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From "Antoine Levy-Lambert" <levylamb...@tiscali-dsl.de>
Subject Re: evolving techniques for large projects
Date Mon, 02 Jun 2003 16:32:33 GMT
Some elements for your choice/evaluation :

- in ant 1.6alpha, there are 2 new tasks which can be of use for you :
     - subant ===> this one is like ant, applied to a fileset containing n
build files
looks like (check the exact syntax from the doc)
                 <subant>
                       <fileset includes="**/*.xml"/>
                </subant>
   - import
   import is a bit like the xml entity include but somewhat better (I do not
know exactly how it works, this is what I gathered)

In other words, there is more support for large projects or
project/subprojects combinations in ant1.6alpha than in 1.5.3 or earlier.

- concerning gump
a number of Apache projects are built every night using gump. At least one
of the ant developers is running builds on his own development machine with
gump.

I hope this helps.

Antoine

----- Original Message -----
From: "Shackelford, John-Mason" <john-mason.shackelford@pearson.com>
To: "'Ant User'" <user@ant.apache.org>
Sent: Monday, June 02, 2003 6:11 PM
Subject: evolving techniques for large projects


> I am about to refactor our project's build files and wanted to check in to
> see if the state-of-the-art for handling large projects has changed any in
> the last year.
>
>
> PROBLEM:
>
> We have a large application made up of 25 components each of which has its
> own build file and use a master build file to kick the whole thing off.
Our
> major complaint with the current build system is that it performs poorly.
> Since we are reliant on the <ant> task to call down into each build file
we
> do not benefit from the dependency tree ant normally builds and so many
> targets are run and rerun. We to be able to build each component
> independently, so each component build file calls the build files of
> components on which it is dependent. Even though each component has
> up-to-date checking the over head of each component calling its
dependencies
> is rather significant.
>
> POSSIBLE SOLUTIONS:
>
> 1. master build file has proxy targets
>
> Hatcher & Loughran recommend against having components call their
> dependencies given the performance impact and the danger of coupling
> projects too tightly (214) though they acknowledge that this may be an
> inevitable in a growing project with many interdependent components even
> given a clean dependency graph (219).
>
> Hatcher & Loughran suggest using proxy targets in the master build file so
> that we gain the benefit of ant's own dependency computation (219-220).
> While this does allow us to avoid the expense of duplicate <ant> calls
from
> the master build file, it requires us to either to (a) move all knowledge
> regarding the component decencies from the component build files
themselves
> such that a component can not be built independent of the master build
file
> or (b) add targets to all components which by-pass component dependency
> checking & building for use by the master build file.
>
> Losing the ability to build components without the master build file (or
> some manual intervention) may  be insignificant if components are never
used
> alone since another project using the shared components will likely have
its
> own master build file and dependency resolution.
>
>
> 2. single logical build file and broken into physical files via XML
entities
>
> While this allows ant to use it's native dependency tree to avoid running
> targets multiple times, and partitions the project into smaller physical
> files, component build files will lack <project> tags and will cease to
> function independent of the master build file.
>
>
> 3. single build file
>
> While this jeopardizes the independence of components (as does option 2)
and
> forces the maintainer to deal with a very large file, it does allow us to
> leverage ant's own dependency graph while avoiding the confusion the XML
> entities introduce.
>
>
> 4. ant 1.6's  <import>
>
> Other than allowing the master file to conditionally include targets from
> other build files, and its simplicity, I do not have a clear understanding
> as to how this will contribute anything beyond an XML entity based
solution.
> I could use some education here.
>
>
> 5. Gump, Maven, etc.
>
> Other build tools seem to have developed specifically for builds with many
> interdependent components; however, adding entirely new tools to the mix
> increases the effort required of developers in environments where the
build
> system is distributed and used widely by developers with varying levels of
> configuration management expertise & interest.
>
>
> IMHO, THE BEST OF ALL POSSIBLE WORLDS
>
> While the following solution may pose insurmountable (or perhaps very
> awkward) development requirement challenges, from a usability perspective
it
> seems to me that the best solution would be if ant's native dependency
> resolution mechanism would allow users to include targets from other
> functioning build files. (Perhaps this is what Ant 1.6's <import> would
> do--I am unclear about it.) For example one could specify:
>
> <project name "master-build-file">
>    <buildfile name="componentA" location="../A/build.xml"/>
>    <buildfile name="componentB" location="../B/build.xml"/>
>    <target name="build-everything"
>            depends="init,componentA:build,componentB:build">
> ....
>
> Thus one could indicate to ant that targets should be drawn from several
> build files, and could build a dependency graph across files. The
> <buildfile> directive would tell ant to import targets from the a
particular
> build file and append the prefix (indicated in the name parameter) to the
> import targets so as to prevent naming collisions. Ant would then build it
> dependency graph and begin executing the default target, or target
specified
> on the command line, etc.
>
>
> REQUEST FOR FEEDBACK
>
> I would be interested to know (a) if I have missed any solutions for large
> project configuration, or misrepresented the strengths & weaknesses of the
> solutions presented (b) if the <import> task offers a better solution than
I
> have understood, (c) if there is any merit to my final suggestion.
>
>
> John-Mason Shackelford
>
> Software Developer
> Pearson Educational Measurement - eMeasurement Group
>
> 2510 North Dodge St.
> Iowa City, IA 52245
> ph. 319-354-9200x6214
> john-mason.shackelford@pearson.com
> http://etest.ncspearson.com
>
>
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