21 IncTyler Julian
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In this tutorial we'll show you how to build and host a simple game of skill on your 21 Bitcoin Computer where users must answer a trivia question correctly to win bitcoin.
You will need the following items:
- A 21 Bitcoin Computer, with built-in mining and software
- The latest version of the 21 software, obtained by running
21 updateas described in the [setup][18] process. - Do the [Introduction to the 21 Bitcoin Computer][19] tutorial
- Do the [Working with Multiple 21 Users][20] tutorial
If you've done all that, you are ready to go. Let's get started!
Follow the instructions in the
[Working With Multiple 21 Users][20] tutorial to set
up the twenty-client, twenty-server, and twenty-server-2 users
and install Flask.
Now let's set up a folder to house our app:
mkdir trivia-server && cd trivia-server
Go to that directory, open a file named trivia-server.py in a text editor,
and paste in the following code:
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import os
import json
import random
# import flask web microframework
from flask import Flask
from flask import request
# import from the 21 Developer Library
from two1.lib.wallet import Wallet
from two1.lib.bitserv.flask import Payment
app = Flask(__name__)
wallet = Wallet()
payment = Payment(app, wallet)
question_bank = {
'Who is the inventor of Bitcoin': 'Satoshi Nakamoto',
'How many satoshis are in a bitcoin': '100000000',
'What is the current coinbase reward (in BTC) for mining a block': '25'
}
question_list = list(question_bank.keys())
# endpoint to get a question from the server
@app.route('/question')
def get_question():
return question_list[random.randrange(0,len(question_list))]
# machine-payable endpoint that pays user if answer is correct
@app.route('/play')
@payment.required(1000)
def answer_question():
# extract answer from client request
answer = request.args.get('selection')
# extract payout address from client address
client_payout_addr = request.args.get('payout_address')
# extract question from client request
client_question = request.args.get('question')
# check if answer is correct
if answer.lower() == question_bank[client_question].lower():
try:
txid = wallet.send_to(client_payout_addr, 2000)
except Exception as e:
return ('Exception : ' + str(e), 500)
return "Correct!"
else:
return "Incorrect response."
if __name__ == '__main__':
app.run(host='0.0.0.0')
We're all set! This microserver includes our bitcoin payment processor and a flask route with some simple game logic to handle client requests.
Make sure the server has some bitcoin for payouts by running:
21 mine
Now run the following command to start the server:
python3 trivia-server.py
Now open up a new terminal window and connect to your 21 Bitcoin
Computer as twenty-client. Create a folder to house the client
project:
mkdir trivia-client && cd trivia-client
Let's import our wallet and a BitTransferRequests client for making
bitcoin-enabled HTTP requests in a new file called play.py. Then
we'll finish out the file with the code to send the request to the
server:
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import json
import os
# import from the 21 Developer Library
from two1.commands.config import Config
from two1.lib.wallet import Wallet
from two1.lib.bitrequests import BitTransferRequests
# set up bitrequest client for BitTransfer requests
wallet = Wallet()
username = Config().username
requests = BitTransferRequests(wallet, username)
# server address
server_url = 'http://localhost:5000/'
def play():
# get the question from the server
response = requests.get(url=server_url+'question')
question = response.text
ans = input("Question: {}?\n".format(question))
sel_url = server_url + 'play?question={0}&selection={1}&payout_address={2}'
answer = requests.get(url=sel_url.format(question,ans, wallet.get_payout_address()))
print(answer.text)
if __name__ == '__main__':
play()
That's it! Run the following code to start the game.
python3 play.py
If you get a question right, the twenty-client should win some
bitcoin (which will show after they're confirmed on the blockchain)
and the twenty-server will see its bitcoin balance decrement.
If you get the following error message, make sure to run 21 mine and
21 flush to get enough on-chain satoshis on the server. The server may
also need to wait for a confirmation before sending a second payment.
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">
<title>500 Internal Server Error</title>
<h1>Internal Server Error</h1>
<p>The server encountered an internal error and was unable to complete your request. Either the server is overloaded or there is an error in the application.</p>
You've learned how to build a very simple game in which someone can win or lose bitcoin. Given these fundamentals, you can extend the code to build a trivia game or other game of skill. Here are some ideas on what to build next:
- Write a simple 2-player game of skill, like checkers or chess, with a prize for the winner. A full list of abstract strategy games for inspiration is [here][109] and [here][110].
Learn game theory by implementing one of the famous two-player games. A full list is [here][111]. * Extend this example by creating a database of trivia questions on different topics. You can also reuse or modify existing trivia quiz banks like the ones [here][112] or [here][113], though make sure that you have the license to these questions! * Make this example high performance by replacing the simple Flask server with a proper deployment on the underlying hardware. See [this][114] and [this][115] for more information.
If you build anything like this and want to earn some bitcoin for your efforts, write it up and submit it as a [bitcoin tutorial][116]. If we decide to publish it on our site, you'll win $200 in BTC!
You can also come to our Slack channel at slack.21.co to find other folks with 21 Bitcoin Computers to play your game and give feedback. We look forward to seeing you there!
Just as a reminder, you can send bitcoin mined or earned in your
21.co balance to the blockchain at any time by running 21 flush . A transaction will be created within 10 minutes,
and you can view the transaction id with 21 log.
Once the transaction has been confirmed, you can check the
balance in your bitcoin wallet from the command line with
wallet balance, and you can send bitcoin from your
wallet to another address with wallet sendto $BITCOIN_ADDRESS $BTC_AMOUNT --use-unconfirmed. Make sure
to use the amount in BTC, not in Satoshi; the
--use-unconfirmed flag ensures that you can send even if you
have unconfirmed transactions in your wallet.
Ready to try out your bitcoin-payable server in the wild? Or simply want to browse and purchase from other bitcoin-enabled servers? Head over to the [21 Developer Community][117] at slack.21.co to join the bitcoin machine-payable marketplace hosted on the 21 peer-to-peer network.
Check out all the Bitcoin Apps you can build with the 21 Bitcoin Computer.
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Authors
Tyler Julian
If you have any questions or issues, please drop us a line at [[email protected] ][119] or join our Slack community.
This content is licensed under a [Creative Commons Attribution-ShareAlike 4.0 International License][120].
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(c) 2016, 21.co
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http://stackoverflow.com/questions/11067191/public-domain-trivia-database-for-game [114]: http://blog.miguelgrinberg.com/post/the-flask-mega-tutorial-part-xvii-deployment-on-linux-even-on-the-raspberry-pi [115]: http://tutos.readthedocs.org/en/latest/source/ndg.html [116]: /submit-bitcoin-tutorial [117]: https://slack.21.co/ [118]: /cdn-cgi/l/email-protection#c2fde4b1b7a0a8a7a1b6ff96aaabb1e2aeadada9b1e2aeaba9a7e2a3e2a5adada6e2b0a7b1adb7b0a1a7e2a4adb0e2aea7a3b0acabaca5e2aaadb5e2b6ade2a0b7abXld Bitcoin apps&body=Here's the URL: https%3A//21.co/learn/build-a-simple-bitcoin-game/ [119]: /cdn-cgi/l/email-protection#f3808683839c8187b3c1c2dd909c [120]: https://creativecommons.org/licenses/by-sa/4.0/ [121]: //twitter.com/21 [122]: //medium.com/@21