View source for OtfDataBinding

{{DISPLAYTITLE:Open Test Framework - Data Binding & Mapping}}[[Category:OTF]]
==Data Binding==
Data binding is the process that establishes a connection between the application UI and business logic. In other words, if an OTX [[Variable]] changes its value, the elements that are bound to the data reflect changes automatically and vice versa. For example, if the user edits the value in a TextBox control, the OTX Variable bound to the TextBox via a [[Core.Parameters|Screen Signature Parameter]] is automatically updated to reflect that change. And if the OTX Variable changes its value the content of the TextBox control will be updated immediately, see picture below.

{{ImageStyleCenter|OtfDataBinding.png|600|Data Binding - Bounds OTX variables to external devices such as GUI, DLLs etc.}}

==Mapping==
Data Binding requires a Mapping between OTX and the external data at Runtime. This mapping is applied to the parameters of the following signatures:
* [[Core.Signatures.ScreenSignatures|OTX Screen Signature]]
* [[Core.Signatures.DeviceSignature|OTX Device Signature]]
Mapping means that an external data, like the Text property of an Label control, is mapped to a Screen Signature [[Core.Parameters|IN-Parameter]]. An the Screen Signature IN-Parameter is bound to an OTX [[Variable]] of type [[String]].

The main advantage of mapping is the clear separation between business logic and external data. And it is very easy to adjust in the OTF:

# Bind Variables to Signature Parameters
# Map the Signature Parameters to External I/O

{{Important|But there is also one disadvantage: It cannot be evaluated events that are not associated with data, e.g. Button-Click event. In such cases a Variable of type [[Core.DataTypes.SimpleDataType.Boolean|Boolean]] should be bound to the button. Each click will change the value of that variable from False to True to False etc.}}

{{ImageStyleCenter|Mapping.png|800|Mapping - Integration of external data}}