Hi All --
Frank McCabe wrote...
One definition of semantics is in terms of the objects/concepts of
interest and their relationships. I.e., to model the semantics of some
*thing* identify the objects of interest and
then their relationships.
I tried recently to make a partial order (lattice) of some of the
things that people mean when they use the word 'semantics', such as:
logical model theory, real world URI types for data a la RDF, OWL
ontologies, the meaning of an English statement**, etc. Making such a
lattice turns out to be a hard task.
But what one can do is to pull back to just those notions of
'semantics' that are likely to be useful in IT in the next few years.
I'd propose:
(1) declarative semantics of rule systems (model theory or fixpoint
theory) and proofs of soundness and completeness of rule engines wrt to
the theory
(2) In the spirit of Frank's relationships between objects of
interest , some better way than we have at the moment of
computing with relations between English sentences.
There's more about this in
http://www.w3.org/2004/12/rules-ws/paper/19 , and in the other papers
in last weeks' W3C Rules Interoperability Workshop.
So, anyone disagree with (1) and (2) ? There are surely some other
notions of 'semantics' that folks on this forum think will likely be
useful in IT in the next few years.
Cheers, --
Adrian
** My favorite gripe about ontologies is that the only English
sentences they contain are comments, which are simply ignored by
machines.
--
Internet Business Logic -- online at www.reengineeringllc.com
Reengineering LLC, PO Box 1412, Bristol, CT 06011-1412, USA
Phone 860 583 9677 Mobile 860 830 2085 Fax 860 314 1029
Duane Nickull wrote:
This
thread just started on the SOA Reference Model TC list. Any comments?
Duane
-------- Original Message --------
Subject: Re: [soa-rm] Semantics (was: Re: [soa-rm] Re: Autonomous
Services?)
Date: Mon, 02 May 2005 13:26:49 -0700
From: Francis McCabe <fgm@xxxxxxxxxxxxxxx>
To: Duane Nickull <dnickull@xxxxxxxxx>
CC: soa-rm@xxxxxxxxxxxxxxxxxxxx
References:
<955953BEFC7F5C4AA0F1428F3F335F1CE327B8@xxxxxxxxxxxxxxxxxxxxxxxxxx>
<4274B7B4.4080208@xxxxxxxxxxxxxxxxxxx>
<427655BD.4050704@xxxxxxxxx>
<7FD249D5-A9A6-477A-98B6-D091BA15006E@xxxxxxxxxxxxxxx>
<42766875.60606@xxxxxxxxx>
Ahh, well, you begin to point at something deep here... about the
relationship between syntax and semantics.
One definition of semantics is in terms of the objects/concepts of
interest and their relationships. I.e., to model the semantics of some
*thing* identify the objects of interest and then their relationships.
Syntax, on the other hand, is all about written _expression_; and the
manipulation thereof.
The problem that most logicians skirt over is this: in order to
describe the semantics of some *thing*; you have to write it down --
i.e., you need syntax to do semantics. Something of a paradox.
I have come to the conclusion that the relationship (sic) between
syntax and semantics (proof theory and model theory), is primarily one
of perspective: semantics is *about* relationships, and syntax is
*about* structure.
Which is a long-winded way of saying that, yes, you can do a lot with
syntax manipulation. However, where simple-minded syntax manipulation
breaks down is in the broader context: I can re-write one form of a
telephone number to another because I (i.e., not part of any spec.)
happen to know they are equivalent for my purposes.
The other big issue with purely syntactic operations is that there is
no support for distinguishing valid transformations from invalid ones.
Often to prove a syntactic transformation is valid (sanctioned by the
semantics) is non-trivial. What a sound logic gives you is a
once-and-for-all proof that certain transformations are valid.
Frank
On May 2, 2005, at 10:50 AM, Duane Nickull wrote:
Frank:
I just skimmed this work and find it very interesting. There are a
couple of sections we may wish to ponder in our context.
Section 1.1 - definitions. Clean separation of the Semantic Model
(probably what also may be termed ontology) from the concept of
semantics itself. There is also another separation of semantics
annotation (where something like UDEF would be categorized) from the
notion itself.
