Widget Types

There are two types of widgets:

Absolute Widgets

Absolute widgets usually process and integrate data coming from different source contexts. For example, a complex Human-Machine Interface widget in a process control application shows data coming from different sensors and has buttons or other active components for sending commands to the actuators. Such a widget should be absolute.

Absolute widget bindings cannot include relative references.

Relative Widgets

Relative widgets are designed to process data from a certain context and its children. This is useful when creating a form or a custom interface for representing data coming from one Device or system resource. Relative widgets are usually activated using the Launch Widget action of the context whose data should be processed. For example, in a network management system you may have a relative widget called CPU Load Chart. You could right-click a Mail Server Device in AggreGate Client and select CPU Load Chart from context menu.

Validity Expression

Relative widgets have a so-called validity expression. It helps AggreGate Server determine what contexts the widget can work with. It is written using the built-in Expression Language. When a new widget is created, or the validity expression itself is updated, AggreGate Server evaluates this expression for every context in the system. If the expression evaluates to true, the server considers that the widget "understands" the data of this context and installs a Launch Widget action into it.