectories.

    If you have one deployment plan for the application: 

    cp c:\downloads\myApplicationPlans\plan.xml c:\deployments\production\myApplication\91Beta\plan

    If you have two deployment plans for the application: 

    cp c:\downloads\myApplicationPlans\plan1.xml c:\deployments\production\myApplication\91Beta\plan1

    cp c:\downloads\myApplicationPlans\plan2.xml c:\deployments\production\myApplication\91Beta\plan2

    If you do not have an existing deployment plan, you can create one using the Administration Console as described in Configuring Applications for Production Deployment. The Administration Console automatically stores newly-generated deployment plans in the \plan subdirectory of the application installation directory.

  7. To install the application using Administration Console, select the application installation directory. By default, the Administration Console will use a plan named plan.xml, if one is available in the \plan subdirectory. The Administration Console does not identify plans in subdirectories other than the \plan subdirectory; in other words, plans in \plan1 or \plan2 subdirectories are not identified by the Administration Console. Therefore, if multiple plans for your application are available, indicate, in config.xml, the plan you would like to use. See Configuring Applications for Production Deployment. For information on config.xml, see Creating WebLogic Domains Using the Configuration Wizard.

    After installing the application, you can configure, deploy, or distribute the application as necessary.

    You cannot specify an application installation directory when using the weblogic.Deployer tool, and the tool does not use an available plan.xml file by default. You must specify the actual deployment file(s) and plan to use for deployment. See Deploying Applications and Modules with weblogic.deployer.

 

Using FastSwap Deployment to Minimize Redeployment

Today's web application developers expect to make changes to a deployed application and see those changes immediately by refreshing the browser. On the Java EE side, developers have to typically go through the following cycle to see their changes in action.

Edit -> Build -> Deploy -> Test

These steps, along with the many required descriptor elements, makes developing applications with Java EE seem complex and top-heavy. Among these steps, the Build and Deploy cycles are necessitated by Java and by the application server being employed. IDEs are trying to make the Edit and Build steps seamless by providing incremental compilation support. On the server side, the WLS FastSwap deployment feature makes the Deploy and Test cycles just as seamless.

 

How FastSwap Deployment Works

Java EE 5 introduces the ability to redefine a class at runtime without dropping its ClassLoader or abandoning existing instances. This allows containers to reload altered classes without disturbing running applications, vastly speeding up iterative development cycles and improving the overall development and testing experiences. The usefulness of the Java EE dynamic class redefinition is severely curtailed, however, by the restriction that the shape of the class – its declared fields and methods – cannot change. The purpose of FastSwap is to remove this restriction in WLS, allowing the dynamic redefinition of classes with new shapes to facilitate iterative development.

With FastSwap, Java classes are redefined in-place without reloading the ClassLoader, thereby having the decided advantage of fast turnaround times. This means that you do not have to wait for an application to redeploy and then navigate back to wherever you were in the Web page flow. Instead, you can make your changes, auto compile, and then see the effects immediately.

 

Supported FastSwap Application Configurations

The following application configuration are supported when using FastSwap deployment:

 

Enabling FastSwap In Your Application

To enable FastSwap in your application, add the following element to the weblogic-application.xml file.

<fast-swap>true</fast-swap>

For more information on the weblogic-application.xml elements, see Enterprise Application Deployment Descriptor Elements in Developing Applications with WebLogic Server.

FastSwap can also be enabled for a standalone web-application by adding the <fast-swap> element to the weblogic.xml file. For more information on the weblogic.xml elements, see weblogic.xml Deployment Descriptor Elements in Developing Web Applications, Servlets, and JSPs for WebLogic Server.

 

Overview of the FastSwap Process

The following steps describe how the FastSwap deployment process works:

  1. Once FastSwap is enabled at the descriptor level, an appropriate ClassLoader is instantiated when the application is deployed to WLS.

  2. Open a browser to see the application at work. Then modify (add/edit/delete) the methods and/or classes (see Limitations When Using FastSwap) and compile them.

    It is recommended that you use an IDE such as Eclipse or IntelliJ and setting the compile-on-save option so that java files are compiled on saving. Also note that the FastSwap agent does not compile Java files.

  3. Refresh the browser or send a new request to the application.

    The FastSwap agent tries to find all classes that have been modified since the last iteration by looking at all directories in the classpath. Considering an exploded application with a single web application, the following directories are examined for any class file modifications based on their timestamps: 

    ExampleApp/APP-INF/classes

    ExampleApp/webapp/WEB-INF/classes

    The FastSwap agent redefines the modified classes in the application and then serves the request.

