Impressive !
Isn't this a generalized implementation of Berin's call back proposal. I like it. It steals away the most powerful concept from JSPs and gives it to Cocoon. How did you guys do input/form handling? Ivelin ----- Original Message ----- From: <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Friday, April 26, 2002 11:38 AM Subject: Creating dynamic content using JSP like Tag implementation > > > Hi all, > > let me start with a short introduction of my company and what we have done so > far. > Before being founded on April 1, 2001 as BASF IT Services we were an integrated > part of BASF Aktiengesellschaft in Ludwigshafen, Germany and BASF Computer > Services in Europe. We focus on high-quality IT-Development and Services > throughout Europe. E-Commerce is one of our businesses we have been working with > since several years and where we are very experienced in developing successful > solutions for BASF. > End of 2000, BASF started their global E-Commerce initiative named > "WorldAccount", focusing on a worldwide and integrated extranet platform for > their customers (have a look at it: http://worldaccount.basf.com). > To realize such a complex solution we had the idea to develop a publishing > framework which should also cover issues like session management, multi-language > support, layout and security. After evaluating Cocoon2 we decided to base on the > concepts of Avalon and the basic interfaces of Cocoon2, but due to its pre-alpha > version we needed to do some additional development (interpreted Sitemap, > LayoutTransformer, RequestProcessor, ValidationEngine, ErrorHandler, simple > module concept (like Blocks but really simple)......) > One other example: instead of using XSP-Logicsheets we developed a > tag-implementation similar to JSP-tags, but which uses a SAX-pipeline instead of > an output stream. The tags are interpreted during run-time by the appropriate > tag-transformer. > We needed approx. half a year to develop this framework where then the > WorldAccount functionalities could be placed on top and finally could go-live in > the 3rd quarter of 2001. In the last few months we transferred our framework to > Cocoon2 and would now like to present some of our solutions to the Open Source > community, hoping we can help to become Cocoon2 even more powerful and > successful than it already is. > > Ok, lets start with the Java-Code ;-) also part of the attachment. > The Tag Interface: > > public interface Tag extends XMLPipe, Component > { > String ROLE = Tag.class.getName(); > > /** > * Evaluate body content > * Valid return value for doStartTag. > */ > int EVAL_BODY = 0; > > /** > * Skip body evaluation. > * Valid return value for doStartTag. > */ > int SKIP_BODY = 1; > > /** > * Continue evaluating the page. > * Valid return value for doEndTag(). > */ > int EVAL_PAGE = 2; > > /** > * Process the end tag for this instance. > * > * @returns EVAL_PAGE. > * @throws SAXException. > */ > int doEndTag(String namespaceURI, String localName, String qName) throws > SAXException; > > /** > * Process the start tag for this instance. > * <p> > * The doStartTag method assumes that parent have been set. > * It also assumes that any properties exposed as > * attributes have been set too. When this method is invoked, the body > * has not yet been evaluated. > * > * @returns EVAL_BODY or SKIP_BODY. > */ > int doStartTag(String namespaceURI, String localName, String qName, > Attributes atts) throws SAXException; > > /** > * Get the parent (closest enclosing tag handler) for this tag handler. > * > * @returns the current parent or null if none. > */ > Tag getParent(); > > /** > * Set the <code>SourceResolver</code>, objectModel <code>Map</code> > * and sitemap <code>Parameters</code> used to process the request. > */ > void setup(SourceResolver resolver, Map objectModel, Parameters parameters) > throws SAXException, IOException; > > /** > * Set the parent (closest enclosing tag handler) of this tag handler. > * Invoked by the implementation object prior to doStartTag(). > * > * @param parent The parent tag or null. > */ > void setParent(Tag parent); > } > > > > The Tag Implementation works like a JSP Tag but generate SAX output. > > Simple Tag Implementation: > > public class XMLDateTag extends AbstractTag > { > public int doStartTag(String namespaceURI, String localName, > String qName, Attributes atts) > throws SAXException > { > String date = new Date(System.currentTimeMillis()).toString(); > characters(date.toCharArray(), 0, date.length()); > return EVAL_BODY; > } > } > > In the current implementation the Tag's are configured in cocoon.xconf. All Tags > are managed by a ComponentSelector and grouped by a namespace (name of the > taglib Element). We are using URN's as namespace. The name of a tag is then > mapped to it's implementation. > > Example configuration: > > <component role="org.apache.cocoon.xml.taglib.TagSelector" > class="org.apache.cocoon.components.ExtendedComponentSelector"> > <taglib name="urn:apache:taglib:general" > class="org.apache.cocoon.components.ExtendedComponentSelector" > logger="sitemap.tag"> > <tag name="date" class="org.apache.cocoon.xml.taglib.general.XMLDateTag" > logger="sitemap.tag.xmldate" /> > <tag name="..." class="..." /> > </taglib> > <taglib name="urn:apache:taglib:... /> > <tag ..... /> > </taglib> > </component> > > Simple example page: > > <page> > <title xmlns:tag="urn:apache:taglib:general">Hello</title> > <content> > <para>This is my first Cocoon page!</para> > <para>Today, <tag:date /></para> > </content> > </page> > > How does it work? > > In the pipeline you need to configure the TagTransformer and add it to your > pipeline. Set the pool-min to "0" because of a bug in excalibur, instead you run > in a endless loop. > > <map:transformer name="tag" > src="org.apache.cocoon.transformation.TagTransformer" > pool-max="64" pool-min="0" pool-grow="2" > logger="sitemap.transformer.tag"> > <transformer-hint>tag</transformer-hint> > </map:transformer> > > The TagTransformer looks if the namespace of an element belongs to a configured > taglib namespace and tag name (see startElement). If it founds a Tag, this Tag > is dynamically inserted to the current SAX-Pipeline and the doStartTag method is > called. If the Tag implements some "SAX Event handling" methods, the Tag is able > to work like a Transformer. The default behavior is a XMLPipe. The doEndTag > method is called if the endElement SAX Event is called (see endElement of > TagTransformer) and the Tag is removed from the pipeline. In the doStartTag > and/or in the doEndTag you can emit additional SAX events to the Pipeline (see > XMLDateTag which only sends the current date). Tags can be nested and a inner > Tag can get a reference to the parent Tag (getParent method). > The TagTransformer can be configured with a "transformer-hint". If the > TagTransformer add a Tag to the Pipeline the Transformer which belongs to this > hint is also add to the pipeline (after the Tag). If this hint is the > TagTransformer itself, a Tag can send out other Tags which are automatic > interpreted again. > > Any comments ? > If you find this usefull, is it possible that a committer put this to scratchpad > ? > > Thanks Volker > > (See attached file: source.zip) > ---------------------------------------------------------------------------- ---- > --------------------------------------------------------------------- > To unsubscribe, e-mail: [EMAIL PROTECTED] > For additional commands, email: [EMAIL PROTECTED] --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, email: [EMAIL PROTECTED]
