wiki:CustomFormatting

Custom Metadata Display

Date 2012/04/19
Contact(s) ​Jesse Eichar
Last edited
Status committed
Assigned to release 2.8
Resources R&D Camptocamp
Code ​https://github.com/jesseeichar/geonetwork/compare/formatter
Ticket #875

Overview

Provide a service for viewing metadata documents with a custom XSL which is identified via the URL, instead of the normal Geonetwork metadata.show. In addition provide administration tools for managing the XSL files.

Proposal Type

  • Type: New Service
  • App: GeoNetwork
  • Module:

  • Email discussions:
  • IRC discussions:

Voting History

  • None as yet

Motivations

Certain Geonetwork installations are used by several districts for similar purposes but occasionally the districts would like the ability to have links to metadata documents that have custom formatting and branding. A service which can be used to format a metadata according to a custom XSL could be useful in the following use-cases:

  • Embed the metadata into other sites
  • Share metadata through some sort of distribution channel that should have a certain type of branding
  • provide a lightweight CSW based search client which displays the metadata with the custom/branded formatting

Proposal

Several new services would be added to the org.fao.geonet.services.metadata.format package:

  • Format - Obtain the metadata, localization files, etc... and execute the xsl transform.
    • Format will have two services mapped to it (html and xml), with respective content types
    • Format services will be accessible by all users
  • services.metadata.format.Register - Service for uploading an xsl file or zip file, it will require admin access
  • services.metadata.format.Download - Service for downloading the zip file containing the XSL and associated resources, it will require admin access
  • services.metadata.format.Remove - Service for deleting an xsl file and related resources, it will require admin access

There will be an Administration User interface for managing the Format bundles files. Using the Administration user interface the administrator (and only administrator) can upload either a single xsl file which is the formatter/transformer, or a zip file that contains a file called view.xsl and other resources required by the view.xsl.

The view.xsl will have the format (using the service metadata.formatter.xml?debug=true&id=<id>&xslid=<xslID> will show untransformed xml that can be used by transform): 

/root
  / <metadata>
  / schemas
    ....
  / strings
    ....
  / url
  / locUrl
  / resourUrl
  / resource/strings

The schemas will have schema labels, codelists etc... (localised) and strings will be the normal localized strings as well.

If the uploaded zip file has a loc directory the files in loc/???/*.xml will be added to the xml under the viewStrings.

The viewURL will be a path for loading resources like images and css files.

Documentation to be added

Metadata formatter

Introduction

The metadata.show displays a metadata document using the default metadata display stylesheets. However it can be useful to provide alternate stylesheets for displaying the metadata. Consider a central catalog that is used by several partners. Each partner might have special branding and wish to emphasize particular components of the metadata document.

To this end the metadata.formatter.html and metadata.formatter.xml services allow an alternate stylesheet to be used for displaying the metadata. The urls of interest to an end-user are:

  • /geonetwork/srv/<langCode>/metadata.formatter.html?xsl=<formatterId>&id=<metadataId>
    • Applies the stylesheet identified by xsl parameter to the metadata identified by id param and returns the document with the *html* contentType
  • /geonetwork/srv/<langCode>/metadata.formatter.xml?xsl=<formatterId>&id=<metadataId>
    • Applies the stylesheet identified by xsl parameter to the metadata identified by id param and returns the document with the *xml* contentType
  • /geonetwork/srv/<langCode>/metadata.formatter.list
    • Lists all of the metadata formatter ids

Another use-case for metadata formatters is to embed the metadata in other websites. Often a metadata document contains a very large amount of data and perhaps only a subset is interesting for a particular website or perhaps the branding/stylesheets needs to be customized to match the website.

Administration

A metadata formatter is a bundle of files that can be uploaded to Geonetwork as a zip file (or in the simplest case just upload the xsl).

An administration user interface exists for managing these bundles. The starting page of the ui contains a list of the available bundles and has a field for uploading new bundles. There are three upload options:

  • *Single xsl file* - A new bundle will be created for the xsl file and the name of the bundle will be based on the xsl file name
  • *Zip file (flat)* - A zip file which contains a view.xsl file and other required resources at the root of the zip file so that when unzipped the files will be unzipped into the current directory
  • *Zip file (folder)* - A zip file with a single folder that contains a view.xsl file and the other required resources so that when unzipped a single directory will be created that contains the formatter resources.

