Overview

OSGi is a module system and service platform for the Java programming language. It uses a more modular classloader hierarchy, which requires some additional configuration when using Scalate.

Required imports

When deploying a WAR file in Karaf using a war: URL, the bundle automatically gets imports for javax.servlet and javax.servlet.http.

In order for Scalate to work properly, a few additional imports are required.

org.osgi.platform
org.osgi.services.packageadmin
javax.swing.tree

When using Apache Karaf (or another environment that uses Pax Logging), you can optionally add:

org.slf4j to allow Scalate to use the provided logging services

Using war:

The required imports can be added dynamically when installing the WAR file by using these options on the war: URL:

Import-Package to specify the required imports
Webapp-Context to specify the web application context root

Example: to install a file name documentation.war on Karaf

osgi:install -s war:file:documentation.war?Webapp-Context=documentation&Import-Package=org.slf4j,javax.servlet,javax.servlet.http,org.osgi.framework,org.osgi.service.packageadmin

Maven bundle plugin

Another way to add the required imports, is by including the necessary configuration in your WAR file directly at build time. This can be done with the Maven bundle plugin:

<plugin>
  <artifactId>maven-war-plugin</artifactId>
  <configuration>
    <archive>
      <manifestFile>
        ${project.build.outputDirectory}/META-INF/MANIFEST.MF
      </manifestFile>
    </archive>
  </configuration>
</plugin>
<plugin>
  <groupId>org.apache.felix</groupId>
  <artifactId>maven-bundle-plugin</artifactId>
  <executions>
    <execution>
      <id>bundle-manifest</id>
      <phase>process-classes</phase>
      <goals>
        <goal>manifest</goal>
      </goals>
    </execution>
  </executions>
  <configuration>
    <supportedProjectTypes>
      <supportedProjectType>jar</supportedProjectType>
      <supportedProjectType>bundle</supportedProjectType>
      <supportedProjectType>war</supportedProjectType>
    </supportedProjectTypes>
    <instructions>
      <Import-Package>
        javax.servlet,javax.servlet.http,
        org.osgi.framework,org.osgi.service.packageadmin,
        javax.swing.tree,
        org.slf4j
      </Import-Package>
      <Bundle-ClassPath>.,WEB-INF/classes</Bundle-ClassPath>
      <Embed-Directory>WEB-INF/lib</Embed-Directory>
      <Embed-Dependency>
        *;scope=compile|runtime
      </Embed-Dependency>
      <Embed-Transitive>true</Embed-Transitive>
      <Webapp-Context>documentation</Webapp-Context>
    </instructions>
  </configuration>
</plugin>