Java Network Programming and Distributed Computing

Description

• Copyright 2002
• Dimensions: 7-3/8" x 9-1/4"
• Pages: 488
• Edition: 1st

• Book
• ISBN-10: 0-201-71037-4
• ISBN-13: 978-0-201-71037-3

Java's rich, comprehensive networking interfaces make it an ideal platform for building today's networked, Internet-centered applications, components, and Web services. Now, two Java networking experts demystify Java's complex networking API, giving developers practical insight into the key techniques of network development, and providing extensive code examples that show exactly how it's done. David and Michael Reilly begin by reviewing fundamental Internet architecture and TCP/IP protocol concepts all network programmers need to understand, as well as general Java features and techniques that are especially important in network programming, such as exception handling and input/output. Using practical examples, they show how to write clients and servers using UDP and TCP; how to build multithreaded network applications; and how to utilize HTTP and access the Web using Java. The book includes detailed coverage of server-side application development; distributed computing development with RMI and CORBA; and email-enabling applications with the powerful JavaMail API. For all beginning to intermediate Java programmers, network programmers who need to learn to work with Java.



Sample Content

Online Sample Chapter

Transmission Control Protocol and Java

Table of Contents

Preface.


Acknowledgments.


1. Networking Theory.

What Is a Network?

How Do Networks Communicate?

Communication across Layers.

Advantages of Layering.

Internet Architecture.

Internet Application Protocols.

TCP/IP Protocol Suite Layers.

Security Issues: Firewalls and Proxy Servers.

Summary.

2. Java Overview.

What Is Java?

The Java Programming Language.

The Java Platform.

The Java Application Program Interface.

Java Networking Considerations.

Applications of Java Network Programming.

Java Language Issues.

System Properties.

Development Tools.

Summary.

3. Internet Addressing.

Local Area Network Addresses.

Internet Protocol Addresses.

Beyond IP Addresses: The Domain Name System.

Internet Addressing with Java.

Summary.

4. Data Streams.

Overview.

How Streams Work.

Filter Streams.

Readers and Writers.

Object Persistence and Object Serialization.

Summary.

5. User Datagram Protocol.

Overview.

DatagramPacket Class.

DatagramSocket Class.

Listening for UDP Packets.

Sending UDP Packets.

User Datagram Protocol Example.

Building a UDP Client/Server.

Additional Information on UDP.

Summary.

6. Transmission Control Protocol.

Overview.

TCP and the Client/Server Paradigm.

TCP Sockets and Java.

Socket Class.

Creating a TCP Client.

ServerSocket Class.

Creating a TCP Server.

Exception Handling: Socket Specific Exceptions.

Summary.

7. Multi-threaded Applications.

Overview.

Multi-threading in Java.

Synchronization.

Interthread Communication.

Thread Groups.

Thread Priorities.

Summary.

8. Implementing Application Protocols.

Overview.

Application Protocol Specifications.

Application Protocols Implementation.

Summary.

9. HyperText Transfer Protocol.

Overview.

HTTP and Java.

The Common Gateway Interface (CGI).

Summary.

10. Java Servlets.

Overview.

How Servlets Work.

Using Servlets.

Running Servlets.

Writing a Simple Servlet.

SingleThreadModel.

ServletRequest and HttpServletRequest.

ServletResponse and Http Response.

ServletConfig.

ServletContext.

Servlet Exceptions.

Cookies.

HTTP Session Management in Servlets.

Summary.

11. Remote Method Invocation (RMI).

Overview.

How Does Remote Method Invocation Work?

Defining an RMI Service Interface.

Implementing an RMI Service Interface.

Creating Stub and Skeleton Classes.

Creating an RMI Server.

Creating an RMI Client.

Running the RMI System.

Remote Method Invocation Packages and Classes.

Remote Method Invocation Deployment Issues.

Using Remote Method Invocation to Implement Callbacks.

Remote Object Activation.

Summary.

12. Java IDL and CORBA.

Overview.

Architectural View of CORBA.

Interface Definition Language (IDL).

From IDL to Java.

Summary.

13. JavaMail.

Overview.

Installing the JavaMail API.

Testing the JavaMail Installation.

Working with the JavaMail API.

