distributed computing and java - · pdf filedistributed computing and java ... what is the...

Distributed Computing and Java™

Sang ShinJava™ Technology Evangelist

[email protected]

2

Topics

Overview of Distributed computing Java APIs for distributed computing

JDBCRMIJava IDL (Corba)Java Servlets and JSPJ2EE™

Jini™ Network Technology and JavaSpaces (We will learn from next week)

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Objectives

Understand the value of distributed computing (network computing)

Get some exposure to the evolution of distributed computing

Understand the 7 fallacies of distributed computing

Get some exposure to distributed computing technologies of Java

Overview ofDistributed Computing (Network Computing)

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Virtual Fish Tank

“Most people grow up with a 'centralized mindset,' assuming that organized patterns can be created only by centralized control. The VFT exhibit helps people move beyond the centralized mindset, giving them a chance to create and participate in an artificial ecosystem -- and learn how patterns can, in fact, arise from decentralized interactions.”- Michael Resnick, MIT Media Lab

Things - 1014

Computers 108

Embedded Computers

1011

Desktops

TransfersTransfers TransactionsTransactions ContentContent Telemetry Telemetry ControlControl

Clients

Functions

Organization

Protocols

Waves of Network Computing

IP v6IP v4 IP Layer

SwitchesSwitches

PackagesPackages

ThermostatsThermostats

ClothesClothesPhonesPhones

TVsTVsCarsCars

GamesGames

Things - 1014

Computers 108

Embedded Computers

1011

Desktops

Client/Server

Web ApplicationsWeb Applications

Web Web ServicesServices

FractalFractal

PolyarchicalPolyarchical

N-tier

FTPTelnet

HTTPXRPC/XDR

SMTP

Clients

Functions

Organization

Protocols

SOAPSOAPRMI/IIOPRMI/IIOP

JiniJiniIdentityIdentity

UDDIUDDI

LDAPLDAP

JXTAJXTA

Waves of Network Computing

IP v6IP v4 IP Layer

PhonePhoness

TVsTVsCarsCars

GamesGames

SwitchesSwitches

PackagesPackages

ThermostatsThermostats

ClothesClothes

TransfersTransfers TransactionsTransactions ContentContent TelemetryTelemetry ControlControl

Platform EvolutionCatchCatchPhrasePhrase

The NetworkThe NetworkIs the Is the

ComputerComputer ObjectsObjectsLegacy to Legacy to the Webthe Web

The Computer The Computer Is theIs the

NetworkNetwork

Network of Network of Embedded Embedded

ThingsThingsNetworkNetworkof Thingsof Things

ScaleScale

When/PeakWhen/Peak

LeafLeafProtocol(s)Protocol(s)

DirectoryDirectory(s)(s)

SessionSession

100s100s 1,000s1,000s 1,000,000s1,000,000s 10,000,000s10,000,000s 100,000,000s100,000,000s 100,000,000100,000,000ss

1984/19871984/1987 1990/19931990/1993 1996/19991996/1999 2001/20032001/2003 1998/20041998/2004 2004/20072004/2007

XX XX +HTTP+HTTP(+JVM)(+JVM)

+XML+XMLPortalPortal +RMI+RMI UnknownUnknown

NS, NS+NS, NS+ +CDS+CDS +LDAP(*)+LDAP(*)+UDDI+UDDI

+ebXML +ebXML reg/repreg/rep

+Jini +Jini Lookup Lookup serviceservice

+?+?

RPC, XDRRPC, XDR +CORBA+CORBA +CORBA,+CORBA,RMIRMI

+SOAP,+SOAP,XMLXML +RMI/Jini+RMI/Jini +?+?

SchematicSchematic

Design Patterns

Client-Server 3-Tier

Web Application

Web Services

HybridP2P Fractal

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Three Laws of Computing Moore's Law

Computing power doubles every 18 months

Gilder's LawNetwork bandwidth capacity doubles

every 12 months Metcalfe's Law (Net Effect)

Value of network increases exponentially as number of participants increases

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Public Internet

Corporate Internet

Firewall

WorkgroupServer

WebServerTelco

Server

Pager

Cell Phone

Thin Client

Thin Client

PDA

NT Workstation

Solaris™

Workstation

Solaris Workstation

VideoServer

Current Enterprise Reality

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What is a distributed system?

