1. WEB API

2. API

3. APPLICATION PROGRAMMING INTERFACE
API
APPLICATION PROGRAMMING INTERFACE
is a set of subroutine definitions, protocols, and tools for building application software.
Purpose
API make it easier for developers to use certain technologies in building applications.

4. API Documentation describing API: Implementations:
List of functions (endpoints)
Calls (requests)
Returns (responses)
Implementations:
Library or framework that can be imported to develop an application
OS interfaces between an app and OS (POSIX, MacOS API, Windows API)
Remote APIs on remote servers

5. WEB (Remote) APIs
A server-side programmatic interface allows the client application to communicate with the server
Based on one or more publicly exposed endpoints and a defined request–response message system.
Uses the network to provide its services

6. NET Protocols IP TCP HTTP HTTPS
Address resolving and delivering packets
Transmission Control between applications over IP
Content container Level (application protocol)
Security Level
URL: Protocol + address + port + path on server (URI)
_https://best.server.com:8080/API/endpoints/cars?brand=FERRARI&color=RED

7. Web Services Desktop Apps Mobile apps DB Other servers Web API Smart
zhttps://best.server.com:8080/API/endpoints/cars?brand=FERRARI&color=RED
Desktop Apps
INTERNET
Endpoint
Mobile
apps
WEB
SERVER
Requests
Endpoint DB
Endpoint
Other
servers
Responses
Endpoint
Web API
Endpoint
Smart
Teapot

8. SOAP vs REST Simple Object Access Protocol
REpresentational State Transfer
is a protocol
uses services interfaces
Works on top of any communication
Protocol, even asynchronously
(TCP HTTP FTP SMTP)
Only XML
Security and authorization are
part of the protocol
Fully described and provide
information to users (WSDL)
is an architectural style
URL based services
HTTP/HTTPS only
JSON , XML, TEXT, HTML
Authorization and security must
be implemented separately
Easy to implement

9. Principles of REST
RESOURCES expose easily understood directory structure URIs.
REPRESENTATIONS transfer JSON or XML to represent data objects and attributes.
MESSAGES use HTTP methods explicitly (for example, GET, POST, PUT, and DELETE).
STATELESS interactions store no client context on the server between requests. The client holds session state.

10. HTTP methods
GET - Retrieve information. GET requests must be safe and idempotent, meaning regardless of how many times it repeats with the same parameters, the results are the same
POST - Request that the resource at the URI do something with the provided entity
PUT - Store an entity at a URI. PUT can create a new entity or update an existing one.
PATCH - Update only the specified fields of an entity at a URI
DELETE - Request that a resource be removed; however, the resource does not have to be removed immediately.
HEAD, OPTIONS, TRACE and CONNECT

11. CRUD - HTTP REQUESTS IN REST
DB operations
GET
POST
PUT
DELETE
PATCH
SELECT rows
INSERT new row
UPDATE row
DELETE row
UPDATE certain field

12. HTTP request status codes
indicate the result of the HTTP request.
1XX - informational
2XX – success (200 -OK, 201 – Created,204 - No Content)
3XX - redirection
4XX - client error (400-Bad Request, 401 Unauthorized, Forbidden, PNF)
5XX - server error

13. Request Structure A request line GET /images/logo.png HTTP/1.1
Request header fields
Accept-Language: en
Content-Type: text/html
Cookie: <cookie-list>
An empty line.
An optional message body.
JSON, TEXT, XML

14. Response Structure
A status line which includes the status code and reason message
HTTP/ OK
Response header fields
Content-Type: text/html
Allow: GET, HEAD.
An empty line.
An optional message body
JSON, TEXT, XML

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