You can make various changes to applications and their modules without having to stop the server and start it again. Making these types of changes is known as hot deployment and dynamic reloading.
This article assumes that your application files are deployed on a server and you want to upgrade the files.
Hot deployment is the process of adding new components (such as WAR
files, EJB Jar files, enterprise Java beans, servlets, and JSP files) to a running server without having to stop the application server process and start it again.
Dynamic reloading is the ability to change an existing component without needing to restart the server in order for the change to take effect.
Dynamic reloading involves:
Changes to the implementation of a component of an application, such as changing the implementation of a servlet
Changes to the settings of the application, such as changing the deployment descriptor for a Web module
As opposed to the changes made to a deployed application described in Updating applications,
changes made using hot deployment or dynamic reloading do not use the administrative console or a wsadmin scripting command. You must directly manipulate the application files on the server where the application is deployed.
If the application you are updating is deployed on a server that has its application class loader policy set to Single,
you might not be able to dynamically reload your application. At minimum,
restart the server after updating your application.
Important: Do not use hot deployment to update components in a production deployment manager managed cell. Hot deployment is well-suited for development and testing, but poses unacceptable risks to production environments. Full or partial resynchronization might erase hot deployed components. Also, running the restoreconfig command might overwrite changes made to expanded application files. Further, hot deployed components are not migrated between versions of WebSphere Application Server. To add new components or modules to an enterprise application, reassemble the application EAR file so it has the new components or modules and then redeploy the EAR file.
Locate your expanded application files. The application files are in the directory you specified when installing the application or,
if you did not specify a custom target directory, are in the default target directory, profile_root/installedApps/cell_name. Your EAR file, ${APP_INSTALL_ROOT}/cell_name/application_name.ear, points to the target directory. The variables.xml file for the node defines ${APP_INSTALL_ROOT}. It is important to locate the expanded application files because, as part of installing applications, a WebSphere application server unjars portions of the EAR file onto the file system of the computer that will run the application. These expanded files are what the server looks at when running your application. If you cannot locate the expanded application files, look at the binariesURL
attribute in the deployment.xml file for your application. The attribute designates the location the run time uses to find the application files.
For the remainder of this information on hot deployment and dynamic reloading, application_root represents the root directory of the expanded application files.
Locate application metadata files. The metadata files include the deployment descriptors (web.xml, application.xml, ejb-jar.xml, and the like),
the bindings files (ibm-web-bnd.xmi, ibm-app-bnd.xmi, and the like), and the extensions files (ibm-web-ext.xmi, ibm-app-ext.xmi,
and the like). Metadata XML files for an application can be loaded from one of two locations. The metadata files can be loaded from the same location as the application binary files (such as application_root/META-INF)
or they can be loaded from the WebSphere configuration tree, ${CONFIG_ROOT}/cells/cell_name/applications /application_EAR_name/deployments/application_name/. The value of the useMetadataFromBinary flag specified during application installation
controls which location is used. If specified, the metadata files are loaded from the same location as the application binary files. If not specified,
the metadata files are loaded from the application deployment folder in the configuration tree. For the remainder of this information, metadata_root represents the location of the metadata files for the specified application or module.
Required: If you are running WebSphere Application Server on a group of machines using Network Deployment and you are changing an application on a particular node, disable automatic synchronization.
Click System administration > Node agents > node_agent_name >
File synchronization service in the console navigation tree.
When you run WebSphere Application Server on a group of machines using Network Deployment and you change a file on the disk in the expanded application directory for a particular node, you can lose those changes the next time node synchronization occurs. In the Network Deployment environment, the configuration stored by the deployment manager is the master copy and any changes detected between that master copy and the copy on a particular machine trigger the master copy to be downloaded to the node.
Optional: Examine the values specified for Enable class reloading and Reloading interval on the settings page for your enterprise application.
If reloading of application files is enabled and the reload interval is greater than zero (0), the application files are reloaded after the application is updated. For Web modules such as servlets and JavaServer page (JSP) files,
a Web container reloads a Web module only when the IBM extension reloadingEnabled in the ibm-web-ext.xmi file is also set to true. You can set reloadingEnabled to true when editing your Web module's extended deployment descriptors in an assembly tool.
Change or add the following components or modules as needed: