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Constraining Application and Application Hosting Relationships

A constraint is a requirement that a configuration value be set in a certain way. Constraints can be created in one layer against settings in another layer. For example, constraints can be set from the application layer against settings on the application hosting layer and vice versa. The application layer is modeled in Application Designer. The application hosting layer is modeled in Logical Datacenter Designer. For further information, see Overview of the System Definition Model (SDM). However, constraints can also be created in the same layer. For example, in Logical Datacenter Designer, zone constraints can be authored against the logical servers the zones contain as well as the applications hosted on that logical servers within the zones. For more information, see Walkthrough: Creating a Security Zone Part 1.

The fact that constraints can operate on either the application or the application hosting layer means that infrastructure architects can specify constraints against the application layer and that developers can request a required set of features in the target deployment environment, thus communicating back to the infrastructure architect important requirements of the application. The architect can then decide whether they want to make changes to the logical datacenter to accommodate those requests.

The following types of constraints are provided:

  • Implicit constraints.

  • Pre-defined constraints.

  • User-defined constraints.

Implicit Constraints

Implicit constraints are those that are associated with a particular logical server or application prototype available in the Toolbox. This topic provides a list of implicit constraints for the prototypes that ship with Distributed System Designers.

Pre-defined Constraints

This topic discusses the group of constraint dialog boxes that are provided for different logical server prototypes.

User Defined Constraints

Discusses how to define your own constraint based on the settings available for configuring constraints.