Designing of pre-stressed concrete with an internet based software

Kollinger, Michael

Designing of pre-stressed concrete with an internet based software

Ingenieurwissenschaften - Bauingenieurwesen

Zusammenfassung

Inhaltsangabe:Abstract:
The increasing interest in the Internet of the recent years results in a growing number of users as well as improved network infrastructure, quality and performance. This is the basis for a new kind of software, which is running via the Internet. That means the software is installed an a server connected to the Internet and accessed and executed by a remote client. Such Internet based software provides several benefits. Once distributed by a server, Internet based software is available world-wide and depending on its implementation it can be executed without previous installation on the client machine.
Further software updates and patches are not distributed to the users any more. Only the server has to be updated and the new version is available to all users immediately. For commercial use it is not necessary that customers buy the software any more, they download and pay only the module they need or they pay just for every access with the server application. It is also possible to place a high-performance or application specific computer at the server side and provide computation time for special tasks to the users.

Inhaltsverzeichnis:Table of Contents:
Abstract1
Chapter 1: Introduction1
Chapter 2: Project Objective1
Chapter 3: Methodology2
3.1An Overview of TCP/IP Protocols and the Internet2
3.1.1Definition of Internet2
3.1.2What is TCP/IP?2
3.1.3The TCP/IP Protocol Architecture2
3.1.4The Network Interface Layer2
3.1.5The Internet Layer2
3.1.6The Transport Layer Protocol (TCP)3
3.1.7The TCP/IP Application Layer3
3.1.8TCP/IP Paket3
3.1.9TCP/IP Transport Diagram4
3.2What are Ports?4
3.3What is a Socket?4
3.4Programming Languages5
3.4.1Advantages of Java5
3.4.1.1Java is Distributed6
3.4.1.2Java is Interpreted6
3.4.1.3Java is Architecture Neutral and Portable6
3.4.2Advantages of C++6
3.4.2.1C++ is High Performanced6
3.4.2.2C++ is Platform independent with QT7
3.4.2.3C++ is a popular Language7
3.4.2.4C++ is a powerful Language7
3.4.3Solution of our Task7
Chapter 4: Detail Description of the Program8
4.1Class Overview of the Program8
4.1.1UML Illustration of the Java Client8
4.1.2Detail Descriptionof the Java Client8
4.1.2.1AppletClient Class8
4.1.2.2NetClient Class10
4.1.2.3SocketOpener Class10
4.1.2.4ClientInputStream Class10
4.1.2.5ClientOutputStream Class11
4.1.3UML Illustration of the QT Server11
4.1.4Detail Descriptionof the QT Server12
4.1.4.1Main […]

Leseprobe

Inhaltsverzeichnis

ID 5671

Kollinger, Michael: Designing of pre-stressed concrete with an internet based software / Michael

