container format for jigsaw modules

[Dalibor Topic]

Dalibor Topic wrote:

> Comments, ideas, etc. welcome.

A few further notes:

* I'm looking at adding a container format to Jigsaw - not a package 
manager, no fancy remote repository format, no such protocols, etc.
Just a simple way to transfer a (set of) module(s) from A to B in a
fixed form without having to port/require RPMs, debs, svr4, IPS, etc.
to exist on all platforms. IPS is almost there, but it lacks a 
fixed format.

* I would prefer to keep the internals of the jxr format flexible as 
long as possible - it's specific to Jigsaw, and doesn't have to 
follow the classical 'take JAR files and then throw something into
the magic directory' approach. Even if we don't end up picking xar
as the underpinnings of jxr, the separation of meta-data and payload
is a very useful property, along with the idea to push meta-data first.
hash it, compress it, etc.

* xar stores metadata as xml. That may not be a great choice for 
Jigsaw's metadata, if jmod needs to extract it on its own and 
can't rely on using a native xar tool to do it.

cheers,
dalibor topic

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