Algorithms and Software for Interactive Discovery and Composition of Semantic Web Services

Project Summary

Recent advances in networks, information and computation grids, and WWW have resulted in the proliferation of a multitude of physically distributed and autonomously developed software components and services in various domains including e-Business and e-Science. Real world applications in these domains call for effective tools for developing composite services using available sets of component services. Existing approaches to web service composition suffer from a very significant limitation in that they require the user (or service developer) to provide a specification of the desired behavior of the composite service (goal) in its entirety. More importantly, the current approaches adopt a single-step request-response paradigm to service composition. That is, if a specified goal service is unrealizable (which would be the case if the goal service specification is incomplete), the process simply fails. It is typically difficult for a developer to provide the complete goal service specification that is needed in the absence of a detailed knowledge of the specifications of the component services available. This argues for an iterative approach to service composition wherein an abstract (and perhaps incomplete) goal service specification can be iteratively reformulated (with guidance from the system) until a composition that realizes the desired goal functionality is found, or the user decides to abort.

To address this need, we have introduced a framework for Modeling Service Composition and Execution (MoSCoE). MoSCoE models services using Symbolic Transition System (STS) which are labeled transition systems augmented with guards on transitions and state variables over an infinite-domain. MoSCoE, given an abstract (high-level and possibly incomplete) STS specifications of a goal service Tg, and of available component services T1,T2.. Tn, identifies a subset of the component services that when composed with a choreographer C, realize the goal service Tg. A unique feature of MoSCoE is its ability, in the event of failure to realize a goal service, to identify the specific states and transitions of the goal STS that need to be modified. This information enables the user to reformulate the goal specification (iteratively) until a composition that realizes the goal specification is found or the user decides to abort.

Work in progress is aimed at extensions of MoSCoE to exploit relationships among services and among failure causes to reduce the computational complexity of interactive service composition, the use of ontologies and inter-ontology mappings to facilitate composition of composite services from semantically heterogeneous component services, and systematic evaluation of the performance of MoSCoE on a wide range of benchmark service composition tasks.

Anticipated results of this research include open source software for rapid, discovery of component services and interactive assembly of complex web services from user specifications.

Funding

• ITR: Algorithms and Software for Knowledge Acquisition from Semantically Heterogeneous, Distributed Data, Vasant Honavar (PI), National Science Foundation.
• CSR--SMA: Software Verification Using Plug and Play Components , Andrew Miner (PI), and Samik Basu (Co-PI), National Science Foundation.
• Safety Analysis of Evolving Product Lines, Robyn Lutz (PI), National Science Foundation.

Personnel

Dr. Vasant Honavar, Professor of Computer Science and of Bioinformatics and Computational Biology, Iowa State University

Dr. Samik Basu, Assistant Professor of Computer Science, Iowa State University

Robyn Lutz, Professor of Computer Science, Iowa State University

Jyotishman Pathak, Ph.D. Student, Computer Science.

Publications

1. Pathak, J., Basu, S., Lutz, R., and Honavar, V. (2006). Applying Tabled-Logic Programming to Web Service Development using Abstraction, Composition and Reformulation. Proceedings of the IEEE International Conference on Tools With Artificial Intelligence (ICTAI 2006), Washington, DC, IEEE Press. In press.
2. Pathak, J., Basu, S., Lutz, R., and Honavar, V. (2006). Parallel Web Service Composition in MoSCoE: A Choreography Based Approach. Proceedings of the IEEE European Conference on Web Services (ECOWS 2006), Zurich, Switzerland, IEEE. In press.

Software

In progress.