Biplav Srivastava

A service creation environment based on end to end composition of Web services

The demand for quickly delivering new applications is increasingly becoming a business imperative today. Application development is often done in an ad hoc manner, without standard frameworks or libraries, thus resulting in poor reuse of software assets. Web services have received much interest in industry due to their potential in facilitating seamless business-to-business or enterprise application integration. A web services composition tool can help automate the process, from creating business process functionality, to developing executable workflows, to deploying them on an execution environment. However, we find that the main approaches taken thus far to standardize and compose web services are piecemeal and insufficient. The business world has adopted a (distributed) programming approach in which web service instances are described using WSDL, composed into flows with a language like BPEL and invoked with the SOAP protocol. Academia has propounded the AI approach of formally representing web service capabilities in ontologies, and reasoning about their composition using goal-oriented inferencing techniques from planning. We present the first integrated work in composing web services end to end from specification to deployment by synergistically combining the strengths of the above approaches. We describe a prototype service creation environment along with a use-case scenario, and demonstrate how it can significantly speed up the time-to-market for new services.

Synthy: A system for end to end composition of web services

The demand for quickly delivering new applications is increasingly becoming a business imperative today. However, application development is often done in an ad hoc manner resulting in poor reuse of software assets and longer time-to-delivery. Web services have received much interest due to their potential in facilitating seamless business-to-business or enterprise application integration. A web service composition system can help automate the process, from specifying business process functionalities, to developing executable workflows that capture non-functional (e.g. Quality of Service (QoS)) requirements, to deploying them on a runtime infrastructure. Intuitively, web services can be viewed as software components and the process of web service composition similar to software synthesis. In addition, service composition needs to address the build-time and runtime issues of the integrated application, thereby making it a more challenging and practical problem than software synthesis. However, current solutions based on business web services (using WSDL, BPEL, SOAP, etc.) or semantic web services (using ontologies, goal-directed reasoning, etc.) are both piecemeal and insufficient. We formulate the web service composition problem and describe the first integrated system for composing web services end to end, i.e., from specification to deployment. The proposed solution is based on a novel two-staged composition approach that addresses the information modeling aspects of web services, provides support for contextual information while composing services, employs efficient decoupling of functional and non-functional requirements, and leads to improved scalability and failure handling. We also present Synthy, a prototype of the service composition system, and demonstrate its effectiveness with the help of an application scenario from the telecom domain.

Understanding approaches for web service composition and execution

Web services have received much interest due to their potential in facilitating seamless business-to-business or enterprise application integration. Of particular interest is the Web Service Composition and Execution (WSCE) process - the creation of a workflow that realizes the functionality of a new service and its subsequent deployment and execution on a runtime environment. A significant number of solutions have been proposed in the literature for composition and execution of web services. However, in order to choose a suitable technique for an application scenario, one needs to systematically analyze the strengths and weaknesses of each of these solutions. To this end, we present an analysis that includes formalization of the WSCE process, a classification of existing solutions into four distinct categories (approaches), and an in-depth evaluation of these approaches. Our evaluation is based on multiple metrics that we deem critical for a WSCE system, e.g. composition effort, composition control, and ability to handle failures. We also present an application of this analysis to three different scenarios.

SEMAPLAN: Combining Planning with Semantic Matching to Achieve Web Service Composition

In this paper, we present a novel algorithm to compose Web services in the presence of semantic ambiguity by combining semantic matching and AI planning algorithms. Specifically, we use cues from domain-independent and domain-specific ontologies to compute an overall semantic similarity score between ambiguous terms. This semantic similarity score is used by AI planning algorithms to guide the searching process when composing services. Experimental results indicate that planning with semantic matching produces better results than planning or semantic matching alone. The solution is suitable for semi-automated composition tools or directory browsers

Planning the project management way: Efficient planning by effective integration of causal and resource reasoning in RealPlan

In most real-world reasoning problems, planning and scheduling phases are loosely coupled. For example, in project planning, the user comes up with a task list and schedules it with a scheduling tool like Microsoft Project. One can view automated planning in a similar way in which there is an action selection phase where actions are selected and ordered to reach the desired goals, and a resource allocation phase where enough resources are assigned to ensure the successful execution of the chosen actions. On the other hand, most existing automated planners studied in Artificial Intelligence do not exploit this loose-coupling and perform both action selection and resource assignment employing the same algorithm. The current work shows that the above strategy severely curtails the scale-up potential of existing state of the art planners which can be overcome by leveraging the loose coupling. Specifically, a novel planning framework called RealPlan is developed in which resource allocation is de-coupled from planning and is handled in a separate scheduling phase. The scheduling problem with discrete resources is represented as a Constraint Satisfaction Problem (CSP) problem, and the planner and scheduler interact either in a master-slave manner or in a peer-peer relationship. In the former, the scheduler simply tries to assign resources to the abstract causal plan passed to it by the planner and returns success. In the latter, a more sophisticated i°multi-module dependency directed backtrackingi± approach is used where the failure explanation in the scheduler is translated back to the planner and serves as a nogood to direct planner search. RealPlan not only preserves both the correctness as well as the quality (measured in length) of the plan but also improves efficiency. Moreover, the failure-driven learning of constraints can serve as an elegant and effective approach for integrating planning and scheduling systems. Beyond the context of planner efficiency, the current work can be viewed as an important step towards merging planning with real-world problem solving where plan failure during execution can be resolved by undertaking only necessary resource re-allocation and not complete re-planning.

