Skip to content
An example for developers showing an application built on EOSIO combining UAL, Manifest Spec, and Ricardian Contracts
Branch: master
Clone or download
TaraTritt Merge pull request #28 from EOSIO/develop
Merge Develop to Master
Latest commit 10fd4e0 Jun 18, 2019
Type Name Latest commit message Commit time
Failed to load latest commit information.
.github adds pull request template Mar 26, 2019
eosio Update to v0.7.0 of the manifest spec May 20, 2019
public Update to v0.7.0 of the manifest spec May 20, 2019
src Updated version and moved to public dependencies May 28, 2019
.eslintignore Initial commit Mar 20, 2019
.eslintrc Initial commit Mar 20, 2019
.gitignore Initial commit Mar 20, 2019
.nvmrc Add nvmrc and Required Tools section May 28, 2019 Update Mar 21, 2019
LICENSE Update LICENSE Mar 28, 2019
default.env Initial commit Mar 20, 2019
docker-compose.yml Initial commit Mar 20, 2019
package.json Bump package versions and depedencies Jun 17, 2019
yarn.lock Merge pull request #27 from EOSIO/v0.1.1 Jun 18, 2019

🌴 Tropical Example

Tropical Example is a mock application for renting properties. It will be referenced throughout this guide as an example for application developers to start building secure applications with a good user experience on the EOSIO blockchain.


About EOSIO Labs

EOSIO Labs repositories are experimental. Developers in the community are encouraged to use EOSIO Labs repositories as the basis for code and concepts to incorporate into their applications. Community members are also welcome to contribute and further develop these repositories. Since these repositories are not supported by, we may not provide responses to issue reports, pull requests, updates to functionality, or other requests from the community, and we encourage the community to take responsibility for these.


The following open source repositories are utilized in Tropical Example:

Table of Contents

Universal Authenticator Library (UAL)

An Authenticator provides the ability to communicate with an authentication provider. Authentication providers generally allow users to add, modify, and delete private / public key pairs and use these key pairs to sign proposed transactions.

UAL allows developers to support multiple Authenticators with only a few lines of code. This significantly reduces the start up time of creating applications by removing the need to detect and create an interface for interacting with the Authenticators.

UAL provides users with a common login interface in which they can select the Authenticator of their choice to interact with the EOSIO protocol. Once a user selects the Authenticator of their choice and logs in, the application developer will have access to an activeUser object which contains all necessary fields and functions to sign transactions and customize their user experience.


First install your UAL Renderer of choice. Tropical Example uses the UAL Renderer for ReactJS and the rest of the examples will be demonstrating usage with the React Renderer. Please view the UAL documentation for links to all available renderers with documentation and examples of their usage.

yarn add ual-reactjs-renderer

Then install the Authenticators you want to allow users to interact with. Tropical Example uses the following Authenticators:

yarn add ual-eosio-reference-authenticator
yarn add ual-scatter
yarn add ual-lynx
yarn add ual-token-pocket


In your root React component (for most projects this will be index.js) wrap your App component with UALProvider.

The UALProvider requires an array of Chains you wish your app to transact on, an array of Authenticators you want to allow users to interact with, and an application name. Each Authenticator requires at least an array of Chains that you want to allow the Authenticator to interact with and a second options parameter that may be required. Please see the documentation of the Authenticator if this options argument is required and what fields are necessary.

// UAL Required Imports
import { UALProvider } from 'ual-reactjs-renderer'
// Authenticator Imports
import { EOSIOAuth } from 'ual-eosio-reference-authenticator'
import { Scatter } from 'ual-scatter'
import { Lynx } from 'ual-lynx'
import { TokenPocket } from 'ual-token-pocket'
const appName = 'Tropical Example'

// Chains
const chain = {
  chainId: process.env.REACT_APP_CHAIN_ID,
  rpcEndpoints: [
      protocol: process.env.REACT_APP_RPC_PROTOCOL,
      host: process.env.REACT_APP_RPC_HOST,
      port: process.env.REACT_APP_RPC_PORT,

