HTTP (HyperText Transfer Protocol) is the foundation of data communication on the World Wide Web, enabling the fetching of resources such as HTML documents, images, videos, and other types of content. Here's an in-depth look at HTTP:
History
- HTTP was developed by Tim Berners-Lee at CERN in 1989 as part of the project to create the World Wide Web. The first version was simply referred to as HTTP/0.9, which was extremely basic and only allowed for the retrieval of HTML files.
- HTTP/1.0, introduced in 1996, added features like headers, request methods beyond GET, and the ability to handle other types of documents besides HTML.
- HTTP/1.1, standardized in RFC 2616 in 1999, improved upon HTTP/1.0 by adding persistent connections, allowing multiple requests and responses to be sent over a single TCP connection, and introducing pipelining, where multiple requests can be sent without waiting for responses.
- HTTP/2, formalized in 2015, aimed to reduce latency by compressing headers, multiplexing requests over a single connection, and server push capabilities.
- HTTP/3 is currently being developed, focusing on using QUIC (Quick UDP Internet Connections) to reduce latency further by using UDP instead of TCP.
Core Concepts
- Request-Response Model: HTTP uses a client-server model where the client sends a request to the server, which then returns a response.
- Stateless Protocol: Each request from client to server is independent, meaning the server does not retain information about the client between requests. However, mechanisms like cookies can be used to maintain state.
- Methods: HTTP defines several request methods like GET, POST, PUT, DELETE, etc., each with a specific purpose in interacting with resources.
- Status Codes: Responses include status codes like 200 (OK), 404 (Not Found), and 500 (Internal Server Error), indicating the result of the request.
- Headers: Both requests and responses can include headers for additional information, like content type, content length, cookies, etc.
- URIs: Uniform Resource Identifiers are used to identify resources on the web.
Security
While HTTP itself does not provide security, it can be secured using:
Modern Developments
- HTTP/2: Introduced features like multiplexing, header compression, and server push to improve performance.
- HTTP/3: Aiming to solve issues related to head-of-line blocking by using QUIC.
References
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