Abstract
This chapter introduces a conceptual model for the design of Web 2.0 applications relying on rich Internet application (RIA) technologies. RIAs extend Web application features by allowing computation to be partitioned between the client and the server and support core Web 2.0 requirements, like real-time collaboration among users, sophisticated presentation and manipulation of multimedia content, and flexible human-machine interaction (synchronous and asynchronous, connected and disconnected). The proposed approach for the design of Web 2.0 applications extends a conceptual platform-independent model conceived for Web 1.0 applications with novel primitives capturing RIA features; the conceptual model can be automatically converted into implementations in all the most popular RIA technologies and frameworks like AJAX, OpenLaszlo, FLEX, AIR, Google Gears, Google Web toolkit, and Silverlight.
TopBackground
The Web and desktop applications are rapidly converging: Web applications keep adding new features overcoming the traditional Web sites capabilities, and desktop applications are quickly becoming Internet-enabled to offer functionalities typical of distributed, collaborative, on-line systems (Brent, 2007). The term Web 2.0 has been used to describe a new class of Web applications strongly centred around a prominent role of the end-users. Web 2.0 applications demand also a novel development paradigm (Farrell, 2007), to overcome the limitations of the traditional HTML interfaces w.r.t. desktop applications both in terms of content presentation and manipulation (HTML was designed for documents, not GUIs, and multimedia support is limited) as well as in terms of interaction (server-side computation implies full page refresh at each user-generated event).
Rich Internet Applications provide the technological core for Web 2.0 development enabling powerful, in terms of content presentation and manipulation, and reactive interfaces for collaborative applications that work seamlessly in a connected and disconnected fashion. In the next sections we illustrate how RIAs achieve improved interactivity, thanks to their flexible architecture, we report a short overview of the main RIA technologies, and describe the state of the art of RIA development methodologies.
Key Terms in this Chapter
Dynamic Modelling: modelling process aiming at the definition of the behaviour of the application.
Data Design: Design process aiming at the definition of the application’s data.
Rich Internet Applications: Web applications that have the features and functionality of traditional desktop applications, offering online and offline capabilities, sophisticated user interfaces, the possibility to store and process data directly on the client-side, and high levels of user interaction
Web Architecture: Organization of a Web system defined in terms of structure, behaviour, communication, and composition of its components
Client-server: Computing architecture separating a client from a server, typically implemented over a computer network. A client is a software or process that may initiate a communication session, while a server can not initiate sessions, but is waiting for a request from a client
Web Engineering: Discipline studying the approaches, methodologies, tools, techniques, and guidelines for the design, development, evolution, and evaluation of Web applications
Model Driven Development: Software development approach based on the systematic use of models as the key artifacts throughout the engineering lifecycle, from system specification and analysis, to design and testing