Architectures of Web applications : design and implementation of database backed information systems

Abstract

Information processing is the key issue of the 20th Century. While databases are designed to store information and the World Wide Web has turned out to be the place for the gathering and distribution of information, there are inherent difficulties in linking them together. A new design methodology is presented to implement complex functionality and to integrate legacy systems. The finite state machine model well known from static hypertext documents is remodeled to be suitable for dynamically generated hypertext. The key idea is to use an object-based client-server model to design the user interface layout, the middleware functionality and the database transactions in a homogenous way. A Web based toolset has been implemented to automatically generate the different applications from a design language. For searching a database backed Web application universal relations and natural language interfaces known from database theory are combined with keyword searches known from the Web to define a metadata model. Generic interfaces for both Intelligent Software Agents and robots from search engines have been implemented. Evaluation of the proposed methods has been carried out with two real-life applications implemented successfully with both pure HTML and Java investigating different client-server tradeoffs and persistence frameworks: For less than 200-300 user interactions pure HTML typically outperforms Java in terms of network traffic. The techniques described in this thesis will help to make the design of database backed Web applications faster, easier and less error prone.