2.1 Principles of Application Layer

2.1.1 Network Application Architectures

2.1.2 Process Communicating

2.1.3 Transport Services Available to Applications

2.1.4 Transport Services Available Provided by the Internet

2.1.5 Application-Layer Protocols

2.1.6 本书涉及的网络应用

5种重要的：Web、文件传输、电子邮件、目录服务、流式视频、P2P