Re: [soa-rm] SOA System

[Michael Stiefel <development@reliablesoftware.com>]

Matt, re your comment that "SO is OO, basically, with some value-add
infrastructure such as discovery and description."  

Now this raises an interesting point in our definition of service
abstraction. Normally people cite as one of the differences between SO
and OO the fact that the former is more loosely coupled. 

Would you maintain that OO systems that can work with wire formats of
object systems (such as COM and CORBA) that allowed runtime dynamic
binding of heterogenous systems fall into the SO category? 

Or do you see looser coupling as a useful feature that is much more
easily achieved with newer implementation technologies such as Web
services, and therefore have nothing to do with SO.

Michael

At 05:29 PM 5/18/2005, Matthew MacKenzie wrote:
> Hamid,
>
> I really must disagree with almost every point you make.  See
> inline.
>
>
> On 18-May-05, at 2:50 PM, Hamid Ben Malek wrote:
> <snip/>
> > Answer: One SOA
> > service by itself does not do much. A set of SOA services is called an
> > “SOA System”. When we say “SOA”, we generally assume the existence of an
> > SOA system which is the subject of discourse.
> It doesn't
> matter how many services there are.  What matters is that the
> architecture is service oriented.  That means a single service and a
> single consumer would technically be service oriented.
>
>
> >  
> >
> > Question: Is it
> > necessary to call services only in sequence?
> >
> > Answer: Yes and
> > No. In fact, the question stated like this does not make sense. There are
> > two cases. The first case is when the initial caller is a simple service
> > consumer (that is a client which is not an SOA service). The second case
> > is where the caller is an SOA service. For the first case, the client
> > makes calls in a sequence only. However, that does not mean that the
> > messages will be delivered in that sequence. All the messages go through
> > the SOA Fabric and they may arrive in different order or at the same
> > time. For the second case where the caller is an SOA service, there is a
> > possibility of calling in parallel (instead of in sequence). In fact, an
> > SOA service may even initiate a complex process which consists of a
> > mixture of parallel and sequential calls (For example, initiating a BPM
> > process whose activities are the SOA services within an SOA
> > system).
>
> Why should I care about call sequence in SOA-RM's context?
>
> > 1.   
> > Incremental Deployment: This is the second big difference between
> > Object-Orientation and Service-Orientation. In object orientation, an
> > application must be deployed as a whole (as one single unit). In service
> > orientation, an application is always deployed incrementally. Various
> > services are added at various times without breaking the functionality of
> > the whole system.
>
> Not true either.  I can change Xalan on my JBoss installation with
> reinstalling my application. 
>
> SO is OO, basically, with some value-add infrastructure such as discovery
> and description.  
>
> -Matt