Exception handling is a programming language feature that can help increase the reliability of programs. However, not much work has been done on exception handling in visual programming languages. We present an approach for improving the exception handling mechanism in Forms/3, a declarative visual programming language based on the spreadsheet paradigm. We show how this approach can be added without sacrificing referential transparency and lazy evaluation in Forms/3. We then present a comparison of the Forms/3 exception handling mechanism with the mechanisms available in Java, C++, Prograph, Haskell and Microsoft Excel, based on their expressive powers. / Graduation date: 1998

Visual programming languages employ visual representation to make programming easier and make programs more reliable and more accessible. Visual program testing becomes increasingly important as more and more visual programming languages and visual programming environments come into real use. In this work, we focus on one important class of visual programming languages: form-based visual programming languages. This class of languages includes electronic spreadsheets and a variety of research systems that have had a substantial impact on end-user computing. Research shows that form-based visual programs often contain faults, but that their creators often have unwarranted confidence in the reliability of their programs. Despite this evidence, we find no discussion in the research literature of techniques for testing or assessing the reliability of form-based visual programs. This lack will hinder the real use of visual programming languages. Our work addresses the lack of testing methodologies for form-based visual programs. In this document, we first examine differences between the form-based and imperative programming paradigms, discuss effects these differences have on methodologies for testing form-based programs, and analyze challenges and opportunities for form-based program testing. We then present several criteria for measuring test adequacy for form-based programs, and illustrate their application. We show that an analogue to the traditional "all-uses" dataflow test adequacy criterion is well suited for testing form-based visual programs: it provides important error-detection ability, and can be applied more easily to form-based programs than to imperative programs. Finally, we present a testing methodology that we have developed for form-based visual programs. To accommodate the evaluation model used with these programs, and the interactive process by which they are created, our methodology is validation-driven and incremental. To accommodate the user base of these languages, we provide an interface to the methodology that does not require an understanding of testing theory. We discuss our implementation of this methodology, its time costs, the mapping from our approach to the user interface, and empirical results achieved in its use. / Graduation date: 1998

Declarative visual programming languages (VPLs), including spreadsheets, make up a large portion of both research and commercial VPLs. Spreadsheets in particular enjoy a wide audience, including end users. Unfortunately, spreadsheets and most other declarative VPLs still suffer from some of the problems that have been solved in other languages, such as ad-hoc (cut-and-paste) reuse of code which has been remedied in object-oriented languages, for example, through the code-reuse mechanism of inheritance. We believe spreadsheets and other declarative VPLs can benefit from the addition of an inheritance-like mechanism for fine-grained code reuse. This dissertation first examines the opportunities for supporting reuse inherent in declarative VPLs, and then introduces similarity inheritance and describes a prototype of this model in the research spreadsheet language Forms/3. Similarity inheritance is very flexible, allowing multiple granularities of code sharing and even mutual inheritance; it includes explicit representations of inherited code and all sharing relationships, and it subsumes the current spreadsheet mechanisms for formula propagation, providing a gradual migration from simple formula reuse to more sophisticated uses of inheritance among objects. Since the inheritance model separates inheritance from types, we investigate what notion of types is appropriate to support reuse of functions on different types (operation polymorphism). Because it is important to us that immediate feedback, which is characteristic of many VPLs, be preserved, including feedback with respect to type errors, we introduce a model of types suitable for static type inference in the presence of operation polymorphism with similarity inheritance. / Graduation date: 1999

Until now, attempts to extend the one-way constraint evaluation model of the spreadsheet paradigm to support complex objects, such as colored circles or user-defined types, have led to approaches featuring either a direct way of creating objects graphically or strong compatibility with the spreadsheet paradigm, but not both. This inability to conveniently go beyond numbers and strings without straying outside the spreadsheet paradigm has been a limiting factor in the applicability of spreadsheets. In this thesis we present a technique that removes this limitation, allowing complex objects to be programmed directly--and in a manner that fits seamlessly within the spreadsheet paradigm--using direct manipulation and gestures. We also present the results of an empirical study which suggests that programmers can use this technique to program complex objects faster and with fewer errors. The graphical definitions technique not only expands the applicability of spreadsheet languages, it also adds to their support for exploratory programming and to their scalability. / Graduation date: 1997

Scientists in the biological sciences need to retrieve information from a variety of data collections, traditionally maintained in SQL databases, in order to conduct research. Because current assistant tools are designed primarily for business and financial users, scientists have been forced to use the notoriously difficult command-line SQL interface, supplied as standard by most database vendors. The goal of our research has been to establish the requirements of scientific researchers and develop specialized query assistance tools to help them query data collections across the Internet. This thesis describes our work in developing HyperSQL, a Web-to-database scripting language, and most importantly, Query Designer, a user-oriented tool for designing query interfaces directly on Web browsers. Current browsers (i.e., Netscape, Internet Explorer) do not easily interoperate with databases without extensive "CGI" (Common Gateway Interface) programming. HyperSQL is a scripting language that enables database administrators to construct forms-based query interfaces intended for end-users who are not proficient with SQL. Query results are formatted as hypertext-clickable links which can be used to browse the database for related information, bring up Web pages, or access remote search engines. HyperSQL query interfaces are independent of the database computer, making it possible to construct different interfaces targeting distinct groups of users. Capitalizing on our experience with HyperSQL, we developed Query Designer, a user-oriented tool for building query interfaces directly on Web browsers. No experience in SQL and HTML programming is necessary. After choosing a target database, the user can build a personalized query interface by making menu selections and filling out forms--the tool automatically establishes network connections, and composes HTML and SQL code. The automatically generated query form can be used immediately to issue a query, customized, or saved for later use. Results returned from the database are dynamically formatted into hypertext for navigating related information in the database. / Graduation date: 1997

Thesis (M.Sc.)--York University, 2007. Graduate Programme in Computer Science. / Typescript. Includes bibliographical references (leaves 120-123). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:MR29315

Thesis (Ph. D.)--Worcester Polytechnic Institute. / Keywords: Meta modeling; schema change; frameworks; integration; schema heterogeniety; schema modeling. Includes bibliographical references (p. 381-395).

Thesis (Ph. D.)--Worcester Polytechnic Institute. / Keywords: Replacement strategy; Query rewriting; Query containment; Semantic caching; Query; XML. Includes bibliographical references (p. 210-222).

Thesis (M.S. in Computer Science)--Washington State University. / Includes bibliographical references.

Thesis (M.Phil.)--Hong Kong University of Science and Technology, 2003. / Includes bibliographical references (leaves 40-43). Also available in electronic version. Access restricted to campus users.