HTTP and Web API Overview

CS – Advanced Programming Concepts

Chess Server Review

Clients and Server Diagram

Chess Server Diagram

HTTP Overview

How HTTP Works

HTTP Request Diagram

Client connects to Server

• Client establishes a network connection with the server
• A connection allows the client to send bytes to the server and vice versa

Client connects to Server (cont. 1)

• In order to connect, both the client machine and server machine must have IP addresses (e.g., 128.187.80.20)
• The client program must know the server’s IP address in order to connect
• Just like you must know someone’s phone number in order to call them
• IP addresses are hard to work with and remember, so we normally specify a server’s IP address using a “domain name” (e.g., “www.google.com”)
• The client uses the “domain name service” (DNS) to convert the server’s domain name to an IP address

Client connects to Server (cont. 2)

• The server machine will probably be running multiple programs, many of which will be using the internet
• Therefore, the server’s IP address is not sufficient for the client to connect to the server program�����

• Each server program communicates on a particular “port” number (e.g., 80). A port number is an unsigned integer in the range 1 - 65535
• The client must know both the server program’s IP address and port number in order to connect to it

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HTTP GET Requests

Browsing the Web with HTTP �(GET Request)

• URL
• https://www.google.com:443/images/branding/googlelogo/1x/googlelogo_color_272x92dp.png

Browsing the Web with HTTP �(GET Response)

Web API Call with HTTP (GET Request) – Get “event” request

• URL
• http://macho.cs.byu.edu:7979/event/12345

Web API Call with HTTP (GET Response)

Ticket to Ride Web API GET example

• Get list of games
• Description: Returns list of currently-running games
• URL Path: /games/list
• HTTP Method: GET
• Request Body: None
• Response Body: JSON of the following form:

{ "game-list": [

{ "name": "the game", "player-count": 3 },

{ "name": "work game", "player-count": 4 },

{ "name": "church game", "player-count": 2 }

]

}

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HTTP POST Requests

Browsing the Web with HTTP �(POST Request)

• URL
• https://www.google.com:443/search

Browsing the Web with HTTP �(POST Response)

Web API Call with HTTP (POST Request)

• URL
• https://macho.cs.byu.edu:7979/login

Web API Call with HTTP �(POST Response)

Ticket to Ride Web API Post Example

• Claim route
• Description: Allows player to claim route between two cities
• URL Path: /routes/claim
• HTTP Method: POST
• Request Body: JSON of the following form:

{ "route": "atlanta-miami" }

• Response Body: None

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HTTP Methods

(request types)

HTTP Methods

• GET: Retrieve data
• A read operation in a REST API
• Body should normally not be included in request
• POST: Submit something to the specified resource, often causing a change or side effect
• A create operation in a REST API
• Body included in request

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• PUT: Replace the specified resource
• An update operation in a REST API
• Body included in request
• DELETE: Delete the specified resource
• A delete operation in a REST API
• Body should normally not be included in request
• Other methods that are rarely used
• HEAD, OPTIONS, TRACE, PATCH

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Citations

Diagrams created by Ken Rodham and Jerod Wilkerson