jkesselm 2003/02/13 12:49:25 Modified: java/src/org/apache/xml/xdm Tag: xslt20 XDMDesign.html Log: Update current XDM status description. Revision Changes Path No revision No revision 1.1.2.2 +12 -22 xml-xalan/java/src/org/apache/xml/xdm/Attic/XDMDesign.html Index: XDMDesign.html =================================================================== RCS file: /home/cvs/xml-xalan/java/src/org/apache/xml/xdm/Attic/XDMDesign.html,v retrieving revision 1.1.2.1 retrieving revision 1.1.2.2 diff -u -r1.1.2.1 -r1.1.2.2 --- XDMDesign.html 13 Feb 2003 18:20:42 -0000 1.1.2.1 +++ XDMDesign.html 13 Feb 2003 20:49:24 -0000 1.1.2.2 @@ -9,8 +9,7 @@ <p>XDM is intended to be an abstract API for the XPath Data Model. Its goal is to provide a single efficient view of a variety of back-end -implementations, ranging from DTM tables to DOMs to databases to -Java object graphs. +implementations, ranging from DTM tables to DOMs to databases. <p> Architecturally, XDM will replace the public DTM APIs. It should certainly be more efficient for non-tabular data, as well as being @@ -97,33 +96,24 @@ or missing. <h2>Implementation Status</h2> <p> -A first-draft implementation of these interfaces is in progress, as -the org.apache.xml.xdm.ref package. For testing purposes, this draft -is being wrapped around the existing DTM public APIs. Once we have it -running, we will begin to optimize away the old Node Handle-based -public DTM API in favor of an XDM implementation which is directly -aware of and optimized for the SAX2DTM/XNI2DTM implementation's -back-end tables, along with one that directly accesses a DOM tree -(based on the DOM2DTM2 experiment). -<p> -At this time, the basic code framework has been sketched. The basic -manager and tree-walker have been implemented, as has the shared code -of cursors and the Self cursor. Coding continues on cursors for other -axes, but that shouldn't be difficult -- it's mostly a matter of -wrapping these around DTM's low-level Axis Traversers. +At this time, the basic code framework has been sketched, and we +have a version of XDM which runs on top of DTM Traversers. +This is not maximally efficient; it was just maximally fast to prototype. +I have also adapted a few of the DTM Unit Tests -- simple as they are -- +to run against XDM as an initial validation. <p> There are still some issues to be resolved; these are flagged in the code with our usual %REVIEW%, %OPT% and %BUG% eye-catchers. <h2>Implementation Plan</h2> <p> -I'll finish drafting the various axis cursors, then convert the DTM -unit tests to run against the XDM APIs in order to do some initial -validation of this module. My best estimate is that I can reach this -point in ten more ays's worth of coding. -<p> -Once that has been done, we can begin the task of adapting a copy of +Our next step will be to try adapting a copy of Xalan to run against XDM rather than DTM, replacing Node Handles and DTM Iterators with Cursors and Tree Walkers. This should not be difficult, but will be time-consuming and poses risks of human error. I do not currently have a sizing estimate for this task. +<p> +After that's running, we will come back and start optimizing XDM, +phasing out Node Handles and letting XDM become our public model API. +We will also begin writing XDM wrappers around some of the other +models -- such as an XDM for DOM based on the DOM2DTM2 experiment. </body>
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