Based on the verification-driven learning (VDL) model, we have proposed a methodology for turning real-world software systems into platforms for CS students to carry out active and in-depth studies in software development. The purpose of the VDL model is to enrich the context of software engineering education. VDL cases can be a supplement to other teaching approaches to software engineering.

We have proposed a verification-driven learning model that facilitates students' involvement in real-world computing tasks starting from their early computing courses and continuing throughout their entire computing studies. The initial purpose of the verification-driven learning model is to enrich the context of lessons, courses, and the CS programs, especially in the early stage of students' learning. Verification-driven learning cases can serve to supplement other teaching approaches such as process-oriented learning model. Students' independent practice of verification will encourage them to consider the real-world applications throughout the simulation.

This paper reports a framework that makes it possible to carry out safe regression test selection for verification of Web services in an end-to-end manner. The Safe RTS technique has been integrated into a systematic method that monitors distributed code modifications and automates the RTS and RT processes. In doing so, a number of issues due to concurrent changes are recognized and solved.

Web applications and Web services have to undergo rapid modifications, and these modifications must be supported by rapid verification. While regression testing (RT) is a major component of most major testing systems, the related techniques have only just begun to be applied to Web services. One of the more important techniques, Regression test selection (RTS) aims to reduce the cost of performing RT. This paper reports a control flow graph-based approach that makes it possible to apply a safe RTS technique to Web services in an end-to-end manner. Safe RTS techniques ensure that no modification revealing tests will be left unselected. A simplified purchase order system that involves in three Web services is used to illustrate the use of our approach.

Regression testing (RT), testing software with previously used test cases, is a mainstream practice in software maintenance. Regression test selection (RTS) is to reduce the number of tests which need to be retested. Safe RTS techniques add the assurance that no modification-revealing test case will be left unselected. Several effective safe RTS techniques were developed for traditional applications, but none of them can be directly applied to Web services, even though there have been RT tools and techniques for Web services test-case generation, and ranking competing services. We have developed an approach to adapt Rothermel and Harrold's safe RTS technique to Web services. This approach was designed to be automated. In doing so, we have recognized a set of challenging issues that arise as a result of multiple concurrent modifications in distributed, autonomous, but still interconnected services. We believe not only these issues are common to any automated RTS approach, the needs for the solutions to these issues will also become more and more keen as composite Web services are getting more and more ubiquitous.

This paper reports a safe regression test selection (RTS) approach that is designed for verifying Web services in an end-to-end manner. The Safe RTS technique has been integrated into a systematic method that monitors distributed code modifications and automates the RTS and RT processes.

In this paper, we will focus on providing a solution to using the message exchange pattern, single-request/multiple-response (SRMR) in the context of Web services and secured enterprise environments. SRMR messaging is important because it can be used to model real world problems elegantly. However, SRMR messaging is not directly supported by Web services, and is hampered by current in-practice security schemes, such as firewalls and proxy servers. We have proposed a client-side framework to utilize SRMR Web services with the realities of network security in mind. The central component of our framework is a Web service clearinghouse, which serves as both a communication proxy and a message manager that realizes the correlation between clients' calls and the services' responses. Using our framework and the code generation utilities, we have implemented a number of nontrivial systems that use SRMR Web services.

In this paper, we report on a client-side framework that allows applications to consume Web services that adhere to the callback pattern in the context of network security schemes. This framework supports extensions of the callback pattern such as the one-request-multiple-response pattern, also allows the applications to consume the callback results in a flexible way.

Web services have been opening a wide avenue for software integration. We have reported our experiments with three applications that are built by utilizing and providing Web services for geographic information systems (GIS). The services are designed to handle a large number of concurrent requests. It is clear that performance has to be the central consideration in design of GIS Web services. The lessons learned from these experiments include the application of the rich metadata message approach, choosing large size of unstructured data but limiting the structured message's sizes, and minimizing COTS software customization.

In this paper, we report an architectural design that integrates a large-scale PeopleSoft human resource system into the J2EE framework by using the vendor's messaging mechanism. A unique situation of this project is that the COTS part and the J2EE components are designed at the same time. The designers have to make more choices than those in the cases of wrapping legacy systems. In addition to performance and scalability, we have paid attention to the manageability of COTS product upgrading. In doing so, we have recommended five integration design strategies, among which the application-level data replication strategy is very effective.

