Joan Peckham

Semantic data models

Semantic data models have emerged from a requirement for more expressive conceptual data models. Current generation data models lack direct support for relationships, data abstraction, inheritance, constraints, unstructured objects, and the dynamic properties of an application. Although the need for data models with richer semantics is widely recognized, no single approach has won general acceptance. This paper describes the generic properties of semantic data models and presents a representative selection of models that have been proposed since the mid-1970s. In addition to explaining the features of the individual models, guidelines are offered for the comparison of models. The paper concludes with a discussion of future directions in the area of conceptual data modeling.

Broadening participation in computing: issues and challenges

In this paper we survey the literature to identify the issues and challenges of broadening participation in computer science, and provide some suggestions to address these challenges. Our attention focuses on redefining the way we approach computing education so that we can successfully entice students to computing that have not traditionally participated, thereby promoting diversity and increasing the total numbers of computing professionals. Based on the literature review, we propose an interactional model from the social sciences to inform the way in which we might restructure and broaden the definition of computing and provide some examples of strategies that we have found to be successful in practice.

RTSORAC: A Real-Time Object-Oriented Database Model

A real-time database is a database in which both the data and the operations upon the data may have timing constraints. We have integrated real-time, object-oriented, semantic and active database approaches to develop a formal model called RTSORAC for real-time databases. This paper describes the components of the RTSORAC model including objects, relationships, constraints, updates, and transactions.

The protein fluorescence and structural toolkit: Database and programs for the analysis of protein fluorescence and structural data.

Protein fluorescence is a powerful tool for studying protein structure and dynamics if we have a means to interpret the spectral data in terms of protein structural properties. Our previous research successfully provided this support through the development of individual software modules implementing the algorithms for fluorescence and structural analyses. Now we have integrated the developed software modules, introduced a new program for the assignment of tryptophan residues to spectral‐structural classes, and created a web‐based toolkit PFAST: protein fluorescence and structural toolkit: http://pfast.phys.uri.edu/. PFAST contains three modules: (1) FCAT is a fluorescence‐correlation analysis tool, which decomposes protein fluorescence spectra to reveal the spectral components of individual tryptophan residues or groups of tryptophan residues located close to each other, and assigns spectral components to one of five previously established spectral‐structural classes. (2) SCAT is a structural‐correlation analysis tool for the calculation of the structural parameters of the environment of tryptophan residues from the atomic structures of the proteins from the Protein Data Bank (PDB), and for the assignment of tryptophan residues to one of five spectral‐structural classes. (3) The last module is a PFAST database that contains protein fluorescence and structural data obtained from results of the FCAT and SCAT analyses. Proteins 2008.

The present and future of computational thinking

1. Summary Intellectual constructs and tools that are widely used to solve the problems of society have been woven into educational programs. For example, the three R’s (reading, ‘riting & ‘rithmetic) are core to a strong fundamental education, and practitioners and researchers routinely apply these tools to their daily work. Computing has become an essential and pervasive problemsolving toolset. This development has fostered much discussion about the role of computing in a modern education, the broadening nature of computing majors and concentrations and their place in post-secondary institutions, for example, [6,7]. Computer science educators recognize the importance of improving information technology (IT) skills and fluency, and a number of studies have developed guidelines on how to do this [3,4]. However, computer science has analytical concepts and tools that offer educational benefits beyond simple IT fluency.

The design of real-time extensions to the Open Object Oriented Database system

The paper describes real time extensions to the Open Object Oriented Database system using the RTSORAC data model. This model combines an object oriented data model, real time requirements, flexible transactions, semantic relationships among objects, and active database features. Several extensions to the Open Object Oriented Database system, including development of interfaces for real time objects and real time transactions, use of a real time operating system, incorporation of real time object management, and incorporation of real time transaction management, are also described.

Data model for extensible support of explicit relationships in design databases

We describe the conceptual model of SORAC, a data modeling system developed at the University of Rhode Island. SORAC supports both semantic objects and relationships, and provides a tool for modeling databases needed for complex design domains. SORACs set of built-in semantic relationships permits the schema designer to specify enforcement rules that maintain constraints on the object and relationship types. SORAC then automatically generates C++ code to maintain the specified enforcement rules, producing a schema that is compatible with Ontos. This facilitates the task of the schema designer, who no longer has to ensure that all methods on object classes correctly maintain necessary constraints. In addition, explicit specification of enforcement rules permits automated analysis of enforcement propagations. We compare the interpretations of relationships within the semantic and object-oriented models as an introduction to the mixed model that SORAC supports. Next, the set of built-in SORAC relationship types is presented in terms of the enforcement rules permitted on each relationship type. We then use the modeling requirements of an architectural design support system, called Arch Objects, to demonstrate the capabilities of SORAC. The implementation of the current SORAC prototype is also briefly discussed.

Implementing Relationships and Constraints in an Object-Oriented Database Using a Monitor Construct

Semantic models have shown the utility of arbitrary user-defined relationships for defining the semantics of database information, while object-oriented models have developed a strong paradigm for the expression of individual database entities. The SORAC project merges the strengths of these two models by extending the object-oriented model through the addition of active semantic relationships. These active relationships express and enforce the constraints imposed on an object by the participation of the object in some group of related objects. The SORAC system is supported by the data definition language OIL (Object Interaction Language), which automatically maps schema specifications to a database implementation supported by the ONTOS Object Database Management System. By providing an automatic mapping from the semantic data model to the object-oriented database, the SORAC system provides a consistent semantic and structural view of the data.

Extending the behavioral capabilities of the object-oriented paradigm with an active model of propagation

Object-oriented design techniques have begun to play a critical role in increasing productivity, assuring correctness, and modeling both the structure and behavior of applications. However, while most object-oriented models support intra-class behavior definition through encapsulation, inter-class relationships and behavior are supported in only a limited sense, i.e., within ISA or inheritance hierarchies. This is a serious draw-back when attempting to model advanced applications such as software-development environments (SDEs) and CAD/CAM. In order to model these critical inter-class relationships and behavior, our goal is to incorporate propagation actions into an object-oriented data model at the design-phase level. This results in increased accuracy in the modeling of information, more complete specification of system behavior, elimination of some side effects, and decreased application coding errors. To meet this goal, this paper presents the active model of propagation (AMP) which supports the specification of inter-class relationships during the design phase to permit system enforced propagation.

Multiple Perspectives of Design Objects

The process of large scale design decomposes into a number of specialized tasks, each requiring its own representation of the design. It is important to maintain consistency among the different representations of a design. In this paper, we describe an approach to the creation of specialized representations that addresses the problems of incorporating behavior and relationships while maintaining consistency among different representations. We call a specialized representation a perspective, which is defined as a partition of the global schema that supports some functionally-oriented task. Each perspective corresponds to some stage in the design process. In this project, we are concentrating on how multiple representations of a design may be formed, how they relate to one another in terms of structure and behavior, and how they relate to the entire design process. We are building a prototype of a system which supports the creation and maintenance of perspectives. This system will consist of a perspective definition facility that allows a new perspective, including derived classes to be specified and a perspective maintenance facility which keeps the different representations consistent with each other.