Kyung-Goo Doh

Composing programming languages by combining action-semantics modules

This article demonstrates a method for composing a programming language by combining action-semantics modules. Each module is defined separately, and then a programming-language module is defined by combining existing modules. This method enables the language designer to gradually develop a language by defining, selecting and combining suitable modules. The resulting modular structure is substantially different from that previously employed in action-semantic descriptions.It also discusses how to resolve the conflicts that may arise when combining modules, and indicates some advantages that action semantics has over other approaches in this respect.

The service modeling process based on use case refactoring

Service-Oriented Architecture (SOA) is an architecture for a system or application that is built using services that implement business functionality with proper granularity. If the granularity of a service is finer, the flexibility and reusability of the service is lower. Therefore, it is critically important to identify what pieces of functionality will become services and to define the interfaces of those services. In this paper, we define a process to identify services by use case refactoring. Task trees are defined to restructure use cases, and five refactoring rules are introduced along with a running example. Because this modeling process can choose the correct levels of abstraction and granularity, it can be helpful in identifying coarse-grained services.

Abstract Parsing: Static Analysis of Dynamically Generated String Output Using LR-Parsing Technology

We combine LR(k)-parsing technology and data-flow analysis to analyze, in advance of execution, the documents generated dynamically by a program. Based on the document languages context-free reference grammar and the programs control structure, the analysis predicts how the documents will be generated and parses the predicted documents. Our strategy remembers context-free structure by computing abstract LR-parse stacks . The technique is implemented in Objective Caml and has statically validated a suite of PHP programs that dynamically generate HTML documents.

A practical string analyzer by the widening approach

The static determination of approximated values of string expressions has many potential applications. For instance, approximated string values may be used to check the validity and security of generated strings, as well as to collect the useful string properties. Previous string analysis efforts have been focused primarily on the maxmization of the precision of regular approximations of strings. These methods have not been completely satisfactory due to the difficulties in dealing with heap variables and context sensitivity. In this paper, we present an abstract-interpretation-based solution that employs a heuristic widening method. The presented solution is implemented and compared to JSA. In most cases, our solution gives results as precise as those produced by previous methods, and it makes the additional contribution of easily dealing with heap variables and context sensitivity in a very natural way. We anticipate the employment of our method in practical applications.

Composing Programming Languages by Combining Action-Semantics Modules

Abstract This article demonstrates a method for composing a programming language by combining action-semantics modules. Each module is defined separately, and then a new module is defined by either extending or combining existing modules. This method enables the language designer to gradually develop a language by selecting, extending and combining suitable language modules. The resulting modular structure is substantially different from that previously employed in action-semantic descriptions. We also discuss how to resolve the conflicts that may arise when combining modules, and indicate some advantages that action semantics has over other approaches in this respect.

Adaptable Web Services Modeling Using Variability Analysis

Web services have recently come into focus as they are able to make software systems flexible, reusable, and cost-effective. In distributed Web services environments, Web services should be very adaptable because the potential number of services can be extremely large and target consumers and service providers have to face various circumstances. To promote the adaptability of services, the variability on Web services should prudently be considered and modeled. In this paper, we present a method for modeling highly adaptable Web services by analyzing the variability with respect to architectural and behavioral features. We define modeling aspects of Web services to extract the variability and variation points. We focus on the modeling of variability of Web services from variation points of structural features and behavioral features. In this work, we try to describe how adaptable Web services are developed with a suitable description of the variability as a technique for customizing systems based on Web services.

A Trust Type Based Model for Managing QoS in Web Services Composition

Given the distributed, heterogeneous nature of Web services, the availability and reliability of Web services is uncertain. Moreover, service providers may have varying levels of quality. A way to understand and manage the quality attributes is needed. In this paper, we present an approach for the dynamic composition of Web services with quality of services (QoS) attributes. We adopt a concept of mediator to select credible services for service requestors. In our model, mediators evaluate services and assign trust ratings. A mediator includes a multi-dimensional quality model based on a set of non-functional properties that are transversal to all Web services, for example, their cost and reliability. In particular, we use the trust type inference rule to rate the trustworthy for selecting services optimally. Based on the QoS model, we present dynamic service selection approach to select and aggregate services to satisfy users QoS requirements. This approach can be used to prune services that would be composed and thus avoid service composition execution plans that would be unacceptable to service requestors.

Formal Identification of Right-Grained Services for Service-Oriented Modeling

Identifying the right-grained services is important to lead the successful service orientation because it has a direct impact on two major goals: the composability of loosely-coupled services, and the reusability of individual services in different contexts. Although the concept of service orientation has been intensively debated in recent years, a unified methodic approach for identifying services has not yet been reached. In this paper, we suggest a formal approach to identify services at the right level of granularity from the business process model. Our approach uses the concept of graph clustering and provides a systematical approach by defining the cost metric as a measure of the interaction costs. To effectively extract service information from the business model, we take activities as the smallest units in service identification and cluster activities with high interaction cost into a task through hierarchical clustering algorithm, so as to reduce the coupling of remote tasks and to increase local task cohesion.

Generic Information System Using SMS Gateway

In the last few years, SMS (Short Message Service)has made a big impact on the way we communicate. Instead of communicating over the phone using voice, people rather prefer SMS not only for messaging but also for information exchange. This paper proposes a method of building an extendable generic application which can be used to provide various types of information services using mobile SMS. Mobile users send required information through an SMS to a mobile gateway that forwards it to the generic application. Given the user-provided information, the generic application automatically generates an appropriate query.

Trust Type Based Semantic Web Services Assessment and Selection

As multiple service providers make themselves available on-line, the trustworthiness of services becomes significant. In Web services environments, services from different providers might have to be combined to establish a complete service. Although the individual service can be trusted, the composed service is not guaranteed against trust. Thus there must be a way to determine the composed service is trusted. This paper presents a trust type model to deduce the trust level of composed services. Then, we present a conceptual framework which enables trust based service discovery and selection. Using the inferred trust type of the composed service as the weight, we can evaluate service candidates and select the best match of them. Finally we describe the experiment results to validate our QoS based service selection.