Re: [soa-rm] SOA System

[Duane Nickull <dnickull@adobe.com>]

Hamid:

I do not speak for Matt, but my observation is the disagreement is on 
the scope of the RM. The rest of the TC has agreed on the charter 
defined concept of the RM. We also have reached a sort of consensus on 
the fact we need to document something as well as the RM for the RM to 
be more useful to end users. Accordingly, we agree to place the sort of 
things you are advocating in a reference architecture and also in 
Appendix B. I realize it is a huge commitment for any person to read all 
the email from this TC, however this has been discussed and sort of 
resolved before.

The gist is that RM is abstract, RA is more concrete, architecture is 
specialized and concrete.

I am sure we will start a sub committee once the RM is solidified to 
work on RA. I think we all welcome participation in that regard.

Duane




Hamid Ben Malek wrote:

> Matt, you either disagree for the sake of disagreeing, or (if this is 
> not the case), your vision of SOA is as far from mine than the outer 
> edge of the universe from my office. In either case, I don’t see it 
> useful to argue. Normally people argue when their opinions are not 
> that far from each other. But if I talk about oranges and you talk 
> about electrons (not even apples), there is no point for me in 
> continuing this discussion. I, however, will answer the points you raised.
>
>     * For the question about calling a service in sequence, I did not
>       asked that question. The question was asked by Duane, and I was
>       simply giving him an answer.
>     * For the possibility of changing xalan without re-installing
>       JBoss, I think you confuse “configuration” and “deployment”.
>       Deployment is when you install the application for the first
>       time. Configuration is when you modify the state of the
>       application after deployment (such modifying some configuration
>       files, or upgrading the libraries used by the application). I
>       was talking about deployment, and not configuration. If JBoss
>       needs xalan for example, then I cannot deploy JBoss without
>       xalan, because when you try to start JBoss server, it will crash
>       and burn right away and the service would never be up.
>     * For the independence of services, if you think this is not
>       important and that SO is just OO with other extra-things, then
>       you have missed the whole point. You are violating one of the
>       holiest principles in SOA (the second principle), namely
>       “Service Autonomy”.
>
> Regards,
>
> Hamid.
>
> ------------------------------------------------------------------------
>
> *From:* Matthew MacKenzie [mailto:mattm@adobe.com]
> *Sent:* Wednesday, May 18, 2005 2:30 PM
> *To:* SOA-RM
> *Subject:* Re: [soa-rm] SOA System
>
> 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
>