// Authenticators
const eosioAuth = new EOSIOAuth([chain], { appName, protocol: 'eosio' })
const scatter = new Scatter([chain], { appName })
const lynx = new Lynx([chain])
const tokenPocket = new TokenPocket([chain])

const supportedChains = [chain]
const supportedAuthenticators = [eosioAuth, scatter, lynx, tokenPocket]

  <UALProvider chains={supportedChains} authenticators={supportedAuthenticators} appName={appName}>
    <App />

UAL Context

The UAL Renderer for ReactJS uses Context to expose the objects and functions needed to interact with UAL. The context is created by the UALProvider. There are two methods to gain access to this context:

  1. The withUAL HOC (Higher Order Component) can be used to pass the UALProvider context as props to the wrapped component.
  • When using the withUAL HOC all of the UALProvider context will be available under the parent prop ual
  import { withUAL } from 'ual-reactjs-renderer'
  class Example extends React.Component {
    render() {
      const { ual: { logout } } = this.props
      return <div onClick={logout}>Logout</div>

  export default withUAL(Example)
  1. The static contextType property can be set on a class to the renderer's exported context object, UALContext. This allows the context to be referenced using this.context within the class.
  • Using the static contextType to access the context is currently only supported by React component classes and not supported by functional components. For functional components, withUAL must be used if access to the context is required.
  import { UALContext } from 'ual-reactjs-renderer'
  class Example extends React.Component {
    static contextType = UALContext

    render() {
      const { logout } = this.context
      return <div onClick={logout}>Logout</div>



By default, the UALProvider provides a modal at the root level of your application. This modal will render the login buttons of all the configured Authenticators that can be detected in the user’s environment. The modal is hidden by default, but can be displayed and dismissed by calling the functions showModal and hideModal, respectively. Both functions are set in the UALProvider context.

import { withUAL } from 'ual-reactjs-renderer'
class App extends React.Component {
  displayLoginModal = (display) => {
    const { ual: { showModal, hideModal } } = this.props
    if (display) {
    } else {

export default withUAL(App)

Account Name

After logging in, an activeUser object is returned by the Authenticator and set in the UALProvider context.

On the activeUser object a getAccountName method is available. This method returns a promise, which will resolve to a string containing the signed in account name.

import { UALContext } from 'ual-reactjs-renderer'
class UserInfo extends React.Component {
  static contextType = UALContext
  async componentDidMount() {
    const { activeUser } = this.context
    if (activeUser) {
      const accountName = await activeUser.getAccountName()
      this.setState({ accountName })


In order to propose transactions, your application needs access to the activeUser object returned by the logged in Authenticator.

At the time of signing, call activeUser.signTransaction with a valid transaction object and a configuration object. This will propose the transaction to the logged in Authenticator.

It is highly recommended in the transaction configuration to provide a expireSeconds property of a time greater than at least 300 seconds or 5 minutes. This will allow sufficient time for users to review and accept their transactions before expiration.

import { UALContext } from 'ual-reactjs-renderer'
import { generateTransaction } from 'utils/transaction'
class Property extends React.Component {
  static contextType = UALContext
  onLike = async () => {
    const { login, displayError } = this.props
    // Via static contextType = UALContext, access to the activeUser object on this.context is now available
    const { activeUser } = this.context
    if (activeUser) {
      try {
        const accountName = await activeUser.getAccountName()
        const transaction = generateTransaction(accountName)
        // The activeUser.signTransaction will propose the passed in transaction to the logged in Authenticator
        await activeUser.signTransaction(transaction, { broadcast: true, expireSeconds: 300 })
        this.setState({ liked: true })
      } catch (err) {
    } else {

export default Property

The method activeUser.signTransaction returns a promise, which, if signing is successful, will resolve to the signed transaction response.


If you want to logout, you can use the logout function set in the UALProvider context.

import { UALContext } from 'ual-reactjs-renderer'
class UserInfo extends React.Component {
  static contextType = UALContext
  renderDropdown = () => {
    const { logout } = this.context
    return (
      <div className='user-info-dropdown-content'>
        <UserDropdown logout={logout} />

export default UserInfo


Errors thrown by UAL are of type UALError, which extends the generic Error class, but has extra information that is useful for debugging purposes.

Login Errors

During login, errors are set in the UALProvider context.