A collection of processes/processors that do not share memory or a clock

13

Why Distributed Systems?

Resource sharing Higher performance Flexible Reliable Scalable Cheaper Manage’able (it depends)

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Characteristics of Distributed Systems Complex programming Heterogeneous

Hardware, OS, networking behavior, object model, programming language

Inherent problemsNetwork latencyConcurrency issuesPartial Failure

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7 Fallacies of Distributed Computing The network is reliable Latency is zero Bandwidth is infinite The network is secure Topology doesn't change There is one administrator Transport cost is zero

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Terminology

Naming and TransparencyLocation transparency Location Independence

Stateful vs. Stateless Failure Detection and Recovery

ReplicationLog based Recovery

Parameter Marshaling/Unmarshaling

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Distributed Coordination

Mutual Exclusion Atomicity Concurrency Control Deadlock Handling Election Algorithms Transaction

2 phase commit

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Distributed Systems

Evolution

RPC (procedural)

ORB(object based)

80s

RMI(object oriented)

90s

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Early Distributed Systems

RPCDCE, ONC

Distributed File Systemsexample - NFS, SMB

Databasesexample - Oracle

Transaction Processing Monitorsexample - CICS

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At the root of it all ...

SocketsSocket, ServerSocket, SocketImpl classes

UsesData compressionmulticastcustom protocols, etc.

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What is JDBC?

Java APIs for manipulating relational databases

Uses standardized SQL

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JDBC Architecture

MS SQL

SPISybasedriver

DB2driver

Oracledriver

JDBC Driver Manager

BridgeODBC

Sybase DB2 Oracle

Java application Java application

JDBC API

24

A 2-tier Example

Database

Database

Frontend

Frontend

Frontend

JDBC

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JDBC Status

Core API in JDK 1.1 onwards JDBC 3.0 Core and Extension API

currently available JDBC drivers available for wide-range

relational databases

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JDBC Resources

Java Packagesjava.sqljavax.sql

Websites java.sun.com/products/jdbc

BooksDatabase Programming with JDBC and

Java by George E. Reese, George H. Reese

RMI (Remote Method Invocation)

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What is RMI?

New Distributed system paradigm Natural extension of the OO paradigm Seamless integration of objects (objects

everywhere) Allows method invocation across JVM

boundaries Can pass or receive objects to/from

remote object Code moves with the object (code movement)

Distributed garbage collection Activation

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A 3-tier Example

Database

Database

Frontend

Frontend

Frontend

Business Logic

RMI JDBC

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RPC Architecture (General)

ClientProxy

ServerProxy

Wire

The proxies deal with parameter marshaling/unmarshaling

31

RMI Architecture

JavaClient

Stub

JavaServer

Skeleton

The Stubs/Skeletons deal with Serializing/De-serializing

JRMP

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Class Loading

RMI loads classes if not available locallyRemote object, stub, skeleton, parameter

and return value classes Loaded classes subject to installed

security manager

ClientServer

Lookup

Remote Reference + stub code

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Object Serialization

Used for passing objects by value Write/read objects and graphs of objectsLightweight PersistenceObjects are converted into byte streamsCustomization on a per-class basis is

possible

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RMI Development Process

Four step development Define the interfaces to your remote

objects Implement the remote objects Run rmic on remote implementation

classes Make code network-accessible

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RMI Deployment

rmiregistryProvides a bootstrap service to locate the

first server object Start the server Start the client

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RMI Status

Core since JDK 1.1 New Features in JDK 1.2

Activation Custom socket types API enhancements Performance improvements

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Customer Feedback

Many customers like RMI: Easy to program No need to learn separate IDL Supports full Java programming language

semantics (value objects) Ideal for communication between Java

applications

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Customer Feedback (Cont’d)

Many customers like CORBA: Standardizing on CORBA IDL and IIOP Multi-vendor Cross-language Allows communication between Java

applications and C++ Common input: Why not RMI over

IIOP?

