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Posted to dev@cocoon.apache.org by Daniel Fagerstrom <da...@nada.kth.se> on 2007/08/19 21:20:29 UTC

Default Expression Language

Thanks to Grzegorz efforts, we are now close to be able to use the same 
exprssion language and object model both in the sitemap and in templates.

The whole thing is plugable, so those who have large investments in the 
current syntax and models can continue using them.

But while flexibillity is good for back compability it is confusing for 
new users. So we should try hard to decide what should be the default 
expression language and expression syntax.

Once I preffered JXPath as my webapps where XML-centric and I used XSLT 
and XPath everywhere. But now my webapps is more Java based, so JEXL or 
JS seem more natural. Of these I prefer JEXL as JS is a little bit to 
powerful as an EL for my taste.

But is the rest of world really using JEXL, JS or JXPath as ELs? 
Wouldn't it be a better idea to use the Unified Expression Language (EL) 
of JSP 2.1 (JSR-245) 
(http://en.wikipedia.org/wiki/Unified_Expression_Language). To me it 
seem like a rather good EL and there are several Apache licenced 
implementations, Tomcat has one and there is another one called JUEL 
http://juel.sourceforge.net/.

WDYT?

/Daniel

Re: Default Expression Language

Posted by Ralph Goers <Ra...@dslextreme.com>.
For 2.2 I suggest that what we recommend should be the default. However, 
it should clearly be documented how to reconfigure to match 2.1.  As far 
as which one to choose, I would look at:
1. Compatible license
2. Documentation
3. Performance
4. Ease of integration. (i.e. doesn't have to be ripped from some other 
jar, doesn't have a lot of dependencies we don't already have, etc.)

Ralph

Daniel Fagerstrom wrote:
> Thanks to Grzegorz efforts, we are now close to be able to use the 
> same exprssion language and object model both in the sitemap and in 
> templates.
>
> The whole thing is plugable, so those who have large investments in 
> the current syntax and models can continue using them.
>
> But while flexibillity is good for back compability it is confusing 
> for new users. So we should try hard to decide what should be the 
> default expression language and expression syntax.
>
> Once I preffered JXPath as my webapps where XML-centric and I used 
> XSLT and XPath everywhere. But now my webapps is more Java based, so 
> JEXL or JS seem more natural. Of these I prefer JEXL as JS is a little 
> bit to powerful as an EL for my taste.
>
> But is the rest of world really using JEXL, JS or JXPath as ELs? 
> Wouldn't it be a better idea to use the Unified Expression Language 
> (EL) of JSP 2.1 (JSR-245) 
> (http://en.wikipedia.org/wiki/Unified_Expression_Language). To me it 
> seem like a rather good EL and there are several Apache licenced 
> implementations, Tomcat has one and there is another one called JUEL 
> http://juel.sourceforge.net/.
>
> WDYT?
>
> /Daniel

Re: Default Expression Language

Posted by Ralph Goers <Ra...@dslextreme.com>.
Actually, now that you mention it one of the things I've disliked about 
flow is that you can only specify a single interpreter per sitemap. One 
should be able to have a single sitemap that uses multiple expression 
languages, possibly even in the same pipeline.

Alfred Nathaniel wrote:
> On Sun, 2007-08-19 at 21:20 +0200, Daniel Fagerstrom wrote:
>   
>> Thanks to Grzegorz efforts, we are now close to be able to use the same 
>> exprssion language and object model both in the sitemap and in templates.
>>
>> The whole thing is plugable, so those who have large investments in the 
>> current syntax and models can continue using them.
>>
>> But while flexibillity is good for back compability it is confusing for 
>> new users. So we should try hard to decide what should be the default 
>> expression language and expression syntax.
>>
>> Once I preffered JXPath as my webapps where XML-centric and I used XSLT 
>> and XPath everywhere. But now my webapps is more Java based, so JEXL or 
>> JS seem more natural. Of these I prefer JEXL as JS is a little bit to 
>> powerful as an EL for my taste.
>>
>> But is the rest of world really using JEXL, JS or JXPath as ELs? 
>> Wouldn't it be a better idea to use the Unified Expression Language (EL) 
>> of JSP 2.1 (JSR-245) 
>> (http://en.wikipedia.org/wiki/Unified_Expression_Language). To me it 
>> seem like a rather good EL and there are several Apache licenced 
>> implementations, Tomcat has one and there is another one called JUEL 
>> http://juel.sourceforge.net/.
>>
>> WDYT?
>>
>> /Daniel
>>     
>
> Maybe there is no good default at all!
>
> How about specifying in the sitemap which expression language is used in
> it?  And if this specification is missing, the default is the good old
> input module.
>
> Cheers, Alfred.
>
>   

Re: Default Expression Language

Posted by Alfred Nathaniel <an...@apache.org>.
On Sun, 2007-08-19 at 21:20 +0200, Daniel Fagerstrom wrote:
> Thanks to Grzegorz efforts, we are now close to be able to use the same 
> exprssion language and object model both in the sitemap and in templates.
> 
> The whole thing is plugable, so those who have large investments in the 
> current syntax and models can continue using them.
> 
> But while flexibillity is good for back compability it is confusing for 
> new users. So we should try hard to decide what should be the default 
> expression language and expression syntax.
> 
> Once I preffered JXPath as my webapps where XML-centric and I used XSLT 
> and XPath everywhere. But now my webapps is more Java based, so JEXL or 
> JS seem more natural. Of these I prefer JEXL as JS is a little bit to 
> powerful as an EL for my taste.
> 
> But is the rest of world really using JEXL, JS or JXPath as ELs? 
> Wouldn't it be a better idea to use the Unified Expression Language (EL) 
> of JSP 2.1 (JSR-245) 
> (http://en.wikipedia.org/wiki/Unified_Expression_Language). To me it 
> seem like a rather good EL and there are several Apache licenced 
> implementations, Tomcat has one and there is another one called JUEL 
> http://juel.sourceforge.net/.
> 
> WDYT?
> 
> /Daniel

Maybe there is no good default at all!

How about specifying in the sitemap which expression language is used in
it?  And if this specification is missing, the default is the good old
input module.

Cheers, Alfred.