Kollinger - Hamburg: Diplomica GmbH, 2002

Zugl.: München, Technische Universität, Studienarbeit, 2002

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Printed in Germany

Contents

Contents of tables

Abstract ... 1

Chapter 1 : Introduction... 1

Chapter 2 : Project Objective ... 1

Chapter 3 : Methodology... 2

3.1

An Overview of TCP/IP Protocols and the Internet... 2

3.1.1

Definition of Internet... 2

3.1.2

What is TCP/IP?... 2

3.1.3

The TCP/IP Protocol Architecture ... 2

3.1.4

The Network Interface Layer ... 2

3.1.5

The Internet Layer... 2

3.1.6

The Transport Layer Protocol (TCP) ... 3

3.1.7

The TCP/IP Application Layer ... 3

3.1.8 TCP/IP

Paket ... 3

3.1.9

TCP/IP Transport Diagram ... 4

3.2

What are Ports? ... 4

3.3

What is a Socket? ... 4

3.4 Programming

Languages... 5

3.4.1 Advantages

Java... 5

3.4.1.1 Java is Distributed ... 6

3.4.1.2 Java

Interpreted... 6

3.4.1.3 Java is Architecture Neutral and Portable ... 6

3.4.2 Advantages

C++ ... 6

3.4.2.1 C++ is High Performanced... 6

3.4.2.2 C++ is Platform independent with QT ... 7

3.4.2.3 C++ is a popular Language ... 7

3.4.2.4 C++ is a powerful Language ... 7

3.4.3

Solution of our Task... 7

Chapter 4 : Detail Description of the Program ... 8

4.1

Class Overview of the Program ... 8

4.1.1

UML Illustration of the Java Client ... 8

4.1.2

Detail Description of the Java Client ... 8

4.1.2.1 AppletClient

Class... 8

4.1.2.2 NetClient

Class... 10

4.1.2.3 SocketOpener

Class... 10

4.1.2.4 ClientInputStream

Class... 10

4.1.2.5 ClientOutputStream

Class ... 11

4.1.3

UML Illustration of the QT Server ... 11

4.1.4

Detail Description of the QT Server ... 12

4.1.4.1 Main

Application... 12

4.1.4.2 NetServer

Class ... 12

4.1.4.3 ServerSocket

Class... 12

4.1.4.4 ClientSocket

Class... 13

4.2 Data

Handling ... 13

4.2.1

Data Handling Windows versus Unix (Little Endian Big Endian) ... 13

4.2.2 Streams ... 14

4.2.2.1 What is a Stream?... 14

4.2.2.2 Text Versus Binary Streams... 14

4.2.2.3 Solution for our Task... 14

4.2.3 Characters... 15

Contents

4.2.3.1 ASCII ... 15

4.2.3.2 Unicode ... 15

4.2.3.3 UTF-8 ... 15

4.2.4

Data Handling with Characters in Java ... 16

4.2.5

Data Handling with Characters in QT... 17

4.2.6

Functions Overview : Sending Data from Java Client to QT Server ... 19

4.2.7

Functions Overview : Sending Data from QT Server to Java Client ... 20

Chapter 5 : Demonstration of the Result ... 21

5.1 Example... 21

5.2 Input ... 23

5.3 Status

Bar ... 24

Chapter 6 : Conclusions... 25

6.1

Program before after... 25

6.2 Advantages ... 25

6.3 Disadvantages... 25

Chapter 7 : Furtherwork... 26

References ... 27

Appendix A : Implementation... 27

Appendix B : ASCII Character Codes ... 28

Appendix C : Unicode Character Code... 29

Appendix D : ClientOutputStream Class Reference ... 30

Appendix E : ClientInputStream Class Reference... 38

Sourcecode : AppletClient ... 48

Sourcecode : QTServer... 70

Designing of pre-stressed concrete with an internet based software

Abstract

This paper presents an example of an Internet based software using the Socket API

and the TCP/IP protocol.

Chapter 1 : Introduction

The increasing interest in the Internet of the recent years results in a growing number

of users as well as improved network infrastructure, quality and performance. This is the basis

for a new kind of software, which is running via the Internet. That means the software is

installed an a server connected to the Internet and accessed and executed by a remote client.

Such Internet based software provides several benefits. Once distributed by a server, Internet

based software is available world-wide and depending on its implementation it can be

executed without previous installation on the client machine. Further software updates and

patches are not distributed to the users any more. Only the server has to be updated and the

new version is available to all users immediately. For commercial use it is not necessary that

customers buy the software any more, they download and pay only the module they need or

they pay just for every access with the server application. It is also possible to place a high-

performance or application specific computer at the server side and provide computation time

for special tasks to the users.

Chapter 2 : Project Objective

The aim of this software is to split an existing program for designing pre-stressed

concrete into two parts, the computational and the user interface part. This two part should

communicate via Internet und get network functionality.

For the development of the network connection suitable libraries in Java and C++ are

available to implement the TCP/IP based communication. Concerning the current planning,

the server programs should be implemented in C++ and the platform independent clients in

Java.

· User interactions

· Vizualize data

· Compute data

Communication

Client

· User interactions

· Vizualize data

Server

· Compute data

Designing of pre-stressed concrete with an internet based software

Chapter 3 : Methodology

3.1 An Overview of TCP/IP Protocols and the Internet

3.1.1 Definition of Internet

The Internet is a worldwide system of computer networks - a network of

networks in which users at any one computer can, if they have permission, get

information from any other computer.

