Many newer application programmers are realizing the need to open their core functionality to a greater audience. Providing easy, unfettered access to your core API can help get your platform accepted, and allows for mashups and easy integration with other systems.

→ REST is the underlying architectural principle of the web and depends on HTTP headers for direction.
→ HTTP is oriented around verbs and resources. GET, POST(most commonly used)
→ To modify and remove, PUT and DELETE used respectively.

Basic Authentication level:  Security and data binding is the most pririty when you are creating APIs. Here are some basic points needed to be check:

→ SSL support, https
→ Check the request type, request source, browser, device
→ It may have a key/device id to check that the request made from a registered device

Followings are the example API URI,

URL          | HTTP Method  | Operation

/api/user/3  | GET          | Returns a JSON object containing some information for a user

/api/add     | POST         | Adds new user data to be stored in server

API request and response : To get a detailed information about a specific user, followings are the example request and response in JSON format to be parsed and used.

Request

GET /user/3
Accept: application/json

Response

200 OK
Content-Type: application/json

{
"user": {
"id": 3,
"name": "Jack",
"country": "Austria",
}
}