Module 1 CS290

HTTP (Hypertext Transfer Protocol)

A protocol describing how clients and servers exchange messages.

URL (Uniform Resource Locator)

A naming infrastructure used to represent resources (documents) on the web.

HTML (Hypertext Markup Language)

A markup language for describing the structure of documents retrieved over the web.

The 3 Core Technologies of the WWW

HTTP, URL, and HTML.

CRUD (Acronym)

Create, Read, Update, and Delete.

Web Server (Function)

Supports writing and running programs to process HTTP requests and business logic.

CSS (Cascading Style Sheets)

A language used for describing the presentation (styling) of web documents.

JavaScript (Primary Role)

A programming language used for client-side interactivity and server-side logic.

Web Services (Definition)

Applications where the end user of a document is a program, often using JSON or XML.

TCP/IP Protocol (Analogy)

The mechanism that establishes the "phone connection" so HTTP can "speak."

DNS (Domain Name System)

A system that maps human-readable hostnames to IP addresses.

HTTP Request: Part 1

The Request Line (Method, Resource, Version).

HTTP Request: Part 2

Request Headers (Name:Value pairs).

HTTP Request: Part 3

A blank line.

HTTP Request: Part 4

An optional body (used in POST, empty in GET).

GET Method (Use)

Used to retrieve or read a resource from a server.

POST Method (Use)

Used to add or send data to a server.

HTTP Status Code 200

OK: The request was successful.

HTTP Status Code 400s

Client Error: The request failed due to incorrect syntax or client issues.

HTTP Status Code 500s

Server Error: The request failed due to a problem on the server side.

Content-Type Header

Tells the client the format of the resource (e.g., text/html).

URI (Uniform Resource Identifier)

A broad category that includes both URLs (locations) and URNs (names).

URL Scheme (Example)

The protocol used (e.g., http, https, ftp, file).

URL Domain Name

The name of the host machine where the resource is located.

URL Port 443

The standard port number reserved for HTTPS servers.

URL Path to Resource

Identifies the specific file or program on the server (e.g., /a/b/c.html).

URL Query Parameters

Optional key-value pairs preceded by a "?" used to provide extra data to a program.

URL Anchor/Fragment

Preceded by a "#", it links to a specific location within the resource.

The "Home Page" Convention

Most servers map a request for "/" to "/index.html".