Advanced Messaging with JavaMail.

Summary.

Index. 0201710374T03292002

Preface

Welcome to Java Network Programming and Distributed Computing. The goal of this book is to introduce and explain the basic concepts of networking and discuss the practical aspects of Java network programming.

This book will help readers get up to speed with network programming and employ the techniques learned in software development. If you’ve had some networking experience in another language and want to apply your existing skills to Java, you’ll find the book to be an accelerated guide and a comprehensive reference to the networking API. This book does not require you to be a networking guru, however, as Chapters 1–4 provide a gentle introduction to networking theory, Java, and the most basic elements of the Java networking API. In later chapters, the Java API is covered in greater detail, with a discussion supplementing the documentation that Sun Microsystems provides as a reference.

What You’ll Learn

In this book, readers will learn how to write applications in Java that make use of network programming. The Java API provides many ways to communicate over the Internet, from sending packets and streams of data to employing higher-level application protocols such as HTTP and distributed computing mechanisms.Along the way, you’ll read about:

How the Internet works, its architecture and the TCP/IP protocol stack

The Java programming language, including a refresher course on topics such as exception handling

Java’s input/output system and how it works

How to write clients and servers using the User Datagram Protocol (UDP) and the Transport Control Protocol (TCP)

The advantages of multi-threaded applications, which allow network applications to perform multiple tasks concurrently

How to implement network protocols, including examples of client/server implementations

The HyperText Transfer Protocol (HTTP) and how to access the World Wide Web using Java

How to write server-side Java applications for the WWW

Distributed computing technologies including remote method invocation (RMI) and CORBA

How to access e-mail using the extensive JavaMail API

What You’ll Need

A reasonable familiarity with Java programming is required to get the most out of this book. You’ll need to be able to compile and run Java applications and to understand basic concepts such as classes, objects, and the Java API. However, you don’t need to be an expert with respect to the more advanced topics covered herein, such as I/O streams and multi-threading. All examples use a text interface, so there’s no need to have GUI experience.

You’ll also need to install the Java SDK, available for free from Sun Micro-systems (http://java.sun.com/j2se/). Java programmers will no doubt already have access to the SDK, but readers should be aware that some examples in this text will require JDK 1.1, and the advanced sections on servlets, RMI and CORBA, and JavaMail will require Java 2.

A minimal amount of additional software is required, and most of the tools for Java programming are available for free and downloadable via the WWW. Chapter 2 includes an overview of Java development tools, but readers can also use their existing code editor. Readers will be advised when examples feature additional Sun Microsystems software.

Companion Web SiteAs a companion to the material covered in this book, the book’s Web site offers the source code in downloadable form (no need to wear out your fingers!), as well as a list of Frequently Asked Questions about Java Networking, links to networking resources, and additional information about the book. The site can be found at http://www.davidreilly.com/jnpbook/.Contacting the Authors

We welcome feedback from readers, be it comments on specific chapters or sections or an evaluation of the book as a whole. In particular, reader input about whether topics were clearly conveyed and sufficiently comprehensive would be appreciated. While we’d love to receive only praise, honest opinions are valued (as well as suggestions about coverage of new networking topics).

Feel free to contact us directly. While we can’t guarantee an individual reply, we’ll do our best to respond to your query. Please send questions and feedback via e-mail to: jnpbook@davidreilly.com.

