8.1 Overview of Global Types

An administrative VOB stores definitions of global types and makes them available to all client VOBs that link to the administrative VOB. You can use global types to increase the scope of a type object from a single VOB to a group of VOBs. For example, you can have all VOBs in your local area network use the same set of type objects by linking them to the same administrative VOB. You can create any number of global type objects in one or more administrative VOBs.

A client VOB uses global types from an administrative VOB as follows:

1. A developer attempts to create an instance of a type, but there is no type object in the client VOB. For example, a developer wants to create a v3_bugfix branch in a particular element, but branch type v3_bugfix does not exist in the client VOB.

2. Rational ClearCase LT determines which administrative VOB is associated with the client VOB by scanning for an AdminVOB hyperlink in the client VOB.

3. If it finds a global type (branch type v3_bugfix in this example) in the administrative VOB, ClearCase LT creates a copy of the type object in the client VOB. This capability is called auto-make-type.

4. ClearCase LT uses the local copy of the type object to create the instance that the developer wants. (In this case, it creates the v3_bugfix branch for the desired element in the client VOB.)

A local copy is linked to the global type object by a GlobalDefinition hyperlink. Operations performed on a global type affect all its local copies. Similarly, operations performed on a local copy affect the global type, and by extension, all other local copies.