Caching Technologies for Web Applications

The emergence of the Web has transformed the execution environment of transactional, server-side applications. Three- and four-tier application environments involving browser-based clients and Web/application/database servers are the norm these days. The generation and distribution of dynamic Web pages has also increased dramatically. Attaining good end-to-end performance under these circumstances requires the use of caching technologies. Caching is being deployed at different stages in the software and hardware hierarchies. In this presentation, I will provide an introduction to different in-use and emerging caching technologies. In addition, I will discuss the tradeoffs involved with different caching granularities and cache deployment points. I will also give a brief introduction to the DBCache project at IBM Almaden in which DB2 is being extended with caching functionality.

Keynote Speaker II

Prof. John Mylopoulos, University of Toronto, Canada

John Mylopoulos is the Bell Laboratories chair in Information Systems in the Department of Computer Science of the University of Toronto. He received his PhD degree from Princeton University in 1970, and joined the faculty of the University of Toronto the same year. His research interests include semantic data models, requirements engineering, and knowledge management. He is the recipient of the first Outstanding Services Award given by the Canadian AI Society (CSCSI), a co-recipient of the most influential paper award of the 1994 International Conference on Software Engineering, a fellow of the American Association for AI (AAAI) and a past president of the VLDB Endowment. He is co-editor-in-chief of the Requirements Engineering Journal, published by Springer-Verlag, and has served on the editorial board of the VLDB Journal, ACM Transactions on Software Engineering (TOSEM), ACM Transactions on Information Systems (TOIS), ACM Computing Surveys, and the Data Semantic Journal. He has also contributed to the organization of major international conferences, including program co-chair of the International Joint Conference of AI (1991), program chair of the International IEEE Symposium of Requirements Engineering (1997), and general chair of the Very Large Databases Conference (2004.) Professor Mylopoulos has published more than 200 refereed publications and eight edited books.

Keynote: Data Semantics Revisited: Databases and the Semantic Web
Abstract:

Data in a data source are useful because they model some part of the real world, its subject matter (or application, or domain of discourse). The problem of data semantics is establishing and maintaining the correspondence between a data source, hereafter a model, and its intended subject matter. The model may be a database storing data about employees in a company, a database schema describing parts, projects and suppliers, a website presenting information about a university, or a plain text file describing the battle of Waterloo. The problem has been with us since the development of the first databases. However, the problem remained under control as long as the operational environment of a database remained closed and relatively stable. In such a setting, the meaning of the data was factored out from the database proper, and entrusted to the small group of regular users and/or application programs.

The advent of the web has changed all that. Databases today are made available, in some form, on the web where users, application programs and uses are open-ended and ever changing. In such a setting, the semantics of the data has to be made available along with the data. For human users, this is done through an appropriate choice of presentation format. For application programs, however, this semantics has to be provided in a formal and (hence) processable form. Hence the call for the Semantic Web.

We critically review some of the concepts and technologies under development, intended to meet the Semantic Web challenge. We then propose a formal framework for assigning meaning to data through composite mappings from a model to its intended subject matter. Our proposal adopts a formal semantics framework proposed in [Smith87], and postulates that every model must come with a meaning defined in terms of a mapping to another model. This recursive definition of semantics terminates with a mapping to a formal model of a class of applications. To illustrate the scope and potential benefits of our proposal, we focus on database schemas (both conceptual and logical) and present an example involving several schemas and the mappings among them.

This is a speculative talk. The research that will flesh out the details and actual benefits of this framework are ahead of us. The seminar is based on joint work with Alex Borgida and Yuan An.