The First RichCoin Bank of Santa Barbara

CS290B – Spring 2014

Hiranya – Alex – Chris – Emre - Stratos

Roadmap

• Introduction• APIs• Tutorial and demo• AWS for RichCoin• Questions

Introduction

• Central storage for all the RichCoins you’re going to mine this quarter.

• Validates submitted coins for correctness and uniqueness.

• Keeps score.• Accessible via a secure REST API.

System Design

Web Server

Database

Queue

Coin Validator

Client (You)

API Features

• Secured– OAuth 2.0 bearer token profile

• Throttled (Rate Limited)– Gold, Silver and Bronze tiers

• Separate production and sandbox environments

• Versioned

APIs

• Vault API– Mint new coins– Retrieve already minted coins

• Scoreboard API– Retrieve current score

• Admin API– Only for admins

Accessing the APIs: Step 1

• Send an e-mail to hiranya@cs.ucsb.edu• Specify following details:

– Group name: avengers2014– Group members:

• Steve Rogers• Tony Stark• Bruce Banner

• You will get a reply back with login credentials for the RichCoin API Store.

Accessing the APIs: Step 2

• Change your password…

• https://euca-128-111-179-147.eucalyptus.race.cs.ucsb.edu:9443/carbon

• Login using the username and password sent in the email.

• Click on “Configure” tab left to the main menu.• Select “Users and Roles”.• Click on “Change My Password”.

Accessing the APIs: Step 3

• Register your applications…

• https://euca-128-111-179-147.eucalyptus.race.cs.ucsb.edu:9443/store/

• Login using your username and password.• Select “My Applications”.• Enter a meaningful name for the application

you’re going to implement using the APIs.

Accessing the APIs: Step 4

• Subscribe to the APIs…

• Click on each API, select the application you registered in the previous step, select a throttling tier and click “Subscribe”.

Accessing the APIs: Step 5

• Obtain API keys…

• Select “My Subscriptions”.• Make sure your application is selected in the

dropdown.• Click “Generate Keys”.– You can generate separate keys for production and

sandbox environments.

Accessing the APIs: Step 6

• At this point you are all set.• Simply send your API key to the server along

with all your requests.• API key should be sent as a HTTP

Authorization header:– Authorization: Bearer <Your-API-Key>

Production & Sandbox Setups

• You can get separate keys to access the production and sandbox environments.

• APIs and their URLs are identical in the two environments.

• Use the sandbox environment to test your application.• For the contest we will only consider the score in the

production environment.

• Note: Sandbox environment is not backed up and your data may get lost.

Throttling/Rate Limiting

• The access tier you selected when subscribing to an API determines how many requests you can send to an API in a minute.– e.g. Gold tier: Allows 20 req/minute

• Once you exceed your per-minute quota, you will start receiving errors (503 Service Unavailable).

Vault API

• Minting a new coin• POST a JSON payload to /vault/1.0.0– solution: Your solution matrix encoded into a string of 1’s

and 0’s (row-major form)– clientTimestamp: A UTC timestamp generated from the

client machine (milliseconds since epoch)

{ “solution”: “100000011000100”, “clientTimestamp”: 123456}

Vault API: Response

• When you submit a new solution, you will get a unique ID back in return.

• Use this ID to query the status of your solution.– GET /vault/1.0.0/<Unique-ID>

{ “coinId” : “1ab3jshfshns”, “ status” : 0, …. }

Scoreboard API

• Retrieve the current score• Send a GET request /scoreboard/1.0.0• You get a JSON payload back with all the users

and the number of coins they have mined– Application details available in payload for each

user– Scores are sorted in descending order

API Quick ReferenceAPI Call Description

POST /vault/1.0.0 Mint a new coin

GET /vault/1.0.0 Get all coins mined so far

GET /vault/1.0.0/<coinId> Get a specific coin

GET /scoreboard/1.0.0 Get the current scoreboard

GET /scoreboard/1.0.0/<username> Get the score of a specific user

Coin Status CodesCode Description

0 Pending validation

1 Coin validated successfully (Yay!)

2 Coin failed to validate (Back to the mines)

• Every RichCoin resource you obtain from the API has a “status” attribute.

• You can get a coin status of “2” due to many reasons. The exact reason is sent as an error code in the “reason” field (see next slide).

Error CodesError Code Description

100100 clientTimestamp was unacceptable.

100101 Solution was incorrect.

100102 Solution was isomorphic to an existing solution.

100103 Solution was malformed.

100104 Provided coin ID was invalid.

200100 Database error.

200101 Unexpected runtime error.

• Last 2 are not your fault. Send us an e-mail if you ever see them.

Common Errors/Mistakes

• Calling APIs without subscribing or without the API key

• Sending the API key in a wrong format– Must be sent in the Authorization header prefixed

by the string “Bearer ” (there should be a space between “Bearer” and the API key)

• Getting the production and sandbox keys mixed up

Common Errors/Mistakes

• Invalid clientTimestamp value in the request to mint coins– Must be a UTC timestamp (Milliseconds elapsed

since Unix epoch)– Make sure your clock is synchronized against some

well-known time service• Exceeding your throttling limit (per-minute,

per-API quota)

Known Issues

• Location header on the response to /vault/1.0.0 is wrong.

• We are working on getting a more static hostname for the service endpoint.– Until then some changes may occur– Do not hardcode the hostnames to your apps yet

• API Console feature in API store doesn’t work.• If you see any other weirdness, let us know

asap.

Application Development Best Practices

• Log all important events and API calls.– With timestamps

• Keep local copies of the RichCoins mined.– Make a copy of the solution matrix before

submitting to the bank• “In large distributed systems, component

failures are the norm rather than the exception.” – GGL03

Sample Client App

• We implemented an interactive tool to invoke and test the APIs– Implemented in Python– Can use as an example on how to call the API

programmatically• Simply add your API key to settings.yaml and

fire away

AWS for RichCoin

CS290B – Spring 2014Alex Pucher

AWS for RichCoin

• Single account per group– Only EC2 and S3– Limited to USD 100.0 per group– Using spot instances recommended

• You go over, you get nuked– You’ll get a warning (maybe)– Don’t store critical data on AWS

AWS for RichCoin

• You’ll receive:– Group account and password– AWS creds– EC2 Key pair– S3 bucket

• Must use your key pair and assigned bucket– Else, access is blocked

Disclaimers

• Policy enforcement questionable– Message if something doesn’t work but should– Stuff may disappear

• DO NOT store critical data on AWS

• https://richcoin.signin.aws.amazon.com/

Questions?