[armedbear-devel] ABCL packaging ASDF system in jars (was Re: Disabling "built-in" output translation)

[Mark Evenson]

On 5/17/11 3:28 PM, Faré wrote:
[…]
> Hope this helps.

I'm gonna need a bit more time to chew over the ASDF code, but thanks 
for the general direction.  I must confess that in spite of the 
reasonable looking documentation and having contributed the function 
translation code to ASDF, its whole output translation API has never 
really gelled in my understanding as a totality.  Maybe I can contribute 
some examples to the texinfo file when the fuzz in my understanding 
resolves a bit.

> BTW, for cl-launch and XCVB, I indeed am looking for a way to create
> bundles from compiled stuff. How do I create a jar from ABCL and a set
> of lisp files, precompiled or not?

A reasonable packaging mechanism for ABCL plus "compiled stuff" composed 
of ASDF system definitions that works well in a Java ecosystem is 
precisely the itch I'm in the process of scratching for ABCL right now. 
  The base unit of packaging in Java is the jar file, which is nothing 
more than a ZIP archive with (possibly) some Java-the-language specific 
metadata.  Currently, one can package an ASDF definition in a jar file, 
push the location of the asd file into ASDF:*CENTRAL-REGISTRY* using the 
[ABCL JAR-PATHNAME conventions][1] for which a subsequent 
ASDF:LOAD-SYSTEM will do the right thing.

[1]: 
http://trac.common-lisp.net/armedbear/browser/trunk/abcl/doc/design/pathnames/jar-pathnames.markdown

For instance, if you were to package up cl-ppcre installed via 
[quicklisp][10^9monkey-wants-this] in a jar file via

   unix$ cd ~/quicklisp/dists/quicklisp/software && jar cfv 
/tmp/cl-ppcre-2.0.3.jar cl-ppcre-2.0.3

[10^9monkey-wants-this]: http://www.quicklisp.org

one could subsequently enable an ASDF controlled load of this system via

   CL-USER> (push "jar:file:/tmp/cl-ppcre-2.0.3.jar!/cl-ppcre-2.0.3/" 
asdf:*central-registry)

When loaded, ASDF will compile the system to the user cache.

Some problems here that I'm working through:

1)  You can't immediately load FASL out of the jar.  In my current 
hackish way—i.e. without comprehending your advice yet—one has first 
ASDF compile the system with output translations disabled, and then

  (defmethod asdf:perform ((o asdf:compile-op) (c asdf:cl-source-file)))
  (setf (asdf::output-translations) '((t t))))

in the target JVM to load the ABCL FASLS from the jar.

2) One has to specify the absolute path on the local filesystem (or 
potentially via a URI) for the jar, which makes things a bit fragile in 
the typical Java ecosystem usage which shuffles jars around like win32 
DLLs (or, to be fair, Unix dynamic libraries) relying merely on the 
filename to keep things straight.  My current insight into a way around 
would be to define another PATHNAME extension in ABCL for CLASSPATH 
entries, i.e. "classpath:cl-ppcre-2.0.3.jar!/cl-ppcre-2.0.3/" would 
refer to the named jar in the JVM CLASSPATH if it exists.

3)  ABCL [has a bug][#149] that currently prevents ASDF systems located 
in the top-level entry of a JAR from being accessed.

[#149]: http://trac.common-lisp.net/armedbear/ticket/149

4)  The extremely nice use of [JSS][jss] and [ABCLD's slight 
modification][abcld] of ASDF to also refer to jar files to dynamically 
load into the JVM probably needs to be rewritten, otherwise we run into 
the situation whereby we have jars (i.e. the packaged Java code) within 
the ASDF packaged jar which A) needs changes within ABCL to completely 
work and B) would be rather inefficient in that the naive implementation 
  each request for a new entry in the JAR within a JAR would require a 
complete "reseek" through the enclosed ZIP file.

[jss]: http://code.google.com/p/lsw2/source/browse/#svn%2Ftrunk%2Fjss
[abcld]: 
http://code.google.com/p/abcl-dynamic-install/source/browse?repo=abcld

5)  A fear of mine: if I enable all this, I presume that people would 
start going around creating 'abcl.jar' files with different inclusions 
of different ASDF packagings.  Without a real smart dynamic 
introspection system that essentially solves the problems in JVM's 
classpath we would end up with, at the minimum, a rather hostile 
situation for the end user.  "Put 'abcl.jar' in your classpath."  "I 
did, and it still didn't load Maxima."  "Well, what's the checksum of 
your abcl.jar?" "c48d359a23ee"  "Oh, you need 846f78c279cb".  Ideally, I 
would like to come up with a mechanism that would require that 
'abcl.jar' come from "official" ABCL packaging, but would somehow be 
able to introspect the JVM classpath to include ASDF definitions.

Comments solicited.

-- 
"A screaming comes across the sky.  It has happened before, but there
is nothing to compare to it now."