即时通讯系统设计英文论文
The server sends back a TCP segment containing its chosen initial Sequence Number, an acknowledgment of the client's Sequence Number, and a Window size indicating the size of a buffer on the server to store incoming segments from the client.
The client sends a TCP segment to the server containing an acknowledgement of the server's Sequence Number.
Figure 3.1.1 process of sending messages between servers and cients based on TCP
3.1.2 The UDP
UDP provides a connectionless datagram service that offers unreliable, best-effort delivery of data transmitted in messages. This means that the arrival of datagrams is not guaranteed; nor is the correct sequencing of delivered packets. UDP does not recover from lost data through retransmission. UDP is used by applications that do not require an acknowledgment of receipt of data and that typically transmit small amounts of data at one time.
Figure 3.1.2 process of sending messages between servers and cients based on UDP
3.2 Detail design
3.2.1 Data Flow Diagram
3.2.1.1 Client Data Flow Diagram
Figure 3.2.1.1 Client Data Flow Diagram
3.2.1.2 Server Data Flow Diagram
Figure 3.2.1.2 Server Data Flow Diagram
3.2.2 User case Diagram
3.2.2.1 User case Diagram server
Figure 3.2.2.1 The user case diagram for the server
3.2.2.2 User case Diagram client
Figure 3.2.2.2 The user case diagram for the client
3.2.3 Class Diagram
3.2.3.1 Client Class Diagram
Figure 3.2.3.1 Client Class Diagram
3.2.3.2 Server Class DiagramFigure 3.2.3.2 Server Class Diagram
3.2.4 Sequence Diagram
3.2.4.1 Client Sequence Diagram
Figure 3.2.4.1 Client Sequence Diagram
http://www.youerw.com/Diagram
Figure 3.2.4.2 Server Sequence Diagram3.3 Implementation
3.3.1 The main function
The chatting application have four main function, there is Single person to person chatting、Single to Multiple chatting、File transmission、Audio chatting. The different function can user the different form to running, the next is introducing the four main functions.
3.3.1.1 Single person to person chatting
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.
3.3.1.2 Single to Multiple chatting
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.
3.3.1.3 File transmission
The online users could share the files by peer-to-peer network.
3.3.1.4 Audio chatting
It is an essential function to improve the reality and speed of the communication. The content will get high security.
3.3.2 Diagram of four main functionthe main function user like follow diagram
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