Integrating Agents, Ontologies, and Semantic Web Services
for Collaboration on the Semantic Web
Michael Stollberg and Thomas Strang
DERI
–
Digital Enterprise Research Institute
First International Symposium on Agents and the Semantic Web
AAAI Fall Symposium Series 2005
Arlington, Virginia, 05 November 2005
2
Content
1.
Motivation and Aims
–
Semantic Web vision = automated collaboration support on the Web
–
Aim = technical realization
2.
Framework
–
Conceptual Model
–
Elements (Description and Usage)
•
Model of Agency
•
“Collaboration Services”
•
Goal
-
driven Architecture
3.
Semantic Collaboration Management
–
Collaboration Establishment
–
Collaboration Execution
4.
Conclusions
3
Motivating Example
L
M
P
D
Agent A(P)
Goal:
plan[
-
med. treatment for M
-
chauffeur(P)
-
consistent with calendar(P)]
Plan:
-
check plan from A(L)
-
if OK, then book
else: revise plan
Agent A(L)
Goal:
plan[
-
med. treatment for M
-
chauffeur(P)]
Plan:
1) find suitable doctor
2) coordinate chauffeur(P)
med. info
service
calendar
service
transport
info serv.
owns
owns
O
-
person
O
-
medical
O
-
date&time
O
-
transport
Agent A(D)
Goal:
offer[
-
med. treatment
-
appointement]
Plan:
1) find customer
2) book appointement
owns
book app.
service
doctor
information
(website)
ontology usage
(also for agents,
omitted here)
1:need medical treatment
2: inform, chaffeur(P)
3a: assign goal
3b: make /
find plan
3b: make /
find plan
3a: assign goal
Xb: make /
find plan
Xa: assign goal
4:find
doctor
uses
provides
5:inform, plan
6:revise plan
7:book appointment
interact
uses
8: add plan
from: Berners
-
Lee, T.; Hendler, J.; Lassila, O.:
The Semantic Web. A new form of Web Content that is meaningful
to computers will unleash a revolution of new possibilities.
In: Scientific American 9(5), May 2001.
4
Automated Collaboration Support on
the Semantic Web
•
In fact, the Semantic Web vision proclaims
seamless and automated
collaboration support
on the Web
–
collaboration = cooperative interactions of individuals for achieving complex
objectives or objectives that require purposeful cooperation
–
... is a constituting principle of (human) society
–
… the “Semantic Web” shall provide sophisticated support for this
•
Base Technologies:
–
Software Agents
personal assistants / electronic representatives
–
Ontologies
semantic interoperability
–
(Semantic) Web Services
computation over the Web
•
Technology for Collaboration Support needs to:
–
reflect the epistemology of collaboration
–
integrate base technologies properly
–
comply with technical requirements
5
Our Approach
•
Agents as electronic representatives of collaborating real
-
world entities use:
–
(Semantic) Web resources as information resources
–
(Semantic) Web services as means for automated communication & cooperation
•
Semantic Web Service technologies for collaboration management
•
Semantic descriptions as extension of WSMO
Design Principles
(combining Agent & Web technology for collaboration support)
1.
Agents as Symmetric Collaboration Entities
2.
Ontologies as Data Model
3.
Web Compliance
4.
Goal Driven Architecture
5.
Semantic Collaboration Management
6.
Strict Decoupling and Strong Mediation
7.
