Use hot deployment and dynamic reloading

 

Overview

Applications can be modified without stopping and restarting the application server that hosts the application. This process is called hot deployment and dynamic reloading. Hot deployment is the process of adding new application components to an application server while the application server is running. Dynamic reloading refers to the ability of an application to integrate changes while it is running. Dynamic reloading applies to these changes:

• Changes to the implementation of a component of an application. For example, changes to the implementation of a servlet.

• Changes to the settings of the application. For example, changes to the deployment descriptor for a Web module.

To update an application without stopping and restarting the application server, follow these steps:

1. Locate the expanded application files. If you do not specify a target directory, the application files are located in the default target directory

   /QIBM/UserData/WebAS5/Base/instance/installedApps/cell/appEARfile

   If you cannot locate the expanded application files, look up the application binaries location with the administrative console.

   1. In the administrative console topology tree, expand Applications and click Enterprise Applications.

   2. Click the name of the application that you want to update.

   3. The value specified in the Application Binaries field is the location of the expanded application files.

   The variable application_root represents the directory that contains the expanded application files.

2. Locate application metadata files. The metadata files include the deployment descriptors, such as web.xml, application.xml, and ejb-jar.xml; the bindings files, such as ibm-web-bnd.xmi and ibm-app-bnd.xmi; and the extensions files, such as ibm-web-ext.xmi and ibm-app-ext.xmi. Metadata XML files for an application can be loaded from either of these locations:

   • The application EAR file directory: application_root/META-INF.

   • The application deployment directory:

     /QIBM/UserData/WebAS5/Base/instance/config/cells/cell/applications

   The value of the useMetadataFromBinary attribute, which is specified when you install an application, determines which location is used. To determine which location is used, follow these steps:

   1. In the administrative console topology tree, expand Applications and click Enterprise Applications.

   2. Click the name of the application that you want to update.

   3. If the Use Metadata From Binaries field is selected, the metadata files are loaded from the application EAR file directory. If it is not selected, the metadata files are loaded from the application deployment directory.

   The variable metadata_root represents the location of the metadata files for the specified application or module.

3. If you are running WAS Network Deployment and you change an application on a specific node, the changes can be lost when the deployment manager synchronizes its configuration with the nodes. To prevent the loss of updated configuration, make the changes to the application files in the Network Deployment instance and synchronize the configurations.

   You can also configure the file synchronization service to exclude the files that you are updating.

4. Change or add components or modules.

5. Some of these changes specify that restart the application before the changes take effect.

 

See also

• Change or add application files
• Change or add WAR files
• Change or add EAR files
• Change the HTTP plug-in configuration