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RMI over IIOP

RMI over IIOP supports a large subset of JDK 1.1 RMI API over CORBA IIOP

Joint work between: IBM, Netscape, Oracle, Sun, Visigenic

With input from many other partners

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RMI over IIOP

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RMI over IIOP (Simplified)

Java ClientORB

AnyServerORBIIOP

The ORBs deal with parameter marhalling/unmarshalling

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RMI over IIOP Features

True subset of RMI over JRMP Uses CORBA objects-by-value

extension Allows genuine interoperability with

C++ and other languages RMI over IIOP combines:

RMI style ease of use plus cross-language interoperability

No Distributed Garbage Collection

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What is Java IDL

Java IDLUses OMG's Java Language Mapping Layered on Internet Inter ORB Protocol

(IIOP) Generates Portable Stubs/Skeletons

44

Java IDL Development

45

Java IDL runtime

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Language Description Pros consSGML Language for

describingdocuments

Completeandextensible

Complex

HTML HyperTextMarkupLanguage

Simple Focus onrendering;Not Extensible

XML eXtensibleMarkupmetaLanguage

Simple,extensible

Need othertechnologiesin conjunction

What Is XML?

eXtensible Markup metaLanguage Universal Data description

mechanism

48

XML and Java Technology

Complementary technologiesXML is portable reusable dataJava Technology is portable behavior

Both are Web-friendly, open, vendor neutral, Unicode support

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What is Needed?

XML “Basic Plumbing” classes:Ability to parse XML:

Parser(s) SAX DOM Namespaces Support in parser(s)

50

XML Schema

XML = Data without syntax? Schemas specifies syntax of XML

documentDTDXML schema

52

What Is the Java™ 2 Platform, Enterprise Edition (J2EE)?

Open and standard based platform for

developing, deploying and managing n-tier, Web-enabled, server-centric

enterprise applications

53

The Java™ 2 Platform

High-EndServer

Java TechnologyEnabled Desktop

WorkgroupServer

Java TechnologyEnabled Devices

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What Do You Get from J2EE?

API and Technology specifications Development and Deployment

Platform Reference implementation Compatibility Test Suite (CTS) J2EE BluePrints

55

J2EE 1.3APIs and Technologies

Java 2 SDK, Standard EditionRMI/ IIOP

JDBC™ Java Messaging Service

JNDIServlet

JavaServer Pages™JavaMail

JavaBeans™ Activation FrameworkEnterprise JavaBeansJava Transaction API

Java Transaction ServiceConnector Architecture

ECPerf™

Version1.31.03.0

1.0.2b 1.2.1

2.31.21.2

1.0.12.0

1.0.11.11.01.0

56

What is EJB Technology?

Cornerstone of J2EE A server-side component technology Easy development and deployment of

Java technology-based application that are:Transactional, distributed, multi-tier,

portable, scalable, secure, …

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Why EJB Technology?

Leverages the benefits of component-model on the server side

Separates business logic from system code

Provides framework for portable components Over different J2EE-compliant servers Over different operational environments

Enables deployment-time configurationDeployment descriptor

58

EJB Architecture

59

What is a Servlet?

Java™ objects which extend the functionality of a HTTP server

Dynamic contents generation Better alternative to CGI, NSAPI,

ISAPI, etc.EfficientPlatform and server independentSession managementJava-based

60

Servlets vs. CGI

CGIBased

Webserver

CGIBased

Webserver

Request CGI1Child for CGI1

CGIBased

Webserver

Servlet Based Webserver

JVM


Request Servlet1

CGIBased

Webserver


JVMServlet1


Request CGI2

Request Servlet1

CGIBased

WebserverChild for CGI2


JVMServlet1


Request CGI2

Request Servlet1

Request Servlet2

CGIBased



JVMServlet1

Servlet2


Request CGI2

Request CGI1

Request Servlet1

Request Servlet2

CGIBased


Child for CGI1


JVMServlet1

Servlet2


Request CGI2

Request CGI1

Request Servlet1

Request Servlet2

Request Servlet1

CGIBased


Child for CGI1


JVMServlet1

Servlet2


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01 public class ExampleServlet extends HttpServlet {02 public void doGet(HttpServletRequest request,03 HttpServletResponse response)04 throws ServletException, IOException05 {06 response.setContentType(“text/html”);07 PrintWriter out = response.getWriter();08 out.println(“Good Day USA!<BR>”);09 Date rightNow = new Date();10 out.println(“The time is: “ + rightNow);11 }12 }

Code for a Simple Servlet

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What is JSP Technology?

