Network

Hypertext Markup Language (HTML)

• A text-based approach to describe how content contained within an HTML file is structured.

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Hypertext Transfer Protocol (HTTP)

• It enables communications between clients and servers.
• It works as a request-response protocol between a client and server.

Anatomy of an HTTP request

• An HTTP request must have the following:
  • An HTTP method (like GET)
  • A host URL (like https://api.spotify.com/)
  • An endpoint path (like v1/artists/{id}/related-artists)
  • Optional:
    • Body
    • Headers
    • Query strings
    • HTTP version

Anatomy of an HTTP response

• A response must have the following:
  • Protocol version (like HTTP/1.1)
  • Status code (like 200)
  • Status text (OK)
  • Headers
  • Optional:
    • Body

HTTP methods

• POST, PUT, PATCH, and DELETE can change data on the server.

1. GET

• It requests data from a specified resource.

• Query string (name/value pairs) is sent in the URL of a GET request.

• It reads or retrieves a resource.

• A successful GET returns a response containing the information you requested.

• In a weather app, GET retrieves the current weather for a specific city.

2. POST

• It creates a new resource.

• It requires a body in which you define the data of the entity to be created.

• A successful POST request would be a 200 response code.

• In a weather app, POST adds weather data about a new city.

• POSTing multiple times would create multiple separate orders.

3. PUT

• It updates the entire resource with data that is passed in the body payload.

• If no resource matches the request, it will create a new resource.

• In a weather app, PUT updates all weather data about a specific city.

• Multiple PUT requests will update the same existing order.

4. HEAD

• It is like GET without the response body.

5. DELETE

• It deletes the specified resource.

• In a weather app, DELETE deletes a city we no longer wanted to track for some reason.

6. PATCH

• It modifies a part of a resource.

• You only need to pass in the data that you want to update.

• In a weather app, PATCH updates the rainfall for a specified day in a specified city.

7. OPTIONS

• It describes the communication options for the target resource.

8. CONNECT

• It starts a two-way communication (a tunnel) with the requested resource.

9. TRACE

• It performs a message loop-back test that tests the path for the target resource (useful for debugging purposes).

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Secure Shell (SSH)

• A network protocol that gives users, particularly system administrators, a secure way to access a computer over an unsecured network.

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Transmission Control Protocol (TCP)

• TCP and IP are the basic rules that define the Internet.
• TCP is a standard that defines how to establish and maintain a network conversation by which applications can exchange data.
  • It determines how to break application data into packets that networks can deliver.
  • It sends packets to and accepts packets from, the network layer.
  • It manages flow control.
  • It acknowledges all packets that arrive.
  • It handles the retransmission of dropped packets, as it’s meant to provide error-free data transmission.

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User Datagram Protocol (UDP)

• It reduces latency and jitter by not reordering packets or retransmitting missing data.
• It discards invalid data packets.