Web services-- Web-accessible programs and devices – are a key application area for the Semantic Web. With the proliferation of Web services and the evolution towards the Semantic Web comes the opportunity to automate various Web services tasks. Our objective is to enable markup and automated reasoning technology to describe, simulate, compose, test, and verify compositions of Web services. We take as our starting point the DAML-S DAML+OIL ontology for describing the capabilities of Web services. We define the semantics for a relevant subset of DAML-S in terms of a first-order logical language. With the semantics in hand, we encode our service descriptions in a Petri Net formalism and provide decision procedures for Web service simulation, verification and composition. We also provide an analysis of the complexity of these tasks under different restrictions to the DAML-S composite services we can describe. Finally, we present an implementation of our analysis techniques. This implementation takes as input a DAML-S description of a Web service, automatically generates a Petri Net and performs the desired analysis. Such a tool has broad applicability both as a back end to existing manual Web service composition tools, and as a stand-alone tool for Web service developers.

In this paper we present DAML-S, a DAML+OIL ontology for describing the properties and capabilities of Web Services. Web Services -- Web-accessible programs and devices -- are garnering a great deal of interest from industry, and standards are emerging for low-level descriptions of Web Services. DAML-S complements this effort by providing Web Service descriptions at the application layer, describing what a service can do, and not just how it does it. In this paper we describe three aspects of our ontology: the service profile, the process model, and the service grounding. The paper focuses on the grounding, which connects our ontology with low-level XML-based descriptions of Web Services.

. The Semantic Web should enable greater access not only to content but also to services on the Web. Users and software agents should be able to discover, invoke, compose, and monitor Web resources offering particular services and having particular properties. As part of the DARPA Agent Markup Language program, we have begun to develop an ontology of services, called DAMLS, that will make these functionalities possible. In this paper we describe the overall structure of the ontology, the service profile for advertising services, and the process model for the detailed description of the operation of services. We also compare DAML-S with several industry efforts to define standards for characterizing services on the Web. 1

The Semantic Web should enable greater access not only to content but also to services on the Web. Users and software agents should be able to discover, invoke, compose, and monitor Web resources o ering particular services and having particular properties. As part of the DARPA Agent Markup Language program, we have begun to develop an ontology of services, called DAML-S, that will make these functionalities possible. In this white paper we describe the overall structure of the ontology, the service pro le for advertising services, and the process model for the detailed description of the operation of services.

. We present a connectionist realization of parameterized schemas that can model high-level sensory-motor processes and be a candidate representation for implementing reactive behaviors. The connectionist realization involves a number of ideas including the use of focal-clusters and feedback loops to control a distributed process without a central controller and the expression and propagation of dynamic bindings via temporal synchrony. We employ a uniform mechanism for interaction between schemas, low-level somatosensory and proprioceptive processes, and high-level reasoning and memory processes. Our representation relates to work in connectionist models of rapid --- reflexive --- reasoning and also suggests solutions to several problems in language acquisition and understanding. 1 Introduction Performing goal-directed behavior in an uncertain and dynamic environment requires an agent to use representations that tightly couple action and reaction and that are highly responsive to envi...

Web services -- Web-accessible programs and devices -- are a key application area for the Semantic Web. With the proliferation of Web services and the evolution towards t he Semantic Web comes the opportunity to automate various Web services tasks. Our objective is to enable markup and automated reasoning technology to describe, simulate, compose, test, and verify compositions of Web services. We take as our starting point the DAML-S DAML+OIL ontology for describing the capabilities of Web services. We define the semantics for a relevant subset of DAML-S in terms of a first-order logical language. With the semantics in hand, we encode our service descriptions in a Petri Net formalism and provide decision procedures for Web service simulation, verification and composition. We also provide an analysis of the complexity of these tasks under different restrictions to the DAML-S composite services we can describe. Finally, we present an implementation of our analysis techniques. This implementation takes as input a DAML-S description of a Web service, automatically generates a Petri Net and performs the desired analysis. Such a tool has broad applicability both as a back end to existing manual Web service composition tools, and as a stand-alone tool for Web service developers.

Building a knowledge base for a specific domain traditionally involves a subject matter expert and a knowledge engineer. One of the goals of our research is to eliminate the knowledge engineer. There are at least two ways to accomplish this goal: train domain experts to write axioms (i.e., turn them into knowledge engineers) or create tools that allow users to build knowledge bases without having to write axioms. Our strategy is to create tools that allow users to build knowledge bases through instantiation and assembly of generic knowledge components from a small library. In many ways, creating such a library is like designing an ontology: What are the most general kinds of events and entities? How are these things related hierarchically? What is their meaning and how is it represented? The pressures of making the library usable by domain experts, however, leads to departures from the traditional ontology design goals of coverage, consensus and elegance. In this paper we describe our component library, a hierarchy of reusable, composable, domain-independent knowledge units. The library emphasizes coverage (what is an appropriate set of components for our task), access (how can a domain expert find appropriate components) and semantics (what knowledge and what kind of representation permit useful composition). We have begun building a library on these principles, influenced heavily by linguistic resources. In early evaluations we have put the library into the hands of domain experts (in Biology) having no experience with knowledge bases or knowledge acquisition. Keywords knowledge engineering, ontologies, knowledge reuse

Querying the Web today can be a frustrating activity because the results delivered by syntactically oriented search engines often do not match the intentions of the user. The DARPA DAML project aims at overcoming this problem by allowing webpages to be marked up in a way that indicates the meaning of the content. In this paper we present our vision of a DAML-enabled search architecture. We present a set of queries of increasing complexity that should be answered efficiently in a Semantic Web. We describe several scenarios illustrating how queries are processed, identifying the main software components necessary to facilitate the search. We examine the issue of inference in search, and we address how to characterize procedures and services in DAML, enabling a DAML query language to find websites with specified capabilities. Key Words: semantic web, DAML, inference, services. Word Count: 7800 words. 1

Building a knowledge base for a given domain traditionally involves a subject matter expert and a knowledge engineer. One of the goals of our research is to eliminate the knowledge engineer. There are at least two ways to achieve this goal: train domain experts to write axioms (i.e., turn them into knowledge engineers) or create tools that allow users to build knowledge bases without having to write axioms. Our strategy is to create tools that allow users to build knowledge bases through instantiation and assembly of generic knowledge components from a small library.

In the emerging e-Science, a Grid computing environment is coming into shape. However, the features of "rapid customised assembly of services" and "autonomic computing" have yet been adequately addressed in existing Grid prototypes [Atkinson et al. ]. Our project is set up to apply deductive synthesis to automate Grid service assembly, using proof planning technology, provided that Grid services and applications can be specified in a suitable logic.