[GERONIMO-133] [PATCH] LocalEntity Resolver and LoaderUtil Enhancements

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Component/s: core
• Assignee: David Jencks
• Reporter: Kristian Kohler
• Created: 26/Dec/03 18:21
• Updated: 16/Jul/06 18:00
• Resolved: 01/Aug/04 20:29

Description

Hi

this is a patch for the LocalEntity Resolver and LoaderUtil Classes.

Why i think this patch should be applied:

• There were some complaints about working or developing offline with Apache Geronimo. Most problems arises from remote resolving of entities.
  If someone develops a piece a code which requires some external DTDs or Schemas it may work for him because we works online. The "new" Implementation offers a flag indicating if the resolver may return null or throw an exception. Returning null is a signal to the parser to open a regular URI connection to the given system identifier.
  With this flag it's possible to disable all remote lookups and prevent different online/offline behaviour.

• Validating of DTDs and Schema.
  The current Implementation of the LoaderUtil doesn't validate schema and DTDs and there is no ErrorHandler to report the failures.
  The "new" LoaderUtil ueses a DOMParser Implementation which supports DTD and Schema validation. (ok it's a Xerces feature - if someone knows how to use this the "standard way" please let me know. )

• The current EntityResolver is implemented as MBean. The LoaderUtil class which uses the LocalEntityResolver instantiates the EntityResolver every time rather then using it over the JMX bus.
  You may add new Mappings to the LocalEntityResolver but they will never be used.
  The "new" LoaderUtil Implementation uses the LocalEntity Resolver over JMX.

• The current LocalEntity Resolver uses a property file for mapping a PublicID to a SystemID.
  This approach is useful but doesn't work. Property files must not contain spaces in there key values.

Example:
-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN=c:/work/dummy/web.dtd

is not a valid entry.

OASIS has published a Catalog standard to define such mappings.
(see http://www.oasis-open.org/specs/a401.htm)
Apache provides an appropriate Java library.
(http://xml.apache.org/commons/components/resolver/index.html)

The "new" LocalEntiotyResolver uses this catalog standard to determine the PublicID/SystemID mappings.

• There are new Unit Tests which tests the functionality of the
  LocalEntityResolver.
  I have adjusted the other tests accordingly.

How the LocalEntityResolver works:

First of all the Resolver is registered as MBean
(geronimo.xml:role=EntityResolver). It is configured with:

• CatalogFile (OASIS Catalog file)
• LocalRepository (local directory where to lookup dtd and schema)
• FailOnUnresolvable

When resolving an entity the resolver first checks the catalog file to determine a PublicID or SystemID mapping. If there is now mapping configured the Resolver tries to resolve via a local directory where dtd and schema files are present(LocalRepository). If no dtd or schema is found a lookup into the classpath is done. If nothing is found the FailOnUnresolvable signals if an exception should be thrown.

Kristian