Network Communication

Four Layers of Network Communication

Understanding Sockets Deeply

1. A network communication tool calling the OS kernel. On creation, choose TCP (“three-way handshake, four-way wave-off”) or UDP one-shot communication.

2. Sockets sit below the application layer.

What the Application Layer Solves

What content you transmit, e.g.:

• FTP transfers files;

• SSH remote commands.

• SMTP and POP3 email;

• Most common: HTTP

From Plain Text to HTML

Plain text structure is poor for display; structured data helps. Wrapping text is HTML:

For browser interaction, add JavaScript; browsers add a JS parser.

Extract JS parsing—even as backend—that is Node.js.

HTTP

Hypertext Transfer Protocol; the browser is the client.

HTTP status codes: http://tool.oschina.net/commons?type=5

Server Development Work

• Parse client request messages

• Support multithreaded concurrent access

Parameter Passing

• Query string after ? in URL