cocoon-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Ivelin Ivanov" <ive...@apache.org>
Subject Re: Creating dynamic content using JSP like Tag implementation
Date Sat, 27 Apr 2002 04:16:08 GMT

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: <volker.schmitt@basf-it-services.com>
To: <cocoon-dev@xml.apache.org>
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: cocoon-dev-unsubscribe@xml.apache.org
> For additional commands, email: cocoon-dev-help@xml.apache.org


---------------------------------------------------------------------
To unsubscribe, e-mail: cocoon-dev-unsubscribe@xml.apache.org
For additional commands, email: cocoon-dev-help@xml.apache.org


Mime
View raw message