soa-rm-editors message

Subject: RE: [soa-rm-editors] Fwd: [soa-rm] Definition(s) of "service"

From: Ken Laskey <klaskey@mitre.org>
To: soa-rm-editors@lists.oasis-open.org
Date: Thu, 11 Aug 2005 13:58:34 -0400

This isn't about us answering back to the TC on our work plan but us figuring out how to tackle the problem. If we are successful, the TC sees the benefit from us organizing the material in a way they can comment easily and, if necessary, vote. Duane's request is reasonable and probably necessary but not trivial.

That's what I had in mind.

Ken

At 10:29 AM 8/11/2005, Matthew MacKenzie wrote:

We need not respond. We do what we want.

I’m not going to take notes at the editors meeting for the TC’s benefit…the product of the meeting should speak for itself, no?

From: Ken Laskey [ mailto:klaskey@mitre.org]
Sent: Wednesday, August 10, 2005 11:22 PM
To: soa-rm-editors@lists.oasis-open.org
Subject: [soa-rm-editors] Fwd: [soa-rm] Definition(s) of "service"

So,how do we respond to this?

The wiki may help on this but I think one of the topics at the editors' mtg may be how to glean key thoughts from an overactive email list, using the service definition as a first challenge.

Ken

Begin forwarded message:

From: Duane Nickull <dnickull@adobe.com>
Date: August 10, 2005 3:50:32 PM EDT
To: Ken Laskey <klaskey@mitre.org>
Cc: soa-rm@lists.oasis-open.org
Subject: Re: [soa-rm] Definition(s) of "service"

Ken:

Thank you for owning this! Good luck next week.

May I suggest that the Editors use the WIKI page during their meeting?

Duane

Ken Laskey wrote:

Duane,

I hate to say this (and my fellow co-editors may disagree) but I think the task needs to be taken on by the editing team as a whole. My SOA mailbox has over 2300 messages with many threads having a bearing on this, and even a cursory scan will be a significant effort. Also, as the current designated editor for the service section, I don't see a good way of just dumping it onto someone else.

I would be willing to be talked out of this position.

Ken

At 12:25 PM 8/9/2005, Duane Nickull wrote:

I would like to request a volunteer or volunteers to own this issue and ensure that none of the depth of this conversation is lost. We have passed around heaps of good thoughts. The owner would essentially be responsible for capturing the views / opposing views and keeping documentation up to date as this gets discussed. The owner would not be entitled to simply gloss over with their own point of view but would act much like an editor - reflecting the consensus or the TC or noting the lack thereof.

Anyone interested in owning this?
Duane

Frank McCabe wrote:

I strongly resist the tendency of equating service with the 'back end
capability' (or whatever). This is a dangerous and non-scalable
direction to go in:

1. The implementation of a service is none of the service consumer's
business.
2. The service consumer should not even be able to figure out how a
service is delivered. If it can, then you will get security risks and/ or scalability issues
3. A given capability may not be fully exposed in a given service
4. A given service provider agent may not *have* the capability
offered in its service -- it may know someone who knows ... it may
not be possible to characterize the capabilities of a service provider.
5. From the point of view of the service consumer, fundamentally, it
cannot (normally) distinguish the surface aspects of interacting with
a service and the deeper aspects that rely on the service's
realization (e.g. this is an Oracle database so be careful with your
SQL)

On the other hand, the service consumer interacts with a service in
order to achieve an effect. In most interesting cases this is a 'real- world effect'. The consumer is interested in the fact that the bank
account has been credited.

Interestingly, these real world effects can *also* be expressed in
public semantic terms -- without relying on representing the internal
state of the resource. For example, a bank customer wants to know
that his or her account has a certain balance. This is a fact that is
warranted by the bank; not simply by the database resource that the
bank happened to use to store the account information. I.e., there is
a public 'on-the-wire' assertion that the bank attests whenever a
authorized request (again, note the on-the-wire nature of this) is
made to the appropriate bank service.

