= Proposal title =

|| '''Date''' || 2010/09/07 ||
|| '''Contact(s)''' || Simon Pigot ||
|| '''Last edited''' || ||
|| '''Status''' || in progress ||
|| '''Assigned to release''' || 2.7.x ||
|| '''Resources''' || Available ||

== Overview ==

It should be possible to plug-in Metadata Schemas (including profiles). This means that a user/admin should be able to use a service to add a profile/schema to their existing !GeoNetwork installation without having to make manual changes to config, Java code, xslts and javascript.

=== Proposal Type ===
 * '''Type''': Core Change
 * '''App''': !GeoNetwork
 * '''Module''': Kernel, Data Manager

=== Links ===
 * '''Documents''':
 * '''Email discussions''':
 * '''Other wiki discussions''':

=== Voting History ===
 * Not yet proposed.

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== Motivations ==
To add a schema to !GeoNetwork a user currently has to:

 * add the schema and ancillaries to web/geonetwork/xml/schemas directory
 * add codelists and labels xml files to web/geonetwork/WEB-INF/config.xml
 * add presentation xslts to web/geonetwork/xsl and import them into web/geonetwork/xsl/metadata-utils.xsl
 * modify web/geonetwork/xsl/{metadata.xsl,metadata-utils.xsl} to switch on schema for full and brief mode processing
 * add brief, summary and full presentation xslts to web/geonetwork/xml/csw/schemas
 * add schema detection code to the autodetectSchema method in !DataManager.java
 * add namespaces used for elements to the tooltip javascript (web/geonetwork/scripts/editor/tooltip.js and web/geonetwork/scripts/editor/simpletooltip.js)
 * schemas added to !GeoNetwork exist inside the web application deployment making it more difficult to manage upgrades and new deployments of !GeoNetwork

This is not only tedious but requires a fair bit of knowledge to ensure that the installation is not broken by inappropriate or incorrect changes. In some cases these changes are large enough that communities with national schemas/profiles will create their own branch of !GeoNetwork to support their schema/profile. This should not be necessary.

Removing the need to make code changes and consolidating schema information will make adding a schema to !GeoNetwork much easier. Having plug in schemas/profiles will also remove the need to create a code branch to support the schema/profile.  

== Proposal == 

Make the following changes:

 * consolidate presentation xslts into the schema directory
 * remove the need for switch on schema type in metadata.xsl and metadata-utils.xsl
 * provide the ability to rewrite xslt imports using a URI resolver and oasis catalog file
 * allow users to rewrite schemaLocation hints using an oasis catalog file/files
 * add a !SchemaManager class to encapsulate and provide schema information to other classes in !GeoNetwork
 * rewrite the Info service so that it no longer requires the namespace URI to be provided by the tooltip requests (will use !SchemaManager to get this info instead)
 * change schema autodetection code to use information from the !SchemaManager (we use some code and ideas from the enhanced schema autodetect approach developed by Dominic Owen of USGIN)
 * move codelist and label xml file caching for schemas from Jeeves guiservices to !GeoNetwork guiservices - no longer necessary to add these files to the gui section of web/geonetwork/WEB-INF/config.xml
 * Add localized strings support for strings that may be used in the presentation xslts - no longer necessary to add these to the gui section of .....
 * move templates and sample-data into schema directory and change gast and other code to use the !SchemaManager to obtain paths to these directories
 * add services that accept a schema zip file directly or URL of a schema zip file or UUID of a metadata record with schema zip archive attached, which retrieve and unpack the schema from the zip file into the schemaPlugins directory, and adds the schema to the list of schemas that !GeoNetwork knows about (no config changes required) - add, delete and update
   
=== Backwards Compatibility Issues ===

 * Those installations with their own schemas and profiles will need to recast them into the plugin format - this means moving common strings and presentation xslts etc to the schema directory

=== New libraries added ===

xml-commons-resolver 1.2 - Apache lib to support resolving various XML entities and URIs using oasis catalogs

== Risks ==

None known

== Participants ==
 * Simon Pigot
 * Dominic Owen, USGIN - schema autodetect code
 * Other members of the !GeoNetwork community. In Australia: Craig Jones - IMOS/eMii, John Hockaday - OSDM, Xiangtan Lin - CSIRO, Yarralumla