Alex Lau

An Empirical Study on Web Service Evolution

The service-oriented architecture paradigm prescribes the development of systems through the composition of services, i.e., network-accessible components, specified by (and invoked through) their WSDL interface descriptions. Systems thus developed need to be aware of changes in, and evolve with, their constituent services. Therefore, accurate recognition of changes in the WSDL specification of a service is an essential functionality in the context of the software lifecycle of service-oriented systems. In this work, we present the results of an empirical study on WSDL evolution analysis. In the first part, we empirically study whether VTracker, our algorithm for XML differencing, can precisely recognize changes in WSDL documents by applying it to the task of comparing 18 versions of the Amazon EC2 web service. Second, we analyze the changes that occurred between the subsequent versions of various web-services and discuss their potential effects on the maintainability of service systems relying on them.

Migration of SOAP-based services to RESTful services

Web services are designed to provide rich functionality for organizations and support interoperable interactions over a network. Web services are mainly realized in two ways: 1) SOAP-based services and 2) RESTful services. For the service providers, RESTful services can improve system flexibility, scalability, and performance as compared to the SOAP-based Web services. It is equally attractive to end users as it is consume less resources (i.e., battery, processor speed, and memory). Additionally, REST-based services do not include complex standards and heterogeneous operations; and hence are easier to consume and compose as compared to SOAP-based Web services. We provide an approach to migrate SOAP-based services to RESTful services. We identify resources from a SOAP-based Web service by analyzing its service description and mapping the contained operations to resources and HTTP methods. To demonstrate the effectiveness of our approach, we conduct a case study on a set of publicly available SOAP-based Web services. The results of our case study show that our approach can achieve high accuracy of identifying RESTful services from the interfaces of SOAP-based services. Our approach can improve the performance for invoking Web services after SOAP-based services are migrated to RESTful services.

An Automatic Approach for Extracting Process Knowledge from the Web

Process knowledge, such as tasks involved in a process and the control flow and data flow among tasks, is critical for designing business processes. Such process knowledge enables service composition which integrates different services to implement business processes. In the current state of practice, business processes are primarily designed by experienced business analysts who have extensive process knowledge. It is challenging for novice business analysts and non-professional end-users to identify a complete set of services to orchestrate a well-defined business process due to the lack of process knowledge. In this paper, we propose an approach to extract process knowledge from existing commercial applications on the Web. Our approach uses a Web search engine to find websites containing process knowledge on the Internet. By analyzing the content and the structure of relevant websites, we extract the process knowledge from various websites and merge the process knowledge to generate an integrated ontology with rich process knowledge. We conduct a case study to compare our approach with a tool that extracts ontologies from textual sources. The result of the case study shows that our approach can extract process knowledge from online applications with higher precision and recall comparing to the ontology learning tool.

Business process adaptation on a tracked simulation model

Business processes need to adapt to changes in the operating conditions and to meet the service-level agreements (SLAs) with a minimum of resources. Changes in operating conditions include hardware and software failures, load variation and variations in user interaction with the system. An integral component to adaptation is the awareness over the behavior of self and environment (or having an estimation of the current situation). Aiming at estimation, this paper investigates the automatic building of a dynamic predictive model of the business process that is used for business process optimization. The model is a simulation model whose parameters are tuned at run time by tracking the system with a particle filter.

A concept analysis approach for guiding users in service discovery

Web services are widely used as basic constructs to build complex distributed applications with fast speed and low cost. However, existing service discovery techniques provide users with poor results which require substantial human intervention to filter the services to locate the desired ones. In particular, users often have no prior knowledge of the functional description of the available services on the Web. The queries formulated by the users may not match well with the service descriptions of existing services. As a consequence, a users query can result in a large number of returned services. In this paper, we propose an approach that derives the semantic concepts conveyed in the service descriptions and clusters the services based on the concepts. As a result, each concept is associated with a set of relevant services. To understand the semantic meanings of a users query, we identify concepts behind the query and recommend related concepts associated with services. Our approach also guides users to formulate their queries. We conducted a case study and found that the average precision and recall of our approach for service discovery are respectively, 83% and 100%. We also performed a user study which shows that for 85% of time, a user reformulates their queries using the suggestion provided by our approach to improve the precision of the retrieved services.

Effective collaboration and consistency management in business process modeling

There is an ever-increasing demand on modern companies to adapt quickly to fast changes in their environment, such as new opportunities and threats. Agility is the most valuable thing a company should have as a flexible organization -- the flexibility to meet new market demands and to seize opportunities before they are lost. Business Process Modeling (BPM) is a promising approach to enable agility in business process adaptation, by exposing business processes to relevant stakeholders at the right level of abstraction and giving them a medium to express and implement change.

Dynamic context-aware applications: approaches and challenges

The continuous evolution from goods-centric to service-centric businesses requires new and innovative approaches for building, running, managing and evolving business applications. The complexity of these modern, decentralized and distributed computing systems presents significant challenges for businesses. End-users increasingly demand that businesses provide smart software systems that are flexible, resilient, location-based, service-oriented, decentralized, energy-efficient, customizable, self-healing and self-optimizing. A system with such dynamic properties must be capable of adjusting its behavior at run-time in response to its perception of its environment and its own state in the form of fully or semi-automatic self-adaptation.

The 2nd Workshop on Practical Ontologies

The 2nd Workshop on Practical Ontologies affiliated with CASCON 2010, aimed to bring together researchers and practitioners with interests and experience in knowledge representation, to discuss different approaches and trends in the research to make ontology infrastructures more practical, adaptable and applicable to highly distributed and dynamic knowledge contribution and management.