David Reilly and Michael Reilly
September 2001

0201710374P03282002

Index

A

Absolute filename, 233

Abstract classes, 69

accept() method, 161, 162

AccessException class, 332

ACK (acknowledgment) packet, 139

Activatable class, 334-336, 345

Activatable objects

   activation description, 335

   activation descriptor, 336-337

   activation ID, 335

   creating new instances, 338

   stub, 336

Activatable remote object

   creation of, 368-369

   notification of, 366

   registering, 369-376

ActivatableLightBulbServer application, 369-376

ActivatableLightBulbServer class, 373

ActivateFailedException exception, 339

Activation, 334-339

   remote objects supporting, 334-336

   security manager, 373

Activation descriptor

   associated with default activation group, 337

   associated with specified activation group, 336-337

   codebase of class represented by, 337

   creation of, 374-375

   hashcode, 337

   name of class represented by, 337

   object represented, 337

Activation descriptor object, 336

Activation group descriptor, 374

Activation group ID, 337

Activation groups, 338-339

ActivationDesc class, 336-337

ActivationDesc() method, 336-337

ActivationException exception, 339

ActivationGroup class, 338

ActivationGroupDesc class, 338

ActivationGroup.getSystem() method, 374

ActivationGroupID class, 338

ActivationGroupID() method, 338

ActivationID class, 339

ActivationSystem class, 374

ActivationSystem interface, 339, 374

ActivationSystem.registerGroup method, 374

ActivatonGroup.createGroup() method, 374

Active objects no longer active, 335

Active Server Pages, 240

activeCount() method, 197, 198

activeGroupCount() method, 197

Adapter class, 433

addConnectionListener() method, 407, 410

addFolderListener() method, 409, 410

addFrom() method, 405

addMessageChangedListener() method, 410

addMessageCountListener() method, 410

addReceipt() method, 405

addRecipients() method, 405

Address class, 404

Address mask, 16

Address Mask Request/Address Mask Reply ICMP message, 16

addStoreListener() method, 409

addTemperatureListener() method, 360

addTransportListener() method, 415

allowThreadSuspension() method, 197

“allowUserInteraction” field, 257, 259

AlreadyBoundException class, 332

AltaVista search engine, 281, 285

Apache JServ add-on, 293

Apache JServ Web site, 293

Apache Web server, 293

Apache Web site, 293

API (Application Program Interface), 37-38

appendMessages() method, 410

Applets, 43

   digitally signed, 39

   firewall restrictions, 355-356

   games, 41

   inability to bind to TCP ports, 354

   limitations, 33

   network access restrictions, 39

   network connection restrictions, 355

   RMI (remote method invocation), 354-356

   security policies limitations, 287

   security restrictions, 39

Application layer, 8

Application protocols

   implementation, 207-236

   lower-level (Open Systems Interconnection) model layers, 205

   RFC (Request For Comment) documents, 206

   specifications, 206-207

Applications

   communicating through ports, 144

   interoperating, 205

   sequential access to data, 139

   stand-alone, 39

Architecture evolution, 8-9

ARP (Address Resolution Protocol), 14

ARPANET, 8-9

Array of characters, printing, 88

ArrayOutOfBoundsException exception, 198

autoexec.bat file, 295

Automatic error control, 142-143

Automatic garbage collection, 30-31

available() method, 72

AWT (Abstract Windowing Toolkit), 46, 358, 428

AWTError class, 46

B

“Backwards” CGI script, 285

badVariable variable, 290

BEA Weblogic Web site, 294

Berners-Lee, Tim, 224

BindException exception, 165, 166

bind() method, 331, 341

Blocking I/O, 71

Block-level synchronization, 188-189

Blocks of code, locking, 188

Boolean value, printing, 87

Borland Enterprise Application Server Web site, 294

Borland JBuilder, 52

Borland Web site, 52

Browsers, 18

   responding to requests from, 229

   runtime environments, 36

Buffered stream

   InputStream object, 80

   sizing, 81

Buffered writer, 103

BufferedInputStream class, 80-81, 81, 255

