#entarch This post follows discussions with Graham Berrisford of Avancier about the relationship between Enterprise Architecture (EA) and Solution Architecture (SA).
What seems to make sense is to describe EA/SA as a twin-track process (similar to the twin-track process that aligns service development with solution development in SOA).
Twin-track is essentially an abstract process pattern, used to align two activity
streams at different levels of granularity. As far I recall, I first encountered it in the Select Perspective methodology, described in two books by my friend and former colleague Paul Allen. The CBDI SAE methodology also uses the twin-track approach.
In SOA, there is a stream of activity to produce and maintain services,
and another stream of activity to use these services to build solutions.
These two streams need to be connected but not synchronized.
The two tracks may be separated organizationally - split into different
teams or org units, or even separate companies - provided that there are
suitable governance mechanisms for allocating resources and responsibilities, and resolving issues. People may specialize in one or other stream.
A twin-track processes doesn't assume either top-down or bottom-up. In
some cases, you could start with the solution requirements and then
specify the desired services (top-down). In other cases, you could start
with a set of available services, and then assemble these into solutions
(bottom-up). In practice, the twin-track approach accommodates a mixture
of top-down and bottom-up. The important point however is that the two
have to be connected at a series of touch-points.
We can now describe the relationship between enterprise architecture and
solution architecture in similar terms. If solution architecture is
disconnected from enterprise architecture, then the solution architects
are likely to produce point solutions instead of enterprise solutions.
Conversely if enterprise architecture is disconnected from solution
architecture, then it is likely to produce grand, simplistic and
ultimately unimplementable schemes.
Again, we don't have to assume that either EA or SA is dominant, but
that they work together towards common goals.
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