Handler classifier overview

The capabilities of the Handler classifier are made available when you code a handler. The type defines a series of interactions with the user or with other EGL logic, as necessary to support one or another user interface technology. Different kinds of handlers have different structure and use.

The next table lists the stereotypes that are available for a Handler type.

Stereotype Purpose
none specified To provide an object that might include both fields and functions.
You can used the handler to build an EGL text report, which is a character-based output that you can develop quickly. In this case, an EGL program or other logic might act as follows:
  • Declare a variable based on the handler.
  • Use the variable to invoke a set of functions, one after the next, so as to structure the report and to embed business data into it.
BIRTHandler To customize a Business Intelligence and Reporting Tools (BIRT) report, which is a graphically sophisticated output whose structure is based on a pre-specified design file. For details on BIRT, see http://www.eclipse.org/birt.
An EGL program or other logic might act as follows:
  • Declare a handler; that is, a variable that is based on the Handler type.
  • Use EGL syntax to create a BIRT report engine (a Java™ object) and to provide to that engine a reference to the design file and to the handler.
  • Place business data into the handler, for inclusion in the report.
  • Invoke one of the engine's report-creation methods.
RUIHandler To provide client-side web applications.

In brief, the handler places EGL and Dojo widgets on a web page and responds to events such as a user's button click. The technology supports data validation, access of remote services, and quick update of sections on the web page.

A Rich UI handler is not necessarily the basis of a variable. However, if one handler creates a variable that is based on a second, the first handler can display the widgets and access the functions, widgets, and other fields that were declared in the second.

RUIWidget To define a new widget for use by other EGL Rich UI developers.