API Provides a way for applications to use the functionality and data for application to use the functionality and data of other applications over HTTP to feed a web application GUI with images, tests, and videos.

API consumers have the ability to request resources from API endpoints.

These endpoints represent specific parts of the API and are accessed using URLs. Each of the examples provided represents a distinct API, showcasing different functionalities and resources that can be interacted with.

API Endpoints :

• example.com/api/3/users/
• example.com/api/v3/customers/
• example.com/api/updated_on/
• example.com/state/1/

Collection: a group of resources such as /api/profiles/users

Subcollection:

refers to collection within a particular resource

/api/users/{user_id}/settings

Gateway:

• filters bad request
• monitor incoming traffic
• route each req. to proper service or microservice
• it also handles security controls such as authentication, encryption in transit using ssl, rate limit, load balancing

Microservices:

Modular piece of web app that handles a specific function

<aside> 💡 API Doc. might user colon or square bracket or curly bracket /api/v2/:customer_id or /api/v2/[customer_id] or /api/v2/{customer_id}

</aside>

API Contract : said to API Documentation

Standard web API Types

Restful API:

• Rest stands for representation state transfer
• it is set of Architectural constrant that defines how web shoulid work
• designed to improve upon inefficiencies of other older APIs, such as SOAP API
• Rest API Primiarly user the HTTP method GET, POST, PUT & DELETE to accomplish CRUD

API consumer can request resources from API endpoints, which is a URL for interacting with part of API

Acronym CRUD

Stands for Create, Read, Update and Delete

• Create a process of making new req. accomplished through POST method

• Read data retrieval, through GET req.

• Update: record modification through POST OR PUT overwritten

• Delete: Erasing record through Delete or POST

  ---

  6 Constraint

  Restful API depends/ works on 6 Constants, Rest is essentially a set of guidelines for an HTTP resource-based architecture.

  1. Uniform Interface: RestAPI Should have a uniform interface, the req. devices should not matter. All be able to access server in same way
  2. Client/ Server: RestAPI Should have client/ Server architecture, client are consumer of req. info. while server are provider of that info.
  3. Stateless: RestAPI should not require stateful communication
  4. Cacheable: Response from Rest API Provider should indicate weather the response is cacheable
  5. Layered System: Client should be able to req. data from endpoint without knowing about the underlying server architecture
  6. Code on Demand (Optional): Allows for code to be send to the client for execution

RESTful API may be different. It may have different method beyond CRUD It’s our set of authentication requirement, subdomain instead of Endpoint different rate-limit requirement

It can be configured to call their RestAPI without adhering to the standard

An RestAPI GET req. used to find out how many bedsheet are in store inventory

GET /api/v3/inventory item/pillow HTTP/1.1
HOST: googleshop.com
User-Agent: Google/11.0
Accept: application/json               
                                REQUEST

googleshop.com provided all information it had about bedsheet consumer need to filter the response if they need some specific details like only name & value.

The amount of data sent back is depends on how API is being programmed by the API providers

HTTP/1.1 200 OK
Server: RESTful server/0.1
Cache-control: no store
Content-type: application/json
{
"item":{
   "id":00101
   "name": "bedsheet"
   "count": 25
   "price":{
"currency": "USD"
"value":"19.99"
}
}
}
                  RESPONSE

Some Common Headers from that it’s high probability that it could be RESTful API

1. Authorization: used to pass the token or credentials to the API Providers

Authorization: Bearer Abdf123Ab

1. Content-type

used to indicate the type of media being transferred these diff from Accept, which states the media type you want to receive.

• application/json