About Deployment

• The Deployment Life Cycle

• Types of J2EE Archive Files

• Naming Conventions

The Deployment Life Cycle

After installing the Application Server and starting a domain, you can deploy (install) J2EE applications and modules. During deployment and as the application is changed, an application or module can go through the following stages:

1. Initial Deployment

   Before deploying an application or module, start the domain.

   Deploy (install) an application or module to a specific stand-alone server instance or cluster. Because applications and modules are packaged in archive files, specify the archive file name during deployment. The default is to deploy to the default server instance server.

   If you deploy to server instances or clusters, the application or module exists in the domain’s central repository and is referenced by any clusters or server instances you deployed to as targets.

   You can also deploy to the domain using the asadmin deploy command, not the Admin Console. If you deploy the application or module only to the domain, it exists in the domain’s central repository, but no server instances or clusters reference it until you add references, as explained in The Deployment Life Cycle.

   Deployment is dynamic: you don’t need to restart the server instance after deploying application or module for applications to be available. If you do restart, all deployed applications and modules are still deployed and available.

2. Enabling or Disabling

   By default, a deployed application or module is enabled, which means that it is runnable and can be accessed by clients if it has been deployed to an accessible server instance or cluster. To prevent access, disable the application or module. A disabled application or module is not uninstalled from the domain and can be easily enabled after deployment.

3. Adding or Deleting Targets for a Deployed Application or Module

   Once deployed, the application or module exists in the central repository and can be referenced by a number of server instances and/or clusters. Initially, the server instances or clusters you deployed to as targets reference the application or module.

   To change which server instances and clusters reference an application or module after it is deployed, change an application or module’s targets using the Admin Console, or change the application references using the asadmin tool. Because the application itself is stored in the central repository, adding or deleting targets adds or deletes the same version of an application on different targets. However, an application deployed to more than one target can be enabled on one and disabled on another, so even if an application is referenced by a target, it is not available to users unless it is enabled on that target.

4. Redeployment

   To replace a deployed application or module, redeploy it. Redeploying automatically undeploys the previously deployed application or module and replaces it with the new one.

   When redeploying through the Admin Console, the redeployed application or module is deployed to the domain, and all stand-alone or clustered server instances that reference it automatically receive the new version if dynamic reconfiguration is enabled. If using the asadmin deploy command to redeploy, specify domain as the target.

   For production environments, use rolling upgrade, which upgrades application without interruption in service. For more information, see “About Rolling Upgrades.”

5. Undeployment

   To uninstall an application or module, undeploy it.

Types of J2EE Archive Files

A software provider packages an application or module into a archive file. To deploy the application or module, specify the archive file name. The content and structure of the archive file is defined by the specifications of the J2EE platform. Types of J2EE archive files are as follows:

• Web Application Archive (WAR): A WAR file consists of Web components such as servlets and JSPs, as well as static HTML pages, JAR files, tag libraries and utility classes. A WAR file name has the .war extension.

• EJB JAR: The EJB JAR file contains one or more enterprise beans, the components used for EJB technology. The EJB JAR file also includes any utility classes needed by the enterprise beans. The name of an EJB JAR file has the .jar extension.

• J2EE Application Client JAR: This JAR file contains the code for a J2EE application client, which accesses server-side components such as enterprise beans via RMI/IIOP. In the Admin Console, a J2EE application client is referred to as an “application client.” The name of the J2EE application client JAR file has the .jar extension.

• Resource Adapter Archive (RAR): A RAR file holds a resource adapter. Defined by the J2EE Connector Architecture specifications, a resource adapter is a portable component that enables enterprise beans, Web components, and application clients to access resources and foreign enterprise systems. A resource adapter is often referred to as a connector. A RAR file name has the .rar extension.

• Enterprise Application Archive (EAR): An EAR file holds one or more WAR, EJB JAR, RAR or J2EE Application Client JAR files. An EAR file name has the .ear extension.

The software provider might assemble an application into a single EAR file or into separate WAR, EJB JAR, and application client JAR files. In the administration tools, the deployment pages and commands are similar for all types of files.

Naming Conventions

In a given domain, the names of deployed applications and modules must be unique.

• If deploying using the Admin Console, specify the name in the Application Name field.

• If deploying using the asadmin deploy command, the default name of the application or module is the prefix of the JAR file that you are deploying. For example, for the hello.war file, the Web application name is hello. To override the default name, specify the --name option.

Modules of different types can have the same name within an application. When the application is deployed, the directories holding the individual modules are named with _jar, _war and _rar suffixes. Modules of the same type within an application must have unique names. In addition, database schema file names must be unique within an application.

Using a Java package-like naming scheme is recommended for module filenames, EAR filenames, module names as found in the <module-name> portion of the ejb-jar.xml files, and EJB names as found in the <ejb-name> portion of the ejb-jar.xml files. The use of this package-like naming scheme ensures that name collisions do not occur. The benefits of this naming practice apply not only to the Application Server, but to other J2EE application servers as well.

JNDI lookup names for EJB components must also be unique. Establishing a consistent naming convention might help. For example, appending the application name and the module name to the EJB name is one way to guarantee unique names. In this case, mycompany.pkging.pkgingEJB.MyEJB would be the JNDI name for an EJB in the module pkgingEJB.jar, which is packaged in the application pkging.ear.

Make sure package and file names do not contain spaces or characters that are illegal for the operating system.