Today, the Internet is a public, cooperative, and self-sustaining facility

accessible to hundreds of millions of people worldwide. Physically, the

Internet uses a portion of the total resources of the currently existing public

telecommunication networks. Technically, what distinguishes the Internet is its

use of a set of protocols called TCP/IP (for Transmission Control

Protocol/Internet Protocol). Two recent adaptations of Internet technology, the

intranet and the extranet, also make use of the TCP/IP protocol.

3.1.2 What is TCP/IP?

TCP\IP or Transmission Control Protocol \ Internet Protocol is a stack or

collection of various protocols. A protocol is basically the commands or

instructions using which two computers within a local network or the Internet

can exchange data or information and resources.

3.1.3 The TCP/IP Protocol Architecture

The TCP\ IP Suite is a stacked suite with various layers stacked on each other,

each layer looking after one aspect of the data transfer. Data is transferred from

one layer to the other. The Entire TCP\ IP suite can be broken down into the

below layers-:

3.1.4 The Network Interface Layer

The Network layer owns the responsibility of delivering data between different

systems in different interconnected networks.

3.1.5 The Internet Layer

The Internet Protocol, provides services that are roughly equivalent to the

Network Layer. This service is sometimes referred to as unreliable because the

network does not guarantee delivery nor notify the end host system about

packets lost due to errors or network congestion. IP datagrams contain a

Designing of pre-stressed concrete with an internet based software

message, or one fragment of a message, that may be up to 65,535 bytes in

length. IP does not provide a mechanism for flow control.

IP Header:

3.1.6 The Transport Layer Protocol (TCP)

The Transport layer is responsible for the reliable transfer of data between

systems. It manages the communication session including flow control,

ordering of information, error detection, and recovery of data.

TCP Header:

3.1.7 The TCP/IP Application Layer

All of the capabilities of networking begin in the Application layer. File

transfer, messaging, web browsing, and other applications are in this layer.

Each such application will appropriately invoke processing of data for

transmission through well-defined interfaces to layer(s) below this one.

3.1.8 TCP/IP

Paket

Designing of pre-stressed concrete with an internet based software

3.1.9 TCP/IP Transport Diagram

3.2 What are Ports?

On computer and telecommunication devices, a port (noun) is generally a

specific place for being physically connected to some other device, usually

with a socket and plug of some kind. Typically, a personal computer is

provided with one or more serial ports and usually one parallel port. The serial

port supports sequential, one bit-at-a-time transmission to peripheral devices

such as scanners and the parallel port supports multiple-bit-at-a-time

transmission to devices such as printers.

In programming, a port is a "logical connection place" and specifically, using

the Internet's protocol, TCP/IP, the way a client program specifies a particular

server program on a computer in a network. Higher-level applications that use

TCP/IP such as the Web protocol, Hypertext Transfer Protocol, have ports with

preassigned numbers. These are known as "well-known ports" that have been

assigned by the Internet Assigned Numbers Authority (IANA). Other

application processes are given port numbers dynamically for each connection.

When a service (server program) initially is started, it is said to bind to its

designated port number. As any client program wants to use that server, it also

must request to bind to the designated port number.

Port numbers are from 0 to 65536. Ports 0 to 1024 are reserved for use by

certain privileged services. For the HTTP service, port 80 is defined as a

default and it does not have to be specified in the Uniform Resource Locator

(URL).

Some examples of reserved Port numbers:

FTP

Telnet

HTTP

3.3 What is a Socket?

Sockets is a method for communication between a client program and a server

program in a network. A socket is defined as "the endpoint in a connection."

Sockets are created and used with a set of programming requests or "function calls"

sometimes called the sockets application programming interface (API). The most

common sockets API is the Berkeley UNIX C interface for sockets. Sockets can

also be used for communication between processes within the same computer.

