next jpkg steps

[Dalibor Topic]

Lillian Angel wrote:
> Dalibor Topic wrote:
>> Hi everyone,
>>
>> JavaOne was fun. The jpkg tool had a slice of keynote time [1], and
>> the feedback was in general very positive. So, time to think about
>> what we want it to do next. On my list of things jpkg needs next are
>>
>> * lots of fresh jtreg tests
>> * rpm backend
>> * svr4/ips backend
>>
>> >From the JavaOne feedback, developers are also interested in using
>> jpkg for generating JNLP descriptors, OSGi bundles, Maven artifacts,
>> multi-module JARs, and a whole bunch of other interesting things. That
>> implies that we'll at some point probably need a simple way to create
>> jpkg backends as plugins for the tool.
>> Ideas, code and jtreg tests in particular ;) are welcome.
>>   
> 
> 
> I would like to help with the rpm backend and the jtreg tests. Can you
> send me more information on how to get started?

I've cleaned up a few tiny things, there is a bit more to do, but let's
get you started - cleanups and refactoring of jpkg can progress alongside.

To get the code:

hg fclone http://hg.openjdk.java.net/jigsaw/jigsaw

The code for jpkg is in jdk/src/share/classes/org/openjdk/jigsaw/cli/Packager.java
It's based on the code for the jmod tool (right next to it in the 
directroy), and uses classes from org.openjdk.jigsaw (the actual
jigsaw implementation), java.lang.module (the module interface).
The Debian package creation is done via a class called Deb - and I've
added a skeleton class for RPM generation now, so that when jpkg
get called with the rpm keyword, it'll get run instead of the Deb class. 

It has basically two methods one needs to care about when adding a new
package format:

writeMetaData - which takes care of converting metadata from jigsaw's
format to the package manager's (like translating dependencies)

that basically boils down to:

* translate module names to RPM names
* translate module versions to RPM versions
* translate module dependency names, versions and constraints to RPM dependency format

buildPackage - which takes care of building the actual package
using native packaging tools and adding post/pre install scripts,
for example.

* fakeroot & rpmbuild analogue of fakeroot & dpkg-deb
* post/pre install scripts to install/configure a module using jmod into the library

Feel free to factor the current deb packaging code out into sub-classes
as you need them, I assume you may be able to reuse a bit of it in your own
(or turn it into utility methods).

Building: 

The code is based on an older version of JDK 7, so you'll have to work around
the build not working without the ugly binary plugs (or poke mr to resync with
current). Since the build actually builds debian packages in jdk/make/modules/Makefile,
you'll want to change the all target to not build all-debs on Fedora, and instead
go with RPM tools, based on a makefile variable, for example.

Playing around:

Once you've built the code, I'd suggest looking at the jtreg tests in 
jdk/test/org/openjdk/jigsaw and playing a bit with them to understand how jmod works.
Going from there, we should discuss what's necessary to do for RPM on IRC, for
example. I suspect the current code is due for a bit of refactoring ;)

cheers,
dalibor topic
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