Hi all, like Saliya ask I want to describe my use case and search for your opinion.
Use case description: Forrest Dispatcher [2] The idea of the dispatcher is to provide a template approach for structuring a resulting document [1] and aggregate arbitrary data sources. The underlying templates are called structurer [3] and can configure multiple output formats. You can use two different tags in the structurer [4] that will influence the resulting document. There are hooks that are the styling side of the structurer, you can imitate arbitrary html skeleton with their help. On the other hand you have contracts that are basically providing the actual data. Till now all contracts that we have are basic xsl stylesheets the dispatcher invoke a transformation on them [5]. The result of this transformation will be in a envelope like data structure: <forrest:content xmlns:forrest="http://apache.org/forrest/templates/1.0";> <forrest:part> Content going to the location defined by the structurer.</forrest:part> <forrest:part xpath="/html/head"> <meta content=" Content going to a fixed location defined by the contract (here: /html/head)." name="Description" /> </forrest:part> </forrest:content> The interesting part here is <forrest:part xpath="/html/head"/>. That will request that the content within the tag should be injection in the given xpath. The structurer [4] has a similar attribute <structure type="html" hooksXpath="/html/body">. The first forrest:part in above example does not provide a @xpath meaning it want to store the result in the hierarchical location which is determinate in the structure. In our case the first content part will be stored in /html/body and the second part in /html/head Meaning contracts can request to inject resulting data in arbitrary xpath location of the resulting document. The current active location has solved the problem by using DOM, but the code we used is a wee bit complex and speed wise enhanceable. That let us to create a StAX based implementation http://svn.apache.org/repos/asf/forrest/trunk/whiteboard/dispatcher. In this implementation the result of above transformation of contracts is stored as XMLEvents in a list. Each xpath is then stored in a Map as key of this list object [7] processContractResult(InputStream resultStream). In the end of processing of the structure each list of XMLEvents entries of the map is passed to a writer [7] createResultStax(XMLEventWriter writer). That works fine if you do have one main list of events but when you want to inject in arbitrary location of the document that is not working fine since it loose the overall hierarchical order (the OM). This is the reason I am looking into AXIOM since I hope to solve the problem of injection without using DOM. salu2 [1] http://svn.apache.org/repos/asf/forrest/trunk/whiteboard/dispatcher/docu/diagrams/dispatcher-overview-flow.png [2] http://forrest.apache.org/pluginDocs/plugins_0_80/org.apache.forrest.plugin.internal.dispatcher/ [3] http://forrest.apache.org/pluginDocs/plugins_0_80/org.apache.forrest.plugin.internal.dispatcher/how/howto-dispatcher-structurer.html [4] http://svn.apache.org/repos/asf/forrest/trunk/whiteboard/dispatcher/testing/org/apache/forrest/dispatcher/master.structurer.xml [5] http://svn.apache.org/repos/asf/forrest/trunk/whiteboard/dispatcher/docu/diagrams/dispatcher-xsl-contract.png [6] http://svn.apache.org/repos/asf/forrest/trunk/whiteboard/dispatcher/testing/org/apache/forrest/dispatcher/master.contract.xml [7] http://svn.apache.org/repos/asf/forrest/trunk/whiteboard/dispatcher/java/org/apache/forrest/dispatcher/impl/XMLStructurer.java -- Thorsten Scherler thorsten.at.apache.org Open Source Java consulting, training and solutions
