3 - Customize your kingdom (Windows)

Zero to DAPP 3 of 4 for Windows (or macOS/Linux)

In this page, you examine and modify the Animal Kingdom DApp you built in part 2. You’ll review the underlying code and locate the portions of it which fulfill the requirements necessary to qualify an application for App Mining. You’ll expand your knowledge of the application by extending it. Finally, you’ll learn how to deploy a DApp.

This page contains the following topics

Before you get started

Before you continue, make sure you can locate the key files and directories (folders) in your project. You’ll need to make sure you have opened a terminal and have changed directory to the top of your Animal Kingdom project.

If you find it easier to navigate, you can use the Finder as well. Just remember you’ll need the command line to run your project.

Understand the Animal Kingdom application code

The Animal Kingdom application has two major components, React and Blockstack. React is used to build all the web components and interactions. You could replace React with any framework that you like; Blockstack is web framework agnostic. This section does not explain the React in any detail; The discussion focuses on the Blockstack Javascript library the DApp instead.

The Blockstack Javascript library is all a developer needs to create a DApp. It grants the application the ability to authenticate a Blockstack identity and to read and write to the user’s data stored in a Gaia hub.

Authenticating user identity

The src/App.js file creates a Blockstack UserSession and uses that session’s isUserSignedIn() method to determine if the user is signed in or out of the application. Depending on the result of this method. The application redirects to the src/SignedIn page or to the src/Landing.js page.

 import React, { Component } from 'react'
 import './App.css'
 import { UserSession } from 'blockstack'

 import Landing from './Landing'
 import SignedIn from './SignedIn'

 class App extends Component {

   constructor() {
     this.userSession = new UserSession()

   componentWillMount() {
     const session = this.userSession
     if(!session.isUserSignedIn() && session.isSignInPending()) {
       .then((userData) => {
         if(!userData.username) {
           throw new Error('This app requires a username.')
         window.location = `/kingdom/${userData.username}`

   render() {
     return (
       <main role="main">
           {this.userSession.isUserSignedIn() ?
             <SignedIn />
             <Landing />

 export default App

The first time you start the application, this code determines if the user has signed into the DApp previously. If not, it opens the Landing.js page. This page offers the user an opportunity to Sign in to Blockstack.

Clicking the button ends up calling the redirectToSignIn() method which generates an authentication request and redirects the user to the Blockstack Browser to approve the sign in request. The actual Blockstack sign-in dialog depends on whether the user already has an existing session in the Blockstack Browser.

Signing in with an identity is the means by which the user grants the DApp access. Access means the DApp can read the user profile and read/write user data for the DApp. Data is encrypted at a unique URL on a Gaia storage hub.

The source code imports UserSession from the Blockstack library. Data related to a given user-session is encapsulated in the session. In a web browser, UserSession default behavior is to store session data in the browser’s local storage. This means that app developers can leave management of session state to users. In a non-web browser environment, it is necessary to pass in an instance of AppConfig which defines the parameters of the current app.

App Mining Requirement: Blockstack Authentication

To participate in application mining your application must integrate Blockstack authentication.

Get and put user data to a Gaia Hub

Gaia is the Blockstack data storage hub (https://hub.blockstack.org). Once a user authenticates, the application can get and put application data in the user’s storage. After a user signs in, the SignedIn.js code checks the user’s Gaia profile by running the loadMe() method.

loadMe() {
    const options = { decrypt: false }
    this.userSession.getFile(ME_FILENAME, options)
    .then((content) => {
      if(content) {
        const me = JSON.parse(content)
        this.setState({me, redirectToMe: false})
      } else {
        const me = null

        this.setState({me, redirectToMe: true})

Most of the imports in this file are locally coded React components. For example, Kingdom.js, EditMe.js, and Card.js. The key Blockstack imports is the UserSession and an appConfig which is defined in the constants.js file.

The loadMe() code uses the Blockstack’s UserSession.getFile() method to get the specified file from the applications data store. If the users’ data store on Gaia does not have the data, which is the case for new users, the Gaia hub responds with HTTP 404 code and the getFile() promise resolves to null. If you are using a Chrome Developer Tools with the DApp, you’ll see these errors in a browser’s developer Console.