BufferedInputStream() method, 80, 81

BufferedOutputStream class, 85-86, 155

BufferedOutputStream() method, 85

BufferedReader class, 89, 94, 95-96, 125, 153

bufferedReader() method, 95

BufferedWriter class, 102-103, 155, 297

BufferedWriter() method, 103

Buffering together write requests, 102-103

Buffers

   push-back reader, 96

   reading data into, 95

   strings, 100-101

writers, 99

Byte stream, 108-109, 142

ByteArrayInputStream class, 70, 125, 129

ByteArrayOutput Stream class, 131

ByteArrayOutputStream class, 75

Bytecode, 31

C

C#, 53

C++, 29

C and error checking, 45

Cache flag, 257, 259

Caching requests, 260

Callbacks

   local, 358

   object-oriented, 356-358

   remote, 358

   RMI (remote method invocation) implementation, 356-365

   running example, 364-365

Catch statement, 48-49

Catching exceptions, 45-47

CGI (Common Gateway Interface), 240, 277-286

   parameters, 278

   variables and servlets, 300

CGI scripts, 36, 240, 281

Character array readers, 91

Character array writers, 99

Character value, printing, 88

CharArrayReader() method, 91

CharArrayWriter class, 99

CharArrayWriter() method, 99

checkAccess() method, 197

checkError() method, 87

Checksum, 13

Class A IP addresses, 57, 58

Class B IP addresses, 58

Class C IP addresses, 58

Class D IP addresses, 58, 63

Class E IP addresses, 58

ClassCastException exception, 112

Classes

   abstract, 69

   capable of running as threads, 177

   definition at different locations, 350-351

   for following network resources, 34

   RMI (remote method invocation), 329-349

ClassNotFoundException exception, 351

Classpath environment variable, 50, 295

   JavaMail API, 402

Client JVM, uniquely identifying, 339-340

Client sockets, 148-157

   connections, 159

Clients, 145-147

   codebase, 352

   connecting with resource, 256

   CORBA (Common Object Request Broker Architecture), 382-383

   ease of connecting to remote services, 152-153

   error set of status codes, 245

   MIME type in documentation check-in/check-out system, 307

   request header fields, 241-243

   requesting connection to server socket, 161-162

   RMI (remote method invocation), 328

   sending MIME-encoded data to, 302-305

Client/server paradigm, 145-147

clone() method, 348

CloneNotSupportedException exception, 348

close() method, 72, 76-77, 90, 98, 123, 150, 162, 407, 410-411

Codebase directory, 351

Command line

   parameter null value, 252

   passing system properties from, 50-51

Commercial IDE packages, 52-53

Communication

   between applications using ports, 144

   with Web server, 239

Communication pipes, 189, 190-192

Communication ports, 16, 144

Comparing IP addresses, 63

Computer games, 40-41

Computers, 1

Connected pipe reader, 92

ConnectException class, 332

ConnectException exception, 47, 166

ConnectIOException class, 332

ConnectionListener class, 429, 433, 434

Connections

   request method, 273

   used for input or output, 257

connect() method, 92, 100, 123, 149, 256, 407, 408

Constants, 290

“Content-encoding” header field, 257

CONTENT_LENGTH environment variable, 300

“Content-Length” field, 246, 257, 263

“Content-Type” field, 246, 262

Controlling threads, 178-183

Cookie class, 309-311

Cookies, 242, 308

   sending to browser, 247

   servlets, 309-311

   variables, 309

CookieTest servlet, 309-311

copyMessages() method, 411

CORBA (Common Object Request Broker Architecture), 34, 38, 44

   architectural view, 380-383

   clients, 382-383

   distributed lightbulb service, 387

   exception handling, 386

   exporting servant, 391

   IDL (Interface Definition Language), 383

   IIOP (Internet Inter-ORB Protocol), 381-382

   multilanguage abilities, 380

   name service, 382-383

   ORB (object request broker), 381

   removing communication between objects, 395-396

   RMI (remote method invocation), 379

   robustness, 382

   schema, 382

   servant, 382

   services and clients, 380

   writing servant code, 388-392

Country-code top-level domains, 60

CPU (central processing unit), 169

