What is build automation software (for example, Ant)?

Question

I see reference of ant a lot but I don\'t get exactly what its meant to do? from what i\'ve heard its supposed to compile your projects but can\'t i just do that by clicking Run

Answer 1

rogeriopvl is absolutely correct, but to answer your "can't I just do that by clicking Run->Run in Eclipse?" question: that's fine for a project that you're working on on your own, and don't need a repeatable, scriptable build in multiple environments.

If you're working on an open source project, however, or professional software which needs to be able to build on a build server etc, requiring a particular IDE to be running isn't a good idea.

Answer 2

The short answer is that Ant is a great way to create a complete project build that is independent of any particular tool any developer may be using. Without an independent build, things can go haywire quickly - especially for large project teams.

And now for the long answer... I have been brought into several projects without any sense of an independent build. On one project, there was one guy who was not a developer that was tasked with building and deploying the software. He had created 147 separate windows batch files to compile each EJB, each servlet, and each client component. There was no error checking for this build. All log messages, including error messages went to standard out. It was up to him to manually recognize by reading this log which exception or message printed was a normal and which message was an error. He also had to deploy this software he just built. Deploying was equally as complex since there were several load-balanced tiers. Each module had to be placed in the right place manually with options setup to match downstream and upstream tiers. Building and deploying this software took him at least 3 days using this method. Of course, only then could anyone determine if the build "worked". Usually, after this period all the programmers would scramble to debug the build. Programmers would say my module works fine in my IDE. I just click run like this, see?

Indeed, the individual software modules usually worked, but the build and deployment was horribly ineffective. And just as bad, it was equally as difficult for anyone to deploy a build to more than one environment. Management would say, ok you now have this build working in our regression testing environment. Now deploy that same build in this other environment so the sales guys can demo up and coming software. That should be simple to do, but it also took at least 2 days, followed by a "debugging the build" period. Builds and deploys were never simple and never accurate. It really slowed the project down.

Anyway, we replaced this entire procedure with a complete Ant based build and deploy mechanism. The end result was that a complete build could be created and deployed in less than 30 minutes, completely automated. The QA guy managing the builds and deploys could keep a whiteboard of which environment had which build deployed to it and which group was using that environment. This was something that was just not possible with the old system.

Answer 3

You are also referring to the ""Export ant buildfile".

If you write your own Ant script for building your application outside eclipse, you can write your own targets that use the Ant task to delegate to the generated build.xml.

Also, you can configure a project's 'builders' (project properties » Builders) to run any script (ant or otherwise) you want when you build the project, manually or automatically.

Answer 4

Joel (Spolsky) has a great article on "The Joel Test." Many of them revolve around being able to do important things often, quickly and reliably. One of those things is your build.

Answer 5

In many larger companies (and likely some smaller ones), you'll find that production code is not built by the people who developed it. Instead, the developers may check their code into a source code repository and tag it. Then they give this tag to a build team.

The build team, in a separate (clean) area - possibly on some headless server (i.e. with no GUI) - will then check out the code and run a build script. The build script will be completely independent of the desktop environment/IDE.

This ensures that nothing which happens to be on any one developer's computer is "polluting" the build. (Or, more likely, nothing outside source control is required for the system to work!)

So most software you use will never, ever be built from a developer's desktop.

PS. You might also want to look at the idea of Continuous Integration

Answer 6

Ant allows CRISP (complete, repeatable, informative, schedulable, portable) builds. You can find great info on it in this presentation by Mike Clark and in his book, Pragmatic Project Automation.