Riddles

In this lab, we are going to explore how computers talk with each other. Every time you open a webpage in a web browser or use an app on your phone, your device communicates with one or more remote computers--asking for resources like web pages and images and fetching updates. The web page or app is probably also doing some unwelcome communication: loading advertisements and sending away a record of your behavior.

If you think about it, it's incredible that you can request information from any of the billions of computers on the Internet, and get a response almost instantly. In this lab, we are going to work with HTTP (HyperText Transfer Protocol), a protocol computers use to make requests and receive responses from other computers.

HTTP relies on a bunch of other fascinating technologies which we won't explore in this lab, including:

• The domain name system, which translates names like makingwithcode.org into IP addresses like 13.33.165.44
• TCP/IP, the process of packaging messages, routing them across the internet to their destination, and checking that they arrived intact.
• The physical networks of wires (or wifi/satellite links) connecting the computers to each other.

Requests and responses

Applications usually make HTTP requests for you, but you can make also make requests manually. http is a lovely program for making http requests.

💻 Run http -v get https://riddles.makingwithcode.org/all You should see the following:

1
$ http -v get https://riddles.makingwithcode.org/all
2
GET /all HTTP/1.1
3
Accept: */*
4
Accept-Encoding: gzip, deflate
5
Connection: keep-alive
6
Host: riddles.makingwithcode.org
7
User-Agent: HTTPie/3.2.1
8

9

10

11
HTTP/1.1 200 OK
12
Connection: keep-alive
13
Content-Length: 116
14
Content-Type: application/json
15
Cross-Origin-Opener-Policy: same-origin
16
Date: Tue, 05 Mar 2024 00:25:26 GMT
17
Referrer-Policy: same-origin
18
Server: nginx/1.22.0 (Ubuntu)
19
X-Content-Type-Options: nosniff
20
X-Frame-Options: DENY
21

22
{
23
    "riddles": [
24
        {
25
            "correct": 1,
26
            "difficulty": 0.6,
27
            "guesses": 4,
28
            "id": 1,
29
            "question": "Where do you get dragon milk?"
30
        }
31
    ]
32
}

HTTP Verbs

Every HTTP request uses a verb (also called a method). GET and POST are by far the most common, though there are others.

• GET is used when you want to fetch data from the server without changing anything.
• POST is used when you're making a change. For example, logging in, placing an order, unfriending someone on social media.

The riddle server has several additional endpoints; each requires either GET or POST. Give them a try:

Guessing a riddle

To guess the answer to a riddle, send a POST request to /guess, with the id of the riddle you're guessing and your answer. The response will tell you if you are correct. The riddle server keeps statistics on guesses and uses them to calculate riddle difficulty.

http -v post https://riddles.makingwithcode.org/guess id=1 answer="a short-legged cow"

Adding a new riddle

To add a new riddle, send a POST request to /new, with question and answer.

http -v post https://riddles.makingwithcode.org/new question="What have I got in my pocket?" answer="My precious"

After you add a new riddle, get the list of all the riddles and confirm that yours has been added.

Status Codes

So far, every response you have received from the server should have started with HTTP/1.1 200 OK. 200 is a status code, indicating how things went. There are lots of status codes, but in general:

• Codes in the 200s mean the request succeeded.
• Codes in the 300s mean you need to do something else--often the page has moved and you need to go to the new URL.
• Codes in the 400s mean you did something wrong: you asked for something that doesn't exist, you used the wrong verb, you didn't provide the required information, you don't have permission to see this, etc.
• Codes in the 500s mean something went wrong on the server.

Riddle client

The riddle server is a great way to share riddles with friends, but typing out each request will get tiresome quickly. Instead, let's use a client program which makes HTTP requests for us. client.py contains a program which lets us interact with the riddle server from the command line. api.py defines RiddleAPI, or an application programming interface for the riddle server.

Run the client program. You won't get too far before it crashes with a NotImplementedError: some of the methods of RiddleAPI are missing. Your job is to implement them. A few tips:

• Carefully read the RiddleAPI methods which have been implemented: get_all_riddles and guess_riddle. Use these as models for the others.
• RiddleAPI uses a library called requests to send HTTP requests. Use requests.get() for GET requests and requests.post() for POST requests.
• The result of requests.get() or requests.post() is a response object.
  • response.ok is a boolean (True/False) indicating whether the request succeeded (whether its status code is in the 200s).
  • response.json() returns the data structure sent in the response.