Michael,
I never read “direct *or* mediated awareness” as being and exclusive or but as complementary options. I would also be happy with Peter’s proposed tweak.
As for the remainder of your points, I believe the paragraph in question still needs some work. Again, I don’t think there is fundamental disagreements on the ideas but the wording still leaves a bit to be desired.
Peter isn’t available before the meeting and I also do not have the time before the meeting to work the text, so I expect this will become homework for the coming week.
Ken
From: Mike Poulin [mailto:mpoulin@usa.com]
Sent: Wednesday, October 24, 2012 9:37 AM
To: Ken Laskey; Peter F Brown; danny_thornton2@yahoo.com
Subject: direct AND mediated awareness
Gentlemen,
Please, be patient to read this message to the end becuase it is difficult to articulate it as one piece in the conf. call. I have only one objection for the
Suggest "Participants acting in the roles of service consumers and service providers may have direct awareness or mediated awareness where mediated awareness is achieved through some third party acting in the role of a mediator."
In response to what I think is the focus of the emphasis comments, suggest adding to the end of the paragraph: "Those acting in the roles of consumers, providers, or mediators may reside within a single ownership boundary or interactions among them may cross ownership boundaries."
and
"Participants acting in the roles of service consumers and service providers may have awareness of each other directly or gain such mediated awareness where mediated awareness is achieved through some third party acting in the role of a mediator, what we refer to as mediated awareness."
This objection is based on
“Mediated awareness promotes loose coupling by keeping the consumers and services from explicitly referring to each other. Mediation lets interaction vary independently. Rather than all potential service consumers being informed on a continual basis about all services, there is a known or agreed upon facility or location that stores and supports discovery and/or notification related to the service description.”
In essence, I propose to replace "direct awareness or mediated awareness" by "direct awareness and mediated awareness".
Also, I propose to remove the sentence "Mediation lets interaction vary independently" - see my explanations below.
The first change will allow someone who requires a direct awareness to be loose-coupled in all cases (like myself) to sutisfy this requirement as well as someone else who wants to decouple the consumer from the service totally (like "from explicitly referring to each other") to do this.
I believe that all efforts that we have put into defing the notion of Service Contract in combination with our statement that the SOA Ecosystem sits in between Business and Technology require us to preserve business (not only technical) understanding of consumer/service interaction and possible role of a mediating actor. In particular, a business consumer will not deal with a service if the service/provider is unknown up-front. That is, total decoupling will not work for business services and (the second change) "Mediation lets interaction vary independently" is not acceptable. The last quote may take place only within a realm where all participants trust others a priori (which is unrealistic even inside the same company).
By "a direct awareness to be loose-coupled", I mean that the consumer
1) knows about the service;
2) familiar with the Service Description (does not matter how);
3) has decided that this service can meet consumer's needs;
4) has willingness and establishes the trust with this service
- all before sending the first message. If there is a mediating actor in the transaction, this mediator has only one duty - locate the service, which is nominated by the consumer, in the network and arrange for physiscal connection to the service's end-point. How to locate - this is exactly the knowledge and value of the mediator; the consumer is free from this physical details (this is why it is loose-coupling)
If we/anybody allow(s) a mediator to hide the service in full (from the consumer), the consumer has no choice other than to set a Service Contract with this mediator. This service contract must be about all business and technical spects that the consumer needs and, moreover, these aspects should be advertised by the mediator itself to preserve the concept of Service Contract. Have you seen such a mediator? I did not (if such a mediator 'helps' several services, it can down-scale quickly).
Regards,
- Michael