createGroup(..) method, 338

create() method, 411

createRegistry() method, 342

createServerSocket() method, 344, 346

createSocket() method, 344, 346

Current machine IP addresses, 64-65

Customized sockets, 345-347

D

-D flag, 50

Daemon group, 199

Daemon process, 147

Daemon threads, 175-176

Data

   out-of-sequence, 4

   undelivered and time queued for delivery, 155

“DATA” command, 215

Data input stream construction, 82

Data link layer, 7

Data marshaling, 320

Data packets and UDP (User Datagram Protocol), 119-121

Data streams, definition of, 67-68

Data transmission with packets, 4-5

Datagram packet sequence number, 139, 143

DatagramPacket class, 119-121, 125, 131

DatagramPacket() method, 120-121

DatagramSocket class, 122-123, 125, 132, 147, 155

DatagramSocket() method, 122

DatagramSocket.receive method, 124

DatagramSocket.setToTimeout() method, 143

DataInputStream class, 81-83, 108, 125, 255

DataInputStream() method, 82

DataInputStream.readLine() method, 89, 96

DataOutput interface, 109

DataOutputStream class, 86-87

DataOutputStream() method, 86

Datatypes

   printing as text, 87

   reading, 81-83

   writing to file, 86

“Date” header field, 257

DayTime server, 159

DaytimeClient application, 157-159

DaytimeServer application, 163

Deadlock, 181

Debugging servlets, 306

DejaNews Web site, 19

DELETE HTTP requests, 290, 292-293

delete() method, 411

Delphi, 29

Destination Unreachable ICMP message, 15

destroy() method, 197, 290, 291

Developers and firewalls, 23

Development tools

   IDE (integrated development environment), 51-53

   SDK (system development kit), 53

   user interface, 51

Devices, 1, 2

DHCP (Dynamic Host Control Protocol) server, 58

Digitally signed applets, 39

disconnect() method, 123, 272

displayEmails() method, 221

Distributed garbage collection, 339-341

Distributed systems, 43-44

DNS (Domain Name System), 59-61

DNS server, 61

docroot variable, 230

doDelete() method, 290

doGet() method, 290

Domain name resolution, 61

Domain names, 60

doOptions() method, 290

doPost() method, 290

doPut() method, 290

doSomething() method, 368, 369

doTrace() method, 290

Dotted decimal format, 61, 63

Double value, printing, 88

Downloading JSDK (Java Servlet Development Kit), 294

Dropped packets, 118

Dynamic class loading, 332, 349-352, 364, 375

Dynamically assigned IP addresses, 56, 58

E

Echo client, 135-138

Echo Request/Echo Reply ICMP message, 15

Echo server, 138

Echo service, 132-134

E-mail, 399

   retrieving messages, 423-427

   sending file as attachment, 435-438

   sending messages, 418-423

E-mail clients, 18

Emulation, 35

Entity body, 247

   meta-information about, 247

   MIME content type, 246

   number of bytes, 246

enumerate() method, 197-198

Enumeration, unable to access next element, 47

Environment variables, 50

equals() method, 63, 249, 337, 338, 340, 344

Error class exceptions, 45-46

Ethernet address, 3

Ethernet card, 2

Event source

   defining interface, 359

   implementing interface, 359-362

   listeners, 356

Events

   JavaMail, 429-430

   notifying object of, 356-358

   notifying waiting thread of, 192-193

/examples/ directory, 295

/examples/WEB-INF/servlets directory, 295

Exception class and exceptions, 46-47

Exception handlers, 44-50

   catch statement, 48-49

   finally statement, 48, 49

   IDL (Interface Definition Language), 386-387

   sockets, 165-167

   try statement, 48

Exception objects, 45

Exceptions

   catching, 45-47

   causes, 49-50

   definition of, 45

   Error class, 45-46

   Exception class, 46-47

   inheritance, 45

   Java API, 321

   java.rmi.server package, 348

   remote method, 333

   security restrictions, 50

   servlets, 308

   state of network connection, 49

   throwing, 45-47

   types, 45-47

exists() method, 411

“Expires” field, 246-247, 257

ExportException exception, 348

exportObject() method, 334-335, 348

expunge() method, 411

Extensions, 38

External Internet mail service, 409

F

Faulting remote reference, 366-367

fetch() method, 411

FetchURL application, 253-256