Section 1.2 - a great depiction of how semantics relate to Data Model.
page 15-16 - I do not see how this XSL instance to OWL mapping:
<xsl:template match="/">
<Address rdf:ID="Address1">
<has_Receiver rdf:datatype="xs:string">
<xsl:value-of select="POAddress/recepientInstName"/>
<has_StreetAddress rdf:datatype="xs:string">
<xsl:value-of select="concat(POAddress/streetAddr1,POAddress/
streetAddr2)"/>
</has_StreetAddress >
<has_City rdf:datatype="xs:string">
<xsl:value-of select="POAddress/city"/>
</has_City>
<has_State rdf:datatype="xs:string">
<xsl:value-of select="POAddress/state"/>
</has_State>
<has_ZipCode rdf:datatype="xs:string">
<xsl:value-of select="POAddress/zipCode"/>
</has_ZipCode>
<has_Country rdf:datatype="xs:string">
<xsl:value-of select="POAddress/country"/>
</has_Country>
</Address>
</xsl:template>
varies from what a schema can tell you. The basic premise of
containership structure allows the same declarations IMO.
I did like the aspect of context specific semantic reference however.
The aspect of context is missing from many semantics works. An
example - you define something called "party". Seems easy - a party
is an entity assuming a role within an exchange (or something similar
to that). The gotcha is in the implementation. The semantics of
"Party" varies from itself within different hierarchic manifestations.
//PO/Buyer/Party != //PO/Seller/Party
This is potentially a bad example since it could be solved with
ambiguous references but the main notion is that every element has at
least one context qualified. Luckily, we do not have to address a
solution for this but I hope these folks can. It looks like their
xpath statement to OWL grammar works conceptually.
Duane
Francis McCabe wrote:
+1
In fact, I am hard put to understand how you can *store* semantics.
You can only store data. The best that you can do is store a
description of the semantics; but that is not the same thing.
On that theme, IBM and others at the U of Georgia recently released a
paper on semantic annotations of Web services. Have not yet had the
time to digest this properly, but could be interesting... if IBM
makes a play in the standards space with this.
The link to the paper is:
http://www.alphaworks.ibm.com/g/g.nsf/img/semanticsdocs/$file/
wssemantic_annotation.pdf
Frank
On May 2, 2005, at 9:30 AM, Duane Nickull wrote:
John
(aka "Meggan". Hey - how you dress in private is none of our
business ;-)
Just joking!!
This is a good question.
The registry is one way that one could store semantics however
semantics are not required to be explicit and there are other models
for sharing information beside registry. At the abstract level it
represents a facet of the model where the information available is
meaningful. Therefore, a registry will not be in the reference model
as a normative, core element.
We decided to add a non normative section to explain some of these
manifestations. How one goes from "Data Model" to Messages,
Availability to Registry, Policy to on the wire security etc.
It would be great if you could hook up with the person with this
section and offer proof reading services. Value your input.
Duane
meggan hardin wrote:
My assumptions (so far) about the
central metadata concepts have been that the reg/rep holds this data.
Are we delving to the level of defining specific types of resources /
components that should be included in a major component such as the
reg/ rep? I think that the concept of storing semantic metadata as an
independent integration reference point is important enough to be
included in the RM.
FWIW - Contivo terms the semantic metadata repository the "enterprise
vocabulary"...
john
Smith, Martin wrote:
Violent agreement.
martin
________________________________
From: Schuldt, Ron L [mailto:ron.l.schuldt@xxxxxxxx]
Sent: Fri 4/29/2005 6:39 PM
To: Smith, Martin; Sharma, Sameer; Duane Nickull;
john@xxxxxxxxxxxxxxxxxxx
Cc: ebSOA OASIS TC; soa-rm@xxxxxxxxxxxxxxxxxxxx
Subject: RE: [soa-rm] Re: Autonomous Services?
Sameer will correct me if I'm wrong, but I believe that his intent
was
to include the notion of central metadata within a "Reference
Architecture" not the Reference Model. Appendix B is the place where
example use cases would be defined. I suspect that Sameer might be
willing to submit an example use case.
Ron Schuldt
Senior Staff Systems Architect
Lockheed Martin Enterprise Information Systems
11757 W. Ken Caryl Ave.
#F521 Mail Point DC5694
Littleton, CO 80127
303-977-1414
ron.l.schuldt@xxxxxxxx
-----Original Message-----
From: Smith, Martin [mailto:Martin.Smith@xxxxxxx]
Sent: Friday, April 29, 2005 4:19 PM
To: Sharma, Sameer; Duane Nickull; john@xxxxxxxxxxxxxxxxxxx
Cc: ebSOA OASIS TC; soa-rm@xxxxxxxxxxxxxxxxxxxx
Subject: RE: [soa-rm] Re: Autonomous Services?
Sameer - -
Let me practice being Matt <g>:
The term " 'central' metadata" presumes a specific implementation
strategy and should not be in the RM. Perhaps "metadata associated
with
the service should be available in the environment." Now in my
example
SOA for Appendix B, I'll probably show a UDDI services directory, or
maybe a combo registry/repository that can in fact store all the
description metadata.
