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Posted to dev@cocoon.apache.org by vo...@basf-it-services.com on 2002/04/28 15:28:58 UTC
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: cocoon-dev@xml.apache.org |
| 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: <vo...@basf-it-services.com>
To: <co...@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)
>
----------------------------------------------------------------------------
----
> ---------------------------------------------------------------------
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> For additional commands, email: cocoon-dev-help@xml.apache.org
---------------------------------------------------------------------
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---------------------------------------------------------------------
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Re: Antwort: Re: Creating dynamic content using JSP like Tag implementation
Posted by Ivelin Ivanov <iv...@apache.org>.
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: <vo...@basf-it-services.com>
To: <co...@xml.apache.org>
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: cocoon-dev@xml.apache.org
|
> | 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: <vo...@basf-it-services.com>
> To: <co...@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
>
>
>
>
>
>
> ---------------------------------------------------------------------
> To unsubscribe, e-mail: cocoon-dev-unsubscribe@xml.apache.org
> For additional commands, email: cocoon-dev-help@xml.apache.org
>
---------------------------------------------------------------------
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