Core language for web applications

Trabalho apresentado no âmbito do Mestrado em Engenharia Informática, como requisito parcial para obtenção do grau de Mestre em Engenharia Informática

Web applications have a very high demand for rapid development and constant change. Several languages were created for this kind of applications, which are very flexible but many times trade the benefits of strongly-typed programming languages by untyped interpreted languages. With this kind of languages the interaction between different layers in a web application is usually developed using dialects and programming conventions with no real mechanical verifications between the client and server sides, and the SQL code within the application and the database. We present a typed core language for web applications that integrates the typing of the interface definition, business logic, and database manipulation representing these interactions at a high abstract level. Using only one language, typed and with its own instructions to define the interface and the interaction with the database, becomes possible to make static checks. Thereby, avoiding execution errors caused by the usual heterogeneity among web applications. We also describe the implementation of a prototype with a highly flexible programming environment for our language that allows the application development and publishing tasks to be done through a web interface, interacting directly with the application and without loosing the integrity checks. This kind of development relies on an agile development methodology. Therefore, the modifications made to the application are made active using the dynamic reconfiguration mechanism, avoiding the recompilation of the application and system restart.