Title: Message
This discussion sounds like its coming from
a service/application only perspective. We need to scope the SOA
RM very carefully. If we are looking for a SOA RM that can be applied in
any domain, then I am still not a proponent of calling it an 'SOA' RM. If
I apply all components of the SOA reference model, then I have an SOA,
right? The more abstract the reference model the more delta you have
between implementations/specializations, so the RM really would be only
be valuable with specializations as a deliverable. Call it a
'web services' or equivalent RM, but not an SOA RM. The argument that
almost everything is an SOA does not hold water with me. SOA in its final
tangible form has a considerable number of requirements that make it
unique. I see an SOA RM like a 'three-tier' architecture model
that would be more effective, we all know that is www/app/db right? http://www.sei.cmu.edu/str/descriptions/threetier.html
What is it for SOA? I argue it should at a minimum include a
function/process for a registry, in addition it should also include at a minimum
'support' for secure communication.
TM
From: Yunker, John [mailto:]
Sent: Wednesday, December 15, 2004 12:35 PM
To: Chiusano
Joseph; Matthew MacKenzie; ebSOA OASIS TC
Subject: RE: [ebsoa] Does
SOA Require Registry-Based Dynamic Discovery?
First,
let me agree with Matt that "ebXML Registry (big R)" is just one way of
discovery, however any discovery requires that what is being discovered is
registered . Let me further assert that discovery outside of a tightly
controlled group requires some sort of registry (small r) mechanism for
discovery to be effective. These are the assumptions I started
with.
Sorry
if your initial question was only directed towards big R registry!!!
:-)
-----Original Message-----
From: Chiusano Joseph
[mailto:]
Sent: Wednesday, December 15, 2004
9:13 AM
To: Yunker, John; Matthew MacKenzie; ebSOA OASIS
TC
Subject: RE: [ebsoa] Does SOA Require Registry-Based Dynamic
Discovery?
Thanks John - I'm going to take all 4 parts of your excellent comments
below separately, and comment further. You basically said:
An
SOA without registry by definition is limited
[JMC] Limited in what way? I
assume because there is no dynamic discovery, and if the interface
requirements and/or service location changed, it would require an out-of-band
mechanism. I would assert that it is limited if the technical and business
requirements led to an anticipation of updates to the interface requirements
and/or service location on a regular basis - otherwise, is it *really*
limited?
[yunker] Limited in the ability
of the SOA to support broad groups or
communities.
An
SOA without registry by definition is
private
[JMC] So if a SOA-based system is being used
among 2 or more organizations, and the technical and business requirements *do
not lead* to an anticipation of updates to the interface requirements and/or
service location on a regular basis, then the SOA is "private"? Seems
orthogonal to me...
[yunker] Private in that some
out-of-band communication must be
supported.
An
SOA with a registry is open
[JMC] Open to
who? If it does not have a registry, it is not
open?
[yunker] Open, in that you don't
need to be on the mailing list of the service provider to know that a service
is available.
An
SOA with a registry is
dynamic
[JMC] Agree!
(one out of 4 ain't bad ;)
Thanks again!
Kind Regards,
Joseph Chiusano
Booz Allen Hamilton
Strategy and Technology Consultants to
the World
From: Yunker, John
[mailto:]
Sent: Wednesday, December 15, 2004
12:06 PM
To: Chiusano Joseph; Matthew MacKenzie; ebSOA OASIS
TC
Subject: RE: [ebsoa] Does SOA Require Registry-Based Dynamic
Discovery?
From my view the "registry requirement" is
more a function of the distributed nature of the participants, the number
and type of services, and the amount of change. A registry provides a
method for decoupling "the use of an SOA" from "direct communication of
the participants about HOW to use the SOA".
An
SOA without registry by definition is limited and
private
An
SOA with a registry is open and dynamic
John
-----Original Message-----
From: Chiusano
Joseph [mailto:]
Sent: Wednesday,
December 15, 2004 9:01 AM
To: Matthew MacKenzie; ebSOA OASIS
TC
Subject: RE: [ebsoa] Does SOA Require Registry-Based Dynamic
Discovery?
Thanks Matt. From that I take:
- Discovery in general is required for SOA (cannot function without
it)
- Whether it is (what I will call) "fundamental" discovery -
meaning your first example below - or "registry-based" discovery depends
on technical and business requirements.
I just cannot foresee trying to convince a current or potential
customer that they have to put up $XX,XXX for a registry product if the
technical and business requirements do not call for it, just to comply
with someone's definition of the term "SOA".
Kind Regards,
Joseph Chiusano
Booz Allen Hamilton
Strategy and Technology
Consultants to the World
From: Matthew MacKenzie
[mailto:]
Sent: Wednesday, December 15, 2004
11:57 AM
To: Chiusano Joseph; 'ebSOA OASIS
TC'
Subject: RE: [ebsoa] Does SOA Require Registry-Based
Dynamic Discovery?
My opinion is
that a registry is nothing more than a very explicit service discovery
device.
An SOA does
need a method of discovering services, and consuming them, but this
method may in some cases be subtle. For example, my SOA may
operate on the premise that consumers all are aware of an enumeration of
service types, and their port numbers (think /etc/services in the unix
world), and allowable IP ranges for finding services. Clients may
be configured something like:
{
Services imap, http, ssh, daytime, pop3,
portmap
IPRange 192.168.0.0/24
}
A client with
such a configuration does have a way of discovering services that are
available to it, and of course, a way of binding to
them.
Contrast this
with a registry driven SOA:
{
ServiceRegistry http://foo/registry
}
The only
difference is in the implementation detail and verbosity of information
available. Conceptually, they are the
same.
--Matt
MacKenzie
From:
Chiusano Joseph [mailto:]
Sent: Wednesday, December 15, 2004
11:38 AM
To: ebSOA
OASIS TC
Subject:
[ebsoa] Does SOA Require Registry-Based Dynamic
Discovery?
What is the TC's opinion on
the answer to the question of "does SOA require registry-based dynamic
discovery"? I know that Discovery is a pattern in the .047 spec, which
leads me to believe that the position is that SOA does not *require*
registry-based discovery.
For example, suppose
that:
- 2 organizations are using
Web Services in a "SOA-like" manner (meaning shared services represented
as Web Services, that are invoked by other Web Services).
- There is no registry-based
dynamic discovery, perhaps because the organizations agree that these
service locations are completely (or relatively) stable, and that if the
locations change, there will be some out-of-band mechanism for
propagating updated WSDL documents
Are these 2 organizations
therefore *not* using a service-oriented architecture? That is, does the
second point completely negate the first? Or, is it all really a matter
of business and technical
requirements?
Kind
Regards,
Joseph
Chiusano
Booz Allen
Hamilton
Strategy and Technology
Consultants to the World