Frank

On Aug 8, 2005, at 3:02 PM, Chiusano Joseph wrote:

-----Original Message-----
From: Ken Laskey [mailto:klaskey@mitre.org]
Sent: Monday, August 08, 2005 5:50 PM
To: soa-rm@lists.oasis-open.org
Subject: RE: [soa-rm] Definition(s) of "service"

As appeared earlier in this thread, there are contexts in
which it is not necessary to discriminate between the
capability and the service that accesses it,

Ken, are you equating capability with resource? I recall a reference to
resource that fits the above description, but not one to capability.

Joe

Joseph Chiusano
Booz Allen Hamilton
O: 703-902-6923
C: 202-251-0731
Visit us online@ http://www.boozallen.com

and our
discussion of service can make this clear. However, I think
this thread has also shown ample examples of where the
service and the capability are clearly separate concepts and
where it may be useful to allow that difference to be
captured. For example, it is likely for someone to ask if
two services are the same. While we do not address that
particular question, it is far simpler to handle if we know
whether the underlying capability is the same than if we
obscure that difference at first principles.

Ken

At 05:03 PM 8/8/2005, Chiusano Joseph wrote:

-----Original Message-----
From: Frank McCabe [ mailto:frank.mccabe@us.fujitsu.com]
Sent: Monday, August 08, 2005 12:10 PM
To: Ken Laskey
Cc: soa-rm@lists.oasis-open.org
Subject: Re: [soa-rm] Definition(s) of "service"

This is going in a weird direction.
I believed that there was significant consensus that the

notion of

service that we are interested in *is* the
interface/boundary/offering.

The capability behind the service -- that which makes the service
possible -- is private and out of bounds. That capability

is, by the

way, best described using agent terminology.

Respectful non-concur. IMHO, the service *is* the

capability, and the

service *has* an interface through which interaction with that
capability may be possible.

Joe

Joseph Chiusano
Booz Allen Hamilton
O: 703-902-6923
C: 202-251-0731
Visit us online@ http://www.boozallen.com

Frank

On Aug 8, 2005, at 8:50 AM, Ken Laskey wrote:

This is good because it highlights the bits of

confusion we have

to explain our way around.

The user interface is the facade through which the user

interacts with

a service (i.e. inputting information/requests, viewing
results) but there may be delivery capabilities that

are invoked

through relevant services and the delivery capabilities are the
mechanisms through which results are packaged and sent to the
requester/consumer. For example, if I make a request for

an image and

as part of that request, information about my connectivity is
provided, logic (capability) can be executed (possibly

invoked through

a service) to decide which delivery mechanism is most

appropriate

(e.g. high res or low res, what kind of compression, ...).

Ken

At 11:18 AM 8/8/2005, Michael Stiefel wrote:

Actually, I think two things are being confused here.

There is one service being used by several different

applications.

The user interface (i.e. the actually delivery mechanism)

is not part

of the service, or strictly speaking part of the SOA.

Michael

At 10:43 AM 8/8/2005, Ken Laskey wrote:

I'd have to think about this further but in general I

would say yes.

The underlying capability is making pizza and offering

the product

for sale. The mechanisms for accessing the capability are in
person, by phone, online. Note, the capability existed

before there

was online ordering and this is just another

mechanism to access

a capability that already existed.
Interestingly from an orchestration/choreography sense,

the delivery

of the pizza (in person pickup, delivery service from

pizza place,

third-party delivery (e.g. Takeout Taxi around
here)) constitutes another set of capabilities that can

have service

interfaces and can be combined in response to invoking

the ordering

service. All of these can be used for delivery of things

other than

pizza (even the pizza place might also deliver sandwiches).

I think part of the confusion is that a *physical*

delivery service

is a millennia-old, longstanding capability that has

nothing to do

with SOA and is *not* the service in the SOA sense

but it uses a

different aspect of the S word.

Ken

At 07:11 PM 8/7/2005, joe@pantella.net wrote:

Does this imply that if I order a pizza online vs. order a
pizza over the phone vs. order a pizza by walking into the
store, that these are all separate services?

--JJP

-----Original Message-----
From: Ken Laskey [mailto:klaskey@mitre.org]
Sent: Thursday, August 04, 2005 12:35 PM
To: soa-rm@lists.oasis-open.org
Subject: RE: [soa-rm] Definition(s) of "service"

This gets back to the previous discussion when we

talked about

resources, i.e to what extent the service is the

mechanism to

access (possibly coordinate) capability vs. when is it

considered

the capability itself.