Designing of pre-stressed concrete with an internet based software

This is the typical sequence of sockets requests from a server application in the

"connectionless" context of the Internet in which a server handles many client

requests and does not maintain a connection longer than the serving of the

immediate request:

This is the typical sequence of sockets requests from a server application (C

language system) in the "connectionless" context of the Internet in which a server

handles many client requests and does not maintain a connection longer than the

serving of the immediate request:

socket()

bind()

recvfrom()

(wait for a sendto request from some client)

(process the sendto request)

sendto (in reply to the request from the client...for example, send an

HTML file)

A corresponding client sequence of sockets requests would be:

socket()

bind()

sendto()

recvfrom()

Sockets can also be used for "connection-oriented" transactions with a somewhat

different sequence of C language system calls or functions.

3.4 Programming

Languages

3.4.1 Advantages of Java

The idea of Java is pretty simple software that works just about anywhere.

From day one, Java was developed to run on any platform or device that

supported Java, and, Java was designed with networks in mind. Networks like

the Internet. Networks that require applications to be portable, modular and

secure all areas which Java excels. In addition, Java simplifies computing for

both users and for the companies building distributed software applications.

Users don't have to worry about installing and running new applications on

their computers. Companies benefit from the ability to write one piece of code

that can be used on many different platforms.

Today, the most visible examples of Java are nimble, interactive programs

called "applets", which download and run in real time in web browsers,

computers and other devices.

Designing of pre-stressed concrete with an internet based software

Microsystems, the creators of Java, define the programming language of Java

as follows:

A simple, small, object-oriented, distributed, interpreted, robust, secure,

architecture neutral, portable, high-performance, multithreaded, and dynamic

language.

3.4.1.1 Java is Distributed

Distributed refers to the relationship between the objects of the Java code

and whether these objects are on remote or local systems. Since Java is a

distribute language, this means that Java applications can be as easily

accessed from the web via a URL as they are on a local system. As a

distributed language, Java has an extensive library of routines built into

it, which will allow Java application and applets to cope easily with

TCP/IP protocols like HTTP. A significant savings can be realized by

utilizing the existing HTTP infrastructure of a potential client.

3.4.1.2 Java is Interpreted

This is a critical benefit of Java. Although only about 20% of the Java

code is interpreted by the browser, it's this 20% that is critical. Java's

security and it's ability to run cross platform are due to this interpreted

20% is handled locally by the browser. The cross platform benefit is one

of the strongest features of Java. Compare this to the relatively low reach

of player based systems. In addition, this platform independence also

extends to the development environment, allowing Mac, PC and Unix

developers to work together on a single piece of software. In addition, the

interpretation feature of Java also facilitates security, allowing the

browser to ascertain whether a certain application is potentially harmful

prior to invoking it. This level of security is a benefit recognized by users

of the web making Java more widely accepted than other application

delivery methods. The security of Java is also what makes it so robust.

3.4.1.3 Java is Architecture Neutral and Portable

The Java language was designed to run on any platform that is running a

Java compatible browser. The advantage here is in the development of

the application. If a program were developed in another language,

Destiny would have to develop the application multiple times for each

platform it wished to support. This is very costly and time consuming.

With Java, we develop once, and the application can be used on the

widest possible combination of platforms. This results in a lower

development cost, a much quicker time to market, and a much larger

available audience.

3.4.2 Advantages of C++

3.4.2.1 C++ is High Performanced

C++ is not a interpreted language like Java. C++ codes are compiled in

absolute code (machine-code) and runs with a higher performance as

Java. This is a very big advantage for civil engineering, because many

applications in civil engineering have a numerical solution and this

caused usually very calculating-intensive programs.

Designing of pre-stressed concrete with an internet based software

3.4.2.2 C++ is Platform independent with QT

QT is a multiplatform GUI software toolkit written in C++. QT was not

designed for networks and has not the high network functionality like

Java, but there is also a cross platform benefit for Mac, Windows and

Unix.

3.4.2.3 C++ is a popular Language

The vast majority of application developers working in the market today

know C++ programming. It means that C++ applications can be

developed very quickly, because a lot of source code are existing and

there are a high amount of literature and information available.

