Volker,
I don't think that an iterator tag would be of great practical importance for Cocoon, but it would be certainly interesting to demonstrate the technique that one would use to create a tag which reevaluates its body. Since many of the tags share similar code in XMLFormTransformer, I am not sure that splitting it up in 10 classes would be necessarily cleaner. However I am open to suggestions. Ivelin ----- Original Message ----- From: <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Sunday, April 28, 2002 8:28 AM Subject: Antwort: Re: Creating dynamic content using JSP like Tag implementation > > > Ivelin, > > we have for the moment no implementation of a IteratorTag. I thought often > about an implementation and I think that we can implement it similarly as in the > current > JSP Jakarta taglib Implemtierung (http://jakarta.apache.org/taglibs/). If you > are interested, look at the current CVS "jakarta-taglibs" package > "org.apache.taglibs.standard.tag.common.xml" or the documentation in > "standard/doc/web/XML_ControlFlow_FunctionalDescription_1_EA2.html". > The differences between a Transformer and the SAX Tag implementation is, that it > is more modular and avoid the "if else" cascades in a transformer > implementation. > In our applications we have a lot of application specific Tag, not to much > generic Tag. Generic Tags we have, are Tags like i18n translation, comboboxes > for day, month, year .... > > If you like, I can make a suggestion for a IteratorTag implementation based on > the JSP design of the "JSP Standard Tag Library" which uses SAX instead of > Streams ;-) I can also make a proposal for a XFormsTransformer implemented as a > set of Tag's, but for this, I need to have a more detailed look at the current > implementation. > > Regards, > > Volker > > > > |--------+-----------------------> > | | "Ivelin | > | | Ivanov" | > | | <ivelin@apach| > | | e.org> | > | | | > | | 27.04.2002 | > | | 06:39 | > | | Bitte | > | | antworten an | > | | cocoon-dev | > | | | > |--------+-----------------------> > >--------------------------------------------------------------------------- -| > | | > | An: [EMAIL PROTECTED] | > | Kopie: (Blindkopie: Volker Schmitt/BASF-AG/BASF) | > | Thema: Re: Creating dynamic content using JSP like Tag | > | implementation | > >--------------------------------------------------------------------------- -| > > > > > > > Volker, > > After I looked at the implementation of the TagTransformer code, I realized > that it's very similar to the AbstractSaxTransformer class currently in > Cocoon2. > > Can you elaborate a bit on the differences and provide a non trivial example > of a tag. > For example how would an iterator tag look like. > If you see the XMLForm namespace tags, the repeat tag works like this: > > <xf:repeat nodeset="user/favorite"> > <xf:output ref="url"> > <xf:caption>URL :</xf:caption> > </xf:output> > </xf:repeat> > > > If you have time, please look at the XMLFormTransformer in Scratchpad which > extends AbstractSaxTransformer and advise if it could be written more > optimally as a set of tags. > > > Thanks, > > 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] > > > > > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: [EMAIL PROTECTED] > For additional commands, email: [EMAIL PROTECTED] > --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, email: [EMAIL PROTECTED]