I think any consideration of the service as the

capability/resource

should be very limited.

Ken

At 11:07 AM 8/4/2005, Chiusano Joseph wrote:

-----Original Message-----
From: Ken Laskey [mailto:klaskey@mitre.org]
Sent: Thursday, August 04, 2005 11:04 AM
To: Chiusano Joseph; soa-rm@lists.oasis-open.org
Subject: RE: [soa-rm] Definition(s) of "service"

Somehow saying service *provides* capabilities

misses the SOA

motivation to provide an effective way to bring together
the

parts I

need to solve a problem. Integration is often

of disparate

parts

that exist for their own purposes. Service can help

coordinate but

the challenge is to make use of the tools/resources/

capabilities

that already exist, not to create new stovepipes.

Saying the

service provides all this is a tempting

simplification but

I

fear it

will trivialize the concepts most in need of

clarification.

Agree - and I should clarify that I was merely saying that a

service

provides capabilities (in general). Combining a

capability here, a

capability there, here a capability, there a capability,

everywhere a

capability (oops sorry - that's the EIEIO song), we

have composite

capabilities.

Joe

Joseph Chiusano
Booz Allen Hamilton
O: 703-902-6923
C: 202-251-0731
Visit us online@ http://www.boozallen.com

Ken

At 10:35 AM 8/4/2005, Chiusano Joseph wrote:

-----Original Message-----
From: Ken Laskey [mailto:klaskey@mitre.org]
Sent: Thursday, August 04, 2005 10:18 AM
To: soa-rm@lists.oasis-open.org
Subject: RE: [soa-rm] Definition(s) of "service"

I'd still like to emphasize service as the access to
capabilities for which there are extra-service

motivations for

their existence and requirements for use of the

capabilities

that must be

navigated

by the service. Thus,

"A service is a mechanism to enable access

to a set of

capabilities,

I would say that access control mechanisms enable such

access, and that

the service *provides* the capabilities. Note: Use of

"access control"

is too concrete for our RM - I stated it only to
illustrate

the point.

Joe

Joseph Chiusano
Booz Allen Hamilton
O: 703-902-6923
C: 202-251-0731
Visit us online@ http://www.boozallen.com

where the access is provided using a prescribed

interface and is

exercised consistent with constraints and policies as

specified by

the service description."

Ken

At 11:15 PM 8/3/2005, joe@pantella.net wrote:

Just trying to sort through this; some common themes

that seem to

be
acceptable:

A service provides capabilities.
A service is accessible. (If this is true, then
service

cannot be a

verb.) A service has an interface. (If this is true,

then a

service has

a boundary.) A service interface is

prescribed. (Then

a

service and its

interface are distinct, and the interface has

associated rules.

I'm not sure this is true, the interface may

describe the

rules,

but Im not

sure it has rules. In fact, I'm inclined to

suggest that

the interface

defines the rules for accessing the service. Which

would lead me

to suggest that the service interface is more than a

specification of the

data model, but also of the policies

associated with

the

service.)

A service is a set of behaviors. (Not sure I'm on
board

with this,

something about behaviors doesn't sit well.)

Given this, perhaps something like:

"A service is a bounded set of capabilities that are

accessible through

a prescribed interface."

-- JJP

P.S. I think this definition might just be

flexible enough

to navigate

the service offer/contract discussion also.

-----Original Message-----
From: Schuldt, Ron L [mailto:ron.l.schuldt@lmco.com ]
Sent: Thursday, July 28, 2005 12:32 PM
To: Frank McCabe; SOA-RM
Subject: RE: [soa-rm] Definition(s) of "service"

Frank,

While I believe that the previously proposed

definition is

sufficient,

I offer the following as a compromise.

Hopefully, the

notion of

"capabilities" addresses your issue of

needing to get

things done.

"A service is a set of behaviors to provide
capabilities

accessible via

a prescribed interface."

