Wednesday, February 22, 2012

Architectural Antipattern: "Through The Looking Glass"

An anti-pattern is a commonly occurring pattern that is ineffective.

There is an architectural anti-pattern I like to call "Through the Looking Glass". This is when a system is broken into pieces or layers, but the pieces are cut perpendicular to the direction that the team and the business require. A common example is when a set of screens used to access a database system is split system into "front end" and "back end" components.

This "front end" and "back end" split ONLY makes sense if the back end can identify thier required interfaces before the front end is designed. If the "back end" requirements are being driven by the "front end" screens and/or systems, then this split is either #1 wrong or, at a minimum #2 premature. Most often, new systems need a front end to identify APIs that need to be used... it's more economical to build the system in such a manner that a front end change can quickly be migrated to the "back-end" (like rails) and enable using functioning software to be delivered early. The prudent thing is to then refactor and cut the system into pieces when necessary (or ideally just before necessary :).

I personally believe this problem is primarily caused by two things: over specialization and over engineering. Over specialization can be recognized when, for example, database administrators have no idea how the users will use or interact with the data. This can be combated by mixing DBAs into project teams as contributing members, not just people who sit around and wait for change requests to generate tables. Over engineering can be identified by looking for decorations inside the system design that are "for future growth" or other vague non-functional requirements. This can be solved by repeatedly asking the question "Are we actually gonna need this?"

1 comment:

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