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Tag: migration

  • TFS Migration: Sharing common code

    In this latest installment of recording our team’s migration to Team Foundation Server 2010, I’ll be describing how we organized and share our common code libraries.

    The scenario is quite common. We have a Application that provides specific line of business functionality. It leverages several Common libraries that provide underlying functionality that are used by all of the Applications built and supported by our team.

    Previously, when using Visual SourceSafe, we would share these libraries by using the ‘Add Project from Source Control’ feature in Visual Studio to add the common projects to our Application’s solution.

    TFS guidance offered several approaches to sharing these libraries across Applications. The primary approaches are:

    1. Workspace Mapping – add a directory mapping to your workspace for the shared library so it will be updated to your local box alongside your application’s directory structure. This is essentially a client-side solution, since Workspaces are managed on the local development system.
    2. Branching and Merging – use the improved Branching capability in TFS to branch the common project into the source control structure of the application project. This is essentially a server-side solution, since the branched code is maintained by Source Control and will be updated by anyone who does a ‘Get Latest’ on the project directory.

    We have adopted the Branching and Merging approach, but it was not without a lot of experimentation of both methods. In the end, here were the key factors in our choice.

    1. Server side vs. client side. A big part of our goal in organizing our projects is the ability to set up a new development environment quickly. The server side Branch and Merge strategy supports this goal by eliminating one more step (that is, configuring the Workspace) in preparing a new dev environment.
    2. Isolation of potential changes. While it is more and more infrequent, changes do occur to the common libraries. By leveraging a Branch, the branched copy of the common project is isolated from all other consumers of that library, until the changes are merged in to the Main branch for the common library. If we were using the Workspace mapping approach, a check-in of changes would go straight to the Main branch of the shared project, which could cause a ripple effect through other Applications that are using the common code.

    Still, there are other implications and adjustments for our development team, primarily propogating changes. In the case when a change to a common library is merged back to the Main branch, and it is appropriate to propogate those changes to all other consumers, a new effort is required to forward merge the common code out to its consumers. This effort is compounded if the consumer Application itself has multiple branches that would all need the updates. However for our team, this is an acceptable trade off since a) changes are infrequent, and b) the number of consuming applications is manageable. Furthermore, as we continue to expand our automated Build setup, propogation may be something that can be scripted in as part of a nightly build of the common projects.

    For more information about these approaches, you can check out the Patterns & Practices guidance for Team Development with TFS.

  • TFS Migration: Branching and Merging Strategy

    As we are evaluating and planning our migration to Team Foundation Server 2010, considerations for adopting a Branching and Merging strategy for our source control projects has demanded a lot of our attention.

    While using Visual Source Safe, our team rarely if ever used Branching to isolate project so they can be developed or supported in parallel with our main effort. VSS wasn’t so great at executing branching and merging, and we, like many, chose to err on the side of caution and forego branching altogether.

    In TFS Source Control, it seems branching and merging have been improved to a level of comfort where we as a team can have some confidence that executing a branch or merge operation won’t lead us to spend more time cleaning up rather than moving on and doing the development work itself.

    In the end, we have largely concluded to use branches to isolate our releases, but not to isolate our normal development during a sprint. As such, our Main (or Trunk) branch will be the primary (and consequently slightly unstable) code line. After each release, we will create a branch for that deployed version of the product for maintenance purposes.


    Here are some of the key factors in our decision:

    1. branches require a level or “care and feeding” that (for our relatively small team, at least) would have not yielded any great value for our normal development sprint. We rarely have divided teams working on the same product, or long running feature development in parallel to working our product backlog.
    2. branching complicates IIS hosted applications. We choose to use IIS, rather than the Visual Studio Development Server, to host our applications during development. Consequently, every branch requires a reconfiguration of IIS to point to the site’s directory contained in that branch. While this reconfiguration be scripted (as demonstrated here) it still is another step that the developer has to remember to perform.
    3. branching is further complicated when you have shared code libraries that must be replicated to every new branch. While there are some clever approaches to managing workspaces or using Build scripts to update branches, you can alleviate the whole issue by minimizing the branches you create.
    4. we do not have a formal QA team that would require a stable Main branch for testing purposes. Our adoption of Agile is such that our peer reviews and testing are integrated in to our sprint, and consequently we are not ‘handing off’ our product to another team to exercise. If there were a QA team, then it certainly would be more important to keep a highly stable Main branch, and that would merit spawning a new Branch for ongoing development. In our case, it’s just not necessary.

    It is nice to know that TFS Source Control makes branching and merging a more trustworthy operation, and that the tools are there when we need them. But for now, we’ll take the simple road.