FetchURLConnection application, 260-263

Fiber-optic cables, 3

FieldInputStream class, 234

FIFO queue, 76

FileDataSource class, 438

FileInputStream low-level input stream, 70

FileInputStream object, 74

FileInputStreamDemo application, 74

File.listFiles() method, 235

FileNameMap interface, 257-258

Filenames, mapping MIME content types to, 257-258

FileOutputStream class, 78, 112

FileOutputStream low-level output stream, 75

FileOutputStreamDemo application, 78-79

FileReader class, 92, 234

FileReader() method, 92

Files

MIME type, 307

   transferring, 18

FileWriter class, 99

FileWriter() method, 99

Filter input streams

   BufferedInputStream class, 80-81

   DataInputStream class, 81-83

   LineNumberInputStream class, 84

   PushBackInputStream class, 84-85

   pushing back data for reading later, 84-85

Filter output streams

   BufferedOutputStream class, 85-86

   buffering writes, 85-86

   DataOutputStream class, 86-87

   PrintStream class, 87-88

Filter readers

   BufferedReader class, 95-96

   buffering characters, 95

   FilterReader class, 96

   line counter, 97

   LineNumberReader class, 97

   PushBackReader class, 96-97

Filter streams, 68, 79-88

Filtered writers, 102-104

FilterInputStream class, 80

FilterReader class, 96

Filters

   socket streams, 153

   templates, 96, 103

FilterWriter class, 103

FilterWriter() method, 103

finalize() method, 408, 411

Finally statement, 48, 49

Finding

   out about other addresses, 65-66

   RFC (Request For Comments) documents, 206-207

Finger, 19

Firewall tunneling, 355-356

Firewalls, 21-22

   applet restrictions, 355-356

   developers, 23

Flow control, 139-140

flush() method, 77, 85, 98

Folder class, 410-415

Folder.close() method, 427

FolderListener class, 429

fork() command, 32

Frames, 7

FTP (File Transfer Protocol), 18, 206, 268

G

Games, 40-41

Garbage collection, 30-31, 339-341

Garbage collector, unable to free objects, 46

Gateways, 2

Generic socket error, 166

GenericServlet class, 290

“GET” command, 232

GET HTTP requests, 229, 232-233, 239, 290-292

   sending, 278-281

   versions, 240

GET method, 239-240, 277, 278

getAbsoluteName() method, 412

getAddress() method, 63, 121

getAllbyName() method, 63

getAllowUserInteraction() method, 257

getBuffer() method, 101

getByName() method, 63, 66

getClassName() method, 337

getClientHost() method, 345

getContentEncoding() method, 257

getContentLength() method, 257, 300

getContent() method, 250, 257

getContentType() method, 258

getCount() method, 187

getData() method, 121, 337

getDate() method, 257

getDebug() method, 417

getDefaultAllowUserInteractionField() method, 257

getDefaultFolder() method, 409

getDefaultInstance() method, 416-417

getDefaultRequestProperty() method, 257

getDefaultSocketFactory() method, 346

getDefaultUseCaches() method, 257

getDoInput() method, 257

getDoOutput() method, 257

getDuration() method, 341

getEncoding() method, 93, 101

getErrorStream() method, 272

getExpiration() method, 257

getFailureHandler() method, 346

getFile() method, 250

getFileNameMap() method, 257-258

getFlags() method, 405

getFolder() method, 405, 409, 411, 417

getFollowRedirects() method, 272

getFrom() method, 405, 426

getFullName() method, 411-412

getGroupID() method, 337

getHeaderFieldData() method, 258

getHeaderFieldInt() method, 258

getHeaderFieldKey() method, 258

getHeaderField() method, 258

getHeader() method, 300

getHostAddress() method, 63, 64, 65

getHost() method, 250

getHostName() method, 63, 64

getID() method, 335

getInetAddress() method, 123, 150, 162

getInitParameter() method, 305

getInitParameterNames() method, 305

getInput() method, 221

getInputStream() method, 150, 153, 258

getInstance() method, 417

getKeepAlive() method, 151

getLastModified() method, 258

getLength() method, 121

getLineNumber() method, 84, 97

getLocalAddress() method, 123, 151

getLocalHost() method, 63, 64-65

getLocalPort() method, 123, 151, 162

getLocation() method, 337

getLog() method, 345

getMajorVersion method, 306

