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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.
Transmission Control Protocol and Java
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.
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.
Local Area Network Addresses.
Internet Protocol Addresses.
Beyond IP Addresses: The Domain Name System.
Internet Addressing with Java.
Summary.
Overview.
How Streams Work.
Filter Streams.
Readers and Writers.
Object Persistence and Object Serialization.
Summary.
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.
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.
Overview.
Multi-threading in Java.
Synchronization.
Interthread Communication.
Thread Groups.
Thread Priorities.
Summary.
Overview.
Application Protocol Specifications.
Application Protocols Implementation.
Summary.
Overview.
HTTP and Java.
The Common Gateway Interface (CGI).
Summary.
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.
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.
Overview.
Architectural View of CORBA.
Interface Definition Language (IDL).
From IDL to Java.
Summary.
Overview.
Installing the JavaMail API.
Testing the JavaMail Installation.
Working with the JavaMail API.
Advanced Messaging with JavaMail.
Summary.
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 LearnIn 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:
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 AuthorsWe 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
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
Installi