> OO was considered as a new technology enabled by OO
> languages. It won't be OO architecture implemented
> with only procedural languages.
>
Surely OO is a design discipline not a technology? As a matter of fact,
you can do OO in procedural languages, you just need an appropriate set
of abstractions to do it.
Early C++ implementations were done by pre-processing and converting
back into C for the normal compiler to the turn into native code.
I don't associated OO architecture with any particular technology - I
conceive my OO architecture separately and then give it physical
representation by converting it into a set of co-operating components
written in whatever way is appropriate.
> What is the (new) technology that enables SOA? Or What
> is the technology that must be in an architecture to
> be called SOA? I think it is XML and Component
> technology. In the same way one can not develop OO
> software with producal languages, one can not develop
> SOA software without XML and Components.
>
And I think this is fundamentally why we have a problem. Architecture
and technology are two different and separate things. One uses
technology to implement an architecture but there is no specific
requirement to use a particular technology for a specific architectural
discpline - unless of course you introduce non-engineering concerns such
as finance/licensing.
I would of course concede that some technologies might make the
rendering of architecture from logical to physical easier.
> <Anne/> A service, therefore, is a representation of
> this functionality that can be shared by multiple
> applications. A service exposes it functionality
> through a well-defined interface. Service consumers
> (i.e., applications) use the interface to gain access
> to the functionality. </Anne>
>
> What is described here is also applicable to Microsoft
> COM objects (formally known as OLE controls or
> ActiveX) (Java beans as equivelent?) back in 1996.
> Should we say SOA has been already used in 1996?
>
Maybe we should be saying exactly that and in fact some are hence the
comments about being able to do it with CORBA etc. This is because the
basic architectural premise of SOA can be rendered into reality using a
myriad of technologies both old and new.
> I renew my question. What must be included in an
> architecture to be called SOA? One may say nothing.
> It is a style of design. Therefore one can write a SOA
> software using Fortune only? Is it possible?
>
> My hunch is that the technologies required are
> Component (distinct from Object) technology + XML.
> One can write procedural SW with C++ but it is still
> procedural, not OO, SW. To be OO SW, inheritence must
> be used. To be SO SW, it must include service
> description and service choregraphy. Without these, I
> won't call the SW with a SOA eventhough it passes XML
> messages. Without XML, I won't call it SOA either.
>
If I'm building a service-based thing, I need something that can model
services. Probably I need something that can define the
interface/contract for that service and how to locate the services I
desire so I can use them. (The remaining issue is whether those
services are distributed (that is networked) or not - if they're all
in-process I'd qualify them as components, if they aren't, they're
something else and I tend to call those services.)
So what technology might I use? Maybe CORBA, RMI or app servers or WS
or messaging or Jini or whatever.
IMHO - OO is not defined by the fact you use inheritance. In fact, good
OO makes use of a number of other concepts such as aggregation and
composition. Inheritance, really, should only be about sub-typing but
many use it to achieve re-use which is the wrong way to look at it.
Composition and aggregation are about re-use and that's why those
concepts are so visible in SOA.
My two cents,
Dan.
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