Channels ▼
RSS

Tools

SCM: Continuous vs. Controlled Integration


Controlled Integration

Now I don't mean that continuous integration isn't controlled. When I refer to "controlled integration" as opposed to "continuous", I mean that the first one occurs frequently, but not all the time. It normally runs when a certain milestone is reached (the milestone could perfectly be a weekly or daily planned integration).

There is also another difference between continuous and controlled that refers to the roles involved in the process: In a regular continuous scenario, all developers perform integrations and solve merge conflicts in code, which is perfectly acceptable on small, well-trained teams. But even agile teams can be affected by personnel rotation or new members joining, and it is usually not a good idea to have new developers mixing code they don't yet understand.

In controlled integration, a new role is introduced -- the integrator. The integrator can be a seasoned team member who is familiar with a big part of the code and also pretty used to the version control system and the build and release process. But the most important feature that the integrator introduces in the process is not that he knows all the code, which is not even necessary, but he takes responsibility on the integration process. Creating a new stable well-known point to serve as the base for development during the next iteration is integrator's primary goal.

Figure 6 shows an scenario in which well-defined integration points are not present. In such an environment, mainline instability and code-and-fix are likely to appear because developers are starting their tasks from volatile points.

[Click image to view at full size]
Figure 6: Development cycle with no defined integration points.

What a controlled integration process introduces is a set of well-known starting points that developers will use to work against. So, as in Figure 7, developers now will always start working against a well-known and stable baseline. For instance, between BL004 and BL005, everyone will start the new task again BL004 code, so nor unnecessary dependencies nor unstable developer working areas will affect the development process.

[Click image to view at full size]
Figure 7: Well-defined baselines in a controlled integration process.

As a side effect of controlled integration, task-oriented development can be introduced. Now each task a developer works on is handled independently by the version-control system, implementing full parallel development and giving the team a more maneuverability during release creation.

Figure 8 highlights the differences between a task-oriented parallel development and serialized development processes. When task-oriented patterns are supported by the version control, a look to the branching hierarchy reflects how the development was indeed parallel, something that can only be imagined but not traced by serial development.

[Click image to view at full size]
Figure 8: Differences between parallel and serial development.


Related Reading


More Insights






Currently we allow the following HTML tags in comments:

Single tags

These tags can be used alone and don't need an ending tag.

<br> Defines a single line break

<hr> Defines a horizontal line

Matching tags

These require an ending tag - e.g. <i>italic text</i>

<a> Defines an anchor

<b> Defines bold text

<big> Defines big text

<blockquote> Defines a long quotation

<caption> Defines a table caption

<cite> Defines a citation

<code> Defines computer code text

<em> Defines emphasized text

<fieldset> Defines a border around elements in a form

<h1> This is heading 1

<h2> This is heading 2

<h3> This is heading 3

<h4> This is heading 4

<h5> This is heading 5

<h6> This is heading 6

<i> Defines italic text

<p> Defines a paragraph

<pre> Defines preformatted text

<q> Defines a short quotation

<samp> Defines sample computer code text

<small> Defines small text

<span> Defines a section in a document

<s> Defines strikethrough text

<strike> Defines strikethrough text

<strong> Defines strong text

<sub> Defines subscripted text

<sup> Defines superscripted text

<u> Defines underlined text

Dr. Dobb's encourages readers to engage in spirited, healthy debate, including taking us to task. However, Dr. Dobb's moderates all comments posted to our site, and reserves the right to modify or remove any content that it determines to be derogatory, offensive, inflammatory, vulgar, irrelevant/off-topic, racist or obvious marketing or spam. Dr. Dobb's further reserves the right to disable the profile of any commenter participating in said activities.

 
Disqus Tips To upload an avatar photo, first complete your Disqus profile. | View the list of supported HTML tags you can use to style comments. | Please read our commenting policy.
 

Video