UMass Lowell Computer Science 91.460 Java and Distributed Computing Prof. Karen Daniels Fall, 2000

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UMass Lowell Computer Science 91.460 Java and
Distributed Computing Prof. Karen Daniels Fall,
2000

• Lecture 3
• HW1
• Jini Overview
• C Diagnostic Results
• Mon. 9/11/00

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Web Page
Web Page
new
http//www.cs.uml.edu/kdaniels/courses/java2000.
html
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Question from Last Lecture...

• What is socket-based communication?
• In a Java context, Deitel answers this on p. 936
  in introduction to Servlets. Java has networking
  support for
• socket-based communications that enable
  applications to view networking as streams of
  data - a program can read from a socket or write
  to a socket as simply as reading or writing to a
  file.
• packet-based communications that enable
  individual packets of information to be
  transmitted - commonly used to transmit audio and
  video over the Internet.
• Chapter 21 of Deitel treats Java networking

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Homework 1
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Homework 1
Assigned Due Content

• Wed, 9/6 Fri, 9/8 Read Ch 1
  (Deitel)
• Fri, 9/8 Mon, 9/11 Read Ch 1, 2
  (Edwards)
• Fri, 9/15 Read Ch 2, 3 (Deitel)
• Fri, 9/15 Assignment 1, Part 1
• short-answer questions
• Mon, 9/18 Assignment 1, Part 2
  Hello World programming
• (application and applet)

Homework is due at the start of lecture on the
due date.
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Introduction to Java Applications

• Java application is executed using the Java
  interpreter (but not inside browser like an
  applet)
• Application begins execution in main()
• main() is static method inside class

javac Welcome1.java java Welcome1
Welcome1.java
// Save this in file Welcome1.java public class
Welcome1 public static void main( String
args ) System.out.println( "Java is
fun!" )
Welcome1.class
Similar application code is on p.36 of Deitel,
Chapter 2
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HW1 HelloWorld Application

• Refer to p. 36 of Deitel, Chapter 2 for their
  Welcome1.java application
• Modify
• System.out.println( ) statement
• Change name of class and file

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Compiling and Running on a PC
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Introduction to Java Applets

• Java applet is executed inside a WWW browser (or
  appletviewer) using a Java interpreter that is
  inside the browser.

javac Welcome1Applet.java appletviewer
Welcome1Applet.html
// Save this file in Welcome1Applet.java import
java.applet. import java.awt. public class
Welcome1Applet extends Applet public void
paint(Graphics g) g.drawString( "Java
is fun!, 25, 50 )
Welcome1Applet.java
Welcome1Applet.class
Welcome1Applet.html
Save this file in Welcome1Applet.html
ltAPPLET codeWelcome1Applet.class width150
height100gt lt/APPLETgt
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HW1 HelloWorld Applet

• Refer to p. 86 and p. 90 of Deitel, Chapter 3 for
  their WelcomeApplet.java applet
• Modify
• .java file
• g.drawString( ) statement
• Change name of class and file
• Extend Applet instead of JApplet unless you want
  to use Swing here. If extending Applet, import
  java.applet.
• .html file
• Change name of class and file

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Compiling and Running on a PC
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Appletviewer on a PC
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Browser on a PC
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Computing Environment

• Java 2 platform Java 2 SDK v. 1.2.1
• http//www.javasoft.com/products/jdk/1.2
• Jini v. 1.1
• http//www.javasoft.com/products/jini
• UML CS UNIX environment
• Optional
• PC environment (code must also run on UNIX)
• Java integrated development environment
• 2 are on disk with Deitel textbook (NetBeans
  caveat)

Make sure you have a UML CS UNIX account
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Jini Overview
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What is Jini?
Jini Is Not Initials
But seriously...
portions of this slide contributed by Ayal Spitz
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Suns Jini Vision

• Initial Sun marketing focused on hardware
• Appliances in a home or office connecting to a
  network
• Jinis goal is to make it possible for all of
  these appliances to seamlessly detect and
  communicate with one another
• Technology can also support software services

portions of this slide contributed by Ayal Spitz
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What is Jini?

• Java-based connection framework developed by Sun
  Microsystems
• Philosophy
• plug n play network
• blur distinction between hardware and software
• self-healing
• Elements discovery, lookup, leasing, remote
  events, transactions, JavaSpaces

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Background on Jini Technology
Assumes Java and network
Consists of Java classes Works at application
level
proxy manages service interaction
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5 Key Concepts

• Discovery find communities on a network and join
  them
• Lookup use Lookup Service(s) to find services
  and use them
• Leasing resource is loaned to some consumer
  for fixed time period
• Remote Events allow services to notify others of
  their state changes
• Transactions protocol to support multiple
  services moving to safe state

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Some Jini Definitions

• Service an entity on the network (e.g. hardware
  device or software module) that can be used by
  other Jini participants
• Community a group of Jini services that are
  aware of each other (typically workgroup size)
• Group used by Jini APIs to specify and represent
  a community
• But, due to network separation, different
  communities may have same group name
• Federation a collection of communities that are
  aware of each other

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Discovery Example Multiple Community
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Requirements for Service, Client

• Participate in discovery to find a Lookup Service
• Communicate with a Lookup Service to receive
  service proxy

To be a Jini Service
To be a Jini Client

• Either you or a delegate must be able to
• Connect to a TCP/IP network ( )
• Participate in discovery to find a Lookup Service
• Register with a Lookup Service to provide proxy
• Keep leases current

Extra machinery needed - http server(s) for
each machine to offer up downloadable code - RMI
activation daemon
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Hello World in a Jini Setting...
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Who Else is in the Game?(other providers of
coordination frameworks/connection
technologies/service architectures for
distributed computing)

• HAVi
• Sony, Sharp, Toshiba, Philips, RCA, Matsushita,
  Hitachi, Grundig
• Microsoft HP
• ChaiAppliance Plug and Play
• eSpeak
• Universal Plug and Play
• Network protocol level
• XML device description
• Salutation Framework

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Further Information Jini

• Sun web sites
• http//www.javasoft.com/jini
• http//www.jini.org
• Development Books
• Core Jini by W. Keith Edwards
• The Jini Specification by Arnold, OSullivan,
  Scheifler, Waldo, and Wollrath
• Gartner Advisory
• Java Jini A Killer-App Enabler for Network
  Computing? http//gartner.jmu.edu/research/ras/830
  00/83044/83044.html

portions of this slide contributed by Ayal Spitz
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C Diagnostic
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C Diagnostic

• Assess C background
• Will not contribute to the course grade
• Answers on the way out of class
• Name is optional
• Provide code snippets, not entire programs
• Leave unknowns blank

Well summarize results of the diagnostic in
lecture.