Chapter 2:Application Layer Our goals: r learn about protocols r conceptual, by examining popular implementation application-level aspects of network protocols application protocols 冬HTTP transport-layer *FTP service models SMTP POP3 IMAP *client-server DNS paradigm r programming network peer-to-peer applications paradigm socket API 2:Application Layer 32: Application Layer 3 Chapter 2: Application Layer Our goals: r conceptual, implementation aspects of network application protocols v transport-layer service models v client-server paradigm v peer-to-peer paradigm r learn about protocols by examining popular application-level protocols v HTTP v FTP v SMTP / POP3 / IMAP v DNS r programming network applications v socket API