Bindings

Bindings are so named because with them you can tightly bind some data in Iotellect to other data. They comprise the part of the Iotellect core that establishes dependencies between platform elements, such as context entities or UI components, causing function execution, event firing, or variable changes in response to certain conditions or events.

If you are familiar with spreadsheets, then you already know the concept: if you reference a cell in a formula, as soon as you change the referenced cell, the one with the formula is recalculated. That's the analog of bindings in Iotellect.

For example, you can have a textbox in a dialog, which is grayed out. You can't write anything in it. This textbox can have a checkbox next to it saying something like "Enable this setting?". Once the checkbox is checked, the textbox magically becomes white (enabled) and you can write in it. This is done via data bindings, where the value of the checkbox (Enabled or Disabled) is bound to the state of the textbox (Enabled or Disabled). Iotellect data bindings let you do such nice interface tricks using dashboards; this is just one example of their power.

Every binding consists of two mandatory parts:

  • Target is a reference to where the result of the expression will be written once the binding is processed. Depending on the processing environment, reference may refer to a Data Table cell, property of user interface component, etc.

  • Expression defines the value to be written to the binding target when the binding is processed.

If you're not sure what a reference or an expression is, you really should check out relevant sections. Without a thorough understanding of references and expressions, bindings won't make much sense.

Most other bindings, such as model and dashboard bindings, also use the Activator and Condition properties as well as various Flags.

The binding mechanism is widely used throughout Iotellect for different purposes. For example:

  • Model bindings connect entities of a model with other system resources.

  • Bindings in dashboards connect their visual components with the server's data model, defining their lifecycle.

  • Data Table bindings are part of the Data Table format. They define how cells in different columns of one row are related. E.g. fieldC = fieldA + fieldB

  • Class instance bindings allow a field or fields of one or more class instances to be modified.

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