Object Interconnections An Overview of the OMG

This is the final column in our series covering the OMG CORBA Messaging specification [1]. Our previous columns in this series covered the communications models supplied by Messaging [2], explained how to program asynchronous method invocations (AMI) in C++ [3], and described timeindependent invocation (TII) and interoperable routing [4]. We finish this series by highlighting the quality of service (QoS) framework supplied by the OMG Messaging specification. Quality of service (QoS) is a widely accepted term that describes activities and technologies designed to improve and control communication-oriented resource management for applications and systems [5]. Many distributed applications need to selectively configure and optimize various QoS aspects, such as the end-to-end latency of particular requests, the aggregate throughput over some interval, the reliability of one-way message delivery, or how long a client spends waiting for a reply before it times out. Therefore, the OMG Messaging specification defines a QoS framework that allows applications to configure and control various aspects of ORB behavior. This framework defines a set of policy objects, a framework for managing the policies, and extensions to GIOP/IIOP that communicate policies between ORBs.