A Possible EXPath Pkg Version 2

In 2012 a Packaging System specification was developed by the EXPath project for use with applications written in XML - EXPath Pkg. There is very little about Pkg that is XML specific, for the most part it just defines a container and some metadata.

Implementations of this specification emerged for eXist-db, Saxon, and Marklogic. For the most part it appears that the standard never really caught on, apart from the eXist-db implementation to the best of our knowledge there are no other implementations of Pkg still in-use. The specification itself was both incomplete, and lacking in detail. The resulting implementations, including the one for eXist-db, were therefore unsurprisingly rather unsatisfactory to say the least. They lacked many features, and offered many bugs. Major shortcomings include: a lack of sufficient ability to express dependencies between packages, a lack of dependency resolution, and a lack of suitable public/private repositories of dependencies. There have also been other efforts in the XML space both before and after EXPath Pkg to create a satisfactory packaging system, but likewise these don't seem to have had much uptake. Of course, we must acknowledge that building a single new Packaging System from scratch is no small feat, and by extension writing a complete specification to describe the semantics and mechanics of such a system so that others may create interoperable implementations is a task of herculean proportions.

In this paper we look at what a replacement for the EXPath Pkg specification might look like, and how it could alternatively perhaps be implemented through reuse rather than reinvention.