I'd argue that the windowing system example is Interrupt driven, rather than
event driven. That being said, I agree with your statement:

 

> Getting "order placed" to interested parties does not need to be via
pub/sub. Or at least, not necessarily via a message broker.

 

However, I'd assert that there are advantages to a pub/sub approach over a
non-pub/sub approach, not the least being that additional subscribers can be
added into the ecosystem without changes to pre-existing members. 

 

The crux is, IMO, what is the semantic thing that you are pub/sub-ing?

 

If the thing represents a business event (past tense), like order placed,
customer billed, etc, I'd say that pub/sub is a very good solution.

If the thing represents a command (imperative, present tense) like place
order, bill customer, etc, I'd say that pub/sub is a poor solution.

 

I'd like to submit we might call this join of business events, pub/sub, EDA,
and SOA an Event Service Architecture, or ESA, just as a convenience for
comparing approaches.

 

Thoughts?

 

-- 

Udi Dahan - The Software Simplist

 

From: [email protected]
[mailto:[EMAIL PROTECTED] On Behalf Of Rob
Eamon
Sent: 04 December 2008 20:29
To: [email protected]
Subject: [service-orientated-architecture] Re: Roch Clarifies Some Key Terms

 

Which is primarily an issue brought to the fore in a pub/sub approach. 
EDA != pub/sub. For example (very low-level), windowing systems are 
event driven (mouse clicked, window closed, etc.) but are not pub/sub. 

Getting "order placed" to interested parties does not need to be via 
pub/sub. Or at least, not necessarily via a message broker. IMO, 
pub/sub is often used in interactions when it shouldn't be. Indeed, IMO 
pub/sub is rarely the right mechanism to use.

-Rob

--- In [email protected]
<mailto:service-orientated-architecture%40yahoogroups.com> , "Steve Jones" 
<[EMAIL PROTECTED]> wrote:
>
> And then when you add in non-repudiation you have a whole other set 
> of challenges.
> 
> Steve

 

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