Martin
-----Original Message-----
From: Sharma, Sameer [mailto:sameer.sharma@xxxxxxxx]
Sent: Friday, April 29, 2005 2:16 PM
To: Smith, Martin; Duane Nickull; john@xxxxxxxxxxxxxxxxxxx
Cc: ebSOA OASIS TC; soa-rm@xxxxxxxxxxxxxxxxxxxx
Subject: RE: [soa-rm] Re: Autonomous Services?
My feeling is that some of what you are alluding to might be covered
by
UDDI,
however as is happening in an instance of SOA deployment that I am
involved
in - UDDI by itself is not going to be sufficient to express all the
metadata
that is needed for a client to successfully and contextually
interpret
all
that a Web Service does.
My attempted solution is to capture this additional metadata by
leveraging
central metadata services of my enterprise. I guess what I am saying
is
that
the concept of "central metadata" might be a valid candidate as a
component of
the Reference Architecture we are considering.
Since I was unable to participate in the F2F, (due to some last
minute
commitments that I got called into), if this topic was discussed,
please
accept my apologies for bringing it up again.
Thanks!
L
Sameer Sharma
Principal Applications Architect
Lockheed Martin Corporation
Chief Technology Office (CTO)
12506 Lake Underhill Road - MP 166
Orlando, FL-32825
Tel: (407) 306 5640
Fax:(407) 306 1392
-----Original Message-----
From: Smith, Martin [mailto:Martin.Smith@xxxxxxx]
Sent: Friday, April 29, 2005 1:38 PM
To: Duane Nickull; john@xxxxxxxxxxxxxxxxxxx
Cc: ebSOA OASIS TC; soa-rm@xxxxxxxxxxxxxxxxxxxx
Subject: RE: [soa-rm] Re: Autonomous Services?
Folks - -
On my way home from N'awlins Wed night, I had a thought on this
discussion.
I think we expect services in an SOA to be independent of the kind of
shared contextual knowledge we usually presume within a local
computing
environment. We expect that the requesting service will be able to
obtain all the info it needs to use the responding service
successfully
by processing the responding service's description metadata. I do
think
this is a core characteristic of SOA services.
I'm not suggesting we reinstate the use of the word "autonomous" as a
handle for this concept since it demonstrably caused confusion at the
f2f. If we need a handle, perhaps "self-sufficient" or
"self-documenting" or "introspective" (naaah - forget that one.)
Martin
-----Original Message-----
From: Duane Nickull [mailto:dnickull@xxxxxxxxx]
Sent: Friday, April 29, 2005 12:43 PM
To: john@xxxxxxxxxxxxxxxxxxx
Cc: ebSOA OASIS TC; soa-rm@xxxxxxxxxxxxxxxxxxxx
Subject: [soa-rm] Re: Autonomous Services?
We discussed and the submitter withdrew the submission pending
clarification on exactly what is meant by Autonomous nature WRT
services. It may be re-submitted and probably will however we do not
have consensus on it at present.
Duane
john c hardin wrote:
Duane and SOA-RM group -
Can someone enlighten the members of the eb-soa group regarding a
description of Autonomous Services? Any resulting conversations from
the meetings this week, on the subject of Autonomous Services would
be
good also.
thanks
john
--
***********
Senior Standards Strategist - Adobe Systems, Inc. - http://
www.adobe.com
Vice Chair - UN/CEFACT Bureau Plenary - http://www.unece.org/ cefact/
Adobe Enterprise Developer Resources -
http://www.adobe.com/enterprise/developer/main.html
***********
--
***********
Senior Standards Strategist - Adobe Systems, Inc. - http://
www.adobe.com
Vice Chair - UN/CEFACT Bureau Plenary - http://www.unece.org/cefact/
Adobe Enterprise Developer Resources - http://www.adobe.com/
enterprise/developer/main.html
***********
--
***********
Senior Standards Strategist - Adobe Systems, Inc. - http://
www.adobe.com
Vice Chair - UN/CEFACT Bureau Plenary - http://www.unece.org/cefact/
Adobe Enterprise Developer Resources - http://www.adobe.com/
enterprise/developer/main.html
***********
--
Internet Business Logic -- online at www.reengineeringllc.com
Reengineering LLC, PO Box 1412, Bristol, CT 06011-1412, USA
Phone 860 583 9677 Mobile 860 830 2085 Fax 860 314 1029
|
|