James Hendler <hendler@cs.umd.edu>
Bijan Parsia <bparsia@isr.umd.edu>
Evren Sirin <evren@cs.umd.edu>
University of Maryland, College Park
MIND Lab, 8400 Baltimore Ave
College Park, Maryland 20740
301-314-6642
Two years ago this May, the much-cited article, The
Semantic Web appeared in Scientific American. The authors started the
article with a futuristic scenario of what could be done when Semantic Web
technologies would come of age. At this point in time, two years after
publication, the technologies have reached the point where a prototype of all
the pieces can be shown and integrated, as we will show in this demonstration,
using currently available, open-source, Semantic Web tools developed at our lab
or elsewhere. We will also demonstrate the tools individually and discuss how
the demonstration was accomplished.
The first part of the scenario describes the
interaction between devices where one device is able to discover the other
devices in the environment, find out their capabilities and control their
functionality. We designed an architecture where devices describe their
functionality through web service descriptions written in the DAML-S
language, these descriptions are made available for discovery using Universal
Plug and Play (UPnP) technology. We extended the
DAML-S groundings to include UPnP groundings and to directly invoke Web Service
Description Language (WSDL) groundings.
Therefore, using a functionality of the device is same as invoking a web
service. The scenario requires a small device such as a telephone have the
processing power to achieve these goals. This is achieved by assigning a simple
computer, actually a PDA, to handle these responsibilities.
Following this in the scenario
are a number of agents that operate on semantic web to do the tasks for a user.
We represent some of the actions defined in the scenario as web services, e.g.
there will be one web service returning available appointment times for the
doctor. The markup of these web services with DAML-S language allows us to make
discovery, composition and execution by linking the descriptions of services to
ontologies written in the Web Ontology Language, OWL
on the Semantic Web. We have developed a service composition tool to compose
DAML-S descriptions and execute them using the WSDL and UPnP groundings.
Besides the ability to process web services, the
user agent also needs to have a planning capability not only to arrange a
meeting time between different people's schedules but also to find the correct
order of appropriate services to get the information in order to accomplish the
goal. We are using the Simple Hierarchical Ordered Planner (SHOP)
for composing services. SHOP is a domain independent HTN planner that can solve
classical AI planning problems. We developed a way to map the web service
composition task to a planning problem defined for SHOP. By translating DAML-S
services to methods and operators in SHOP, we can solve the problem of finding a
set of services that will achieve some specified goal.
Another important aspect of the scenario is that ontologies
are distributed at different sources and not always directly compatible with
each other. We will show a demo of our software OntoLink which is used to define
semantic mappings between concepts that are defined at different ontologies
through a simple user interface. We will show how some of these mapping tasks
are automated by using some heuristics and how the user can extend these
mappings by defining ad-hoc transformations between the concepts. Same tool is
also used to generate the semantic service descriptions from existing WSDL
descriptions.
The scenario requires the agents of Lucy and Pete share
information with each other based on the fact that they have a pre-defined trust
relation. To accomplish this task, agents first need to authenticate and then
decide how much information can be shared with the other party based on their
trust relationship. We demonstrate a simple rule-based authentication
(substituting for an eventual public key or other such more robust system).
After authentication takes place, one agent must also decide if the other agent
is trusted enough to share the requested information. For this purpose, we have
developed a distributed trust system using social network analysis. Everybody
assigns a trust value to the people they know and using graph theory trust
relationship can be deduced between nodes who did not explicitly state any trust
level to each other but can be linked through people they trust.
Another feature
described in the scenario is people who are not computer experts such as the
clinic's office manager can generate the semantic markups. The demo of RDF/RDFS/OWL-Driven
Mindswap Semantic Web Site will show how
users can view, query and modify the semantic data at the web site. The various
different technologies used for storing the data (e.g. Redland toolkit),
querying the triplestore (e.g. several different scripting languages),
generating user viewable web pages (e.g. XSLT) and interfaces that lets the user
interactively edit the content will be shown.
[1] Mindswap Semantic Web Site http://owl.mindswap.org
[2] The DAML Services Coalition (Ankolekar, A., Burstein, M., Hobbs, J.R.,
Lassila, O., Martin, D., McDermott, D., McIlraith, S.A., Narayanan, S., Paolucci,
M., Payne, T., Sycara, K.): DAML-S: Web Service Description for the Semantic
Web. Proceedings of the First International Semantic Web Conference,
2002.
[3] Nau, D., Au, T., Ilghami,O., Kuter, U., Murdock, J. W.,Wu, D., Yaman, F.:
SHOP2: An HTN Planning Environment. Journal of Artificial Intelligence
Research, 2003.
[4] Sirin, E., Hendler, J., Parsia, B.: Semi-automatic composition of web
services using semantic descriptions. In Web Services: Modeling, Architecture
and Infrastructure workshop at ICEIS2003, Nantes, France, 2003.
[5] Golbeck, J., Parsia, B., Hendler, J. Trust networks on the semantic
web. In Proceedings of Cooperative Intelligent Agents 2003, Helsinki,
Finland, August 2003.
[6] Golbeck, J., Alford, A., Hendler, J. Handbook of Human Factors in Web
Design, chapter Organization and Structure of Information using Semantic Web
Technologies, 2003.
The demo will be carried out at two different computers and will also include a PDA. We will bring these machines with us. The only essential requirement for the demo is network connectivity. The demo uses web services and various other resources on the Internet so without network accessibility it is nearly impossible to carry out the demo. Wireless Internet connection is highly preferred but having separate network cables for both of the computers is also acceptable.
During the demo
we will show outputs from different machines so having two different projectors
would be helpful. This is not a strict requirement but it is much easier for the
audience to follow the demo this way.
The demo will start by describing the scenario in the article. We will first show the demo of device interaction where we will use a PDA as a telephone and one of the computers as a music player. The discovery of the music player by the telephone via UPnP and execution of the music player's sound off service by the phone upon an incoming call will be done.
The demo will
then show how Lucy and Pete will arrange the hospital and doctor appointments
for their mom. Lucy will instruct her planner to do the arrangements using the
interface shown in Figure 1. This interface, which is a generic tool for
presenting a data entry form for the concepts defined in ontologies, will be
used by Lucy to give the necessary information to the planner while some
information such as known addresses automatically suggested for appropriate
fields.
During the planning process we will describe the architecture behind the service composition and execution. The planner will gather information from various different data sources such as Microsoft Outlook to get the schedules, hospital web sites to learn available appointment sites, pharmacies to see where the prescribed treatments can be found and so on. These services are composed by SHOP planner to find a plan that will accomplish the task. The execution of a plan will involve Lucy making changes to Pete’s personal calendar where trust information is used to decide the validity of the action. At this point, some details about the trust network and the implementation will be explained.
The demo will
then show OntoLink tool that is used defined mappings between concepts from
different ontologies (Figure 2). The demo of the tool will explain the
interface, how the mapping process can be automated with syntactic matches and
how user can define ad hoc transformations by generating XSLT stylesheets.
In the last part,
a demo of the Mindswap Semantic Web Site
will be done. Demo will show how information coming from different sources are automatically
incorporated as dynamic content. We will explain how distributed data for
several web sites is combined in a unifying view. Then adding, removing,
and editing data on the site in real time will be demonstrated by using one of
several interfaces such as a web based form
similar to Figure 1.
A general discussion of all the tools and
techniques presented will be done at the
end. The future directions to improve the method will conclude the
demonstration.