by Charlie Alfred
by Charlie Alfred
I am the author of an article on Value-Driven Architecture that was published in the same issue of Microsoft Architecture Journal as the one that you wrote on SOA Governance. I finally had the opportunity to read your article during the past couple of weeks, as well as the earlier one you reference (Metropolis), written by Pat Helland.
It was very interesting to see how you both took the concept in different directions. Pat focused on the service-provider side, and emphasized the benefits of standardization and high-speed transportation (networks). You took a more systemic view and emphasized how diversity often is not limited to service
provider implementations, but instead reaches more deeply to affect the service API’s as well as the workflow management (or other control structures).
Someone at the 2004 Software Product Line Architecture conference in Boston made a very interesting observation:
“The ROI of a software product line comes from leveraging the commonality. However, you cannot achieve this effectively until you also identify and manage the variability.”
I believe this quote sums up a lot of the philosophy difference between Pat’s article and yours. Pat seems to be making the “benefits of leveraging the commonality” argument, while you do a very good job of articulating how difficult “managing the commonality” can be.
Both of these notions are essential and relate back to one of the central themes of the article I wrote on “Value Driven Architecture.” In order to know where to accommodate diversity and where to leverage commonality, you must have a way of identifying and contrasting context-specific challenges
(where each context consists of a set of like-minded stakeholders who are affected by equivalent obstacles and constraints). By contrasting the key challenges and their priorities side-by-side, the architect begins to clarify which challenges are similar enough to leverage with a standardized approach, and which ones require more diverse approaches.
Again, thanks for the thought-provoking article.
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