getMaxPriority() method, 198

getMessageCount() method, 412

getMessageNumber() method, 405

getMessages() method, 412

getMimeType method, 306

getMinorVersion method, 306

getMode() method, 412

getName() method, 199, 412

getNewMessageCount() method, 412

getOutputStream() method, 150, 258

getParameterValues() method, 302

getParent() method, 199, 412

getPasswordAuthentication() method, 417

getPermanentFlags() method, 412

getPermission() method, 258-259

getPort() method, 123, 151, 250

getProperties() method, 417

getProperty() method, 417

getProtocol() method, 250

getProvider() method, 417

getProviders() method, 417

getRealPath() method, 307

getReceiveBufferSize() method, 123, 151

getReceivedDate() method, 405

getRecipients() method, 405

getRef() method, 250

getRegistry() method, 342-343

getReplyTo() method, 405

getRequestMethod() method, 272

getRequestProperty() method, 259

getResponseCode() method, 272

getResponseMessage() method, 272

getRestartMode() method, 337

getSendBufferSize() method, 123, 151

getSentDate() method, 406

getSeparator() method, 412

getServletContext() method, 306

getSession() method, 312

getSocketFactory() method, 346

getSoLinger() method, 151

getSoTimeout() method, 123, 162

getStore() method, 412, 417

getSubject() method, 406, 426

getSystem() method, 338

getTcpNoDelay() method, 151

getTransport() method, 417-418

getType() method, 413

getUnreadMessageCount() method, 413

getURL() method, 259

getURLName() method, 408, 413

getUseCaches() method, 259

getVMID() method, 341

goodVariable variable, 290

Gosling, James, 28

Grouping threads, 194-200

Guaranteed delivery, 138-139, 142

guessContentTypeFromStream() method, 257, 259

GUI applications and multi-threading, 172

GUI design tools, 52

H

Handler class, 231

Handler functions, 291

Hardware, 1

   address, 3

   independence, 9

hashCode() method, 250, 337, 338, 340, 344

HEAD request, 239, 240

Header fields

   assigning value, 260

   modifying and examining, 264-268

   name of nth, 258

   parsing as date, 258

   parsing as number, 258

HelloWorld servlet, 295, 298-299

HelloWorld.class file, 295

“HELO” hostname identification command, 214

Helper class, 395

High ASCII characters, 89

High-level filter streams, 71

Host machine and unique VMID (virtual machine identifier), 340

Hostnames, 14, 63, 65-66, 132

Hosts, 61

hosts.txt file, 60

Host-to-IP-address mappings, 60

HotJava, 28

HTCPCP (HyperText Coffee Pot Control Protocol), 206

HTML, 235

HTTP (HyperText Transfer Protocol), 18-19, 224, 248

   CGI (Common Gateway Interface), 277-286

   connecting client and resource, 256

   HttpURLConnection class, 268-277

   operation of, 237-239

   reading responses, 256-268

   redirects, 272

   sending requests, 256-268

   session management, 312-313

   stateless model, 308, 312

   status codes, 302

   TCP (Transmission Control Protocol), 237

   URL class, 248-250

   URL-Connection class, 256-268

   Web browsers, 237

HTTP clients

   identifying type, 243

   request header fields, 241-243

   TCP connection to Web server, 237-238

HTTP requests

   issuing, 266

   servlet methods, 290

   tracking state, 312

   valid, 293

HTTP response, 238

HTTP servlets, 290

HTTP servers

   connection, 238

   implementation, 224-236

   response header fields, 245-247

   status, 244-245

   transaction, 238

HTTP/1.1, 224

   status codes and integer static constants, 303-304

HTTP_ACCEPTED - HTTP status code (202) field, 269

HTTP_BAD_GATEWAY - HTTP status code (502) field, 272

HTTP_BAD_METHOD - HTTP status code (405) field, 271

HTTP_BAD_REQUEST - HTTP status code (400) field, 271, 291

HTTP_CLIENT_TIMEOUT - HTTP status code (408) field, 271

HTTP_CONFLICT - HTTP status code (409) field, 271

HTTP_CREATED - HTTP status code (201) field, 269

HTTP_ENTITY_TOO_LARGE - HTTP status code (413) field, 271

HTTP_FORBIDDEN - HTTP status code (403) field, 271

HTTP:_GATEWAY_TIMEOUT - HTTP status code (504) field, 272

HTTP_GONE - HTTP status code (410) field, 271

HTTPHeaders application, 264-268

