13.6.1 What Information Do Bridges Need?

   The following potential information about object references has been identified as critical for use in bridging technologies:

• Is it null? Nulls only need to be transmitted and never support operation invocation.

• What type is it? Many ORBs require knowledge of an object’s type in order to efficiently preserve the integrity of their type systems.

• What protocols are supported? Some ORBs support objrefs that in effect live in multiple referencing domains, to allow clients the choice of the most efficient communications facilities available.

• What ORB Services are available? As noted in Section 13.2.3, “Selection of ORB Services? on page 13-4, several different ORB Services might be involved in an invocation. Providing information about those services in a standardized way could in many cases reduce or eliminate negotiation overhead in selecting them.