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org.apache.cocoon.transformation
public class: LinkRewriterTransformer [javadoc | source]
java.lang.Object
   org.apache.avalon.framework.logger.AbstractLogEnabled
      org.apache.cocoon.xml.AbstractXMLProducer
         org.apache.cocoon.xml.AbstractXMLPipe
            org.apache.cocoon.transformation.AbstractTransformer
               org.apache.cocoon.transformation.AbstractSAXTransformer
                  org.apache.cocoon.transformation.LinkRewriterTransformer

All Implemented Interfaces:
    org.apache.avalon.framework.activity.Disposable, org.apache.avalon.framework.activity.Initializable, org.apache.avalon.framework.activity.Disposable, org.apache.avalon.framework.service.Serviceable, org.apache.avalon.framework.configuration.Configurable, Transformer, XMLPipe, org.apache.avalon.excalibur.pool.Recyclable, XMLProducer

Rewrites URIs in links to a value determined by an InputModule. The URI scheme identifies the InputModule to use, and the rest of the URI is used as the attribute name.

Example

For instance, if we had an org.apache.cocoon.components.modules.input.XMLFileModule , configured to read values from an XML file:

<site>
<faq>
<how_to_boil_eggs href="faq/eggs.html"/>
</faq>
</site>
mapped to the prefix 'site:', then <link href="site:/site/faq/how_to_boil_eggs/@href"> would be replaced with <link href="faq/eggs.html">

InputModule Configuration

InputModules are configured twice; first statically in cocoon.xconf, and then dynamically at runtime, with dynamic configuration (if any) taking precedence. Transformer allows you to pass a dynamic configuration to used InputModules as follows.

First, a template Configuration is specified in the static <map:components> block of the sitemap within <input-module> tags:

<map:transformer name="linkrewriter"
src="org.apache.cocoon.transformation.LinkRewriterTransformer">
<link-attrs>href src</link-attrs>
<schemes>site ext</schemes>
<input-module name="site">
<file src="cocoon://samples/link/linkmap" reloadable="true"/>
</input-module>
<input-module name="mapper">
<input-module name="site">
<file src="{src}" reloadable="true"/>
</input-module>
<prefix>/site/</prefix>
<suffix>/@href</suffix>
</input-module>
</map:transformer>
Here, we have first configured which attributes to examine, and which URL schemes to consider rewriting. In this example, <a href="site:index"> would be processed. See below for more configuration options.

Then, we have established dynamic configuration templates for two modules, 'site' (an org.apache.cocoon.components.modules.input.XMLFileModule and 'mapper' (A org.apache.cocoon.components.modules.input.SimpleMappingMetaModule . All other InputModules will use their static configs. Note that, when configuring a meta InputModule like 'mapper', we need to also configure the 'inner' module (here, 'site') with a nested <input-module>.

There is one further twist; to have really dynamic configuration, we need information available only when the transformer actually runs. This is why the above config was called a "template" configuration; it needs to be 'instantiated' and provided extra info, namely:

With the above config template, we can have a matcher like:
<map:match pattern="**welcome">
<map:generate src="index.xml"/>
<map:transform type="linkrewriter" src="cocoon:/{1}linkmap"/>
<map:serialize type="xml"/>
</map:match>
Which would cause the 'mapper' XMLFileModule to be configured with a different XML file, depending on the request.

Similarly, we could use a dynamic prefix:

<prefix>{prefix}</prefix>
in the template config, and:
<map:parameter name="prefix" value="/site/"/>
in the map:transform

A live example of LinkRewriterTransformer can be found in the Apache Forrest sitemap.

Transformer Configuration

The following configuration entries in map:transformer block are recognised:

link-attrs
Space-separated list of attributes to consider links (to be transformed). The whole value of the attribute is considered link and transformed.
link-attr
0..n of these elements each specify an attribute containing link(s) (to be transformed) and optionally a regular expression to locate substring(s) of the attribute value considered link(s). Has two attributes:
name
(required) name of the attribute whose value contains link(s).
pattern
(optional) regular expression such that when matched against the attribute value, all parenthesized expressions (except number 0) will be considered links that should be transformed. If absent, the whole value of the attribute is considered to be a link, as if the attribute was included in 'link-attrs'.
schemes
Space-separated list of URI schemes to explicitly include. If specified, all URIs with unlisted schemes will not be converted.
exclude-schemes
Space-separated list of URI schemes to explicitly exclude. Defaults to 'http https ftp news mailto'.
bad-link-str
String to use for links with a correct InputModule prefix, but no value therein. Defaults to the original URI.
namespace-uri
The namespace uri of elements whose attributes are considered for transformation. Defaults to the empty namespace ("").

