As mentioned above, a standard WAR file typically packages of all its required
WEB-INF/lib. The servlet container will
then add all of the JARs in
WEB-INF/lib to the application’s
The first step of the migration towards benefiting from an OSGi container is to retrieve the dependencies from the dm Server’s bundle repository at runtime. This can significantly reduce the time it takes to build and deploy the application. It also enables the enforcement of policies regarding the use of third-party libraries.
The way in which dependencies are declared in an OSGi environment is
via manifest headers in a bundle’s
As mentioned in Chapter 4, Developing Applications, there are
three ways of expressing dependencies:
The Form Tags application uses JSTL standard tag libraries.
Thus, you need to choose a JSTL provider, for example the
Apache implementation which comes with the dm Server. To use the
Apache implementation of JSTL, you need to express your dependency
as outlined in the following manifest listing.
Because it is a single bundle,
the simplest and therefore preferred manifest header to use.
The Form Tags application requires commons-logging and Spring.
It would be very painful to have to list all the Spring packages one by one.
Equally, considering the number of bundles that make up the
Spring framework, it would be verbose to list each bundle. Therefore
Import-Library is the preferred approach
for expressing the dependency on the Spring framework.
How do you determine the name of a library definition provided by the SpringSource dm Server? Use the SpringSource Enterprise Bundle Repository.
Manifest-Version: 1.0 Ant-Version: Apache Ant 1.7.0 Created-By: 1.5.0_13-119 (Apple Inc.) Bundle-ManifestVersion: 2 Bundle-SymbolicName: org.springframework.showcase.formtags-shared-libs Bundle-Vendor: SpringSource Inc. Import-Library: org.springframework.spring;version="[2.5.4,3.1.0)" Import-Bundle: com.springsource.org.apache.taglibs.standard;version="1 .1.2"
You can see the
directives that instruct the dm Server to add the appropriate package imports to the bundle
classpath used by this WAR file.
Deploying the shared libraries WAR onto the dm Server should result in console output similar to the following:
The console output has been reformatted to fit this document.
[2009-07-01 15:00:14.953] fs-watcher <SPDE0048I> Processing 'CREATED' event for file 'formtags-shared-libs-2.0.0.RELEASE.war'. [2009-07-01 15:00:15.363] fs-watcher <SPDE0010I> Deployment of 'org.springframework.showcase.formtags_shared_libs' version '2' completed. [2009-07-01 15:00:15.364] Thread-20 <SPWE0000I> Starting web bundle '/formtags-shared-libs-2.0.0.RELEASE'. [2009-07-01 15:00:15.816] Thread-20 <SPWE0001I> Started web bundle '/formtags-shared-libs-2.0.0.RELEASE'.
should render the welcome page. Note that for the pre-packaged distributable,
BUILDTAG should be similar to
whereas, for a local build the
-BUILDTAG may be completely
omitted. Please consult the console output, web-based admin console, or log
to determine the exact context path under which the web application has been deployed.