Operating System : Windows XP/ NT/2000/VISTA
Front End : Microsoft Visual C++ 6.0
1.4.2 Client
Hardware Components:
Processor : Minimum Intel Pentium III 1.0 GHz
RAM Memory : Minimum 256MB
Hard Disk : Minimum 20GB
Operating System : Windows XP/ NT/2000/VISTA
Front End : Microsoft Visual C++ 6.0
CHAPTER II
RELATED WORK
2.1 System Overview
Overall the whole system it has three major components: Text chatting (Single to Single, Single to Multiple), File transmission & Audio chatting (Single to Single, Single to Multiple).
The diagram looks like as follows:
Figure 2.1 System Overview diagram
Three Major components:
2.1.1 Text Chatting
The users could send and receive the messages simultaneously. All the messages will be encrypted before sending.
2.1.1.1 Single to Single Communication
This function describes the communication between two people.
Each of them has added the other user to their friend list. They could chat by sending message or audio chatting. The files transmission is also available.
2.1.1.2 Single to Multiple Communication
This function describes the communication among a group of more than threes people. Either of them are in the same group. The message sending and audio chatting are executing for the convenience service.
2.1.3 File transmission
The online users could share the files by peer-to-peer network.
2.1.4 Audio chatting
It is an essential function to improve the reality and speed of the communication. The content will get high security.
Subordinate functions:
2.1.5 Friend list and Blacklist
2.1.6 Online,Busy,Away,Ivisible status display
2.1.7 Chat record
2.1.8 Add friend
2.1.9 Delete friend
2.1.10 Edit personal information
2.1.11 Group list
2.1.12 Leave a message
2.2 The project plan
2.2.1 Milestone of project
Figure 2.2 Milestone of project
2.3 Project Scope
By considering the widespread of internet, this project designed for the instant message chatting and audio chatting between two people or among a specific group. The user could communicate with other online users by audio chatting http://www.youerw.com/when they online, and you can also get the message when you offline, you can see the message when you online next time. You can chatting with you friends of the new form , not like the single person to person, you can set up a multi-user chatting windows ,choose which friends is add , that you can chatting with them at the same window , that is easy to help you to chatting with multi-friends at same time . When you chatting with your friends you can send the emotional icon to your friend and that is very fast to type in not like sending the image. All the chatting information will be encrypted and transferred in a secure way not betray your secret to other. The chatting software also enables you to review the messages you sent before if you have the password, the chatting records are automatically saved using the cryptograph technology. The file transmission function can help you send any file to your friends by using the technology not passing through the severs. Moreover, it provides a series of helpful and effective functions to improve the efficiency of the application itself and comfort of usage of the chatting service.
CHAPTER III
DESIGN AND IMPLEMENTATION
3.1 Outline design
Overall the system, using the CSocket class based on the TCP for the text chatting ,and based on the UDP for the audio chatting . The Windows Sockets API is a standard interface under Microsoft Windows for applications that use TCP and UDP. Windows Sockets provides services that allow applications to bind to a particular port and IP address on a host, initiate and accept a connection, send and receive data, and close a connection. There are two types of sockets:
• A stream socket provides a two-way, reliable, sequenced, and unduplicated flow of data using TCP.
• A datagram socket provides the bidirectional flow of data using UDP.
3.1.1 The TCP
To communicate, an application specifies the protocol, the IP address of the destination host, and the port of the destination application. Once the application is connected, information can be sent and received.
TCP is a reliable connection-oriented delivery service. The data is transmitted in segments.Connection-oriented means that a connection must be established before hosts can exchange data. Reliability is achieved by assigning a sequence number to each segment transmitted. TCP uses byte-stream communications, wherein data within the TCP segment is treated as a sequence of bytes with no record or field boundaries
A TCP connection is initialized through a three-way handshake. The purpose of the three-way handshake is to synchronize the sequence number and acknowledgment numbers of both sides of the connection, exchange TCP Window sizes, and exchange other TCP options such as the maximum segment size. The following steps outline the process:
The client sends a TCP segment to the server with an initial Sequence Number for the connection and a Window size indicating the size of a buffer on the client to store incoming segments from the server.
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