3.4.2.4 C++ is a powerful Language

C++ is used in professional application development because of its

immense flexibility and power. What you can accomplish with C++ is

limited only by your imagination. C++ is used for projects as diverse as

operating systems (UNIX), word processors, graphics (Windows NT user

interface), spreadsheets, database (Oracle) and even compilers for other

languages.

3.4.3 Solution of our Task

Java is designed for network programming and have the vast support and

highest functionality for writing Internet based software. C++ is a very

powerful and fast language and is most suitable for applications in civil-

engineering. For the client is primarily the platform independence and

portability important. Java applets are running in real time in a web browser. In

every computer nowadays are a web browser installed and therefore there is no

installation necessary to run a applet on any computer. The benefits of Java

mentioned above shows, that Java applets are preferable for the Client. For the

server there is the computational speed and the flexibility important. But also

the platform independence is important for easy implementing of the server

program in other operating systems, therefore using QT should be the best

decision.

Designing of pre-stressed concrete with an internet based software

Chapter 4 : Detail Description of the Program

4.1 Class Overview of the Program

4.1.1 UML Illustration of the Java Client

Internet

4.1.2 Detail Description of the Java Client

4.1.2.1 AppletClient Class

The AppletClient class organizes the graphical user interface and visualize

the input and output data. For the Internet communication there will be

created an instance of the NetClient class.

The graphical user interface and the Internet based part are strictly

separated. therefore the network functionality can be implemented easily

in any existing Java software.

Following steps are necessary to implement the network ability:

· Create an instance of the classes NetClient, ClientInputStream and

ClientOutputStream.

The ClientOutputStream class is necessary to save the input data of the

user to a buffered byte array before transferring this data as a data

Designing of pre-stressed concrete with an internet based software

packet to the NetClient. The ClientInputStream class allowed us to get

the input data of the server.

· Before the NetClient class can communicate with the QT server, there

is required to open a Socket.

The static function connectToHost asks the NetClient to open an

Internet socket to the server with the specified IP-address strHost

and the port number nPort. The number 5000 is the timeout of the

socket. During the procedure of the NetClient trying to connect to the

server, the program will be blocked. If there are troubles with the

network or Internet, than the connection to the server may takes very

long. With the timeout of 5000 the procedure will be stopped after 5

second.

· The main idea of this program is not only sending data to the server,

compute this data and send back the result, but also to give some

options to interact with the server. There will be send a data header

ahead to the input data, with it the programmer (or also the user) can

operate the server application. Two variables are provided for this

interactions, the variables sCmdGroup and sCmd. The parameter

sCmdGroup perhaps gives general commands to the server and the

sCmd may specified commands. For example could return the

QTServer only the present server version to the client, if the

sCmdGroup is 0. With the server version, the client can interact in a

right way and may disable or enable some functionality for the user.

The parameter bByteOfChar makes it possible to define the character

byte size. That is maybe necessary to reduce the character data size in

order to increase the performance and speed of the program.

bByteOfChar=1 is defined as a 1-byte ASCII code and

bByteOfChar=2 provides the 2-byte Unicode.

Designing of pre-stressed concrete with an internet based software

4.1.2.2 NetClient Class

The NetClient class manages the Internet based part of the program

and communicate with the QT server. In this class the function

connectToHost is declared and try to open the static method of the

OpenSocket class openSocket. Now everything seems to become very

intricately, but this is the only way to set a timeout to make sure, that the

program are not blocked during the connection procedure to the server.

All the communication with the server will be proceeded in the NetClient

class. By calling the static method send the NetClient will send the

header information and the input data to the server.

For the first call of send, there is no SessionID specified and the

NetClient will send 0 as SessionID to the server. The 0 is a indicator for

the server, that it´s the first call of this client and send back the client a

unique SessionID. The NetClient save this unique SessionID from the

server and will send from now on this ID as the first information in the

header. In this way the server can save local data and informations from

the client and the client doesn´t have to sent the same data twotimes.

4.1.2.3 SocketOpener Class

The SocketOpener class has the only functionality to open a socket to

the specified IP-address and port number and pass the socket stream to the

NetClient.

