What are APIs?

 What are APIs?

What are APIs


- If you look up the term API, you'll probably find a number of definitions—some of which are rather difficult to understand.

- But the key underlying idea is in the name—Application Programming Interface.

- An API is an interface. 

- It's something that has been created to help two different systems interact with one another.

- A key idea to remember is that API functionality is defined independently of the actual implementation of the provider.

- Essentially, you don't need to understand the entirety of the application implementation in order to interact with it through the API.


Application programming interfaces APIs:

1- It doesn't expose the implementation to those who shouldn't have access to it.

2- The API provides a standard way of accessing the application.

3- It makes it much easier to understand how to access the application's data.


How do APIs Work?
How APIs Work

Client-Server Communication:

- When you got to a bank, the bank teller acts as an intermediary or interface between you and the bank vault.

- And this is the same type of relationship we see in client-server communication.

- The user or client makes a request to the API server, which parses the requests, queries the database, formats a response, and then sends it back.

Here is the process listed out:

1- The client sends a request to the API server.
2- The API server parses that request.
3- Assuming the request is formatted correctly, the server queries the database for the information or performs the action in the request.
4- The server formats the response and sends it back to the client.
5- The client renders the response according to its implementation.


Internet Protocols (IPs):

- Internet Protocol (IP) is the protocol for sending data from one computer to another across the internet.

- Each computer must have a unique IP address that identifies it from all other computers connected to the internet.

There are many other internet protocols including:

- Transmission Control Protocol (TCP) is used for data transmission.
- Hypertext Transmission Protocol (HTTP) is used for transmitting text and hyperlinks. 
- File Transfer Protocol (FTP) is used to transfer files between server and client.


RESTful APIs:

- REST stands for Representational State Transfer, which is an architectural style introduced by Roy Fielding in 2000.

Here's a short summary of the REST principles:

- Uniform Interface: Every rest architecture must have a standardized way of accessing and processing data resources.
- This includes unique resource identifiers (i.e., unique URLs) and self-descriptive messages in the server response that describe how to process the representation (for instance JSON vs XML) of the data resource.

- Stateless: Every client request is self-contained in that the server doesn't need to store any application data in order to respond to subsequent requests.

- Client-Server: There must be both a client and server in the architecture.

- Cacheable & Layered System: Caching and layering increase networking.


 Why RESTful are stateless?

- It might appear easier to design a server that isn't stateless. 
- There is a reason why RESTful web servers are not allowed to remember anything about the previous requests that the user has sent. 
- In short, stateless servers make your applications scalable.

Why RESTful are stateless


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