Some Changes for Channels and Transports in the June CTP, Part 1

At this point in the product cycle for WCF, how do we decide what disruptive changes to make? The changes that we're making now typically happen for one of four reasons:

• There's a defect in the product that can't be fixed without introducing some disruption. As we get closer to shipping, there's more discussion about whether it's better to live with the defects we know about as opposed to making a change and having to live with defects we don't know about.
• There's a new feature needed to enable an important customer scenario. In some cases we thought a scenario was already possible but it turns out not to work due to other circumstances. I like to think of this as adding a new feature because what you can do with the product depends on the code we're releasing, not our intentions for that code. The risk of adding a new feature is generally greater than that of fixing a defect in an existing scenario, necessitating this distinction. The window for adding new features ends much sooner than the window for fixing defects.
• There are features that are poorly designed or not being used and we want to eliminate them. Eliminating features has the side benefit of making the product simpler and in many cases easier to use. I love cutting bad features. It means we get to spend more time on things that work and people want to use.
• There are changes we want to make in the future but we have to do something now in order to make those changes possible. Once we make the final release, the cost of breaking compatibility skyrockets. That doesn't mean we should gratuitously future proof things. Often, there is a more-roundabout and less-desirable way of making a change if the straightforward path is blocked by compatibility requirements. However, we want to make the transition of working with a current version to working with a new version as smooth as possible for both us and customers.

I'm going to go over some of the more noticeable changes that we made between the February and June CTP releases. Not all of these are breaking changes for earlier code. In some cases we added significant new functionality without affecting the existing code. Most of these changes do have an impact on earlier versions though.

I'll run the article on binding contexts tomorrow, then continue with this series for the remainer of the week.