Mulitilingual Document handling

Introduction
Implementation
Involved classes, XSPs and XSLTs

Introduction

Mulitilingual Document handling deals with documents of different languages. This affects virtually every part of Lenya, namely many aspects of work flow such as creation, publication, deactivation, deletion. It also affects access control, meta data, etc.

The multilingual capabilities are not a mandatory feature of Lenya. You can easily create monolingual publication by simply replacing a few properties in publication.xconf.

The multilingual capabilities are deeply ingrained in the core of Lenya and as such a conceptual overview has to delve into many areas of Lenya. The main parts of the multilingual capabilities are as follows:

Site tree: The site tree contains information about documents. It has been expanded to also contain information about different language versions of the same document. Different language versions of the same document share the same document-id.
Default language: A publication has a default language. This is the language in which the document is created. However it is not necessarily the case that there is always a document version in the default language as the user is allowed to remove any language version even the one for the default language.
If you specify an URL without a language suffix you are redirected to the default language document.
publication.xconf: This is where the available languages and the default language are specified.
page-envelope: The page envelope exports document specific information such as document-id via an input module. Naturally language specific information for the current document is also available via the page envelope.
Redirection: If you request a document foo.html in a multilingual publication you will internally be redirected to foo_en.html if "en" is the default language.
Special cases: Some special care has to be taken when removing language versions. The current implementation does not allow the user to remove all language versions of a document. There always has to be at least one language version.

Implementation

Site tree

The site tree contains nodes for each document. Each node can contain multiple label nodes for each language version of the document.

<node id="doctypes">
	<label xml:lang="de">Dokumenttypen</label>
	<label xml:lang="en">Document types</label>
	<node id="1column">
		<label xml:lang="de">1 Spalte</label>
	</node>
</node>

The classe SiteTree and SiteTreeNode provide interfaces to the nodes and the corresponding label nodes.

publication.xconf

The languages node in publication.xconf defines the languages that are available for this publication and also defines the default language.

<languages>
  <language default="true">de</language>
  <language>en</language>
</languages>

This information is available via the Publication class (getDefaultLanguage() and getLanguages() methods).

page-envelope

The page-envelope input module exports language related information, namely default-language, document-label, document-language, document-languages and document-languages-csv.

Redirection

The DefaultDocumentBuilder which implements the DocumentBuilder interface, takes care of redirecting language agnostic URLs (such as foo.html) to language aware links (foo_en.html), i.e. language agnostic links are redirected to the language aware link with the default language.

Addition and removal

More language versions are added with the "Create new language version" screen. Existing language versions can be removed with the "Remove Language" screen. These screens are generated by create-language.xsp, create-language.xsl, removelabel.xsp and removelabel.xsl.

The creation of a new language version is done via the create-language target which uses the InsertLabelTask ant task to insert a label in the site tree.

The removal of a language version is done via the remove-language target, which uses the RemoveLabelTask ant task (which removes the label from the site tree).

Involved classes, XSPs and XSLTs

The following classes, XSPs and XSLTs are involved in multilingual document handling:

org.apache.lenya.cms.publication.SiteTree and org.apache.lenya.cms.publication.SiteTreeNode: These interfaces provide acces to the label nodes.
org.apache.lenya.cms.publication.Publication: Provides access to the default language and to all available languages.
org.apache.lenya.cms.publication.PageEnvelope: Exports language related information such as default-language, document-language, etc.
org.apache.lenya.cms.publication.DefaultDocumentBuilder: Builds a document with the given language. The default implementation also takes care of redirecting foo.html to foo_en.html.
$publication-id/lenya/content/authoring/create-language.xsp, $publication-id/lenya/xslt/authoring/create-language.xsl: Generate the "Create new language version" screen.
src/webapp/lenya/content/authoring/removelabel.xsp, src/webapp/lenya/xslt/authoring/removelabel.xsl: Generate the "Remove Language" screen.
org.apache.lenya.cms.ant.InsertLabelTask: Ant task to add a label to the site tree.
org.apache.lenya.cms.ant.RemoveLabelTask: Ant task to remove a label from the site tree.
$publication-id/config/tasks/targets.xml: Defines the create-language and the remove-language target which handle the addition and removal of language versions of a document.