An overview of the CORBA portable object adapter

Abstract

An Object Adapter is an integral part of the Common Object Request Broker Architecture (CORBA). An Object Adapter as- sists an Object Request Broker (ORB) in delivering client re- quests to server object implementations (servants). Services provided by an Object Adapter include: (1) generating and interpreting object references, (2) activating and deactivating servants, (3) demultiplexing requests to map object references onto their corresponding servants, and (4) collaborating with automatically-generated IDL skeletons to invoke operations on servants. This paper provides two contributions to the study of Ob- ject Adapters. First, it outlines the CORBA Portable Object Adapter (POA) specification, which is a recent addition to the CORBA standard that greatly simplifies the development of portable and extensible servants and server applications. The design goals, architectural components, and semantics of the POA are explained. Second, the paper describes the de- sign choices made to adapt the POA for the TAO Real-time ORB. Key design issues regarding efficient demultiplexing, up- call and collocation optimizations, ORB and POA concur- rency configurations, POA synchronization, and predictability are covered.