4005-730 -- Distributed Systems

Alan Kaminsky

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Department of Computer Science

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Rochester Institute of Technology

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4486 + 2220 = 6706

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Distributed Systems

4005-730-01

Spring Quarter 2013

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4005-730 Distributed Systems
Java Message Service Example

Prof. Alan Kaminsky
Rochester Institute of Technology -- Department of Computer Science

Acknowledgment
Documentation
JMS Concepts
Message Queue Example
Publish-Subscribe Example

Acknowledgment

These Java Message Service (JMS) examples are based on the example programs in the Apache ActiveMQ distribution.

Documentation

Java 2 Enterprise Edition 6 (J2EE 6) Javadoc: http://docs.oracle.com/javaee/6/api/index.html
- JMS is in package javax.jms
ActiveMQ: http://activemq.apache.org/
ActiveMQ Javadoc: http://activemq.apache.org/maven/5.8.0/apidocs/index.html

JMS Concepts

Message broker: The server for a MOM system
Connection: Used to communicate with a message broker
Connection factory: An object that creates connections for a particular message broker
Session: A series of messaging operations
- The operations can be grouped into a transaction, or not
- Messages can be automatically acknowledged by the system, or manually acknowledged by the receiver
Queue: For sending and receiving messages (MQ paradigm)
Topic: For publishing and subscribing messages (pub-sub paradigm)
Producer: Thing that sends a message to a queue (MQ) or publishes a message to a topic (pub-sub)
Consumer: Thing that receives a message from a queue (MQ) or subscribes to receive messages from a topic (pub-sub)
Message: An actual message; various types of content supported:
- BytesMessage: A stream of uninterpreted bytes
- MapMessage: A set of (name, value) pairs; names are type String, values are Java primitive types, Strings, or byte arrays
- ObjectMessage: A serializable object
- StreamMessage: A stream of Java primitive types, Strings, or byte arrays
- TextMessage: A String

Message Queue Example

Class Sender (download)
Class Receiver (download)
Class EmbeddedBroker (download)
Demonstration -- Each in a separate window, run:
1. $ java EmbeddedBroker
2. $ java Receiver
3. $ java Sender

Publish-Subscribe Example

Class Publisher (download)
Class Subscriber (download)
Class EmbeddedBroker (download)
Demonstration -- Each in a separate window, run:
1. $ java EmbeddedBroker
2. $ java Subscriber
3. $ java Publisher