Re: [soa-rm] SOA System

[Duane Nickull <dnickull@adobe.com>]

I think this definition is inline with our thoughts so far. A looser 
coupled relationship and services existing in a vaster array of 
environments means that you now have to have the extra components to 
describe the native environment.

D

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?
>
> 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
>