Eric J' Bruno

1
Eric J. Bruno

• www.ericbruno.com
• eric_at_ericbruno.com
• Consultant
• Java C
• Architecture and Development

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Java Messaging

• JMS
• JavaBean Events
• Web-services
• Combining JMSand Web-services
• Distributed softwaresystems design
• Messaging framework

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What is Messaging?

• The communication between and within components
  of a software system.
• More than JMS
• Components may be within the same JVM or not
• Take the same approach

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Why is Messaging Important?

• Complexity
• Most software is not standalone
• Monolithic development is mostly history
• Web-based applications
• Mobile applications

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Lots of Java APIs for Communication

• Java IO / NIO
• JavaBeans
• RMI
• JNDI
• JavaMail
• JMS
• JINI / JavaSpaces
• JXTA

• JAX-RPC (JAX-WS)
• JAXM
• SAAJ
• JMS
• MDB
• J2ME
• CORBA

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JavaBean Events

• Source component
• Listener component
• Event interface
• Event object

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JavaBean Event Downside

• JavaBean events cause dependencies
• Synchronous only
• Confined to one JVM
• Not anonymous

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Java Event Agent

• Anonymous events
• Source and Listener completely abstracted
• Demo!

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Java Remote Method Invocation

• Pure Java remote procedure calls
• Across JVMs
• RPCs are transparent

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CORBA

• Object Management Group
• Allows Java / non-Java communication
• Internet Inter-ORB Protocol (IIOP)

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Enterprise MOM (not McNabbs)

• Reliable exchange of data
• Guaranteed delivery
• Transaction support
• Asynchronous and synchronous
• Queue-based
• Reply-based
• Subscription-based

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Message Paradigms

• Request / Reply
• Analogous to browser / Web server communication

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Message Paradigms

• Queue-based (store-and-forward)
• Messages are persisted
• One receiver per message

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Message Paradigms

• Subscription-based
• Multi-cast like
• Publish-and-subscribe
• One-to-many message delivery
• Anonymous

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Combining Message Paradigms

• Quote System Example
• Demo!

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Advanced Messaging (JMS)

• Message filtering
• Durable subscriptions
• Persistence
• Message acknowledgement
• Reliable messaging
• At-most once
• At-least once
• Once-and-only-once
• Transactions
• Message-Driven Beans (MDB)
• Queue theory

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The Messaging Toolkit

• The JMS Façade
• Abstracts the JMS API details, including the
  interfaces and setup
• Quick and easy event listening
• Quick and east event sending
• Code comparison

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The Messaging Toolkit

• The Event Distributor
• Extends JavaBean events across JVMs
• Transparent
• Uses JMS as the transport
• Developers can be JMS-agnostic
• Makes heavy use of Java Reflection

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The Event Distributor

• Event listener implements the new
  EventListenerDist interface, instead of
  EventListener
• package com.toolkit.messagingpublic abstract
  class EventListenerDist private
  EventDistributor eventDistributor
  EventDistributor.getInstance() public
  EventListenerDist() eventDistributor.onNew
  Listener( this )

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The Event Distributor

• Event source implements the new EventSourceDist
  interface
• package com.toolkit.messagingpublic abstract
  class EventSourceDist private
  EventDistributor eventDistributor
  EventDistributor.getInstance() public
  EventSourceDist() eventDistributor.onNewSo
  urce( this ) public abstract String
  getInterfaceNames()

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The Event Distributor

• Uses Reflection to
• Intercept source events
• Send over JMS
• Call the correct listeners

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The Event Distributor

• Demo!

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Java Component Server

• JMS provides a robust message model
• Messages are safe and guaranteed
• What about your code?
• JMS client software still vulnerable to failure
• Something is needed to monitor JMS producer and
  consumer code

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Java Component Server (JCS)

• The JCS hosts producers and consumers
• You can configure multiple servers to distribute
  them across
• If a component fails, the JCS will detect and
  restart that component
• If the entire JCS server fails, another JCS will
  take over
• Enables cluster-like configuration for your JMS
  code

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Java Component Server (JCS)

• Any of number of servers can be clustered and
  configured

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Java Component Server (JCS)

• JCS Server B fails, Server A takes over

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Java Component Server (JCS)

• JCS component development is easy
• Interface-based development
• Supports Queues, Pub/Sub, Request/Response

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Java Component Server (JCS)

• Components are managed told when to start and
  stop message processing
• Uses Reflection to load, start, and stop
  components
• Provides thread management for parallel
  processing across components
• JCS servers use JMS themselves to send and
  receive heartbear messages

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Java Component Server (JCS)

• Provides a web-based administrative front-end
• Demo!

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JMS SOAP Reliability

• Options
• JMS can be used within a web-service
  implementation
• JMS can be used between parts of an SOA-based
  application
• JMS can be tunneled through HTTP
• SOAP messages can transported over JMS

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JMS SOAP Reliability

• JMS works over the Internet

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JMS SOAP Reliability

• An adapter allows SOAP messages to be transported
  over JMS

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JMS SOAP Reliability

• SOAP over JMS, tunneled through HTTP

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JMS SOAP Reliability

• JMSSOAPConnectionFactory class
• The javax.xml.soap classes are extended

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JMS SOAP Reliability

• Source code
• Demo!