If a bundle is uploaded any existing bundles with the same name will be replaced with the new version.

See Bundle format section below for more details about what files can be contained in the format bundle.

When a format in the formatter list is selected the following options become enabled:

  • Delete - Delete the format bundler from Geonetwork
  • Download - Download the bundle. This allows the administrator to download the bundle and edit the contents then upload at a later date
  • Edit - This provides some online edit capabilities of the bundle. At the moment it allows editing of *existing* text files. Adding new files etc... maybe added in the future but is not possible at the moment. When edit is clicked a dialog with a list of all editable files are displayed in a tree and double clicking on a file will open a new window/tab with a text area containing the contents of the file. The webpage has buttons for saving the file or viewing a metadata with the style. The view options do *NOT* save the document before execution, that must be done before pressing the view buttons.

Bundle format

A format bundle is at minimum a single xsl file. If the xsl file is uploaded it can have any name. On the server a folder will be created that contains the xsl file but renamed to view.xsl.

If a zip file is uploaded the zip file must contain a file view.xsl. The view.xsl file is the entry point of the transformation. It can reference other xsl stylesheets if necessary as well as link to css stylesheets or images that are contained within the bundle or elsewhere.

The view.xsl stylesheet is executed on an xml file with essentially the following format: 

- root 
 - url - text of the url tag is the base url to make requests to geonetwork.  An example is /geonetwork/
 - locUrl - text of the url tag is the localised url to make requests to geonetwork.  An example is /geonetwork/srv/eng/
 - resourceUrl - a base url for accessing a resource from the bundle.  An example of image tag might be:
                 <img src="{/root/resourceURL}/img.png"/>
 - <metadata> - the root of the metadata document
 - loc
  - lang - the text of this tag is the lang code of the localization files that are loaded in this section
  - <bundle loc file> - the contents of the bundles loc/<locale>/*.xml files
 - strings - the contents of geonetwork/loc/<locale>/xml/strings.xml
 - schemas
  - <schema> - the name of the schema of the labels and codelists strings to come
   - labels - the localised labels for the schema as defined in the schema_plugins/<schema>/loc/<locale>/labels.xml
   - codelists - the localised codelists labels for the schema as defined in the schema_plugins/<schema>/loc/<locale>/codelists.xml
   - strings - the localised strings for the schema as defined in the schema_plugins/<schema>/loc/<locale>/strings.xml

If the view.xsl output needs to access resources in the formatter bundle (like css files or javascript files) the xml document contains a tag: resourceUrl that contains the url for obtaining that resource. An example of an image tag is: <img src="{/root/resourceURL}/img.png"/>.

By default the strings, labels, etc... will be localized based on the language provided in the URL. For example if the url is /geonetwork/srv/eng/metadata.formatter.html?xsl=default&id=32 then the language code that is used to look up the localization will be eng. However if the language code does not exist it will fall back to the Geonetwork platform default and then finally just load the first local it finds.

Schemas and geonetwork strings all have several different translations but extra strings, etc... can be added to the formatter bundle under the loc directory. The structure would be:loc/<langCode>/strings.xml. The name of the file does not have to be strings.xml. All xml files in the loc/<langCode>/ directory will be loaded and added to the xml document.

The format of the formatter bundle is as follows: 

config.properties
view.xsl
loc/<langCode>/

Only the view.xsl is required. If a single xsl file is uploaded then the rest of the directory structure will be created and some files will be added with default values. So a quick way to get started on a bundle is to upload an empty xsl file and then download it again. The downloaded zip file will have the correct layout and contain any other optional files.

Config.properties

The config.properties file contains some configuration options used when creating the xml document. Some of the properties include:

  • *fixedLang* - sets the language of the strings to the fixed language, this ensures that the formatter will always use the same language for its labels, strings, etc... no matter what language code is in the url.
  • *loadGeonetworkStrings* - if true or non-existent then geonetwork strings will be added to the xml document before view.xsl is applied. The default is true so if this parameter is not present then the strings will be loaded
  • *schemasToLoad* - defines which schema localization files should be loaded and added to the xml document before view.xsl is applied
    • if a comma separated list then only those schemas will be loaded
    • if all then all will be loaded
    • if none then no schemas will be loaded

Backwards Compatibility Issues

No compatibility issues

Risks

Nothing notable

Participants

  • As above
Last modified 12 years ago Last modified on May 2, 2012, 1:35:42 PM
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