Re: [soa-rm] SOA System

[Francis McCabe <fgm@fla.fujitsu.com>]

Matt, et. al.
  In case this thought has not been raised in future emails ... :)

  I believe that I am correct in stating that, in practice, the best  
aspects of languages like Java is not features such as inheritance  
but the ease with which applications can be slotted together. The key  
feature that enables this Lego®-style assembly is the *interface*. It  
turns out that interfaces make the task of programming large systems  
significantly easier.

  The logical development of the type-only interface is the  
*semantic* interface. But in any case, modern SOAs represent one  
aspect of the trend towards focusing on interfaces as a way of  
controlling complexity and enabling rapid development/deployment etc.

  So, at one level of abstraction, it may be useful to think of SOAs  
as a system of interfaces that allow architectures to be crossed,  
ownership domains to be crossed, different implementation languages  
to be used, different versions to coexists, etc. etc.

  Our task is to try to pick out the keystones that bear the SOA  
hallmark; which seem to me to be what we have: services as *action  
boundaries*™, semantic interfaces, tons of descriptions.

Frank

On May 18, 2005, at 7:22 PM, Matthew MacKenzie wrote:

> Michael,
>
> On 18-May-05, at 5:55 PM, Michael Stiefel wrote:
>
>> 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?
>
> I maintain that in certain situations that they *could* fall into  
> the SO category.  I think that the "loosely coupled" argument is  
> sort of weak, because I am not completely certain that even things  
> like web services end up creating loosely coupled systems!
>
>>
>> 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.
>
> I love loose coupling...but yeah, I do just view it as "a good  
> thing", and not a necessary element of SOA.
>
> -matt