Build is central to CM. It's critical to do it right.
A basic build capability is founded on 2 key fundamentals: the ability to reproduce the build and the ability to automate the build process. Without these two fundamentals, you're fighting an uphill battle. Reproduction of the build implies that you have a CM system able to capture the build definition. Automation helps to ensure that no manual errors can play into the production. But this is just a basic build capability.
To move up the ladder, there's plenty more to be done. First of all, automation must be made available to all levels of the team, from production down to developer. Each member of the team needs the same assurance that the right stuff is being built: developer, integration, verification, production.
It's one thing to automate the build, but in a continuous or regular integration cycle, there could be a lot of work in deciding what's going into the build, especially in larger projects. So what's the secret to successful regular builds? Make sure you have quality going into the builds. To get a series of quality builds it's important to make sure of 2 things: start with a stable build; ensure the changes going into the build are of high quality.
If you've got a half-baked build to start with, don't open the floodgates for other changes. First stablize the build through intensive debugging and changes that move the quality forward only. Once you have a stable build you're in a good position for the second requirement - high quality changes.
High quality changes
High quality software changes are a product of many factors:
- Good people
- Good product architecture
- Effective peer reviews
- Feature and integration testing prior to check-in
- Ensuring the changes that go in are approved
Good people are hard to come by, but good processes, with a good mentor, can make average developers very effective. A mix of software experience, application experience, objectivity and strong design and software engineering skills are desireable.
Good product architecture is key. I remember in my very first job, I had 1 week to get a code generator debugged and working. I looked at the architecture and it just wasn't there. The only way I could make the deadline was to throw out the existing work and rebuild from scratch, although with a good bit of help from the existing work that had been done. The tactic was successful. Now you might not want to throw out your entire flight software or telecom system, but if there are components that are overly complex and lack good architecture, your changes are going to cause problems. Your builds will have bugs that need to be ironed out before restoring a stable build, the first premise for the next build.
Effective peer reviews will eliminate a significant percentage of potential build problems, while at the same time helping to ensure that the architecture remains solid. It's important to have a good peer reivew process, but also a key developer involved, one that understands the architecture and and the wider issues involved. Peer reviews are most effective when they become a teaching tool - it's critical that new developers are aware of this going in.
Your process should not allow code to be checked in unless it has been tested. One of the most effective ways to ensure this is to track the test scripts, whether automated or manual, against the change, along with the test results. These should be reviewed as part of the peer review process. Another key practice is to include a