Using Ant with the JMX Interface

For headless applications (that is, applications not fronted by a web application), class redefinition can be explicitly initiated using the JMX interface. An Ant task that uses the JMX interface can be used to initiate class redefinition, as shown in following Ant FastSwapTask example. Listing 3-1 

<project name='MyProject' default='all' >

  <taskdef name='fast-swap'  classname='com.bea.wls.redef.ant.FastSwapTask'/>

  <target name='all'>

    <!--

      Redefine classes which have changed since they were last loaded.

      Required parameters:

       adminUrl: Connection url

           user: User name

       password: User password

         server: Managed server name

      application: Deployed application name

      Optional parameters:

          module: Name of the module within the application.

                  If not specified, all modules within the application

                  will be processed.

       failonerror: Default=true. If true, task will fail if fast-swap failed.

                  Otherwise, a message will be displayed and the task will

                    return success.

         timeout: Default=300. Timeout in seconds.

      classnames: Comma separated list of classnames to process. If not

                  specified, all classes within specified modules (if any)

                    in the application will be considered.

    -->

    <fast-swap

      adminUrl='t3://localhost:7001'

      user='weblogic'

      password='weblogic'

      server='myserver'

       application='SimpleApp'

      module='SimpleAppCookie'

      failonerror='false'

      timeout='30'

      classnames='examples.servlets.CookieCounter1,

                  examples.servlets.CookieCounter2,

                    examples.servlets.CookieCounter'

    />

  </target>

</project>

 

Application Types and Changes Supported with FastSwap

FastSwap is supported with POJOs (JARs), Web applications (WARs) and enterprise applications (EARs) deployed in an exploded format. FastSwap is not supported with resource adapters (RARs).

The following types of changes are supported with FastSwap:

The following table lists detailed change types supported with FastSwap:

Table 3-1 Supported Application Types and Changes
Scope Java Change Type Supported Notes
Java Class Add method Yes Addition of the finalize method is not supported.
Instance (non-abstract) Remove method Yes Addition of the finalize method is not supported.
a) Add field Yes

b) Remove field Yes

c) Change method body Yes

d) Add constructor Yes

e) Remove constructor Yes

f) Change field modifiers Yes

g) Change method modifiers Yes

Class-level (static) Add method Yes
Remove method Yes

Change body method Yes

Class Hierarchy Changes Change list of implemented interfaces No
Change extends “SuperClass” No

Abstract Java Class Add abstract method Yes
Delete abstract method Yes

All other supported changes (a– g) listed in Instance Yes

“final” Java Class Same supported changes (a– g) listed in Instance Yes
“final” Java Method Same supported changes (a– g) listed in Instance Yes
“final” Java Field Same supported changes (a– g) listed in Instance Yes
Enum Add constants No
Remove constants No

Add/remove methods No
Anonymous Inner Class Add/remove fields NA Not supported by the Java language
Add/remove methods No
Static Inner Class Same supported changes (a– g) listed in Instance Yes
Member Inner Classes (non-static inner classes) Same supported changes (a– g) listed in Instance Yes
Local Inner Classes Same supported changes (a– g) listed in Instance Yes
Java Interface Add method Yes
Java Reflection Access existing fields/methods Yes
Access new methods No New methods are not seen using Reflection and some synthetic methods are exposed.
Access new fields No New fields are not seen using Reflection.
Annotations on Classes Add or remove method/field annotations No
Annotation Type Add or remove methods/attributes No
Exception Classes Same supported changes (a– g) listed in Instance Yes
EJB Interface Add/remove methods No Changes to EJB interfaces involve Reflection, which is not fully supported.
EJB 3.0 Session/MDB EJB Implementation Class Add/remove methods No Any support classes referenced by the EJB classes can be modified.
Add/remove fields No

EJB 3.0 EntityBean Add/remove methods No Any support classes referenced by the EJB classes can be modified.
Add/remove fields No

EJB Interceptors Add/remove methods No Any support classes referenced by the EJB classes can be modified.
Add/remove fields No

 

Limitations When Using FastSwap

The following limitation apply when using FastSwap deployment:

 

Handling Unsupported FastSwap Changes

When FastSwap is enabled, after you recompile a class, FastSwap attempts to redefine classes in existing classloaders. If redefinition fails because your changes fall outside the scope of supported FastSwap changes, the JVM throws an UnsupportedOperationException in the WLS window and in the server log file. Your application will not reflect the changes, but will continue to run.

To implement your changes, you can redeploy the application or affected modules (partial redeploy), depending on the application type and the extent of your changes.

 

Best Practices for Preparing Deployment Files

The following best practices are recommended when preparing applications and modules for deployment: