You can set values that control the class-loading behavior of an
installed enterprise application. Class loaders enable an application to access
repositories of available classes and resources.
About this task
Configure the class loaders of an enterprise application to set class-loader
policy and mode values for this application.
An application class loader
groups enterprise bean (EJB) modules, shared libraries, resource adapter archives
(RAR files), and dependency Java archive (JAR) files associated to an application.
Dependency JAR files are JAR files that contain code which can be used by
both enterprise beans and servlets.
An application class loader is the
parent of a Web application archive (WAR) class loader. By default, a Web
module has its own WAR class loader to load the contents of the Web module.
The WAR class-loader policy value of an application class loader determines
whether the WAR class loader or the application class loader is used to load
the contents of the Web module.
Use the administrative console to configure
the class loaders.
Attention: If an application is running,
changing an application setting causes the application to restart.
On stand-alone servers, the application restarts after you save the
change. On multiple-server products, the application restarts after
you save the change and files synchronize on the node where the application
is installed.
- Click to
access the settings
page for an application class loader.
- Specify whether to reload application classes
when the application or its files are updated.
By default, class
reloading is not enabled. Select Reload classes when application
files are updated to choose to reload application classes. You
might specify different values for EJB modules and for Web modules such as
servlets and JavaServer Pages (JSP) files.
- Specify the number of seconds to scan the application's
file system for updated files.
The value specified for Polling
interval for updated files takes effect only if class reloading
is enabled. The default is the value of the reloading interval attribute in
the IBM extension (META-INF/ibm-application-ext.xmi)
file of the enterprise application (EAR file). You might specify different
values for EJB modules and for Web modules such as servlets and JSP files.
To
enable reloading, specify an integer value that is greater than zero (for
example, 1 to 2147483647).
To disable reloading, specify zero (0).
- Specify the class loader order for the application.
The application class loader order specifies whether the class loader
searches in the parent class loader or in the application class loader first
to load a class. The default is to search in the parent class loader before
searching in the application class loader to load a class.
Select either
of the following values for Classes loader order:
Option |
Description |
Classes loaded with parent class loader first |
Causes the class loader to search in the parent class loader first
to load a class. This value is the standard for Development Kit class loaders
and WebSphere Application Server class loaders. |
Classes loaded with application class loader first |
Causes the class loader to search in the application class loader
first to load a class. By specifying Classes loaded with application
class loader first, your application can override classes contained
in the parent class loader. Attention: Specifying the Classes
loaded with application class loader first value might result
in LinkageErrors or ClassCastException messages if you have mixed use of overridden
classes and non-overridden classes.
|
- Specify whether to use a single or multiple class loaders to load
Web application archives (WAR files) of your application.
By
default, Web modules have their own WAR class loader to load the contents
of the WEB-INF/classes and WEB-INF/lib directories.
The default WAR class loader value is Class loader for each WAR file in application,
which uses a separate class loader to load each WAR file. Setting the value
to Single class loader for application causes
the application class loader to load the Web module contents as well as the
EJB modules, shared libraries, RAR files, and dependency JAR files associated
to the application. The application class loader is the parent of the WAR
class loader.
Select either of the following values for WAR
class loader policy:
Option |
Description |
Class loader for each WAR file in application |
Uses a different class loader for each WAR file. |
Single class loader for application |
Uses a single class loader to load all of the WAR files in your application. |
- Click OK.