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From j...@apache.org
Subject [jira] Commented: (GERONIMO-155) [proposal] resolving for kernel
Date Tue, 17 Feb 2004 21:24:52 GMT
The following comment has been added to this issue:

     Author: Kristian Koehler
    Created: Tue, 17 Feb 2004 1:22 PM
       Body:
Hi

here is the second version of the patch. 

The basic idea can be found here:

http://nagoya.apache.org/eyebrowse/ReadMsg?listName=geronimo-dev@incubator.apache.org&msgNo=6411


What's done "inside":

* a configuration file (system-config.xml etc) could now contain a xml-parser element which
defines a Parser Wrapper for this configuration.
 
<xml-parser>
	<entity-resolver>
		<catalogFile>work/resolver-catalog.xml</catalogFile>
		<localRepository>work</localRepository>
		<failOnUnresolvable>true</failOnUnresolvable>
	</entity-resolver>
</xml-parser>

* each configuration checks inside the doStart() method if a XMLParserWrapper should be configured.

* Configuring a XMLParserWrapper means
  * a ClassloaderFilter is created and all subsequent lookups to DOM or SAXParserFactories
are redirected to a wrapper implementation which is configured with a LocalEntityResolver.
  * BTW nothing is done if the user has set System properties for the factories or has set
up the jaxp.properties file.


Hope someone will apply this patch ;-)

Kristian  
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View the issue:
  http://nagoya.apache.org/jira/secure/ViewIssue.jspa?key=GERONIMO-155

Here is an overview of the issue:
---------------------------------------------------------------------
        Key: GERONIMO-155
    Summary: [proposal] resolving for kernel
       Type: Improvement

     Status: Unassigned
   Priority: Major

    Project: Apache Geronimo
 Components: 
             core

   Assignee: 
   Reporter: Kristian Koehler

    Created: Mon, 2 Feb 2004 1:42 PM
    Updated: Tue, 17 Feb 2004 1:22 PM

Description:
Hi

Building and running Geronimo offline or behind a firewall is nearly impossible. 
Most problems araise from the fact that there are code requiring remote entity resolving.
The current LocalEntityResolver solves that problem for "Geronimo code". Every other module/
service could cause a similar problem. 
Currently I have problems with the Jetty Module requiring a SUN schema file which is not found
by the SAXParser.

One possible solution IMO is a ParserWrapper implementation which wraps the "normal" implemention.
This Wrapper should be made available to all services deployed in Geronimo. A call to 

	SAXParserFactory.newInstance();

should return a Wrapper implementation which returns all other Wrapper implementations (SAXParserWrapper,
XMLReaderWrapper, ...). 

The normal lookup mechanism in the SAXParserFactory is as follows:

* test SystemProperty "javax.xml.parsers.SAXParserFactory"
* lookup in java.home jax.properties
* test META-INF/services/javax.xml.parsers.SAXParserFactory file

The last call could be redirected to the wrapper implementation ("ClassLoader hack"). The
other both calls couldn't be redirected. But I think if a user had set a implementation via
SystemProperty or jaxp.properties file the wrapper implementation should be skipped (warning
message for the user).

IMO all services/modules should be deployed with a ClassLoaderWrapper which redirects all
Parser lookups to a wrapper implementation which wraps the "normal implementation". This "normal
implementation" could be determined via the "normal lookup mechanism".

something like that
------ 8< ------

InputStream stream = localClassLoader.getResourceAsStream("META-INF/services/javax.xml.parsers.SAXParserFactory");
 if (stream != null) {
   InputStreamReader isr = new InputStreamReader(stream);
   BufferedReader reader = new BufferedReader(isr);
   factoryClassName = reader.readLine();
 } else {
   factoryClassName = "org.apache.crimson.jaxp.SAXParserFactoryImpl";
 }

------ 8< ------

So all resolving could be redirected to a LocalEntityResolver. 

Something like the following code could be included in the doStart() method of the Configuration
class. So all deployed Beans should use the wrapper.

------ 8< ------

Class clazz =  
  wrappedClassLoader.loadClass(SAXParserFactoryWrapper.class.getName());
Method setDelegate = clazz.getMethod("setDelegate", 
                           new Class[]{String.class});
        
if (parent == null) {
  setDelegate.invoke(clazz, new Object[]{...)});
} else {
  setDelegate.invoke(clazz, new Object[]{...)});
}

------ 8< ------

I hope my idea is understandable ;-)
Comments?

	Kristian



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