Maximal Automation
6
Conceptual Model
Agent B
Goal
Instance
Agent A
Goal
Instance
has(1,n)
compatible goals =
collaboration partners
automated collaboration
execution
Domain Knowledge
uses(1,n)
has(1,n)
uses(1,n)
Collaboration
Service
Web
Service
Goal Template
Repository
Service
Repository
Collaboration
Service
Web
Service
Owner
Owner
goal
assignment
service
discovery
owns
Ontology
Ontology
Ontology
Ontology
7
Model of Agency
•
Agent = electronic representative of a real world entity
involved in collaborative interactions
–
receives task from owner (objectives represented as Goals)
–
uses “Collaboration Service” as facility for participating in collaborations
automatically executed over the Semantic Web
–
controls own collaboration behavior by using services for collaboration
management
•
Goal
-
driven Collaborative Interface Agents
–
Reactivity & Proactiveness
via interaction with owner and other agents
–
Autonomy
as self
-
controlled collaboration behavior
–
Social Abilities
as purposeful information interchange & communication via
Collaboration Services
•
Semantic description
–
‘data container’ of owner and collaboration information
–
ontologies used as data model
8
Agent Semantic Description
Agents
electronic representative of real world entity that wants to achieve
an objective by collaborative interaction with other
real world entities
Class
agent
hasNonFunctionalProperties
type
nonFunctionalProperties
importsOntology
type
ontology
usesMediator
type
ooMediator
owner
type
owner
collaboration
type
collaboration
history
type
collaboration
Class
owner
hasNonFunctionalProperties
type
nonFunctionalProperties
owner
type
instance
preference
type
axiom
policy
type
axiom
serviceUsagePermission
type
service
Class
collaboration
hasNonFunctionalProperties
type
nonFunctionalProperties
goal
type
goal
single
-
valued
service
type
service
9
Collaboration Services
•
Web Service used by Agents to participate in collaborations
automatically executed over the (Semantic) Web
–
a computational facility accessible over the Web that provides a functionality
useful for an agent to automate collaboration execution
–
can provide very simply or arbitrary complex functionality
–
can “talk” to other agents via their collaboration services
•
dynamically
detected
(possibly
composed
) and
consumed
by
an Agent wrt / via an Goal Instance
–
each objective is solved in a different collaboration
–
agent discovers suitable Collaboration Services (Web service discovery),
possibly determines composite Collaboration Service
–
Goal Instance +Agent data container = input for service execution
•
Semantic description:
–
extended WSMO Web service description
–
“orchestration” defines interaction behavior with other services / resources
for achieving functionality
10
Collaboration Service Description & Usage
Agent A
postcondition
Goal Instance
effect
submission
result
Service
Implementation
(not of interest for
service description)
Capability
Client
-
Interface
WS
Orchestration
Agent B
Service
Implementation
(not of interest for
service description)
WS
Orchestration
Client
-
Interface
(1) = functional suitability
(2) = service usage
(3) = service interaction
(1)
(2)
(1)
(2)
(3)
preferences
postcondition
Goal Instance
effect
submission
result
preferences
WS
nFP
Capability
nFP
11
Collaboration Service Description
Collaboration Services
facility an agent uses for participating in an automatically executed collaboration;
interacts with other agents and utilizes Semantic Web resources via its orchestration
Class
collaborationService
is
-
a
wsmoService
hasNonFunctionalProperties
type
nonFunctionalProperties
importsOntology
type
ontology
usesMediator
type
ooMediator
hasCapability
type
capability
single
-
valued
hasSharedVariables
type
sharedVariable
hasPrecondition
type
axiom
hasAssumption
type
axiom
hasPostcondition
type
axiom
hasEffect
type
axiom
hasInterface
type
interface
clientInterface
type
serviceInterfaceDescription
orchestration
type
serviceInterfaceDescription
Class
serviceInterfaceDescription
sub
-
Class
wsmoServiceInterface
hasNonFunctionalProperties
type
nonFunctionalProperties
importsOntology
type
ontology
usesMediator
type
ooMediator
hasVocabulary
type
concept_in, concept_out, concept_controlled
hasState
type
ontology
hasGuardedTransition
type
if (condition) then
rule
// rule = if
-
then rule | add
-
delete
-
update(fact) | forAll / choose (var)
rule
12
Goals
•
Goal
-
driven Architecture
–
users specify objectives as Goal Instances and assign this to their agent
–
goal creation by instantiation of Goal Templates
–
each objective is solved in a different collaboration
> Goals are the central element of the system
•
Goal = semantic description of an user’s objective that carries
all information needed for automated collaboration execution
via Collaboration Services
–
user objective as “final desired state”
–
constraints on goal resolution process
–
preferences / policies on: collaboration partners, services, time
–
Collaboration Service usage by Goal Instance + Agent data container
•
semantic description:
–