After a user chooses an animal persona and a territory, the user presses Done and the application stores the user data on Gaia.

saveMe(me) {
  this.setState({me, savingMe: true})
  const options = { encrypt: false }
  this.userSession.putFile(ME_FILENAME, JSON.stringify(me), options)
  .finally(() => {
    this.setState({savingMe: false})

The Blockstack putFile() stores the data provided in the user’s DApp data store. By default, putFile() stores data in an encrypted format which means only the user that stored it can view it. You can view the URL for the data store from a user’s profile. Because this application wants other users to view the persona and territory, the data is not encrypted, so the encrypt option is set to false.

If you tested your Animal Kingdom, you can see this on your profile. To see your profile, go to the Blockstack explorer and search for your ID:

App Mining Optional: Gaia Storage

Use of Gaia storage is not required for application mining. Keep in mind, using Gaia may make data storage easier as it is designed to work in the Blockstack Ecosystem.

Application configuration

Your DApp contains three pages Animals, Territories, and Other Kingdoms that are derived from three code elements:

  • The src/constants.js file defines the application’s data profile (AppConfig).
  • The public\animals directory which contains images.
  • The public\territories directory which contains images.

In the next section, you extend your Kingdom’s configuration by modifying these files.

Add a territory

If your application is still running in localhost stop it with a CTRL-C from your keyboard.

  1. Decide what kind of territory to add — desert, ocean, or city!

    This example adds Westeros, a fictional territory.

  2. Search for an image to represent your new territory.

    Google images is a good place to find a JPEG image of Westeros.

  3. Save the image to the public/territories folder in your Animal Kingdom project code.

    Warning: The territory filename must be all lower case and have a .jpg extension. For this example, the territory image is saved in the westeros.jpg file.
  4. Use the ls command to confirm your file appears in territories directory and has the correct name.

     PS C:\animal-kingdom-master> ls .\public\territories\
     Directory: C:\animal-kingdom-master\public\territories
     Mode	LastWriteTime	Length Name
     -a		2/26/2019	6:09	AM	132814	forest.jpg
     -a		2/26/2019	6:09	AM	128272	tundra.jpg
     -a		2/26/2019	6:31	AM	1087534	westeros.jpg
     PS C:\animal-kingdom-master>
  5. Open the src\constant.js file in your favorite editor.
  6. Scroll down to the section that defines the Territories.

    export const TERRITORIES = [
        id: 'forest',
        name: 'Forest',
        superpower: 'Trees!'
        id: 'tundra',
        name: 'Tundra',
        superpower: 'Let it snow!'
  7. Add your new territory.

    export const TERRITORIES = [
        id: 'forest',
        name: 'Forest',
        superpower: 'Trees!'
        id: 'tundra',
        name: 'Tundra',
        superpower: 'Let it snow!'
        id: 'westeros',
        name: 'Westeros',
        superpower: 'The Iron Throne!'
  8. Save and close the constant.js file.
  9. Back in a terminal window, restart your application.

    c:\animal-kingdom-master> npm run start
  10. After the application starts, navigate to the Territories page and look for your Westeros territory.

Add the Blockstack kingdom to Other Kingdoms

Your Animal Kingdom only recognizes two Other Kingdoms. In this section, you add a third, the Blockstack kingdom (https://animalkingdoms.netlify.com).

  1. Open the src/constant.js file in your favorite editor.

    On Windows you can use Notepad.

  2. Scroll down to the section that defines the Other Kingdoms

    export const OTHER_KINGDOMS = [
        app: 'https://animal-kingdom-1.firebaseapp.com',
        ruler: 'larry.id'
        app: 'http://localhost:3001',
        ruler: 'larz.id'

    To add a kingdom, you need its URL and the ID of its owner.

  3. Edit the file and add the https://animalkingdoms.netlify.com which is owned by meepers.id.blockstack.

    When you are done the file will look like this.

    export const OTHER_KINGDOMS = [
        app: 'https://animal-kingdom-1.firebaseapp.com',
        ruler: 'larry.id'
        app: 'http://localhost:3001',
        ruler: 'larz.id'
        app: 'https://animalkingdoms.netlify.com',
        ruler: 'meepers.id.blockstack'
  4. Save and close the constants.js file.
  5. Back in your browser, navigate to the Other Kingdoms page.

