Applications Messaging Standard

[Doug Tody]

On Wed, 7 Feb 2007, Noel Winstanley wrote:

> On 7 Feb 2007, at 16:38, Tony Linde wrote:
>
>> Quick(ish) question re PLASTIC: is the plastic hub something like a message
>> broker?
>
> Its a little like a message broker, but specialized and simplified to the 
> task of inter-application messaging - so not a general messaging solution.
>
> Unlike a messaging system like MSeries or ActiveMQ, Plastic hub 
> implementations don't queue messages, and makes no guarantees about delivery 
> of messages (whilst MSeries guarantee once and once only for every message), 
> or, I believe, ordering of messages.

Depending upon what one is doing, these semantics can be quite important
to the correct functioning of an application.

>> And if so, how does it relate to existing ones such as ActiveMQ
>> (http://activemq.apache.org/home.html)?
>
> PLASTIC is a specification that uses open-standard transports and has 
> multiple implementations.
>
> Most message brokers use a closed communication protocol and don't 
> interoperate well with each other. Although there's , eg, a Java API to 
> messaging systems (JMS), it makes no guarantee that any JMS client can 
> connect to any messsaging system - specific drivers are required (as with 
> JDBC). This is not the case with PLASTIC.

Is PLASTIC a messaging protocol or a messaging infrastructure?  That is,
if I already have a robust messaging infrastructure, can I layer a PLASTIC
adapter on top of this and achieve the same level of interoperability
between applications as with the simple PLASTIC hub?  PLASTIC apps would
still "speak" PLASTIC, but the messaging infrastructure could be anything.

> Plastic is good for quickly exchanging control info between desktop apps. 
> Message Brokers are good for, eg,  processing banking transactions.

Messaging is fundamental to all distributed applications (no one is
saying anything here about transactions, that is a separate matter).
I think the main distinction is that PLASTIC is intentionally limited
in scope, being intended only for simple inter-tool messaging.  As soon
as it grows and you get real distributed applications, as opposed
to independent tools sending an occasional "load this" type message,
then one is back in the realm of the more complex messaging systems.

 	- Doug