Elvin
Encyclopedia
Elvin is a distributed event routing service using a publish/subscribe event delivery model. It was originally developed at the Distributed Systems Technology Centre, an Australian Co-operative Research Centre based at the University of Queensland
which operated from 1992 until mid 2006.
This expression selects messages that have a field named Department with a string value matching "IT" and a Percent-Disk-Free field with an integer value less than or equal to 10. The Elvin subscription language supports a range of operations for matching numeric and string values, including the use of regular expression matching
.
Elvin is oriented around providing a fast, flexible event service that can be federated to form wide-area event notification networks. In order to achieve these goals it does not provide persistence, durability
or guaranteed delivery. Elvin can thought of as providing a middle ground between low-level network multicast
and higher-level, more complex, event brokers such as JMS
.
Commercialization
In 2003, the research group that created Elvin left DSTC to found Mantara software in order to develop commercial applications of Elvin. In November 2006, Mantara announced that it would be ceasing to support Elvin as a standalone commercial product by the end of 2007.
The specifications for the Elvin protocols have been made available at the elvin.org site, and a new implementation of Elvin has subsequently been developed, Avis, an open source (GPL) implementation.
Publications
See also
University of Queensland
The University of Queensland, also known as UQ, is a public university located in state of Queensland, Australia. Founded in 1909, it is the oldest and largest university in Queensland and the fifth oldest in the nation...
which operated from 1992 until mid 2006.
The Elvin Publish/Subscribe Model
Elvin is most distinguished from other such systems by its support of a sophisticated content-based subscription system. Elvin clients subscribe to events using a language that resembles C boolean expressions. For example:
Department "IT" && Percent-Disk-Free <= 10
This expression selects messages that have a field named Department with a string value matching "IT" and a Percent-Disk-Free field with an integer value less than or equal to 10. The Elvin subscription language supports a range of operations for matching numeric and string values, including the use of regular expression matching
Regular expression
In computing, a regular expression provides a concise and flexible means for "matching" strings of text, such as particular characters, words, or patterns of characters. Abbreviations for "regular expression" include "regex" and "regexp"...
.
Elvin is oriented around providing a fast, flexible event service that can be federated to form wide-area event notification networks. In order to achieve these goals it does not provide persistence, durability
Durability (computer science)
In database systems, durability is the ACID property which guarantees that transactions that have committed will survive permanently.For example, if a flight booking reports that a seat has successfully been booked, then the seat will remain booked even if the system crashes.Durability can be...
or guaranteed delivery. Elvin can thought of as providing a middle ground between low-level network multicast
Multicast
In computer networking, multicast is the delivery of a message or information to a group of destination computers simultaneously in a single transmission from the source creating copies automatically in other network elements, such as routers, only when the topology of the network requires...
and higher-level, more complex, event brokers such as JMS
Java Message Service
The Java Message Service API is a Java Message Oriented Middleware API for sending messages between two or more clients. JMS is a part of the Java Platform, Enterprise Edition, and is defined by a specification developed under the Java Community Process as JSR 914...
.
Commercialization
In 2003, the research group that created Elvin left DSTC to found Mantara software in order to develop commercial applications of Elvin. In November 2006, Mantara announced that it would be ceasing to support Elvin as a standalone commercial product by the end of 2007.
The specifications for the Elvin protocols have been made available at the elvin.org site, and a new implementation of Elvin has subsequently been developed, Avis, an open source (GPL) implementation.
Publications
- Elvin has left the building: A publish/subscribe notification service with quenching, 1997, Bill Segall and David Arnold, Proceedings AUUG97, Brisbane Australia, September 1997.
- Content Based Routing with Elvin4, 2000, Bill Segall, David Arnold, Julian Boot, Michael Henderson and Ted Phelps Proceedings AUUG2k, Canberra, Australia, June 2000.
See also
- Publish/subscribe systems
- The elvin.org web site.