[opencms-dev] Re: JSTL Expression Language and OpenCms Macro Excpressions

[Toni Pérez]

On 13/08/06, Fabian Huber <fabian.huber at gmail.com> wrote:
> Hello Toni,
>
> * Yes, I reverted all my changes in the web.xml file.
>
> * The start tag in the web.xml file is:
> <web-app xmlns="http://java.sun.com/xml/ns/j2ee" xmlns:xsi="
> http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="
> http://java.sun.com/xml/ns/j2ee
> http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd" version="2.4">
>
> * The jsp where the problem exists, doesn't use any taglib. The problem is,
> when I try to use OpenCms Macro Expressions. Here is an example:
>
> <%@ page session="false" %>
> <%@ taglib prefix="cms" uri="http://www.opencms.org/taglib/cms" %>
>     <jsp:useBean id="cms" class="org.opencms.jsp.CmsJspActionElement">
>
>     <link rel="stylesheet" type="text/css"
> href="sites/default/kljb/css/articlemodule.css">
>
>     <%
>         cms.init(pageContext, request, response);
>
>          // get the template
>         String template = cms.property("template", "search");
>
>         // The page header
>     cms.include(template, "head");
>         // end of template head
>
>     String number = "${number}";
>
>     %>
>     <h1> Gallery</h1>
>
>
>     <cms:contentload collector="allInFolderDateReleasedDesc"
> param="/kljb/gallery/photos/galery_${number}|photoalbum" editable="true">
>     <table border="0" width="100%">
>     <tr><td width="50%">
>         <h2><cms:contentshow element="Title" /></h2>
>     </td>
>     <td>
>         <cms:contentloop element="Thumbs">
>         <cms:contentshow element="TextBottom" />
>         </cms:contentloop>
>     </td>
>     </tr>
>     <tr>
>     <td>
>         <cms:contentloop element="Thumbs">
>         <cms:contentshow element="TextTop" />
>         </cms:contentloop>
>     </td>
>     <td>
>         <a href="<cms:link><cms:contentshow element="${opencms.filename}"
> /></cms:link>">Ansehen</a>
>     </td>
>
>     </tr>
>     </table>
>
>     <br/><br/>
>
>     </cms:contentload>
>
>
>
>
>     <%
>
>         // The page foot
>         cms.include(template, "foot");
>
>     %>
>
> </jsp:useBean>
>
>
> The JSTL Library is parsing this file and takes the parts underlined as
> Expression Language. In fact, these parts are OpenCms Macro. Both languages
> have the same syntax. So this is the problem. (I don't know, why the OpenCms
> developers decided to take the syntax of Expression Language for Macro
> Expression, too. Ist there any sense?)
>
> You are working with macros in your jsp files and don't get this problem?
>
> Regards,
> Fabian


Hello, Fabian!

Short answer:
In that JSP you could insert the following statement at the beginning:
<%@ page isELIgnored="true" %>
You could see this page to read a little explanation:
http://java.sun.com/products/jsp/syntax/2.0/syntaxref2010.html#15653


Not so short answer:
You could read the "A.1.1.How JSTL 1.1 Backwards Compatibility is
Achieved" point of the JSTL 1.1 specification downloable from here:
http://jcp.org/aboutJava/communityprocess/final/jsr052/index2.html

I paste the most important sentences (in my opinion) of that point:
"The key difference between JSTL 1.0 and JSTL 1.1 is that the
expression language
(EL) has moved from the JSTL specification to the JSP specification. The EL is
therefore now part of the JSP 2.0 specification, and JSTL 1.1 requires JSP 2.0
(J2EE 1.4 platform).

A web application developed for JSP 1.2 has a servlet 2.3 deployment descriptor
(web.xml). JSP 2.0 provides backwards compatibility for JSP 1.2 web
applications by
disabling by default the EL machinery (i.e. evaluation of EL expressions) when a
web application has a servlet 2.3 deployment descriptor. A web application that
uses JSTL 1.0 and which is deployed with a servlet 2.3 deployment descriptor
therefore runs without any modification in a J2EE 1.4 environment because EL
expressions are ignored by JSP 2.0, and JSTL 1.0 keeps evaluating them as was
the case with JSP 1.2."

I hope this helps this time. ;-)
Regards.
    Toni.

P.S.: I also don't know why Alkacon use a syntax similar to the EL in
their Macro Expressions.