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RE: When Is Something Really SOA?
an enabler of an enterprise architecture. An enterprise can be
specified using services, and in fact,
service space. Service data models are terms or vectors of the
enterprise. What distinguishes the enterprise is
it will have a high similarity metric in types of information exchanged as a
result of using the services
it advertises or makes available for discovery. Enterprises are
aggregations of services by the data
supported (although, this is by definition, an information architecture and not
a fact of physical
result of the data models, the service space exhibits
local similarities that roughly approximate the
enterprise boundaries. Distance or angle
measurements among these (terms shared by
synonymy and polysemy) reveal that services cluster and that this cluster
and dynamic enterprise space boundary . Essentially, an
enterprise is a cluster of service terms within
enterprise term. Enterprises are a higher level space of enterprise terms,
and the aggregation of all
discoverable terms constitutes the network space or information space of
resources as defined by the
Wide Web architecture.
Here is a question has been on my
mind for quite some time - I have some strong viewpoints on it, but would like
to hear other viewpoints.
The general question is: When is something really a service-oriented
By this I do not mean "what is an SOA", "what characteristics does an SOA
have", etc. Rather, there seems to be a range of points on a continuum (call
it the "service continuum", perhaps) at which someone may declare that they
have implemented a service-oriented architecture.
In the past, I have pondered the
following more specific question (please note that this is all scoped to Web
Services-based SOA for ease of explanation):
If I have 2 Web Services that
communicate, do I have an SOA?
We can say "certainly not!". One
can do point-to-point integration with Web Services just as easily (to a
certain degree) as without, with redundant Web Services rather than shared Web
Services (a violation of one of the foundational tenets of SOA, which is
Now let's add some more
- The 2 Web Services share another Web Service in
common for their processing (i.e. we now have a "shared services"
- The service provider one or more policies for a service consumer that
interacts with it (these policies may address security, QoS, etc.)
- There is an electronic contract for interaction with the service
provider (e.g. WSDL)
Add to this the fact that many (correctly, IMO)
consider SOA to be a form of Enterprise Architecture, which (at least in my
mind) implies enterprise-level benefits.
So the more specific question is:
Given the second scenario above (with the various
added characteristics) and the fact that many consider SOA to be a form of EA
Is this second scenario large-scale enough that
it *really* may be considered SOA? IOW, how large-scale does such an
implementation need to be to *truly* be considered service-oriented
architecture? When does one arrive at that point?
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