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Description
Exception Summary | |
RMException | Signals that a reliable-multicast-specific failure has occurred. |
A set of packages enabling application
developers to take advantage of emerging reliable multicast (RM) technologies across any
IP network.
These packages provide for sending data to receivers over IP multicast transport sessions (channels). Receivers can choose the channels they want and filter out those they don't. Administrators can impose access controls on channels, filtering access by user, time of day, or content.
While TRAM, a strong reliable multicast transport protocol, is included the transport sub-package also includes a set of APIs that allows new protocols to be plugged in and used by existing applications with little or no change to the applications.
A channel is a multicast transport session that conveys data from one or more senders to one or more receivers. This is conceptually similar to an IP multicast group, but reliable delivery, security, and other features may be added on. One more component completes the model. Each channel has one or more channel managers that are responsible for creating and destroying the channel, configuring it, and managing channel membership (that is, who can send and receive on it).
These are the basic components in the model: channels, senders, receivers, and channel managers.
The transport system is responsible for providing a reliable multicast transport. It may be used directly by the application or indirectly through the channel management system. The transport system is composed of two parts, a set of protocol-independent transport APIs and one or more transport protocols.
Many different reliable multicast transport protocols have been developed and many more are on the way. Therefore, this package defines a Multicast Transport Application Programmer Interface (MTAPI) that channel managers, senders, and receivers may use to configure transport protocols and send and receive data using them.
The Tree-Based Reliable Transport Protocol (TRAM) is a reliable multicast protocol designed to support bulk data transfer with a single sender and multiple receivers. TRAM uses dynamic trees to implement local error recovery to scale to a very large number of receivers without imposing a serious burden on the sender. It also includes congestion control and other techniques necessary to operate efficiently and fairly with other protocols across the wide variety of link and client characteristics that make up the Internet.
The channel management system is responsible for creating, configuring, and destroying channels upon request. The Channel Management Application Programmer Interface (CMAPI) is used to create, manage, and destroy channels. Here is a description of the process.
First, a channel manager is asked to create the channel. Then the channel is configured to specify the channel name, transport protocol to be used, etc. Finally, the channel is enabled. This allows senders and receivers to use the channel.
To access an existing channel, a sender or receiver must contact a channel manager and query it for a list of accessible channels. Then it may request to subscribe to or publish on one of these channels. If access control permits, the channel manager will send appropriate parameters which the receiver may use to subscribe to that channel.
A channel may be configured with one or more dynamic filters. A dynamic filter is a piece of Java code that runs on a receiver and processes the data in a channel, transforming it in some way. For instance, a dynamic filter can block access to entertainment channels during working hours. It can also highlight stories that match a user's interest profile.
Dynamic filters are delivered to receivers when they register for a channel. Different receivers may receive different filters, based on access control or preferences.
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JavaTM Reliable MulticastTM Service version 1.1
Copyright (c) 2001, Sun Microsystems Laboratories, All rights reserved.