Adaptation inWeb Service Composition and Execution

Web services simplify enterprise application integration by facilitating reuse of existing components for creating new services. In a dynamic environment, it is imperative to design a Web service composition and execution (WSCE) system that adapts to failure of component services or changes in their QoS offerings. In this paper, we motivate a staged approach for adaptive WSCE (A-WSCE) that cleanly separates the functional and non-functional requirements of a new service, and enables different environmental changes to be absorbed at different stages of composition and execution. We use Synthy, a prototype service creation environment, to implement our solution and demonstrate its effectiveness

Information extraction from biomedical literature: methodology, evaluation and an application

Journals and conference proceedings represent the dominant mechanisms of reporting new biomedical results. The unstructured nature of such publications makes it difficult to utilize data mining or automated knowledge discovery techniques. Annotation (or markup) of these unstructured documents represents the first step in making these documents machine analyzable. In this paper we first present a system called BioAnnotator for identifying and annotating biological terms in documents. BioAnnotator uses domain based dictionary look-up for recognizing known terms and a rule engine for discovering new terms. The combination and dictionary look-up and rules result in good performance (87% precision and 94% recall on the GENIA 1.1 corpus for extracting general biological terms based on an approximate matching criterion). To demonstrate the subsequent mining and knowledge discovery activities that are made feasible by BioAnnotator, we also present a system called MedSummarizer that uses the extracted terms to identify the common concepts in a given group of genes.

Generating diverse plans to handle unknown and partially known user preferences

Current work in planning with preferences assumes that user preferences are completely specified, and aims to search for a single solution plan to satisfy these. In many real world planning scenarios, however, the user may provide no knowledge or at best partial knowledge of her preferences with respect to a desired plan. In such situations, rather than presenting a single plan as the solution, the planner must instead provide a set of plans containing one or more plans that are similar to the one that the user really prefers. In this paper, we first propose the usage of different measures to capture the quality of such plan sets. These are domain-independent distance measures based on plan elements (such as actions, states, or causal links) if no knowledge of the user preferences is given, or the Integrated Convex Preference (ICP) measure in case incomplete knowledge of such preferences is provided. We then investigate various heuristic approaches to generate sets of plans in accordance with these measures, and present empirical results that demonstrate the promise of our methods.

Scaling up Planning by Teasing out Resource Scheduling

Planning consists of an action selection phase where actions are selected and ordered to reach the desired goals, and a resource allocation phase where enough resources are assigned to ensure the successful execution of the chosen actions. In most real-world problems, these two phases are loosely coupled. Most existing planners do not exploit this loose-coupling, and perform both action selection and resource assignment employing the same algorithm. We shall show that this strategy severely curtails the scale-up potential of existing planners, including such recent ones as Graphplan and Blackbox. In response, we propose a novel planning framework in which resource allocation is teased apart from planning, and is handled in a separate “scheduling” phase. We ignore resource constraints during planning and produce an abstract plan that can correctly achieve the goals but for the resource constraints. Next, based on the actual resource availability, the abstract plan will be allocated resources to produce an executable plan. Our approach not only preserves both the correctness as well as the quality (measured in length) of the plan but also improves efficiency. We describe a prototype implementation of our approach on top of Graphplan and show impressive empirical results.

An Integrated Development Environment for Web Service Composition

Web services provide an instantiation of the loosely coupled service-oriented architecture and facilitate the process of enterprise application integration by encapsulating information, software, and other resources. However, to exploit the true potential of web services, it is critical to develop technologies and tools for composing new services from existing ones. While numerous composition approaches have been developed in the past, very little has been done towards tooling. What is clearly lacking is an Integrated Development Environment (IDE) to ease the process of composition, thereby reducing development time and integration efforts. In this paper, we build on our previous work on service composition, and present an IDE for end-to-end composition of web services. We elaborate on the design of the IDE, describe its integration with existing technologies, and discuss its usability based on the findings of a user survey.