  6. Go to the meepers kingdom by clicking on her kingdom.
  7. Try adding a subject from meepers’s kingdom to yours.

Deploy your DApp on the web

So far, you’ve been running the application locally. This means you are the only person that can use it to create a kingdom. You can make your application available to others by hosting it out on the internet. You can do this for free with a Netlify account.

App Mining Requirement: Review Accessibility

To participate in application mining your application must be available for review. Open source projects must provide the URL to their code. Projects with private repositories can provide their application in a package form.

Before you begin, you need to build a site that is ready to deploy.

  1. In your terminal, press CTRL-C on your keyboard to stop your npm run start build.
  2. Build a website from your code by entering the npm run build command:

    npm run build

    When the command completes, you should have a new build subdirectory in your project.

  3. Open your project in the Finder.
  4. Locate the newly created build subfolder.

  5. Sign up for a free Netlify account

    This example assumes you create an account by providing an email and password.

  6. In your email inbox, find Netlify’s welcome email and verify your account.

  7. Log into Netlify and go to the Overview page in your browser.
  8. Drag your build subdirectory from the Finder into the drop zone in Netlify.

    After a moment, Netlify builds your code and displays the location of your new website.

  9. Click on your website name to display the website.

    You are prompted to sign into this new site with your Blockstack ID.

  10. Click Sign in with Blockstack.

    After you sign in, your website presents you with this message:

    You get this message because, when you authenticate, your DApp at one URL requested a resource (an identity) from another DApp, the Blockstack Browser. A request for a resource outside of the origin (your new website) is called as a cross-origin request(CORs). Getting data in this manner can be risky, so you must configure your website security to allow interactions across origins.

    You can think of CORS interactions as an apartment building with Security. For example, if you need to borrow a ladder, you could ask a neighbor in your building who has one. Security would likely not have a problem with this request (i.e., same-origin, your building). If you needed a particular tool, however, and you ordered it delivered from an online hardware store (i.e., cross-origin, another site), Security may request identification before allowing the delivery man into the apartment building.
    Credit: Codecademy

    The way you configure CORs depends on which company is serving your website. You are using Netlify for this example.

  11. Locate the cors/_headers and cors/_redirects files in your project.

    You can use the Finder or the ls command.

  12. Copy them into your build directory.

    To copy them with the ls command, enter the following in the root of the animal-kingdom-master project.

    cp cors/_headers build
    cp cors/_redirects build

    The name of each file, with the underscore, is essential.

  13. Drag the build file back into the Netlify drop zone.

    After a moment, Netlify publishes your site. Check the published location, it may have changed.

  14. Click on the link and log into your Animal Kingdom.
  15. Recreate your animal persona and territory.

    The Animal Kingdom is identified by its location on the Internet, remember? So, the animal kingdom you created on your local workstation is different than the one you create on Netlify.

Add your Kingdom to our Clan

At this point, your kingdom is isolated. If you know another kingdom, you can add subjects from that kingdom but other kingdoms can’t access your subjects. In this section, you use a free GitHub account to add your kingdom to the Blockstack kingdom.

  1. If you have a GitHub account, go to step 2 otherwise go to GitHub site and create a new account.
  2. Go to the https://github.com/blockstack/animal-kingdom/issues repository on Github.
  3. Click New Issue.

    The new issue dialog appears.

  4. Fill out the issue with the URL from Netlify and your Blockstack id.

    When you are done, your issue will look like the following:

  5. Press Submit new issue.

    The Blockstack team will add your Netlify kingdom to ours. When we do that, we will notify you on the issue and you’ll also get an email.

  6. When you receive the email, login to the Blockstack Animal kingdom to see your kingdom under Other Kingdoms.

Next steps (and a cool tshirt!)

In the next part, you learn about how application mining can fund your DApp development efforts. And you will take a couple of minutes to add your Animal Kingdom DApp to App.co — the Universal App store. Completing this step earns you a limited edition t-shirt.

If you have a twitter account, why not tell some folks about your progress?