JeeWiz Architect's Guide - 'Screen' Reference


	The Model-Driven System Builder

JeeWiz Architect's Guide

Contents

Chapter 15. 'Screen' Reference

The screen model defines screen navigation and mapping of information from screens, through intermediate processing objects attachment to entities (for persistent storage or transfer to other systems).

The screen model's top-level object is an application. Within this, there are various 'pages', which represent the screens the user sees.

Pages have three major aspects:

their visible appearance, which is generated by ASPX pages in .NET and JSP pages in J2EE
the processing behind the pages ( code-behind classes in .NET, action/form classes in Struts), which will in turn interact with back-end systems
the intermediate 'data-view' objects, to hold information that is to be represented on the screens and for communication with the back-end processing objects (session beans and entities).

The standard templates for the screen model produces .NET ASPX/Code-behind pages, or J2EE's Struts and JSP. The screen model has some simplifications when compared to these architectures arising from

excess complexity in Struts (at least, for the vast majority of applications)
facilitating the autogeneration of the connection between the three major aspects of the page mentioned above.

Key simplifications:

the information behind the screen (the page's data-view) is the same data that gets passed to the back-end session objects
there is less variability in the mapping between the page and the actions that it takes

These simplifications have important consequences:

there is less to learn
there is less to specify
smart end-to-end generation becomes possible. For example, changes in information in an entity can ripple all the way through to the front-end screen.