Getting Agile

Talk about a loaded term. Even the term itself, “architecture”, when used in the Agile community can start a heated discussion. When I was coordinator of the International Association of Software Architects Puget Sound chapter, the discussions about “what is architecture” caused passionate debate. I am sure this entry will get some interesting comments, as well.

I don’t believe that this entry will solve the question but I hope to at least give some focus for teams who are dealing with the structural integrity of their applications. First off, a definition of “architecture”:

architecture: noun - “the art or practice of designing and constructing…” or “the complex or carefully designed structure of something” or “the conceptual structure and logical organization of a computer or computer-based system”

Each of these definitions interests me but to put them to practice is quite difficult. They are left to interpretation about what is design, construction, structure, conceptual, and logical. Earlier interpretations of this term interpreted these to mean the high-level structure, architectural style, and finally the stuff that is too expensive to get wrong.

It seems to me that my interpretation is a bit different. Working with tools, practices, and processes over the past 15 years has guided me to a different conclusion. I believe that architecture is how it is SAID:

Structure - how the pieces (components) create a solution (application)
Alignment - the degree to which the application or enterprise structures align to current business objectives and strategy
Integrity - the components that provide stability to the structure (application or enterprise) (ie. automated tests and builds, service-level agreements, network infrastructure, etc…)
Design - a way to conceptually communicate the planned or implemented structure of a component, application, or enterprise (ie. system of names, XP practice of Metaphor, information radiators, etc…)

Using these as the basic building blocks for teams to focus their efforts can be helpful.

The structure is the reality of the solution’s construction. If the structure is too brittle or complex to support future needs then the structure is not sound. If you have been in the software development industry for even short period of time you have probably seen applications that are too brittle or complex.

If the application or enterprise structures are not aligned with current business needs then the value of those structures have deteriorated. We sometimes keep a specific architecture and force-fit new business needs into it because it once was the right architecture to have or we paid a bunch of money for it. Continual restructuring of our architecture to meet today’s business needs is important.

Providing supports to our structure allows for it withstand changes in the environment such as new business needs and updates in technology. Automated tests and builds help us keep the structural integrity of our applications intact while these changes are introduced into our applications and enterprise.

Communicating the conceptual structure of a component, application, or enterprise is important because it is common for new people to work on them and for those structures to interact with other components and applications. Getting someone up to speed on a component or application involves verbal, tactile, written, and visual examples. Much of what is needed can be kept in or close to the codebase along with conversations with existing developers. It is important to understand how components and applications are currently structure conceptually so we can discuss their interactions with other components and applications. For instance, should we connect via library, SOAP, RPC, or REST?

When I think of application architecture I want to focus on just a few principles:

• Application architecture is about changeability, not longevity
• Application architecture decisions should be made closest to where they are implemented as possible
• Application architecture design is not only about our ability to design a solution but also knowing what components, applications, and solutions already exist
• The value for change in a component’s, application’s, or enterprise’s architecture is directly proportional to the cost of not addressing

If the structure is not able to change as the needs of our business change then the solution will become a liability. If someone other than those who are constructing components and applications are deciding on architecture decisions then there will be important information lost in translation between the two. If we keep using the same design hammer (ie. always using 3-tier or IoC for everything) then we are not allowing the strongest solutions to emerge. The value of architecture can usually be described by the cost incurred if it is not taken care of.

Well, let the onslaught of comments commence. I have put out my ideas on architecture. There are many more out there to discuss and I am sure I will hear some of them. I will finish this entry with a quote from Martin Fowler’s “Who Needs an Architect?” article:

“I define architecture as a word we use when we want to talk about design but want to puff it up to make it sound important.”