What's WEI?

WEI is an architectural framework for organizing the models that address the different concerns of Web applications. Each WEI model focuses on one particular concern (navigation, presentation, architectural style, distribution) and at different levels of abstraction (platform-independent, platform-specific).

WEI is also supported by a development methodology for building Web applications, which conforms to the MDA principles, in the sense that it is defined in terms of models and the relationships between them, so transformations can be easily formalized amongst the models until the final implementation is reached.

Problems addressed

Current model-driven Web Engineering approaches provide excellent methodologies and tools for the design and development of Web applications. They address different concerns using separate models (content, structure, layout, business logic, etc.), and use model compilers that produce most of the logic and Web pages of the application from these models. However, as the complexity of Web applications grows (to be able to deliver, e.g., large e-commerce, e-learning, or e-government applications), and new requirements are imposed on Web systems, most of these proposals are showing some limitations:

• They are usually tied to particular architectural styles and technologies, i.e., do not allow the parameterizable construction of Web applications using different platform technologies and architectural styles
• They deal with a fixed set of common concerns (navigation, presentation, etc.). Therefore they are very good at modelling certain aspects, but very weak at modelling others. In addition, they are difficult to extend to model further aspects (such as internal processes, distribution, and some other extra-functional concerns) in a natural, modular and independent way.
• Web applications currently need to interoperate with other external systems. Not all MDWE proposals address this issue at the model level; the integration is mostly achieved at the implementation level.

In this sense, the MDA initiative provides a new approach for organizing the design of an application into separate models so that portability, interoperability and reusability can be achieved through architectural separation of concerns.

WEI goals.

Far from being “yet another Web methodology”, the aims of WEI can be summarized as follow:

• to be able to represent, in terms of models and relationships between them, the concerns required for designing and developing Web applications—following an architectural separation of concerns as prescribed by MDA
• to integrate and harmonize the models and practices proposed by existing approaches, addressing their concerns
• to be extensible so new concerns could be easily added;
• to provide as a common framework (and metamodel) in which current proposals could be integrated and formulated in terms of the MDA principles, hence allowing them to smoothly interoperate (by defining, e.g., interoperability bridges between compatible models coming from different proposals, whenever this is possible) and complement each other, share tools, etc.