URIResolver, Docbook and XSL Transform

Question

I am attempting to transform some Docbook XSL to HTML using Java / Xalan and a mixture of the official Docbook XSL files from https://sourceforge.net/projects/docbook/files/docbook-xsl/1.76.1/ with some local xsl files that provide some customizations and overrides.

I want to prevent my application from having to download external resources or access local files. So I have implemented a class that extends the URIResolver interface.

The problem is that the resolve(final String href, final String base) function is not providing enough information to identify the particular file that is being requested.

For example, one of the local override files is imported from the xsl file using <xsl:import href="../../../xsl/html.xsl"/>. In this case the href parameter for my resolver class is set to ../../../xsl/html.xsl, which is fine. The html.xsl file then imports a file called defaults.xsl. The href parameter is set to only defaults.xsl, and the base parameter is set to null.

This might be followed by an import of http://docbook.sourceforge.net/release/xsl/current/xhtml/docbook.xsl, in which case the href parameter is set to http://docbook.sourceforge.net/release/xsl/current/xhtml/docbook.xsl. However, if the docbook.xsl imports a file called defaults.xsl, the href parameter is also set to defaults.xsl and base is set to null.

The issue is that the href and base parameters don't uniquely identify the resource, and you can't guess which file is being requested by watching the order of the previous hrefs either. Is there some trick to finding out exactly what context a file is being requested in?

Answer 1

Does the Source you are creating the transform from have a system ID? If not, this might be a reason why your base is always null in your URI resolver.

If you are creating transforms from input streams, you can manually assign a system ID to a source. You can generate an artificial one if necessary and use that artificial URI in your URI resolver to map back to a base URI. Also make sure the sources you create in your URI resolver also have system IDs or the same problem will occur with resources imported from those files.