Hi Michael, "Dr. Michael Treichel" wrote: > We would like help implementing access to schema annotations. How do we get > into business?
In general, we thought that annotation should be stored as an XML string in each XML schema component (i.e org.apache.xerces.impl.xs.XSElementDecl), following the XML syntax defined in the XML Schema specification [1]. The writeAnnotation() will invoke SAX or DOM parser that will parse this annotation string, issuing either SAX events or producing a DOM tree. Here some additional information: 1. Traversing of annotation from the schema is done in the org.apache.xerces.impl.xs.traversers XSDAbstractTraverser traverseAnnotationDecl. The schemas are traversed into dom-like structure (see implementation in org.apache.xerces.impl.xs.opti) but traversal is implementation independent (see DOMUtil class). You will need to walk the DTM tree (using DOMUtil) and create annotation string. At this time you will also need to save all the namespace declarations in scope (since you need those declarations to parse the string, etc...) -- XSDocumentInfo has a pointer to the namespaces in scope. You need to get all prefix declarations and add those as namespace declarations (xmlns:prefix="http://...";) to the xs:annotation. Btw, for serialization of the annotations you might look at XMLSerializer (in org.apache.xml.serialize) -- there is a serializeNode method, however I am not sure if it will work since it assumes DOM implementation. 2. The DTM (org.apache.xerces.impl.xs.opti) implementation currently does not create any text nodes, meaning that any text in <documentation> or <appinfo> won't be available... To fix it you need to modify the SchemaDOMParser (org.apache.xerces.impl.xs.opti) parser, to create string when in context of annotation element. This could be done by having a global StringBuffer, appending the data to it in characters() method and retrieving / resetting data at start/endElement calls (assuming there are no comments, PIs, etc in the annotation context). The string could be later stored either as a Text node or just a string field on the DefaultElement node (org.apache.xerces.impl.xs.opti). 2. In the writeAnnotation you will need to get a parser. For performance reasons you might need to implement some kind of synchronized parser pool to avoid creating a new parser for each writeAnnotation method invocation. As far as I know, Xerces grammar implementation is thread/safe (grammars could be added to different grammar pools used by parsers in the different threads). So you must synchronize access to your parser. 3. writeAnnotation allows you to serialize to DOM or SAX. Sax implementation is trivial -- you only need to set correct DocumentHandler on the SAXParser. For the DOM, you will need to make some changes to be able to pass Document object to the DOMParser. As it works now, AbstractDOMParser (org.apache.xerces.parsers) queries document-class property in startDocument(..) method and creates an appropriate document instance. You will need to modify this method to allow using pre-set Document class -- the class could be either set via a new public method or via new INTERNAL xerces property. Let us know if you have more questions. [1] http://www.w3.org/TR/xmlschema-1/#declare-annotation Hope it helps, -- Elena Litani / IBM Toronto --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
