5.5 Constraints

The Constraints tab in the Service Editor makes it possible to include, exclude, or select elements from the GUI. Such as defined fields, conditions, modifiers, and operations. The constraints defined here are only applied to the objects in the GUI, and are not applied to the traffic cases handled by the engine. Figure 34 shows an example of the constraints tab.

Field constraints override the Show in plugins property in the data field definition, see Table 24 for more details on this function.

Figure 34 Constraints Tab in Service Editor

The Constraints tab has two further tabs, Fields and Plug-ins. Selecting either of these tabs allows constraints to be added, edited or deleted. The dialog which opens to allow editing of the constraint is different in both cases. The parameters in the dialog depend on what is chosen in the Plugin to constrain field. Figure 35 is an example of a plug-in constraint dialog.

Figure 35 An Example of a Constraints Dialog

Table 39 Properties in a Constraints Dialog
Property	Description
Plugin to constrain	The name of the plug-in (condition, modifier or node) to constrain. All conditions or all modifiers may also be chosen.
What to constrain	This parameter allows the definition of which property of the plug-in is to be constrained. It is dynamic, depending on the plug-in type, and may include: Condition Feature Field Operation Selection of how to constrain the selected property is also dynamic and may include: Include - Target to include according to the selected plug-in. Exclude - Target to exclude according to the selected plug-in. Select - Target to select as a default condition. Select is only available for the `FieldSelection` condition, when `Condition when a field is selected` is chosen in What to constrain. The target to constrain may be any available field, operation, or feature, for the selected plug-in.
Applies when	It is a condition to fulfill the constraint, in conjunction with a specific field, or field and operation. The parameter is dynamic and may include: Fields is Operation is This property is only available for modifier constraints, when either of the following is selected in What to constrain. `Field when a field is selected` `Operation when a field is selected` `Field when a field and an operation are selected` The data type of the selected field affects the choices available in the drop-down menus.
Resulting constraint	The configured constraint described in words.

Highlighting a constrained target in the list under the constraints tab gives a summary of all the constraints which have been defined for that target. In the example in Figure 34, the MultiFieldOperation modifier has two constraints defined. This list is ordered so that the most specific constraints are always at the bottom. This makes it possible to define more general constraints for many targets, and even more specific constraints for some targets.