Abstract
The Internet has become a prominent platform for the deployment of computer applications. Web-browsers are an important interface for e-mail, on-line shopping, and banking applications. Despite this popularity, the development of web applications is a difficult job through their complex client-server structure. Web applications use client-side processing to speed up their performance. This is often realized by using an interpreter at the browser side. This complicates the development of web applications even more. The programmer has to develop code for both server and client and these parts should co-operate closely to obtain the desired result.
Functional programming languages like Haskell and Clean are a promising development platform for web applications. They support higher order functions that enable a high level of compositional programming where irrelevant details can be hidden for the developer. They support generic programming techniques for automatic generation and handling of web forms, interaction with data sources and server-client communication. An important example of this approach is the iTask system. iTask is a declarative domain specific language embedded in Clean, enabling the creation of dynamic workflow applications. iTask workflows consist of a combination of tasks to be performed by humans and/or automated processes. From iTask specifications complete web-based workflow applications are generated. iTask is built on a single, powerful, concept: the task. iTask uses combinators to combine tasks into new tasks. With combinators tasks can be executed sequentially or in parallel using or- and- or ad-hoc parallelism. The main object of study in this thesis is the extension of iTask with client-side processing while maintaining the declarative nature of the system and the generation of the application from one Clean source. For this a dedicated client-side Clean platform is developed in combination with a mechanism to move processing from server to client.
This thesis also contains an initial study of applications of iTask in the domains of Military and Crisis-Management Operations.
