Feature Assignment ★

Day laborers waiting to be assigned work, Raymondville, Texas, 1939.

...in a multi-person project of medium size or larger, one gets to the point that the work must be partitioned among team members. The initial architecture is complete; where do we go from here? 

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For every non-trivial project, it is impossible to partition the work cleanly.

You have to get the work done; you need to get the new release out the door. And you need everyone working on it. Yet no matter how you slice the work, people will find themselves working on the same piece of code. The essential complexity of the problem (see [BibRef-Brooks1995]) means this will happen in all but the most trivial developments. 

The partitioning of the problem through the architecture is mainly for people's benefit — the code doesn't care. We maintain the integrity of the architecture in order to attempt to maintain the comprehensibility of the problem, and we do this through CodeOwnership. But to a greater or lesser extent, features cut across the architecture. So CodeOwnership is not the right model for developing the features. 

Take, for example, the canonical example of an automatic teller. There are natural architectural entities such as the display subsystem, the input subsystem, and the communication layer, among others. Yet the feature "Display Account Balance" cuts across all of them. 

Therefore: 

Assign features to people for development. A feature development has a finite duration, and is therefore an assignment, not a role.

Feature assignment works together with the role of CodeOwnership to develop the product and maintain its architectural integrity. The developer of a feature will consult with the code owner about changes. 

The owner of the code affected most by a particular feature is often the natural person to receive the assignment of that feature, although it doesn't have to be. 

Features may be assigned to more than one person, or better still, developers may choose to work together to accomplish it (see DevelopingInPairs.) 

There is some danger that FeatureAssignment and CodeOwnership together will tend to encourage excessive management bureaucracy, but that doesn't need to be the case. Features are a natural unit of project tracking, and CodeOwnership need not add anything substantial to the project overhead. 

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The temporary nature of FeatureAssignment, coupled with the role nature of CodeOwnership strikes a balance between maintaining architectural integrity and getting the work done. Note how they together complete DeployAlongTheGrain. 

Note that some project methodologies advocate making assignments every day, with chunks of work that can be completed in a single day. If the project is small, and the work can be appropriately partitioned, this approach may work well. 

FeatureAssignment is broader; it encompasses this approach, but extends to large complex projects, and those where work is so complex that it cannot be broken into such small chunks.