Much research on spatial data retrieval has been accumulated in the past two decades. However, the research of Internet distribution of GIS contents is still in its infancy. This paper describes a systematic approach to optimize Internet distribution of GIS vector maps. The goal is to reduce user-perceived response time and improve viewers' navigation efficiency. At the center of this approach is a hierarchical content management model. Each multiple-layer vector map is divided into partitions, or blocks, of a predetermined size to build a hierarchy. This size is chosen so that most compressed blocks can be downloaded reasonably quickly at typical connection speeds. A front-end cache and a novel application-level locality-based pre-fetching method are devised. Experiments with a Java prototype have shown smooth panning and fast zooming when large map data sets are accessed.

Fault tolerance is important for both sequential and distributed software, and particularly so for long-running applications. The ability to stop an application and restart it, with minimal lost work, is especially useful. If components of the application can be restarted on arbitrary hosts, so much the better. In this paper, we explore Java's potential to support fault tolerant software design. We note that while there are "deficiencies" in these facilities, a little creativity can still yield solutions that would be quite difficult in other programming environments. The main contributions of the paper are several preliminary fault tolerant programming design patterns, aimed at easing the burden of application programmers who must write completely portable fault tolerant applications. This class of applications is growing, as Internet-domain software becomes increasingly prevalent. We expect that with further development the proposed patterns will be applicable to a wide range of sequential and parallel applications.

We report an effort to lift the conceptual level of Java programming for communications in control systems to the level of CODARTS interfaces. Having implemented every component of the communication interfaces defined by CODARTS, we have constructed a Java class library that facilitates a direct mapping from CODARTS design diagram to Java program components. This will not only simplify the programming but also improve the quality of software.

As part of our continuing research on using Petri nets to support automated analysis of Ada tasking behavior, we have investigated the application of Petri net reduction for deadlock analysis. Although reachability analysis is an important method to detect deadlocks, it is in general inefficient or even intractable. Net reduction can aid the analysis by reducing the size of the net while preserving relevant properties. We introduce a number of reduction rules and show how they can be applied to Ada nets, which are automatically generated Petri net models of Ada tasking. We define a reduction process and a method by which a useful description of a detected deadlock state can be obtained from the reduced net's information. A reduction tool and experimental results from applying the reduction process are discussed.

The IS-A relationship (the class-subclass relationship) is one of the most fundamental and important properties in an object-oriented (OO) language and OO database management system (OODBMS). Due to the popularity and domination of relational database management systems (RDBMSs) and the fundamental importance of inheritance, supporting IS-A relationships in a RDBMS becomes very desired, and is essential to adapt a RDBMS to more advanced applications. The authors present an extended SQL system called ESQL which facilitates IS-A relation hierarchies in a RDBMS. The proposed ESQL uses constraints to resolve data redundancy and updating abnormality problems that exist in current OO languages such as C++ and Smalltalk, and OODBMS such as GemStone, PostGres, O/sub 2/, Iris, and Orion. Features such as inheritance constraints, subrelation assertions, mappings, and automatic tuple placement into its most specific subrelation are distinct in ESQL. These features are missing in current RDBMSs, OODBMSs and OO languages.>

Basing on the algebraic representation of Petri net models of Ada tasking programs, the authors have defined a set of linear programming problems to support the static analysis of various queries about tasking behavior, such as queries about deadlock existence, possible parallelism, possible occurrence of an event, reachable states, definite occurrence of events, and quantitative questions. The linear programming problems are defined in such a way that their solutions can be used to guide net simulation to confirm the analysis conclusion. The stress of this method is that the enumeration of the entire state space of a Petri net is avoided. The defined problems are valid as long as the underlying net model is a safe net.>

The application of Petri net reduction to Ada-tasking deadlock detection is investigated. Net reduction can ease reachability analysis by reducing the size of the net while preserving relevant properties. By combining Petri net theory and knowledge of Ada-tasking semantics some specific efficient reduction rules are derived for Petri net models of Ada-tasking. A method by which a useful description of a detected deadlock state can be easily obtained from the reduced net's information is suggested.>

The use of Petri nets for defining a general static analysis framework for Ada tasking is advocated. The framework has evolved into a collection of tools that have proven to be a very valuable platform for experimental research. The design and implementation of tools that make up the tasking-oriented toolkit for the Ada language (TOTAL) are defined and discussed. Modeling and query/analysis methods and tools are discussed. Example Ada tasking programs are used to demonstrate the utility of each tool individually as well as the way the tools integrate. TOTAL is divided into two major subsystems, the front-end translator subsystem (FETS) and the back-end information display subsystem (BIDS). Three component tools that make up FETS are defined. Examples demonstrate the way these tools integrate in order to perform the translation of Ada source to Petri-net format. The BIDS subsystem and, in particular, the use of tools and techniques to support user-directed, but transparent, searches of Ada-net reachability graphs are discussed.>