HTTP (The Hypertext Transfer Protocol)

User Agent

Kind of browser

Tim Berners-Lee

Knighted by Queen Elizabeth for his invention of the World Wide Web. He also invented HTTP and HTML.

Transport

Make client-server connections and optionally control transmission speed, check for errors, etc

Content-Type

Mime type

Accept

Mime types which browser can accept

Content-Length

Number of bytes

Query

Query string for a CGI program

Weak entity tag

Changes only when semantics of entity-body changes

Strong entity tag

Changes when any portion of resource changes

Application

Do useful work like Web browsing, email, and file transfer

Content-Language

English, for example

Physical

Specify what medium connects two nodes, how binary ones and zeros are differentiated, etc

Scheme

The protocol you are using

HTTP: hypertext transfer protocol

The rules governing the conversation between a Web client and a Web server

Server

Type of server

Port

TCP port number that protocol server is using

Path

Path and filename reference of object on server

Data Link

Route data packets within the local area network

Internet

Route packets between networks

Post

Sends information to be stored on server or as input to script

Put

Sends new copy of existing object to server

Communication

Server tells client what type of information is coming before information arrives

Parameters

Any specific parameters that object needs

Content-Encoding

Data compression

Date

Date and time

Expires

Date when file becomes invalid

Last-Modified

Date when last modified

HTML: hypertext markup language

Definitions of tags that are added to Web documents to control their appearance

Delete

Deletes object

Lower Layers

Handle communication between the client and server

Host

Host name or IP number

Fragment

Reference to a subset of an object

Head

Returns information about object

Get

Returns object

If-Modified-Since

Returns object only if more recent than given date Otherwise returns status code 304

Network Protocol

The set of rules governing a conversation between a client and a server

Protocol

The set of rules governing a conversation between people

Gateways

Translates from one protocol or service to another

Authorization

User password

Scripts

• Translates input from client • Calls other programs • Translates output from programs and returns it to client