基于TCP协议的简易即时通信软件设计与实现 - 包含源文件

Instant communication software based on TCP protocol plays a crucial role in today's fast-paced world. This paper discusses the design and implementation of a simple instant messaging system that allows multiple users to communicate in real-time and securely. The system operates on a client-server model, with the bottom-layer communication being facilitated through the SOCKET socket interface. The modern UNIX and Windows operating systems provide kernel-level support for the SOCKET interface, enabling developers to create portable TCP/IP communication programs. This ensures reliable transmission of information over the Internet. The system designed in this paper focuses on facilitating communication within a local area network. The server is responsible for authentication of client logins, storing friend information, and sending heartbeat messages. Clients use a peer-to-peer approach for message exchanges and can also transfer files. The paper begins by discussing synchronous sockets, asynchronous sockets, and multi-threading for concurrent task execution. It then delves into the use of XML serialized messages for communication between clients and servers. By implementing these technologies, the system achieves efficient and secure instant messaging functionality. Keywords: Instant Messaging, File Transfer, Socket, TCP Protocol.