Ron

-----Original Message-----
From: Frank McCabe
[ mailto:frank.mccabe@us.fujitsu.com]
Sent: Thursday, July 28, 2005 10:10 AM
To: SOA-RM
Subject: Re: [soa-rm] Definition(s) of "service"

I hesitate to spoil this party ... but I'm

going to :)

1. There is a distinction between action and result.

(Just ask any

roboticist) Behaviour sounds a child

misbehaving with no

discernible effect. Computer Scientists have a
tendency

to focus on

the purely technical aspects of their work: bytes

shuffling around

at random within hopefully enormous memories.
2. Also, we have to bear in mind that nobody invests

millions of $s (or

even 100's of them) in systems that

contemplate their

navels

or have no

business payoff. I think that we have to directly

address the

reason that services are deployed. 3. One of the

movitating

best practice aspects of SOAs is

that clarity

and 'separation' between the providers of

services and the

consumers of

services leads to more scalable and robust

architectures.

All of the above is fuzzy language; but, at the

same time,

"A service

is a set of behaviors accessible via a prescribed

interface."

sounds a lot like bureauspeak.

I believe that there is strong consensus on the

following

characteristics:
a. The concept of service is 'at the

boundary' between

service

providers and consumers. b. The service is

'there' to get

things done; but doesn't

itself denote

the engine that performs the tasks.
c. There is a reason for using a service.
d. There is a lot of extra metalogical information
about

services that

make it possible for third parties to

develop partners

for services.

I, for one, would prefer a strongly anglo-saxon

phrasing of the

definition of service that speaks to these points.

Frank
ti

--

--------------------------------------------------------------

-------------------
/ Ken
Laskey
\
| MITRE Corporation, M/S H305 phone:

703-983-7934 |

| 7515 Colshire Drive fax:
703-983-1379 |
\ McLean VA 22102-7508
/

--------------------------------------------------------------

--------------------

--

--------------------------------------------------------------

-------------------
/ Ken
Laskey
\
| MITRE Corporation, M/S H305 phone:

703-983-7934 |

| 7515 Colshire Drive fax:
703-983-1379 |
\ McLean VA 22102-7508
/

--------------------------------------------------------------

--------------------

--

-------------------------------------------------------------------

--------------
/ Ken
Laskey

\
| MITRE Corporation, M/S H305 phone:

703-983-7934 |

| 7515 Colshire Drive fax:
703-983-1379 |
\ McLean VA
22102-7508 /

-------------------------------------------------------------------

---------------

-

--

--------------------------------------------------------------------

-------------
/ Ken
Laskey

\
| MITRE Corporation, M/S H305 phone: 703-983-7934 |
| 7515 Colshire Drive fax:
703-983-1379 |
\ McLean VA
22102-7508 /

--------------------------------------------------------------------

--------------

--

--------------------------------------------------------------------

--

-----------
/ Ken
Laskey

\
| MITRE Corporation, M/S H305 phone: 703-983-7934 |
| 7515 Colshire Drive fax:
703-983-1379 |
\ McLean VA
22102-7508 /

--------------------------------------------------------------------

--

------------

--

--------------------------------------------------------------
-------------------
/ Ken
Laskey
\
| MITRE Corporation, M/S H305 phone: 703-983-7934 |
| 7515 Colshire Drive fax:
703-983-1379 |
\ McLean VA 22102-7508
/

--------------------------------------------------------------
--------------------

--
---------------------------------------------------------------------------------
/ Ken Laskey \
| MITRE Corporation, M/S H305 phone: 703-983-7934 |
| 7515 Colshire Drive fax: 703-983-1379 |
\ McLean VA 22102-7508 /
----------------------------------------------------------------------------------

Ken Laskey
MITRE Corporation, M/S H305 phone: 703-983-7934
7515 Colshire Drive fax: 703-983-1379
McLean VA 22102-7508

--
     ---------------------------------------------------------------------------------
/   Ken Laskey                                                                \
|    MITRE Corporation, M/S H305    phone: 703-983-7934   |
|    7515 Colshire Drive                    fax:      703-983-1379   |
\   McLean VA 22102-7508                                              /
    ----------------------------------------------------------------------------------

References:
- Fwd: [soa-rm] Definition(s) of "service"
  - From: Ken Laskey <klaskey@mitre.org>
- RE: [soa-rm-editors] Fwd: [soa-rm] Definition(s) of "service"
  - From: Matthew MacKenzie <mattm@adobe.com>