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From "Jason Rosenberg" <ja...@squaretrade.com>
Subject Re: The RIGHT Direction for ANT (was Re: Problem using script task)
Date Tue, 09 Jan 2001 22:04:55 GMT
In my experience, the "dependency-generator" program to which
you refer is usually a manual process.  Assuming you have built up
a workable build environment, the job of generating the build-sets
and dependent deliverable modules, requires little overhead above
and beyond writing the code itself for which dependencies you are
trying to track.

So, frankly it is essential that the build environment is easy to work
with, and has a set of features which make it easy to create the
"dependency-reading" programs needed for each module.

So, if I have a working template that builds Weblogic EJB's in my 
environment, for instance, then certainly, I don't want to have to 
painstakingly redefine the sequence of compiling and jarring and 
distributing the EJB individually, but rather, I want to reuse it.  
So, I create a template that knows how to build and jar and distribute
my ejb's, knows how to clean up after them, knows how
to update them from cvs, in a standard way.  This is all above
and beyond the simple 'ejbjar' task that is currently an 'optional'
task in Ant.  Because I can write a reusable template that
knows for my environment where all the important classes
are located (for setting the classpath), etc., the ability to
have a reusable, customized procedure, really isn't asking
for too much.

Now, I simply declare that project X is an EJB, and my
template now knows what to do with it.  That is the power
of templating.

I have now done this, but it is rather ugly, since the process of
creating reusable templates amounts to transferring the bulk
of my Ant implementation to javascript code called from the
<script> task.

Your high-browed discussion of dependency-reading vs.
dependency-generating programs is a bit off base, not sure
if it has much of an audience in the real world.

What is the big-"O" order for the job of writing software?
If I write some new code, I also need to define how the
software should be built, and how it should be deployed.
This doesn't add significantly to the 'order'.  Especially,
if the job of stating how to build the module is nothing
more than labelling the project as (an ejb, a java package,
a jsp page, or whatever).

Templating is truly powerful, and I now see how great
it can be, with my Ant/Javascript implementation.  This
would have been a royal pain in the butt with Make.

Probably the biggest flaw in your argument is to have
lumped together Make and Ant as equivalents.  Ant
is clearly much easier and much more powerful and
much more portable than Make.  That's why Ant is
attractive.  It has little to do with dependency tracking.

Jason





----- Original Message ----- 
From: "Jerry Huth" <jerry.huth@Sun.COM>
To: <ant-dev@jakarta.apache.org>
Sent: Tuesday, January 09, 2001 1:57 PM
Subject: The RIGHT Direction for ANT (was Re: Problem using script task)


