Re: JXTG and caching

[Leszek Gawron]

Sylvain Wallez wrote:
Well, it _could_ have a chance to work, but flowscript is definitely not 
the appropriate location to compute cache information for an element of 
the view pipeline.
not the appropriate .. but really there is no other place ..
The problem with JXG is that the template is the generate() method 
_only_ whereas an XSP is the full class, allowing to define getKey() and 
getValidity().

So what about adding two optional attributes on the template's root 
element, defining the cache information?

<page
   xmlns:jx="http://apache.org/cocoon/templates/jx/1.0";
   jx:cache-key='${cocoon.request.get("abc") + "!!spacer!!" + 
cocoon.request.get("bcd")....'
   jx:cache-validity='${new DeltaTimeCacheValidity(60 * 60 * 24)}'>
   ... template ....
</page>

WDYT?
Fine for simple cases but limits of this solution will appear very fast.
I just know what would users do (what I would also do if I wanted something 
more complex)

the .js file:
function validityForView() {
  var validity = new SomeVeryHardToComputeInOneLineValidity();
  return validity;
}
function keyForView() {
  var key = someVeryStrangeKeyFetchedFromSomewhere;
  return key;
}
function showSomeView() {
  cocoon.session.setAttribute( "myViewValidityFunc", validityForView );
  cocoon.session.setAttribute( "myViewKey", keyForView );
  cocoon.sendPage( "view/myview.jx", {} );
}
the template:
<page
   xmlns:jx="http://apache.org/cocoon/templates/jx/1.0";
   jx:cache-key='${cocoon.session.myViewKey()}'
   jx:cache-validity='${cocoon.session.myViewValidityFunc()}'>
   ... template ....
</page>
This and other examples proove that we need a way to extend jxtemplate 
generator with flow functions (or other logic "providers") when simple macro 
is not enough. This may lead to a jsb taglib nightmare but hey: user has got 
his own brain not to put database inserts in there and if he is he's just 
asking for troubles.

I still do not understand why we do have jx:formatDate and jx:formatNumber 
which are just some instances of formatters while there either should be none 
at all or just pluggable ones. Like these:

function stringToSAX( str, consumer, ignoreRootElement ) {
        var is = new Packages.org.xml.sax.InputSource( new java.io.StringReader( str ) 
);
        var ignore = ( ignoreRootElement == "true" );
        var parser = null;
        var includeConsumer = new org.apache.cocoon.xml.IncludeXMLConsumer( consumer, 
consumer );
        includeConsumer.setIgnoreRootElement( true );
        try {   
                parser = cocoon.getComponent( 
Packages.org.apache.excalibur.xml.sax.SAXParser.ROLE );
                parser.parse( is, includeConsumer );    
        } finally {
                if ( parser != null ) cocoon.releaseComponent( parser );
        }
}

function wikiToSAX( str, consumer ) {
        var radeoxStr = radeoxEngine.render( str, radeoxContext );
        var buffer = new java.lang.StringBuffer("<root>" );
        buffer.append( radeoxStr )
        buffer.append( "</root>" );
        var is = new Packages.org.xml.sax.InputSource( new java.io.StringReader( 
buffer.toString() ) );
        var parser = null;
        var includeConsumer = new org.apache.cocoon.xml.IncludeXMLConsumer( consumer, 
consumer );
        includeConsumer.setIgnoreRootElement( true );
        try {   
                parser = cocoon.getComponent( 
Packages.org.apache.excalibur.xml.sax.SAXParser.ROLE );
                parser.parse( is, includeConsumer );    
        } finally {
                if ( parser != null ) cocoon.releaseComponent( parser );
        }
}
Now I have to do the same session trick and build a macro:
        <jx:macro name="wiki-string">
                <jx:parameter name="value"/>
                <jx:set var="ignored" value="${cocoon.session.wikify( value, cocoon.consumer 
)}"/>
        </jx:macro>
I did not mean to sound unpleasant by any way. I would like to contribute 
something more than bug reports but I do not know cocoon's internals that much 
to catch all possible problems.

--
Leszek Gawron