HTTP_INTERNAL_ERROR - HTTP status code (501) field, 272

HTTP_LENGTH_REQUIRED - HTTP status code (411) field, 271

HTTP:_MOVED_PERM - HTTP status code (301) field, 270

HTTP_MOVED_TEMP - HTTP status code (302) field, 270

HTTP_MULT_CHOICE - HTTP status code (300) field, 270

HTTP_NO_CONTENT - HTTP status code (204) field, 270

HTTP_NOT_ACCEPTABLE - HTTP status code (406) field, 271

HTTP_NOT_AUTHORITATIVE - HTTP status code (203) field, 270

HTTP_NOT_FOUND - HTTP status code (404) field, 271

HTTP_NOT_MODIFIED - HTTP status code (304) field, 270

HTTP_OK - HTTP status code (200) field, 269

HTTP_PARTIAL - HTTP status code (206) field, 270

HTTP_PAYMENT_REQUIRED - HTTP status code (402) field, 271

HTTP_PRECON_FAILED - HTTP status code (412) field, 271

HTTP_PROXY_AUTH - HTTP status code (407) field, 271

HTTP_REQ_TOO_LONG - HTTP status code (414) field, 272

HTTP_RESET - HTTP status code (205) field, 270

HttpResponse class, 302-305

HTTP_SEE_OTHER - HTTP status code (303) field, 270

HTTP_SERVER_ERROR - HTTP status code (500) field, 272

HttpServlet class, 290, 297

HttpServletRequest class, 300-302, 312

HttpSession class, 312-313

HTTP_UNAUTHORIZED - HTTP status code (401) field, 271

HTTP_UNAVAILABLE - HTTP status code (503) field, 272

HTTP_UNSUPPORTED_TYPE - HTTP status code (415) field, 272

HttpURLConnection class, 268-277

   accessing HTTP-specific functionality, 273-277

   static fields, 269-272

   usage, 269-273

HTTP_USE_PROXY - HTTP status code (305), 270-271

HTTP_USER_AGENT environment variable, 300

HTTP_VERSION - HTTP status code (505) field, 272

Hubs, 2

Hyperlinks, 224, 237

Hypertext documents, 237

I

IANA (Internet Assigned Numbers Authority), 58, 59

IANA (Internet Assigned Numbers Authority) Web site, 58

IBM Web site, 52

ICANN (Internet Corporation for Assigned Names and Numbers), 58

ICANN (Internet Corporation for Assigned Names and Numbers) Web site, 58

ICMP (Internet Control Message Protocol), 14-16

IDE (integrated development environment), 51-53

IDL (Interface Definition Language), 380

   attributes, 385

   datatypes, 384

   exception handling, 386-387

   interfaces, 384

   mapping schema to Java, 388

   modules, 384

   operations, 385-386

   overview, 383

   writing client code, 392

   writing CORBA service, 387

   writing servant code, 388-392

idl2java.exe program, 388

idlj compiler, 395

idlj.exe, 388

“If-Modified-Since” header, 242, 260

IIS (Internet Information Server), 293

IllegalArgumentException exception, 121, 336

IllegalStateException exception, 410, 414

implAccept() method, 162

inactive() method, 335

INBOX folder, 410, 425-426

increaseCount() method, 186

InetAddress class, 63-66, 131

Informational set of status codes, 244

Infrared, 3

Inheritance

   exceptions, 45

   objects, 74

init() method, 288, 290, 291

Inner classes, 230, 429

Input flag, 259

Input streams, 68, 213

   blocking I/O, 71

   byte array not filled, 82

   closing, 72

   converting line of text to string, 83

   current position in, 72

   double value, 82

   float value, 82

   freeing resources, 72

   int value, 82-83

   length of data read, 82

   long value, 83

   low-level streams, 69-70, 73-75

   moving back to preset mark, 72

   next byte of data, 72

   nonzero byte, 82

   number of bytes to read, 72

   offset within array, 82

   pushing back array contents, 84

   pushing back byte to front of buffer, 85

   pushing back subset of array, 84-85

   readers, 93

   reading, but ignoring bytes, 72-73

   reading byte from, 82

   reading character from, 82

   reading from, 69-75, 84

   reading sequence of bytes to byte array, 72

   reading string with, 83

   sequentially reading, 70-71

   short value, 83

   sizing buffer, 84

   skipping over bytes, 83

   tracking number of lines read from, 84

InputStream class, 71-75, 80, 253, 255, 256, 263

InputStream object, 74, 258

InputStreamReader class, 93, 94, 125

InputStreamReader() method, 93

InputStreamToReaderDemo application, 94

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