In the last decade, the Web 2.0 brought technological changes in the manner of interaction and communication between users and applications, and among applications as well. Rich Internet Applications (RIA) offer user interfaces with a higher level of interactivity, similar to desktop interfaces, embed multimedia contents and minimise the communication between client and server components. Nonetheless, RIAs behave as black boxes that show the information in a user-friendly manner but this information can be only visualised gradually, according to the events triggered by the users on the Web browser, which limits the access of software agents, e.g., Web searchers. In the context of the present Internet, where the value has been moved from the Web applications to the data they manage, the use of open technological solutions is a need. In this way, the Semantic Web was aimed at solving issues of semantic incompatibility among systems by means of standard techniques and technologies (from knowledge representation and sharing to trust and security), which can be the key to solving the issues detected in RIA. Although some solutions exist, they do not cover all the possible types of RIA or they are dependent on the technology chosen for the implementation of the Web application. As a first contribution, this thesis introduces the concept of Semantic Rich Internet Application (SRIA), which can be defined as a RIA that extensively uses Semantic Web technologies to provide a representation of its contents and to reuse existing knowledge sources on the Web. The solution proposed is adapted to the existing RIA types and technologies. The thesis presents the architecture proposed for this type of application, describing its software modules and components. The evaluation of the solution was performed based on a collection of case studies. The development of Web applications, especially in the context of the Semantic Web, is a process traditionally performed manually and, given the complexity of the SRIA applications in this case, it is a process which might be prone to errors. The application of model-driven engineering techniques can reduce the cost of development and maintenance (in terms of time and resources) of the proposed applications, as demonstrated their use in other types of Web applications. Moreover, they can facilitate the adoption of the solution by the community. In the light of these issues, as a second contribution, this thesis presents the Sm4RIA methodology (Semantic Models for RIA) for the development of SRIA, as an extension of the OOH4RIA methodology. The thesis describes the development process, the models (with the corresponding metamodels) and the transformations included in the methodology. The evaluation of the methodology consisted in the development of the case studies proposed. The application of this model-driven methodology can speed up the development of these Web applications and simplify the reuse of external sources of knowledge. Finally, the thesis describes the Sm4RIA extension for OIDE, i.e., an extension of the OIDE CASE tool that implements all the elements of the Sm4RIA methodology.