Some comments from Frank that didn't get back to the list:
Ken:
The POA *is* the action as it is applied.
If the service is the glove, the POA is the iron fist:)
Different people have different definitions of action, (try define:action in google). None of these definitions is all that satisfactory to me.
My definition is adapted from John Sowa:
Action: the application of force by an agent on an object with the intention of achieving an effect.
I.e., its a kind of event. The POA is a characterization of that event. (One reason I like this definition is that is includes all human actions but excludes rocks rolling down the hill hitting other rocks.)
The service interface is the characterization of what it means to perform an action. It is not the action itself though.
Hope that this throws a little light on the matter.
Frank
Per Danny's response, I think he caught my question well with the final line of his response below:
One question
we can ask is can we identify a point of action
meaningful to the reference architecture that would
not have a service interface?
Ken
On Aug 17, 2006, at 1:55 AM, Danny Thornton wrote:
To draw another analogy for the point of action, I
know your mind will be the point of action for
processing this e-mail as you read the e-mail. The
e-mail address and the english language is like a
service interface.
The SOA has many points of action, each point of
action potentially affecting many other points of
action. We can identify points of action in a SOA
relevant to the reference architecture. One question
we can ask is can we identify a point of action
meaningful to the reference architecture that would
not have a service interface?
Danny
--- Ken Laskey <> wrote:
The following are from my notes at the ftf
Point of Action (poa)
- Frank: anchoring mechanism for numerous
things, e.g. policy
enforcement, evaluating needs & capabilities
- Ken: how does poa relate to service
interface? Frank:
service interface includes actions you can perform;
each instance of
use consists of performing action; actual action is
poa; interface
vs. poa is class vs. instance relationship; the
physical action is
the point of action
- [Ken] Given a policy is a desire of one
participant and an
agreement as part of the execution context for
participants to abide
by that policy (i.e. the other participant(s) agree
to make that
policy theirs), the policy enforcement point becomes
the point of
action for enforcing the agreed-upon policy.
- [Frank alternative] A policy is a constraint
that represents
the desire of a participant. A contract is a
constraint that
represents the agreed desires of two or more
participants. A [policy]
enforcement point is the point of action for
enforcing constraints
that represent either policies or contracts.
I've reread this and am still having problems
differentiating between
service interface and point of action. It appears
that poa is more
general because it is the location to which a user
would send a
command for action. If the receiver is a service,
then the poa would
seem to be the service interface. In the policy
example, if the
enforcement mechanism is accessed through a service,
the PEP could be
said to have a service interface.
I still seem to be missing something.
Ken
---
Ken Laskey
MITRE Corporation, M/S H305 phone: 703-983-7934
7515 Colshire Drive fax:
703-983-1379
McLean VA 22102-7508
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---
Ken Laskey
MITRE Corporation, M/S H305 phone: 703-983-7934
7515 Colshire Drive fax: 703-983-1379
McLean VA 22102-7508