4.1.2.4 ClientInputStream Class

During the computing procedure, the NetClient will exchange data and

commands with the QT server. In the ClientInputStream there are

some functions to make the handling with data more comfortable. The

Designing of pre-stressed concrete with an internet based software

next chapter will show, that data handling between two different

programming languages causes a lot of troubles, because each language

organize the data in a unequal way. Especially the character values with

the vast number of different types produce a lot of problems for the

programmer.

The ClientInputStream is derived from the DataInputStream

class of Java and has there full functionality. Addition to this functions,

there are some addition methods available (e.g. readString()), which

are concerted with the communication between Java and QT applications.

For more information look at chapter 4.2

data handling

and the appendix E:

ClientInputStream Class Reference

4.1.2.5 ClientOutputStream Class

According to the description of the ClientInputStream class, the

ClientOutputStream class has the same functionality, just with the

distinction, that with the ClientInputStream you read data from the

socket stream and with the ClientOutputStream you write data to the

socket stream.

The ClientOutputStream is derived from the DataOutputStream

class and the ByteArrayOutputStream class and support the full

range of functions of this classes. As well as the ClientInputStream

class, the ClientOutputStream class has addition methods especially

for exchanging data from the Java client to the QT server. For more

information look at chapter 4.2

data handling

and the appendix D:

ClientOutputStream Class Reference

4.1.3 UML Illustration of the QT Server

Internet

Designing of pre-stressed concrete with an internet based software

4.1.4 Detail Description of the QT Server

4.1.4.1 Main Application

The QTServer organizes the computational part and return the result to

the AppletClient. For the Internet communication there will be

created an instance of the NetServer class.

The main function is very simple. It is just necessary to create the instance

of the NetServer class and call the method connectToPort() of the

NetServer class with a specific port number.

4.1.4.2 NetServer Class

The NetServer class organizes the Internet part of the server. If the

main function calls the method connectToPort(), there will be

created and instance of the ServerSocket class. The constructor of the

ServerSocket class will create itself an instance of a

QServerSocket and bind the QTServer to the specific port.

4.1.4.3 ServerSocket Class

The ServerSocket class is deviated of the QServerSocket and

have there full functionality. The main task of the ServerSocket is to

listen to the specific port and accept incoming requests of AppletClients.

For any incoming request, the ServerSocket will create an instance of

a ClientSocket in a own thread. That instance is now responsible for

the communication with that client.

Designing of pre-stressed concrete with an internet based software

Every ClientSocket get a special SessionID with it the QTServer can

indicate the AppletClient again. The AppletClient itself will save this

SessionID and put it in the data header of the following requests. The

advantages of the SessionID is written in the description of the

NetClient class.

4.1.4.4 ClientSocket Class

The ClientSocket class is deviated of the QSocket class.

The ClientSocket class has the task to open a socket to the

AppletClient and organize the Internet communication. The

ClientSocket runs in a own thread, therefore the data exchange

between server and client is proceeded just in the ClientSocket. The

function readClient() is waiting for incoming data and will run until

the communication is finished. The method bytesAvailable() is

true, until data is send from the AppletClient.

4.2 Data Handling

4.2.1 Data Handling Windows versus Unix (Little Endian Big Endian)

Unix systems store multibyte values in Big Endian order, while Windows

systems store them in Little Endian order. Big Endian stores the high-order

byte at the starting address while Little Endian stores the low-order byte at the

starting address. The low-order byte contains the bits for the lowest possible

values, that is, 0-255, while the high-order byte contains the bits that specify

the large values (that is, 256-65535 in a short integer). (The term endian is

derived from a passage in Jonathan Swift's Gulliver's Travels). Swapping

integer data between computers of different types is a difficult problem unless

you convert the information into ASCII characters.

Designing of pre-stressed concrete with an internet based software

Example in C:

Windows:

Unix:

Big Endian

Little Endian

4.2.2 Streams

4.2.2.1 What is a Stream?

A stream is a sequence of characters. More exactly, it is a sequence of

bytes of data. A sequence of bytes flowing into a program is an input

stream; a sequence of bytes flowing out of a program is an output stream.

