Symphony.

After filtering my content by url param, I need to pass a node from this selection as param to an external/dynamic datasource. Is this possible? Or if i want to use a param in a url path of my dynamic datasource don't I have any other choice but to include this param as a url param in my page?

The application should be pulling monolingual described picture albums, from multilingual site parts(with the same title), because they all need pull the same pictures, but have no uniform way to pass the info to the external datasource, I see no other way but to add unique numberings to each site part, and number the picture albums.

Can you use the Output Parameter from the DS that filters your content? Bottom left of the edit DS page, select the node you want to pass to another data source. It will create a parameter in the form $ds-your-ds-name.

You can use this in the URL of a dynamic DS.

  {$root}/assets/php/do-something.php?q={$ds-your-ds-name}

In the same way your Dynamic DS URL could use the $current-page, $root-page (etc) parameters, which will be the same regardless of language.

 {$root}/assets/php/get-page.php?p={$current-page}