Re: [HiveMind] Basic questions about Service

[Christian Essl]

I think thats realy an intresting question. I mean I don't realy know but I 
think - as you do - a Service provides a specific functionality. However I 
am not sure wheter this must always be data-hiding - just look at a 
database, which provides a good service. I also believe that one of the 
first ideas of OO was that you build big systems out of a number of robust 
small peaces which have a well defined cloased interface so that they can 
evolve independently. That's certainly what services (at least) in HiveMind 
are. Another idea I think was that the small pieces can work together 
without the need of a central main-component, so that new combinations can 
be build flexible. And last I think there is also a notion of competition 
on ideas on how to provide a better service to the user - without 
centralized normativ control. It is up to the user (and anyone can be user) 
what he needs and what service he uses and it is up to the service to 
provide well what it promisses - and if it is just data.

On Wed, 24 Sep 2003 21:39:16 -0400, Harish Krishnaswamy 
<[EMAIL PROTECTED]> wrote:

I am a little confused now. I am confused as to what the boundaries of a 
service are. Is there even a distinction between a Service and a domain 
object? I start seeing people actually suck out the behavior of domain 
objects into services and have the domain object as a simple JavaBeans 
data object. I literally saw an example that had an Employee object which 
represented the database table and an EmployeeService which represented 
the behavior for the Employee object. To me this sounds like its against 
the principles of OO (assign the responsibility to the information 
expert). So this leads to a more basic question - what is a Service? I 
think we need a technical definition for Service. I thought of the 
Service as an interface to a subsystem / a specific function. Am I 
missing something?

-Harish



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