The major advantage of streams is that input/output programming is

device (keyboard, disk, and so on). The program "see" input/output as a

continuous stream of bytes no matter where the input is coming or going

to.

4.2.2.2 Text Versus Binary Streams

Streams fall into two modes: text and binary. A text stream consists only

of characters, such as text data being sent to the screen. Text streams are

organized into lines, which can be up to 255 characters long and are

terminated by an end-of-line, or newline, character. Certain characters is a

text stream are recognized as having special meanings, such as the newline

character.

A binary stream can handle any sort of data including, but not limited to,

text data. Bytes of data in a binary stream are not translated or interpreted

in any special way; they are read and written exactly as is. Binary streams

are used primarily with disk files.

4.2.2.3 Solution for our Task

Text streams are usually converted in a special format. This may caused

some problems if you are using two different programming languages for

Designing of pre-stressed concrete with an internet based software

writing and reading data in a stream as in our task. Binary streams are not

translated or interpreted in any special format, therefore you can handle the

data exactly in this way you want. On the other side, the binary required

less space for the same data as text streams and increase the performance of

the program.

4.2.3 Characters

4.2.3.1 ASCII

ASCII (American Standard Code for Information Interchange) is the most

common format for text files in computers and on the Internet. In an ASCII

file, each alphabetic, numeric, or special character is represented with a 7-

bit binary. In particular, Unicode extends ASCII, so the first 128 Unicode

cells coincide with the ASCII characters. ASCII defines 128 characters, of

which 33 (namely, the first 32 and the last one) are control characters.

See also table of ASCII characters: Appendix B.

4.2.3.2 Unicode

Unicode (UCS-2 ISO 10646) is a 16-bit character encoding that contains

all of the characters (2

= 65,536 different characters total) in common use

in the world's major languages. The Universal Character Set provides an

unambiguous representation of text across a range of scripts, languages and

platforms. It provides a unique number, called a code point (or scalar

value), for every character, no matter what the platform, no matter what the

program, no matter what the language. The Unicode standard is modeled

on the ASCII character set. Since ASCII's 7-bit character size is inadequate

to handle multilingual text, the Unicode Consortium adopted a 16-bit

architecture which extends the benefits of ASCII to multilingual text.

Unicode characters are consistently 16 bits wide, regardless of language, so

no escape sequence or control code is required to specify any character in

any language. Unicode character encoding treats symbols, alphabetic

characters, and ideographic characters identically, so that they can be used

simultaneously and with equal facility. Computer programs that use

Unicode character encoding to represent characters but do not display or

print text can (for the most part) remain unaltered when new scripts or

characters are introduced.

4.2.3.3 UTF-8

The Unicode Standard (ISO 10646) defines a 16-bit universal character set

which encompasses most of the world's writing systems. 16-bit characters,

however, are not compatible with many current applications and protocols

that assume 8-bit characters (such as the Web) or even 7-bit characters

(such as mail), and this has led to the development of a few so-called UCS

transformation formats (UTF), each with different characteristics. Unicode

provides for a byte-oriented encoding called UTF-8 that has been designed

for ease of use with existing ASCII-based systems. UTF-8 is the Unicode

Transformation Format that serializes a Unicode code point as a unique

sequence of one to four bytes. The UTF-8 encoding allows Unicode to be

used in a convenient and backwards compatible way in environments that,

Details

Seiten
Erscheinungsform: Originalausgabe
Erscheinungsjahr: 2002
ISBN (eBook): 9783832456719
ISBN (Paperback): 9783838656717
DOI: 10.3239/9783832456719
Dateigröße: 1.1 MB
Sprache: Englisch
Institution / Hochschule: Technische Universität München – Informatik, Informatik
Erscheinungsdatum: 2002 (Juli)
Schlagworte: internetprogrammierung sockets java applet tcp/ip
Produktsicherheit: Diplom.de

Autor

Michael Kollinger (Autor:in)

Designing of pre-stressed concrete with an internet based software

Zusammenfassung

Leseprobe

Inhaltsverzeichnis

Details

Autor

Michael Kollinger (Autor:in)