Hi Martin,
I looked over your requirements and there is another solution you may consider looking into: JavaServer Faces. JSF contains tags for building HTML based user interfaces and also has the notion of an EL. JSF works in a JSP 1.2/Servlet 2.3 container.
The JSF RI source code and snapshots are available through java.net here:
http://javaserverfaces.dev.java.net
There is also another open implementation called MyFaces available here:
http://sourceforge.net/projects/myfaces
You will notice that the EL in JSF is different and builds upon the commons EL in order to support the JSF lifecycle.
There is also a Struts-Faces integration library which allows you to use JSF in conjunction with Struts:
http://struts.apache.org/faqs/kickstart.html#jsf
Thanks,
Justyna
Martin Shiveral wrote:
David and Martin,
Thanks for replying - it is appreciated. It seems sometimes there just aren't enough hours in the day.
I do intend to email the Struts user community at [EMAIL PROTECTED] as Martin suggested. The reason I mailed the developer list in the first place was to aim my questions at developers who might possibly be extending the EL tags themselves (as I am), including the original developer(s). Please don't interpret my original mail as a criticism of either the original developer(s) or the EL tag library itself and apologies if you think my mail is better suited to the Taglibs user list.
Your replies suggest a reason why few people have extended the EL tags (I have found little purchase on any of the Struts forums) - they are a "bridge" between the JSP 1.2 and JSP 2.0 containers so as David suggests they will have a limited lifespan.
The problem I have is that our project is standardising around WebSphere Studio Application Developer which supports JSP 1.2 therefore I need to extend the Struts-EL tags if I want to support the expression language in our custom tags within WSAD. The JavaServer Pages Standard Tag Library (http://java.sun.com/products/jsp/jstl/1.1/docs/tlddocs/index.html) does not contain tags for creating HTML-based user interfaces so it is not suitable. The Struts Taglib will support expression language in its attribute values but only if the container it runs in is JSP 2.0 (EL support being one of the ney features of JSP 2.0) so it is not suitable either.
My approach so far has been to create a number of custom tags which extend the EL tags to provide the functionality we require (mostly decoration of the underlying tag). The only issue I have encountered with extending the EL tags is that I need to duplicate the "evaluateExpressions" functionality of each EL tag class in my custom tags as the method is declared private (instead of protected) in the EL Tag Library source. I have already examined the Struts-EL Tag Library source (1.1) in some detail and am familiar with how it works. Considering my situation, does this sound like a sensible approach or do you think I have missed something significant?
Regards, Martin S
From: "Karr, David" <[EMAIL PROTECTED]>
Reply-To: "Tag Libraries Developers List" <[EMAIL PROTECTED]>
To: "Tag Libraries Developers List" <[EMAIL PROTECTED]>
Subject: RE: Struts EL tag library stability
Date: Fri, 23 Jul 2004 09:08:18 -0700
As the implementor of struts-el, and not specifically a user of it, I can't comment from the POV of a user, but I can clarify some of the goals of this library, which I think you may have missed.
I implemented struts-el when I saw the need for a "bridge" between Struts on JSP 1.2 containers and the upcoming JSP 2.0 containers, concerning use of the JSTL specifically. Struts-el is intended to be used in a JSP 1.2 container. It is not used in a JSP 2.0 container. So, to address one of your questions, Struts-EL will certainly NOT become part of the core Struts tag library, as there's no point to it. The greatest accomplishment of the struts-el library will be when no one needs it anymore.
I've struggled with the fact that I don't have very much documentation for Struts-EL, but the important thing to realize is that it's just a pairing of the Struts tag library with the JSTL EL (not the JSTL). In fact, virtually the entire tag library could technically be generated. Any tags that are implemented in Struts-EL exactly mirror the interface of the tag in the base tag library (except for two attributes I thought were very convenient in two tags), mostly because all of the tag classes in Struts-EL simply inherit from the corresponding class in the base library, but just pass the parameters through the JSTL EL.
With respect to calling setters of the tags, as Martin Cooper alludes to, it's important to understand the perspective of why this is happening.
> -----Original Message----- > From: Martin Shiveral [mailto:[EMAIL PROTECTED] > > The purpose of this email is to try and get an idea of the > number of users > in the struts community currently using the Struts EL tag library and > determine if the library is a sensible candidate for use > (i.e. whether it > will become a fully fledged part of the core Struts tag > library as opposed > to a contribution and what the level of developer support is > likely to be). > > The Struts EL tag library (see > http://struts.apache.org/faqs/struts-el.html) > is an > extension of the Struts tag library that supports expression language > attribute values instead of the conventional > runtime-expression values. This > tag functionalty would prove useful for the project I am > involved with but > there is not a great deal of Struts-EL documentation > available online. The > Struts 1.1 source download does contain some doumentation but > I find it a > worrying sign that the API for these tags is not available > online (to my > knowledge). > > For the most part we wish to take tags that generate standard > HTML elements > (button, text, textarea etc.) that support EL attribute > values and customise > them by wrapping additional elements around the underlying > functionality. I > have also read in numerous places (most notably the Jakarta > Taglib Developer > Guideline) that "user code should avoid calling a setter > method of a tag > handler for properties that correspond to tag attributes". > The Struts-EL > taglib source seems to break this rule by calling setter > methods from within > the "evaluateExpressions() private method of each tag, which makes me > slightly wary of them. > > Has anyone else extended these tags or encountered any > problems with them? > > Best Regards, > Martin > > _________________________________________________________________ > Use MSN Messenger to send music and pics to your friends > http://www.msn.co.uk/messenger > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: [EMAIL PROTECTED] > For additional commands, e-mail: [EMAIL PROTECTED] > >
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