Specifying the API

The very first thing that has to be defined for any web API is the operations it will expose. According to the REST principles, an operation is exposed by an HTTP method and a URI. The action performed by each operation should not contradict the natural meaning of its HTTP method. The following table specifies the operations of our API in detail:

Method	URI	Description
GET	/contacts	Retrieves all available contacts.
GET	/contacts/:primary-phone-number	Retrieves a single contact by its primary phone number.
POST	/contacts/	Updates a contact, if it exists. Otherwise, it creates a new contact.
PUT	/contacts/	Creates a new contact.
DELETE	/contacts/:primary-phone-number	Deletes an existing contact.
GET	/groups	Retrieves all available groups that have contacts assigned.
GET	/groups:group-name	Retrieves a unique list of all the groups assigned to contacts.
DELETE	/groups/:name	Deletes a group from all the contacts...