// Using withUAL() HOC
// Using static contextType

Transactions Errors

During signing, errors will be thrown by activeUser.signTransaction. It is recommended to use the try...catch statement to capture these thrown errors.

try {
  await activeUser.signTransaction(transaction, transactionConfig)
} catch (error) {
  // Using JSON.parse(JSON.stringify(error)) creates a copy of the error object to ensure
  // that you are printing the value of object at the moment you log it
  console.error('UAL Error', JSON.parse(JSON.stringify(error)))

If you need information not covered in this guide, you can reference the full UAL repository here.

Manifest Specification

Tropical Example follows the Manifest Specification by providing the following:

If you need information not covered in this guide, you can reference the Manifest Specification here.

Ricardian Specification

Tropical Example follows the Ricardian Specification by providing the following:

  • A, which defines the Ricardian Contract of the like action of the tropical contract.
  • Generating the tropical abi file with eosio-cpp by passing the -abigen flag, which will auto generate an abi including the into the ricardian_contract field of the like action.

If you need information not covered in this guide, you can reference the Ricardian Specification here.

Running Tropical Example

Required Tools

  • Yarn with support at ^1.15.2 (latest stable).
  • Docker with support at Docker Engine 18.09.2 (latest stable).
  • Docker Compose.
  • Node.js with support at ^10.15.3 LTS. NOTICE This project will not build on the current version of Node.js 12.3.1 due to an error in a sub-dependency of react-scripts.

This project was bootstrapped with Create React App.


Create a .env file from the default.env

cp default.env .env

Tropical Example uses an environment configuration for the Chain and RPC endpoints. By default it will query the local node setup by Docker Compose in this repo. If you want to use another Chain, update the values in the .env file you created in the first step to set the preferred Chain you wish your app to transact on.

.env file defaults




Run this first to install all the project's dependencies.

Running Nodeos

Before the app can be run, the Tropical Example contract must be deployed on the chain configured in the .env to the account tropical.

This repo provides a docker-compose.yml that will setup and deploy the tropical contract using Docker Compose.

Then run the following to start up a local node:

yarn up

You can view the contract in the eosio/contracts directory.

Running Frontend

yarn start

This command runs the app in the development mode. Open http://localhost:3000 to view it in the browser.

The page will reload if you make edits.


The Docker Compose setup scripts provide an, example account, that can be imported into your Authenticator of choice to login and sign transactions:

⚠️ Never use this development key for a production account! Doing so will most certainly result in the loss of access to your account, this private key is publicly known. ⚠️

# Example Account Public Key
# Example Account Private Key

Docker Compose Command Reference

# Create and start the docker container
docker-compose up eosio
# Stop the docker container
docker-compose down eosio
# Open a bash terminal into the docker container
docker-compose exec eosio /bin/bash



Check out the Contributing guide and please adhere to the Code of Conduct


MIT licensed


See LICENSE for copyright and license terms. makes its contribution on a voluntary basis as a member of the EOSIO community and is not responsible for ensuring the overall performance of the software or any related applications. We make no representation, warranty, guarantee or undertaking in respect of the software or any related documentation, whether expressed or implied, including but not limited to the warranties of merchantability, fitness for a particular purpose and noninfringement. In no event shall we be liable for any claim, damages or other liability, whether in an action of contract, tort or otherwise, arising from, out of or in connection with the software or documentation or the use or other dealings in the software or documentation. Any test results or performance figures are indicative and will not reflect performance under all conditions. Any reference to any third party or third-party product, service or other resource is not an endorsement or recommendation by We are not responsible, and disclaim any and all responsibility and liability, for your use of or reliance on any of these resources. Third-party resources may be updated, changed or terminated at any time, so the information here may be out of date or inaccurate. Any person using or offering this software in connection with providing software, goods or services to third parties shall advise such third parties of these license terms, disclaimers and exclusions of liability., EOSIO, EOSIO Labs, EOS, the heptahedron and associated logos are trademarks of

Wallets and related components are complex software that require the highest levels of security. If incorrectly built or used, they may compromise users’ private keys and digital assets. Wallet applications and related components should undergo thorough security evaluations before being used. Only experienced developers should work with this software.

You can’t perform that action at this time.