1. Multi-agent system for web services
John Akinyele

2. Overview Introduction Background MWS Implementation Discussion
Future Work
Related Work
Conclusion

3. Introduction Web services
a new breed of web application that are self-contained, self-describing, modular applications that can be published, located, and invoked across the web
Web services are a result of the evolving internet/web technologies
Progression of internet technologies
HTML – Semantic Web

4. Introduction
HTML
The initial language used for developing web pages
It is describes the presentation of the document
It limits the development of automated applications that access them.
XML
Extension of HTML
Allow developers to create their own tag definitions
Lacks global consistency

5. Introduction
RDF
specifications provide a lightweight ontology system to support the exchange of knowledge on the Web
An ontology - an explicit formal specification of how to represent the objects, concepts and other entities that are assumed to exist in some area of interest and the relationships that hold among them
provides a means through which web sites with meaningful and globally consistent contents can be defined.

6. Introduction RDF A basis for semantic web technologies
semantic web is the idea of having data on the web defined and linked in a way that it can be used by machines for various applications

7. Introduction MWS “Shopping mall” for personal agents
Contains a directory of services providing various web services
Web services are define with a semantic web ontology based on DAML
The directory is categorized by the type of product being offered

8. Background DAML DARPA Agent Markup Language
An extension to XML and RDF by using ontologies to provide a powerful way to describe objects and their relationships to other objects
It has been tested in various applications:
ITTALKS
Webscripter

9. Background DAML Services
Enable the creation of services that have particular properties which software agents can discover, invoke, compose, and monitor
Service object is the upper ontology for web services.

10. Background DAML Service Object It seeks to answer 3 questions
What does the service require?
How does the service work?
How is the service used?
It has 3 properties
presents – Service Profile
describedBy – Service Model
support – Service Grounding

11. Background DAML Service Profile Describes what service requires
Parameters, contact information etc
2 important subclasses
Advertisement
Used to “advertise” the services provided within a service
Request
Used to “declare” what the agent seeks

12. Background DAML Service Model Defines how the service works
Describes the necessary parameters – input and output, and the produced effect
the “stub” or “skeleton” of the methods/objects of the service.
Can represent methods/objects implemented in a wide variety of application domains

13. Background DAML Service Model The process ontology includes Process
CompositeProcess
Sequence
Condition
If-Then-Else
Iterate
Repeat-Until

14. Background DAML Service Grounding Defines how the service is used
Specifies communication protocol details
HTML
Java RMI, Jini
Specifies data exchange details
Data marshalling
Data format

15. MWS Shopping Mall for agents
Agents access web services that are services are defined with DAML-S
Mall provides categorized list of services
Categorizes by products
Categorization guarantees the type of product in the service.
Implemented with the JADE platform

16. MWS Services Ontology Parser Mall Manager Personal Agents
Service Agents

17. Sample service <mservice:MallService rdf:ID="Schmitt_Bookstore">
<service:presents>
<mservice:MallAdvertisement rdf:ID="Schmitt_Bookstore_Advertisement">
<profile:serviceName>Schmitt Bookstore</profile:serviceName>
<profile:textDescription>Schmitt Bookstore advertisement. Shop and Save</profile:textDescription>
<profile:providedBy>
<profile:ServiceProvider rdf:ID="Schmitt_Service_Provider">
<profile:name>Schmitt Services</profile:name>
<profile:phone> </profile:phone>
<profile:fax> </profile:fax>
<profile:physicalAddress>1000 Hilltop Circle, Baltimore, MD , USA</profile:physicalAddress>
<profile:webURL>
</profile:ServiceProvider>
</profile:providedBy>

18. Sample Service cont’d <mservice:MallserviceCategory>
<mservice:MallProductList rdf:ID="Schmitt_Product_List">
<products:BookProducts rdf:ID="Schmitt_Books">Schmitt Books</products:BookProducts>
<products:OfficeEquipments rdf:ID="Schmitt_Office">Schmitt Office </products:OfficeEquipments>
</mservice:MallProductList>
</mservice:MallserviceCategory>
<profile:serviceType> B2C </profile:serviceType>
<profile:communicationThru>DAML</profile:communicationThru>
</mservice:MallAdvertisement>
</service:presents>
<service:describedBy>
<process:ProcessModel rdf:ID="Schmitt_BuyProcess">
<service:topLevelEvent rdf:about="Schmitt_ProcessModel"/>
</process:ProcessModel>
</service:describedBy>
</mservice:MallService>

19. Implementation Implemented with Java 2 programming language
JADE – Java Agent Development Framework
DAMLJessKB – DAML Jess knowledge base package
DAMLJessKB reads DAML files as a collection of triples via an RDF parser
Reads them into JESS – Java Expert Shell System

20. Implementation Architecture Inter-agent communication DAMLQuery object
Exchange of data via DAML
Invoke services by composing DAML strings
DAMLQuery object
Implementation of the ontology parser
Run queries on DAML Services
Interrogates the model and grounding of services

21. Implementation Architecture AgentMall object
Implements the mall manager
Subclass of jade.core.Agent
Contains a categorized directory of services
Represents the mall manager

22. Implementation Architecture ServiceAgent object
Subclass of jade.core.Agent
Registers itself by accessing the mall manager’s register method
Awaits customers that wish to access its services

23. Implementation Architecture PersonalAgents object
Implements the customer agents
Subclass of the jade.core.Agent
Process user’s request and determine which services it should access.

24. Discussion
The composition of DAML services inherently include some intelligence
Using expert system libraries, agents can access a service with little communication
Errors can be made when creating DAML service objects

25. Future Work Agent Collaboration Joint purchases
Service “advertises” discounts or specials for bulk purchases
Buy 1 get one free, free shipping etc.
Create mall ontologies for discounts and specials

26. Related Work Trading agents Phillip Turner and Nicholas Jennings
Focuses on scalability of the “market”
Dynamic choice of collaboration methodologies

27. Related Work Agent Cities
Initiative to build a network of agent based services
Built on agent technology, semantic web technologies etc
Various types of applications

28. Related Work Semantic web technologies
Other efforts at creating ontologies for web services
WSDL
DAML web queries

29. Conclusion issues with global accessibility
Various implementations of web services
A few web services might become de-facto standards because of benefits