Tuesday, January 6, 2015

Continuously delivering beta versions

I used to think that beta versions are lame. I associated “beta” with poor quality and with pushing validation to the users instead of ensuring high quality internally, through test driven development, clean design and excellent engineering practices. Now we are in progress of making Mockito 2.0 and we are using betas...

Beta version makes it possible to continuously deliver incompatible changes, incrementally. It is high quality: all tests pass, new coverage is meticulously added. Since there are several potentially incompatible changes, it would be hard to implement all of them in one go. We need more time and we still want to deliver continuously. Betas to the rescue!

It makes me think why making a new major version typically involves relatively significant effort. Why isn’t a major version release as simple as it should be? In theory one can develop a software library with high focus on compatibility: deprecate features and APIs with replacements, avoid incompatible changes at all cost, etc. In this mode, releasing a major version could be as simple as removing deprecated code, turning on some new behavior, changing the default settings and that’s it. A few commits and a single push. In practice, it is never that simple. For example, it might be costly to keep old and new behavior in parallel so that it can be toggled in the next major version. In this case, the authors may choose to remove the previous behavior and implement a new one as a part of major version implementation effort. In some cases, it might be actually the best for the end user because he could get the new features faster.

It makes me wonder about developing a software library that is always backwards compatible. I’m afraid it wouldn’t work. It feels that breaking changes are needed from time to time. Otherwise, the development can be slowed down or even paralyzed. Old features, APIs may stand in the way of innovation. It may become hard to tackle new important and challenging use cases. Industry does change, competition is restless, going after new ideas and use cases is unavoidable.

Being always compatible is often impractical. Major version releases typically involve extra effort. The latter bothers me. I’m going to work hard to avoid that in future. Continuous delivery makes releases hassle-free part of every-day routine. Semantic versioning and focus on compatibility make major version releases somewhat challenging and totally interesting. Hassle-free major version releases, on a regular basis, indicate very mature continuous delivery model. I want to be there.

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