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7.6: Always Have a Running Version

  • Page ID
    32405
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    Intent Increase confidence in changes by regularly rebuilding the system.

    Problem

    How do you convince your customer that you are on the right path?

    This problem is difficult because:

    • It can be hard to demo a software system under development, or to discuss problems with users since there is often no stable, running version of the system available.

    • Integrating changes from multiple versions of a system can be slow and painful.

    Yet, solving this problem is feasible because:

    • You don’t have to wait until a component is “finished” before integrating it.

    Solution

    Institute a discipline of integrating new changes and developments on a daily basis.

    Steps

    • Have version management and configuration management systems in place.

    • Make sure you have regression tests in place for the parts you are working on.

    • Institute a discipline of short transactions for checking out system components and checking them back in again. Plan iterations to be as short as possible to allow changes to be integrated into a running system.

    Tradeoffs

    Pros

    • You always have a working version to demo.

    • You can always have a working version to run your regression tests.

    • You can quickly validate your changes, thereby helping you to Build Confidence.

    Cons

    • You must continuously integrate changes.

    Difficulties

    • Large systems may have very long build times. You may need to rearchitect the system first to enable shorter build times.

    • It can be hard to break some kinds of large modifications into meaningful updates that can be individually integrated.

    Rationale

    Many practitioners advocate a process of continuous integration as a way to avoid a risky and painful big-bang integration [Boo94].

    Related Patterns

    Regression Test After Every Change minimizes the risk of defects creeping in during integration.

    Continuous Integration [Boo94] [Bec00] is a proven way to Always Have a Running Version.


    This page titled 7.6: Always Have a Running Version is shared under a CC BY-SA license and was authored, remixed, and/or curated by Serge Demeyer, Stéphane Ducasse, Oscar Nierstrasz.

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