XOM API for Processing XML with Java

[Michael Kay <mike AT saxonica.com>]

The problem is that the JAR URI scheme (invented by Sun, I believe) doesn't 
follow the generic URI syntax defined in the RFCs - it's non-conformant. This 
causes problems all over the place. In Saxon I special-case it to try and 
make it work (java.net.URI can't handle it properly, so I use java.net.URL 
instead). By allowing it, you're providing a convenience to users, but you're 
also opening a can of worms.

Michael Kay
Saxonica

> On 7 Dec 2016, at 12:56, Michael Whapples <software AT mdw.onl> wrote:
> 
> When building a Document in XOM one can pass the builder.build method a 
> string for the base URI. If I pass to this method a jar: URI (eg. 
> jar:file:///D:/mydir/mybook.zip!/mybook.xml) as the base URI I get an 
> exception from XOM. It appears that the Verifier in XOM for verifying the 
> URI does not handle the jar: URI scheme correctly (it complains about a 
> double slash (//) in the path).
> 
> 
> In Java (at least Java7 and higher) the jar: protocol is fully handled and 
> such a URI can be used for accessing files inside a zip file.
> 
> 
> As far as I can tell allowing such a URI to be passed in would not cause 
> issues, the base URI could be used to resolve external resources referenced 
> from the XML file. May be I am missing something inside XOM where this 
> might cause an issue.
> 
> 
> Would it be possible for this to be fixed in future versions of XOM? 
> Alternatively is there another way for me to have the base URI reference a 
> location in a zip file?
> 
> 
> I tried creating a custom URL protocol handler for Java and modified the 
> base URI to use this protocol (eg. 
> zipfile:///D:/mydir/mybook.zip!/mybook.xml) but I could not get the JDK to 
> pick up this protocol handler (I was setting the java.protocol.handler.pkgs 
> system property but with no success). This option seems too complicated, 
> particularly when the jar: protocol is supported by the JDK by default.
> 
> 
> My only solution at the moment seems to be modify the base URI to something 
> XOM is happy with (eg. jar-file:///D:/mydir/mybook.zip!/mybook.xml) pass 
> this modified base URI to build. Then within a entity resolver catch the 
> use of the jar- prefix in the base URI and change it back to jar: and 
> manually resolve the external entity. A lot of work spread over many parts 
> of the code, so far from satisfactory and why I would like a better 
> solution.
> 
> 
> Michael Whapples
> 
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