Vassilis Koutavas wrote:
Thank you both very much! I would've never discovered how this works by myself.

Glad you got it working.

It would be really helpful if you could put your new found skills into a entry for our FAQ, or if you have a little more time perhaps a How-To.

I still don't understand which is the root element of the
aggregation and I don't know how to debug in forrest to find out. I
just matched the root element with "/" in the xsl.

When it comes to understanding the Cocoon components, the best resource is the Cocoon docs. So for the directory generator you have [1] and for the XPath generatpr [2]

I also added the above in the sitemap.xmap, instead of the input.xml,
because I don't find any reason why the input.xmap file needs to
exist. Maybe it has a reason if you speak about seperate modules and
plugins, but none for a single project.

Yes, I pointed you to an example in a plugin, but you opted to put it in to your project sitemap. This is perfectly OK if the work is only appropriate to that particular project. Otherwise you would want to put it in a plugin [3]

Another point in the resume example that I had to change is the value
of the "src" field of the xpathdirectory generator from

{property:content.xdocs}{1}buildings

to

{project:content.xdocs}{1}buildings

Yes, I should have thought to mention that. The Resume plugin is written for 0.8-dev, but you appear to be using 0.7.

Thanks again for your help, and I wish in the future there will be a
*real* reference document for forrest and cocoon. (See Java's API
reference to see how I think it should look like.)

I think if you look at the links I provide below that all the low level documentation is available. What is missing is a nice clear description of how to use this in a specific use case, like yours. It has come up before on this list, so this documentation also exists in the list archives (and thanks to your follow up here it is now even clearer in the archives)

We welcome any further contribution to our docs.

Ross

[1] http://cocoon.apache.org/2.1/userdocs/directory-generator.html
[2] http://cocoon.apache.org/2.1/userdocs/xpathdirectory-generator.html
[3] http://forrest.apache.org/docs_0_70/howto/howto-buildPlugin.html