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.
Before you begin
This
topic assumes that your application files are deployed on a server and you want to upgrade the
files.
See Ways to update enterprise application files and determine
whether hot deployment is the appropriate way for you to update your
application files. Other ways are easier and hot deployment is appropriate
only for experienced users.
Do not use hot deployment if you
intend to export your application, generate a plug-in based on the
application configuration, or perform other application management
in the future. Changes that you make to your application files using
hot deployment are not recognized by administrative console or wsadmin
application management functions. Those functions recognize only the
application files that administrative programs such as the console
or wsadmin present during application installation, update or other
management functions. The application management functions do not
recognize files changed by hot deployment.
About this task
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 enterprise application files, 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, you
must restart the server after updating your application.
Procedure
- 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, app_server_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).
Supported configurations: For IBM
® extension
and binding files, the .xmi or .xml file name extension is different
depending on whether you are using a pre-Java EE 5 application or
module or a Java™ EE 5 or later
application or module. An IBM extension
or binding file is named ibm-*-ext.xmi or ibm-*-bnd.xmi where * is
the type of extension or binding file such as app, application, ejb-jar,
or web. The following conditions apply:
- For an application or module that uses a Java EE version prior to version 5, the file
extension must be .xmi
- For an application or module that uses Java EE 5 or later, the file extension must
be .xml
However, a Java EE
5 or later module can exist within an application that includes pre-Java
EE 5 files and uses the .xmi file name extension.
The ibm-webservices-ext.xmi, ibm-webservices-bnd.xmi, ibm-webservicesclient-bnd.xmi, ibm-webservicesclient-ext.xmi,
and ibm-portlet-ext.xmi files continue to use
the .xmi file extensions.
sptcfg
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.
Important: You
can have useMetadataFromBinaries=true, change an
extracted copy of your application using hot deployment, and have
the changes take effect at run time by following the procedure in
this topic. However, changes that you make to your application files
using hot deployment are not recognized by console or wsadmin application
management functions. Those functions recognize only the original
application files and not the files changed by hot deployment. Do
not use hot deployment if you intend to export your application, generate
a plug-in based on the application configuration, or perform other
application management in the future. Hot deployment enables you to
quickly change application files; it does not support the full management
lifecycle of an application.
For the remainder of this information, metadata_root represents
the location of the metadata files for the specified application or
module.
- Optional: Examine the values specified for Reload
classes when application files are updated and Polling
interval for updated files on the settings page for
your application's class loader.
If reloading
of classes is enabled and the polling interval is greater than zero
(0), the application files are reloaded after the application is updated.
For JavaServer Pages (JSP) files in a Web module, a Web container
reloads JSP files only when the IBM extension jspReloadingEnabled
in the jspAttributes of the ibm-web-ext.xmi file
is set to true. You can set jspReloadingEnabled 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:
- For changes to take effect, you might need to start, stop,
or restart an application.
Starting or stopping enterprise applications provides information
on using the administrative console to start, stop, or restart an
application.
Starting applications using wsadmin scripting and Stopping applications using wsadmin scripting provide information on using
the wsadmin scripting tool.
Results
The application files are updated on the server.
Because
you directly manipulated the application files on the server, you
might not be able to later use the administrative console or a wsadmin
scripting command to work with the files. For example, if you try
exporting a manually changed application using Export on
an Enterprise applications console page, your manual changes to an
application in the installedApps directory are
not exported. To export those changes, you must copy and move the
application files manually.