Re: [soa-rm] Revisiting: Definition of Service Orientation and how it relates to SOA

[Ken Laskey <klaskey@mitre.org>]

Lot of good points - let's see if I can do something useful with them.

First, a service is not a unit of IT (although one of its  
representations may be) but the "doorway" to the means to accomplish  
some task.  (I'm still thinking of the "means" as being a resource, but  
humor me for the moment.)  So service-orientation enables one to access  
various capabilities, ranging from an atomic level to some fairly  
sophisticated combinations.  A SOA is the structure that makes service  
orientation possible.

Who does the orienting?  Well, the combined wisdom of the TC seems to  
be the one orienting the higher level concepts so that a service  
provider can orient their delivered capabilities and the service  
consumer can orient the solution to their problem (by dealing with  
capabilities and not IT units).

Now, think of code you write.  You have something you want to  
accomplish, a capability you want to develop, but then you have to make  
this robust and usable to a more general community and tailorable to  
different communities and ...  So now you build in error checking and  
error handling.  Wouldn't it be nice to give a list of constraints and  
have something else do the checking and sending back messages to the  
external sources of errors?  Now things work and I have to format the  
output.  Do I like formatting the output or do I want to develop more  
capability?  Crystal Reports made a business of providing a report  
generation application.  Wouldn't a similar service be nice?  So one of  
the things a SOA supports is doing the work you want to do and  
outsourcing the drudgery or the things (such as security) that you are  
just not expert enough to do.

For more flexibility, I don't just want one service to take the  
undesirable work off my hands, I want a choice.  And because I know  
that my choice may change depending on circumstances, I want to  
dynamically make the choice.  (Don't you hate it when you get a wedding  
invitation and you have to decide what you want to eat a month from  
now?)  Or even if not with zero latency, I want to be able to easily  
change my choice. I need services to be interchangeable.

And I don't want my choice to lock me into a whole set of other  
choices.  I go to buy a car and I want airbags but I can only get these  
if I get power windows!  I want an interoperability of my choices along  
with interchangeability of parts that I choose.

Finally, what is the polar opposite of services?  The polar opposite is  
NIH, not invented here.  Service orientation says I want to do as  
little by myself as possible.  There are people out there who are  
smarter than me and do some things better than me and I'm going to make  
use of that expertise whenever I can.  That takes a certain level of  
trust because I am giving up control of the details so I can spend my  
energy on the things I can best provide to others.  The opposite is  
assuming everything I need to do is unique and no one can do any of it  
as well as me (or as well as someone I would directly control).  Now  
when you have opposites, you usually have degrees between them.  But  
I'm running out of steam so someone else (if worthwhile) can come up  
with intermediate states.

Sorry for the stream of consciousness presentation but it seemed to  
best fit the questions.

Ken

On May 24, 2005, at 5:28 PM, Metz Rebekah wrote:

> All -
> I recently asked some of my colleagues to share their thoughts on
> Service Orientation and what truly distinguishes Service Oriented
> Architecture from other distributed computing architectures.
>
> Some of their comments called out to me the bias that we, as
> technologists, often maintain unwittingly.  I thought these comments
> were pertinent to the recent discussions and debate that has occurred  
> in
> the SOA-RM TC.
>
> "We invariably impose our knowledge of technology or system
> functionality (how you do things) into discussions of operational
> capabilities or activities (what needs to be done)."
>
> Service Orientation:  "Is that an 'orientation towards services'? If  
> so,
> who is doing the orienting? Is there another position that would be
> opposite 'services'? What would we call that?  What's the polar  
> opposite
> of services?"
>
> "I think that one of the most important things to grasp is that the
> service in "service-oriented" has nothing to do with IT, systems,
> implementation, etc.  It's an operational concept, for example in DoDAF
> vocabulary, a discussion on the OV side of the equation."
>
> In particular, I think that reaching consensus on the answers to these
> questions will help us along in determining what is versus is not a
> critical part of the RM.
>
> Rebekah
>
> Rebekah Metz
> Associate
> Booz Allen Hamilton
> Voice:  (703) 377-1471
> Fax:     (703) 902-3457
>
>
>

------------------------------------------------------------------------ 
------------------
Ken Laskey
MITRE Corporation, M/S H305     phone:  703-983-7934
7515 Colshire Drive                        fax:        703-983-1379
McLean VA 22102-7508