extended WSMO Goal description
–
Management by Goal Templates, Goal Instances, Goal Ontologies
13
Goal Templates and Instances
Goal Template
-
schematic goal description
o
schema of desired final state
o
constraints on resolution process (integrity constraints on states)
-
pre
-
defined at “design time”, maintained by “ administrator
Goal Instance
-
concrete objective specification as Goal Template instantiation
o
proper semantic refinement of its Goal Template wrt. final desired state
o
additional information for service usage
-
created at runtime by users (agent owners) or other agents
after resolution, a Goal Instance can become a Goal Template
14
Goals Semantic Description
Goal Template
predefined schema of user objective (WSMO 1.0 goal plus constraints)
Class
goalTemplate
subClassOf
wsmov1.0Goal
hasNonFunctionalProperties
type
nonFunctionalProperties
importsOntology
type
ontology
usesMediator
type
{ooMediator, ggMediator}
hasPostcondition
type
axiom
hasEffect
type
axiom
hasConstraint
type
axiom
Goal Instance
concrete objective assigned to an agent (instantiated Goal Template, client for service usage)
Class
goalInstance
sub
-
Instance
goalTemplate
hasNonFunctionalProperties
type
nonFunctionalProperties
hasPostcondition
type
axiom
hasEffect
type
axiom
hasConstraint
type
axiom
hasSubmission
type
instance
hasResult
type
instance
goalResolutionStatus
type
goalResolutionStatus
15
Goals Ontologies
-
Goal Ontologies
for efficient management:
o
Nodes = Goals, Arcs = ggMediators that denote “functional correspondence”
o
computed by
Δ
= explicit logical difference between final desired states
GI
{S
1
,S
2
,S
3
}
{S
2
,S
3
}
GT
-
1
Book Flight
GT
-
2
Book Flight
(Star Alliance)
subsume
{S
3
}
GT
-
3
Book Hotel
subsume
{S
5
,S
8
}
{
S
2
,S
3
,
S
5
, S
8
}
GT
-
4
Book US
-
Trip
(flight + hotel)
subsume
GI
{(S
3
, S
8
)}
{(
S
3
,
S5),(
S
3
,
S
8
)}
composition
16
Collaboration Management
Partner
Discoverer
Service
Discoverer
Choreography
Discoverer
GI
{GI}
GI
{S}
boolean
{S}
Collaboration
(preliminary)
(A
i
(G
1
, {S}
1
),
A
2
(G
2
, {S}
2
), ..)
Goal
Instance
Agent
(A
i
(G
1
, {S}
1
-
reduced
),
A
2
(G
2
, {S}
2
-
reduced
),..)
Goal
Instance
…
separately for each GI
each possible service combination
Agent
Collaboration
(final)
Collaboration
Executor
each collaboration
goal resolution for
the goal of each
collaboration partner
goal resolution for
the goal of each
collaboration partner
controlled individually by each agent, functional components as Web Services
17
Collaboration Management Components
Collaboration Establishment
applying “conventional” Semantic Web Service techniques
•
Partner Discovery = find agent with compatible goal
–
compatible final states of Goal Instances of agents
•
Service Discovery = find usable Collaboration Service
–
facility for participating in automated collaboration execution
–
goal final state <> service post
-
state ^ submission <> service pre
-
state
–
composition as sub
-
task of service discovery
•
Choreography Discovery = valid Collaboration Service interaction
–
orchestration compatibility of Collaboration Service of collaborating agents
–
existence of a valid interaction protocol for all needed interactions
Collaboration Execution
execute collaborations as Web Service interaction:
–
feasibility determination (availability of resources, duplication handling)
–
monitors & controls execution
18
Partner Discoverer Architecture
GI
i
Action
-
Resource
Ontology
DiscoveryResult
sets of compatible Goal Instances
(2) GG
Matcher
Discovery Request
initiating Goal Instance
GT
i
(1) Cooperation
Knowledge Filter
GT
g
GI
g
GI
g
instanceOf
instanceOf,
status = ‘open’
Action Compatibility
19
Service Discoverer Architecture
Discovery Request
Goal Instance
Discovery Result
usable Services
Service
Repository
Discovery Result
(intermediary)
Service
Filter
(2) GIS Matcher
GI
i
GT
i
instanceOf
(1) Pre
-
Selector
Action
Equality
20
Choreography Discoverer Architecture
Discovery Request
set of services {S}
Discovery Result
Boolean (service compatibility)
(2) SC
comm
Checker
Choreography Description Translator
(1) SC
info
Checker
WSDL2StateSign
BPEL2ASM
yes
no
21
Conclusions
•
Framework for Collaboration on the Semantic Web
–
agents, goals, Web Services “integrated” for collaboration support
–
SWS technologies for
–
prototype implementation in Semantic Web Fred (SWF)
•
Important Aspects
–
Model of Agency
–
Collaboration Services
–
Goal
-
driven Architecture
–
Semantic Collaboration Management
•
Lessons Learned
–
core (reasoning) tasks are the same in agents and SW / SWS
–
rationale agent paradigm = determine best next action for achieving goal
–
(Semantic) Web Service = determine complete interaction model before
execution
=> which one is “better”, i.e. more applicable
22
< Q&A>
< Thank You />
</ The Big Dream>
Enter the password to open this PDF file:
File name:
-
File size:
-
Title:
-
Author:
-
Subject:
-
Keywords:
-
Creation Date:
-
Modification Date:
-
Creator:
-
PDF Producer:
-
PDF Version:
-
Page Count:
-
Preparing document for printing…
0%
Comments 0
Log in to post a comment