OASIS Mailing List ArchivesView the OASIS mailing list archive below
or browse/search using MarkMail.

 


Help: OASIS Mailing Lists Help | MarkMail Help

soa-rm-ra message

[Date Prev] | [Thread Prev] | [Thread Next] | [Date Next] -- [Date Index] | [Thread Index] | [List Home]


Subject: Re: [soa-rm-ra] OO vs. SOA and what goes into a service


Without meaning to turn this into a REST vs. SOAP debate (to mix the two, I could send a SOAP 1.2 envelope with an HTTP methods called through the web methods option), consider the following:

I develop a service that does a read of a resource and I can give it the resource identifier.
I develop another service that does a save of a resource and I give it what I want saved and the identifier of where to save it.
I develop a service that can delete a resource and ... you get the idea.

Or I can say I want to read, save, delete, ... a timecard record and I develop a timecard service that includes independent operations for read, save, delete, ...

Now I know what the service description looks like for the REST-like example, but I can see increasing complexity if the timecard operations each have a different payload and each have different policies and each ...

I've got a new write-up of service description that tries to capture and better present the essence of this that was in the v0.2 text.  However, having gone back through old email threads, I wanted consensus on what the problem and solution space looks like.

A dominant idea for me is if you can't easily describe it, you will have trouble with visibility, and you probably have something that shouldn't be a single service.

More emails in this thread to process.

Ken


On Jan 22, 2008, at 6:58 PM, Danny Thornton wrote:

The message names can denote the action to take -
AddResourceRequest and AddResourceResponse for
example.  If CRUD operations are performed by a
service, the actions can be realized through CRUD
message types and could be handled by a single
service.  You can define real world effects or
constraints for the action/message just like any other
action/message the service may receive.

In the above model, the interface can have a single
method (like receiveMessage) where the received
message type denotes the action.

The other model is to have separately named methods in
the service for the actions.

A real difference for a service and an OO object is
that service functionality is self contained and it
does not flow across the wire, only the information in
the information model flows across the wire.  With an
OO object both the data and the functionality of the
object flow across the wire.  This is why OO objects
with functionality reak havoc when they are
distributed.  For example, I may accept some
distributed OO object and then find out I have to
compile in another 5,000 libraries (that's how it felt
sometimes) to use it because of all the functionality
that came with it.  

Danny

--- Ken Laskey <klaskey@mitre.org> wrote:

Is it fair (or at least not too distorted) to say
that with OO we  
define an object and look for what we can do to it
(i.e. its methods)  
while with SOA we identify what we want to do (i.e.
business  
functions) and then, if appropriate, look for
objects to do it to?

This gets back to the discussion last October on
what actions get  
bundled together in a service.  From an OO
perspective, I choose an  
object and then attach CRUD methods.  In SOA, would
the CRUD methods  
individually be things I want to do, each with a
describable real  
world effect (and possibly policies on who can do it
and under what  
conditions), and I define services to carry out
those functions?

Are both perspectives/design approaches equally
valid?  What are the  
implications for description and discovery?

Ken


------------------------------------------------------------------------

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





      ____________________________________________________________________________________
Be a better friend, newshound, and 
know-it-all with Yahoo! Mobile.  Try it now.  http://mobile.yahoo.com/;_ylt=Ahu06i62sR8HDtDypao8Wcj9tAcJ 


-----------------------------------------------------------------------------
Ken Laskey
MITRE Corporation, M/S H305      phone: 703-983-7934
7151 Colshire Drive                         fax:       703-983-1379
McLean VA 22102-7508




smime.p7s



[Date Prev] | [Thread Prev] | [Thread Next] | [Date Next] -- [Date Index] | [Thread Index] | [List Home]