Enables separation of business logic from presentationPresentation is in the form of HTML or

XML/XSLTBusiness logic is implemented as Java

Beans or custom tagsBetter maintainability, reusability

Extensible via custom tags Builds on Servlet technology

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Big Picture

HTTP(S)HTTP(S)HTML/XMLHTML/XML

Client

64

JSP

Servlets and JSP - Comparison

HTML code in Java

Any form of Data Not easy to author Underlying

semantics

Java-like code in HTML

Structured Text Very easy to author Code is compiled

into a servlet

Servlets

65

JTS/JTA (Transaction Processing)

Distributed transaction processing JTS: Mapping to CORBA Object

Transaction Service (OTS)Access to standard object transaction

coordinationWho: IBM, Inprise, Bull, WebLogic

JTA: API for transactionsJava interface to transactional systemsWho: Transaction/DB server vendors

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•JNDI (Naming and Directory)

JNDI: Java Naming and DirectoryUnified field theory for namingLDAP, NIS, NIS+, DNS, File, etc. Industry supportBenefits:

Single interface to enterprise network objects Cross platform

67

JMS (Messaging and Pub/Sub)

JMS: Java Message Service APIAsynchronous communicationsPublish and SubscribeReliable QueuesGuaranteed deliveryBenefits:

Single interface to MOM Open and cross platform

Who: TIBCO, IBM, Modulus, Active

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Java 2 Platform, Enterprise Edition API and Technology specifications Development and Deployment

Platform Reference implementation Compatibility tests with branding J2EE BluePrints

69

Platform Value to Developers

Unified platform Choice of platform implementation

PerformanceScalabilityReliabilityManageabilityTools

Increased productivity Portability of code Ready-to-use security framework

70

Client

Client

Client

Client

Client

ClientTier

Enterprise Information

TierMiddle

Tier

Enterprise Information

Systems (EIS):RelationalDatabase,Legacy

Applications,ERP Systems

Enterprise JavaBeans™

Enterprise JavaBeans

Other Services:JNDI, JMS,JavaMail™

J2EEApplication

Server

Web ServerJSP,

Servlets

Firewall

J2EE is End-to-End Solution

HTML/XML

71

JND

I

J2SE

JMS

RM

I/IIO

P

JDB

C

Database

AppClient

App Client Container

HTTP/HTTPS

J2SE

RMIJ2SE

JND

I

JMS

RMI/I

IOP

JDB

C

JTA JavaMail

JAF JND

I

JMS

RMI/I

IOP

JDB

C

JTA

JavaMail

JAF

HTTP/HTTPS

Applet Container

Applet JSP Servlet EJB

Web Container EJB Container

RMI

J2SE

J2EE Containers & Components

72

ComponentsHandle

Containers and Components

Concurrency Security Availability Scalability Persistence Transaction Lifecycle

management Management

Presentation Business Logic

ContainersHandle

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Creation Assembly Deployment

Created by Component Developer

Assembledand Augmentedby Application

Assembler

Processed by Deployer

Deploy

EnterpriseComponents

J2EE Container

J2EE APPJ2EE Modules

Lifecycle illustration

74

Java 2 Platform, Enterprise Edition API and Technology specifications Development and Deployment

Platform Reference implementation Compatibility Test Suite (CTS) J2EE BluePrints

75

What and Why a Reference Implementation? Validates specification Fully-compliant Fully-functional Not commercial quality

ScalabilityPerformance

Use it for prototyping J2EE based applications

76

Compatibility Test Suite (CTS)

Ultimate Java™ technology mission:Write Once, Run Anywhere™My Java-based application runs on any

compatible Java virtual machinesMy J2EE based technology-based

application will run on any J2EE based Compatible platforms

77

J2EE BluePrints

Best practice guidelines, design patterns and design principlesMVC pattern

Covers all tiersClient tierWeb tierBusiness logic (EJB) tierDatabase access tier

Sample codeJava Pet Store

78

Summary

Java is unifying the fragmented distributed systems arena

The ability to be able to move code makes Java unique

Java is able to inter-operate with legacy applications

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