[jira] Commented: (COCOON-1955) [Patch] Allow shielded class loading for a single block

["Alexander Klimetschek (JIRA)" <ji...@apache.org>]

    [ http://issues.apache.org/jira/browse/COCOON-1955?page=comments#action_12451972 ] 
            
Alexander Klimetschek commented on COCOON-1955:
-----------------------------------------------

Just to give an example of a bean configuration:

	<bean id="foo-bar-block"
		class="org.apache.cocoon.blocks.shielding.ShieldingBlockServlet">
		<property name="mountPath" value="/foobar" />

		<property name="blockContextURL"
			value="blockcontext:/foo-bar-block/" />

		<property name="servletClass"
			value="com.foo.bar.FooBarServlet" />
		
		<property name="shieldedGroup" value="my-shielded-servlets" />
	</bean>

The last property shieldedGroup is optional.

> [Patch] Allow shielded class loading for a single block
> -------------------------------------------------------
>
>                 Key: COCOON-1955
>                 URL: http://issues.apache.org/jira/browse/COCOON-1955
>             Project: Cocoon
>          Issue Type: New Feature
>          Components: * Cocoon Core, - Blocks Framework
>    Affects Versions: 2.2-dev (Current SVN)
>            Reporter: Alexander Klimetschek
>         Attachments: cocoon-enable-shielded-block-libs.patch, cocoon-new-shieldingblockservlet.patch
>
>
> == Problem ==
> When trying to integrate Apache Solr in our Cocoon webapplication, we got a problem with conflicting versions of jars. Our jackrabbit block needs an old lucene, whereas Solr wants a fresh new lucene nightly build.
> == Solution ==
> Since we integrate the SolrServlet (and the other servlets from solar) inside a BlockServlet to have them all inside our cocoon webapp with consistent URLs, we considered adding a ShieldingServlet. Thus the BlockServlet wraps the ShieldingServlet which in turn wraps the SolrServlet. The configuration for the BlockServlet bean looks like this:
> 	<bean id="com.mindquarry.search.solr.solr-select-block"
> 		class="org.apache.cocoon.blocks.BlockServlet">
> 		<property name="mountPath" value="/solr-select" />
> 		<property name="servletClass"
> 			value="org.apache.cocoon.bootstrap.servlet.ShieldingServlet" />
> 		<property name="blockContextURL"
> 			value="blockcontext:/mindquarry-solr-block/" />
> 		<property name="properties">
> 			<map>
> 				<entry key="servlet-class"
> 					value="org.apache.solr.servlet.SolrServlet" />
> 				<entry key="bootstrap-classpath-file"
> 					value="/paranoid-classpath.txt" />
> 				<entry key="bootstrap-classloader-debug" value="true" />
> 				<entry key="bootstrap-classloader-factory"
> 					value="org.apache.cocoon.classloader.DefaultClassLoaderFactory" />
> 			</map>
> 		</property>
> 	</bean>
> The directory structure of the solr-block:
>   src/main/resources/
>                            COB-INF/
>                                  paranoid-classpath.txt
>                                  paranoid-lib/
>                                         <shielded-jars>.jar
>                                         (including the jar which contains the solr servlet)
>                             META-INF/
>                                   cocoon/
>                                         spring/
>                                              solr-blockservlet.xml
> The paranoid-classpath.txt contains the following single line:
> lib-dir: context:paranoid-lib
> == The Patch ==
> To get the ShieldingServlet work with the blocks-fw and the basic shielding that is done in the Cocoon webapp anyway (via a ShieldingListener in the web.xml), two things must be done:
> a) The BootstrapClassLoaderManager in cocoon-bootstrap must not store the classloader it creates in a static variable so that in each call of getClassLoader() a new ClassLoader is created. That method is exactly called 2 times in our situation: first by the cocoon webapp shielding listener and then by the ShieldingServlet in our block.
> b) The method BlockContext.getResourcePaths() must be implemented to list the resources in that block context (stuff under COB-INF of that block).
> Lots of the work was done by my colleague Alexander Saar.

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