How do you install JAXP extensions from an applet?

Question

All:
I want to use the JAXP XML parsers and DOM services in an Applet.
How do I get the Java-plugin to download the xerces.jar and xalan.jar files automatically, with my applet jar?
What goes in the applet manifest?
Do I have to alter the xerces and xalan manifests?
Brad

Answer 1

Thanks, but I wish I could report success today.
I believe what I stated before may have been confusing: the extension LIST is, indeed, in the manifest of the applet.jar.
The extension NAMES, and digital signatures, however, are ALSO in the manifest of xerces.jar. I re-read and re-read the documentation and believe I have interpreted it correctly. The xerces.jar is the implementation of the extension, and as such, must pass muster, securitywise, if it is to be allowed to be installed in the jre\lib\ext folder.
You are correct in saying I do not have to unjar the xerces.jar to rebuild it with the correct manifest information. The latest jar tool permits updating an existing jar file. Here is the bat file I currently use to create the installable version of xerces.jar:
copy Original-xerces.jar xerces.jar
jar -ufm xerces.jar manifest.txt
jarsigner -keystore d:\develop\beckrose\java\keystores\underground.keystore xerces.jar underground
(it then prompts for password)
The manifest.txt that is used to update xerces.jar is:
Manifest-Version: 1.0
Created-By: 1.3.0 (Sun Microsystems Inc.)
Name: javax/xml/parsers/
Extension-Name: javax.xml.parsers
Specification-Vendor: Sun Microsystems Inc.
Specification-Version: 1.2
Implementation-Vendor: Sun Microsystems Inc.
Implementation-Vendor-Id: com.sun
Implementation-Version: 1.2.0-EA1
Name: org/apache/xerces
Extension-Name: org.apache.xerces
Specification-Vendor: Sun Microsystems Inc.
Specification-Version: 1.2
Implementation-Vendor: Apache Software Foundation
Implementation-Vendor-Id: org.apache
Implementation-Version: Xerces-J_2_0_0_beta3
The manifest file in the applet.jar refers to these extensions, so that the java plugin knows how and where to fetch them:
Extension-List: parsers xerces
parsers-Extension-Name: javax.xml.parsers
parsers-Specification-Version: 1.2
parsers-Implementation-Vendor-Id: com.sun
parsers-Implementation-Version: 1.2.0-EA1
parsers-Implementation-URL: http://beckrose:8080/underground/opt-pkg/xerces.jar
xerces-Extension-Name: org.apache.xerces
xerces-Specification-Version: 1.2
xerces-Implementation-Vendor-Id: org.apache
xerces-Implementation-Version: Xerces-J_2_0_0_beta3
xerces-Implementation-URL: http://beckrose:8080/underground/opt-pkg/xerces.jar
If you look back at the error message, it does appear that the jaxp factory method is looking for a concrete class of the factory implementation. I believe this is where the plug-in is getting confused. The name of the concrete factory classes are in the META-INF/services folder. However, the concrete factory implementation that it is trying to use is the old crimson parser by default.
In other words, the plugin is not allowing the xerces factory method to find the classname to load. As a result, it is falling back to the default, which is not implemented in the jar file.
Now, it could be that the added manifest attributes and signature file are screwing up xerces or it could be a bug in the plugin.
I don't quite know where to take this right now, so I'll monitor the plugin discussions and check out the xml.apache.org discussions.
All I know is, it should NOT be this hard, this many years after Java 2 has been released.
Brad