> 
> This discussion about whether or not ANT should have more advanced
> features such as templates is amusing because the obvious answer is
> that if your software system is so large that you need such advanced
> features, then your build system should include both a
> dependency-generation program as well as a dependency-reading program.
> 
> ANT and MAKE are dependency-reading programs.  They are meant to read
> dependency scripts and fire the actions.  They are not meant as
> human-written scripting languages for large software systems.
> Dependency-generation programs are those that write out the dependency
> scripts: they generate the ANT or MAKE build scripts so that humans
> don't have to.
> 
> As software systems grow in size, the folly of trying to use the
> dependency scripts to define your whole software build system becomes
> more and more apparent.  No matter how many advanced features you add
> to your dependency-reading program, you will always be able to build
> large software systems easier using a dependency-generation program in
> combination with the dependency-reading program.  
> 
> In fact, the only reason to add advanced features to ANT or MAKE is to
> allow them to be used (however awkwardly) for medium-sized software
> projects.  For large software projects it is clear that using the two
> programs in combination is infinitely easier than trying to build the
> whole system with only a dependency-reading program.  Indeed, MAKE
> has become exorbitantly bloated with "advanced" features over the
> years, but still it is completely inadequate for large software
> systems unless it is used in combination with a dependency-generation
> program.
> 
> Mathematically the reason why using the two programs together is
> easier is that the dependency-generation program requires only
> Constant time effort (it is not dependent on the size of the software
> system being built), whereas dependency scripts always require at
> least some O(n) effort (n is the number of lines of source code being
> built).  Furthermore, using a dependency-generation program allows you
> to minimize the O(n) effort by putting the "smarts" of the build
> system in the dependency-generation program, thus allowing the O(n)
> scripts to be reduced to their smallest possible size.  Indeed, when
> used with a good dependency-generation program, the O(n) effort is so
> small that it is easily handled by the source code developers
> themselves.
> 
> Theoretically if a software system is "sufficiently uniform" than a
> feature as simple as templates could allow ANT or MAKE to be used
> without a dependency-generation program; but of course as software
> systems grow in size, their degree of uniformity inevitably lessens
> due to the increasing need for automation and other advanced build
> features, so there is always a point at which the use of a separate
> dependency-generation program is easier.
> 
> Ultimately, software build systems should provide the most advanced
> build features to the end-user (the software developer) while reducing
> the O(n) build script maintainence effort to its minimal value.  And
> this is precisely why using the two programs in combination is so
> effective: coding the advanced features of a build system in the
> Constant-time part (the dependency-generation program) will always
> require less effort than coding them in the O(n) part (the dependency
> scripts).
> 
> What this means for the future direction of ANT is that we shouldn't
> repeat the mistakes of MAKE by continuing to pile on more and more
> features of dubious usefullness.  Instead we should focus our efforts
> on providing an ANT file generator that is sufficiently general to be
> useful to the software community at large.
> 
> The irony of using a dependency-generator program is that when you
> have one you only need very basic features in the dependency-reading
> program.  ANT doesn't need any more features, it needs a companion ANT
> file generator program!
> 
> ---
> 
> Jerry Huth
> Sun Microsystems
> (650) 786-4658
> jerry.huth@sun.com
> 
> 
> 
> -------------------------------------------------------------------------
> Jason Rosenberg wrote:
> > 
> > > On 1/6/01 9:40 PM, "Jason Rosenberg" <jason@squaretrade.com> wrote:
> > >
> > > > Ant is procedural, and that is what I want.  It is close to being useful,
> > > > to date, but just needs to add a very small set of features to close the
> > > > case.  Simply admitting that it is procedural would really clear the way.
> > > > Let's stop beating around the bush.
> > >
> > > Nope. Let's not. There are things that Ant needs. IMHO, turning into
> > > something procedural isn't one of them. I'd rather just write my
> > > buildscripts in JavaScript if that were the case.
> > >
> > 
> > Well, I got into this debate because I wanted to have reusable templates
> > which are applied across a large set of like modules, etc.  And, as we have
> > seen, Ant 1.2 is still not adequate in terms of templating, etc.  So, this
> > leaves us with having to use JavaScript, via the script task, if we want
> > to have any sort of elegance with Ant.  So, for now, not only are you
> > right in saying that if you want to do anything procedural, you should
> > use JavaScript, you also need to add that you really end up doing
> > everything in JavaScript anyway, even when you are using Ant.
> > 
> > > I come down to the opinion that calling something data or code is pretty
> > > tough. After all, software is just data at some point. :) However there is
a
> > > visceral line drawn about what Ant is good for, and at what point it's not.
> > > That line has been labeled with the somewhat, but sort of useful terms of
> > > "procedural vs. declarative". Neither term is totally appropriate. But we
> > > use them anyway :)
> > >
> > 
> > Ant is a build management tool.  It's purpose is to build software.  This
> > means doing things like javac and javadoc and copy and ejbjar, etc.
> > These are all procedural tasks.  If you want to be able to represent
> > a software build module declaratively, then you need to be able
> > to define it as a data object, with attributes which define how to
> > build it.  In order to do this constructively, you simply have to have
> > templates or sub-routines, etc.
> > 
> > > > Yes, I think the beauty of Ant is that it has the power to keep
> > > > things simple and human readable.  I like the <execute-task>
> > > > idea mentioned by someone on another topic, or possibly a
> > > > simple case:
> > > >
> > > > <case property="caseProperty">
> > > >   <if value="1" execute="doMainCompile"/>
> > > >   <if value="2" execute="doPartialBuild"/>
> > > >   <default execute="showErrorAndFaile"/>
> > > > </case>
> > >
> > > But here you are saying you want a "if" target implementation that could
> > > take any set of attributes and do something. "<execute-target>" only
does
> > > just that. It's a difference. And, imho, it's a big one.
> > >
> > 
> > I don't understand what you said here.
> 
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