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 assists an Object Request Broker (ORB) in delivering client requests 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 Object 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 design choices made to adapt the POA for the TAO Real-time ORB. Key design issues regarding efficient demultiplexing, upcall and collocation optimizations, ORB and POA concurrency configurations, POA synchronization, and predictability are covered.