The attributes considered to contain links are a set of the attributes specified in 'link-attrs' element and all 'link-attr' elements. Each attribute should be specified only once either in 'link-attrs' or 'link-attr'; i.e. an attribute can have at most 1 regular expression associated with it. If neither 'link-attrs' nor 'link-attr' configuration is present, defaults to 'href'.

Below is an example of regular expression usage that will transform links x1 and x2 in <action target="foo url(x1) bar url(x2)"/>:

<map:transformer name="linkrewriter"
src="org.apache.cocoon.transformation.LinkRewriterTransformer">
<link-attr name="target" pattern="(?:url\((.*?)\).*?){1,2}$"/>
<!-- additional configuration ... -->
</map:transformer>

When matched against the value of target attribute above, the parenthesized expressions are:
$0 = url(x1) bar url(x2)
$1 = x1
$2 = x2

Expression number 0 is always discarded by the transformer and the rest are considered links and re-written.

If present, map:parameter's from the map:transform block override the corresponding configuration entries from map:transformer. As an exception, 'link-attr' parameters are not recognised; 'link-attrs' parameter overrides both 'link-attrs' and 'link-attr' configuration.

Fields inherited from org.apache.cocoon.transformation.AbstractSAXTransformer:
EMPTY_ATTRIBUTES,  ignoreWhitespaces,  ignoreEmptyCharacters,  ignoreEventsCount,  ignoreHooksCount,  namespaceURI,  defaultNamespaceURI,  stack,  recorderStack,  request,  response,  context,  objectModel,  parameters,  source,  manager,  resolver,  emptyAttributes
Fields inherited from org.apache.cocoon.xml.AbstractXMLProducer:
EMPTY_CONTENT_HANDLER,  xmlConsumer,  contentHandler,  lexicalHandler
Method from org.apache.cocoon.transformation.LinkRewriterTransformer Summary:
configure,   dispose,   initialize,   recycle,   setup,   startTransformingElement
Methods from org.apache.cocoon.transformation.AbstractSAXTransformer:
addRecorder,   characters,   comment,   configure,   dispose,   endCDATA,   endDTD,   endDocument,   endElement,   endEntity,   endParametersRecording,   endParametersRecording,   endPrefixMapping,   endRecording,   endSAXRecording,   endSerializedXMLRecording,   endTextRecording,   endTransformingElement,   findPrefixMapping,   getMutableAttributes,   ignorableWhitespace,   processingInstruction,   recycle,   removeRecorder,   sendEndElementEvent,   sendEndElementEventNS,   sendEndPrefixMapping,   sendEvents,   sendParametersEvents,   sendStartElementEvent,   sendStartElementEvent,   sendStartElementEventNS,   sendStartElementEventNS,   sendStartPrefixMapping,   sendTextEvent,   service,   setDocumentLocator,   setup,   setupTransforming,   skippedEntity,   startCDATA,   startDTD,   startDocument,   startElement,   startEntity,   startParametersRecording,   startPrefixMapping,   startRecording,   startSAXRecording,   startSerializedXMLRecording,   startTextRecording,   startTransformingElement
Methods from org.apache.cocoon.xml.AbstractXMLPipe:
characters,   comment,   endCDATA,   endDTD,   endDocument,   endElement,   endEntity,   endPrefixMapping,   ignorableWhitespace,   processingInstruction,   setDocumentLocator,   skippedEntity,   startCDATA,   startDTD,   startDocument,   startElement,   startEntity,   startPrefixMapping
Methods from org.apache.cocoon.xml.AbstractXMLProducer:
recycle,   setConsumer,   setContentHandler,   setLexicalHandler
Methods from java.lang.Object:
equals,   getClass,   hashCode,   notify,   notifyAll,   toString,   wait,   wait,   wait
Method from org.apache.cocoon.transformation.LinkRewriterTransformer Detail:
 public  void configure(Configuration conf) throws ConfigurationException 
    Configure this component from the map:transformer block. Called before initialization and setup.
 public  void dispose() 
 public  void initialize() throws Exception 
    Initiate resources prior to this component becoming active.
 public  void recycle() 
    Recycle this component for use in another map:transform.
 public  void setup(SourceResolver resolver,
    Map objectModel,
    String src,
    Parameters parameters) throws IOException, SAXException, ProcessingException 
    Setup this component to handle a map:transform instance.
 public  void startTransformingElement(String uri,
    String name,
    String raw,
    Attributes attr) throws IOException, SAXException, ProcessingException 
    Start processing elements of our namespace. This hook is invoked for each sax event with our namespace.