Experimental Ark SmartBridge Listener

This is a proof-of-concept for an Ark Transaction SmartBridge listener.

How It Works

1. Consumer registers a message with the listener with a callback Url

2. Listener scans Ark network transactions for transactions containing your message token in the SmartBridge data field.

3. Listener sends matching transaction to registered consumer

Limitations

• The SmartBridge data field is very small, so we need to store the message payload externally and pass only the message token in Ark transactions.

• The SmartBridge Listener tokenizes messages in a centralized way. It would be nice to decentralize this using IPFS or some other distributed content network.

Explanation

The SmartBridge Listener scans Ark transactions for matching message tokens. When a matching message is found, it sends the transaction to the consumer for further processing.

In this example, we will create an "Ark Ethereum Contract Service" that allows a user to create an Ethereum contract using an Ark transaction.

This service will accept a block of Ethereum contract code and return a message token, destination Ark wallet, and required Ark amount.

The client will then send an Ark transaction of the required Ark amount to the destination wallet with the message token in the transaction Smartbridge field.

The Ark Transaction SmartBridge Listener will match the message token on the Ark transaction and forward the transaction information to the Ark Ethereum Contract Service, which will create an Ethereum contract with the matching message.

If the listener succeeds, it sends a return transaction to the client Ark wallet with any un-used balance and a message of success.

If the listener fails, it sends a return transaction to the client with the original amount less transaction fees.

Example

0. Set up environment dependencies

   The app requires ark-node to be running at on localhost:4000:

   app.js --genesis genesisBlock.testnet.json --config config.testnet.json
   

   This app also requires Ethereum RPC server to be running on localhost:8545:

   geth --dev --rpc --rpcapi 'web3,eth,debug,personal' --rpccorsdomain="*"
   

   You can find server configurations in application.yml

1. Start the listener application (listens on localhost:8080)

   mvn spring-boot:run 
   

2. Create a Ethereum Contract Message

   The user will need to compile solidity contracts locally using solc compiler. This generates an abi and bin file needed to create the contract.

   solc --bin --abi --optimize -o data/solc-output/ data/sample.sol
   

   The user then creates a contract message with the contract data to the listener service:

   curl -X POST 'localhost:8080/contracts' \
       -F returnArkAddress=ARNJJruY6RcuYCXcwWsu4bx9kyZtntqeAx \
       -F abiJson=@data/solc-output/greeter.abi \
       -F code=@data/solc-output/greeter.bin \
       -F params=@data/sample-params.json \
       -F gasLimit=500000
   

   {
     "token" : "abe05cd7-40c2-4fb0-a4a7-8d2f76e74978",
     "createdAt" : "2017-07-04T21:59:38.129Z",
     "estimatedGasCost" : "214411",
     "estimatedArkCost" : "1.00000000",
     "serviceArkAddress": "AewU1vEmPrtQNjdVo33cX84bfovY3jNAkV", 
     "returnArkAddress" : "ARNJJruY6RcuYCXcwWsu4bx9kyZtntqeAx",
     "contractCode" : "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",
     "contractAbiJson" : "[{\"constant\":false,\"inputs\":[],\"name\":\"kill\",\"outputs\":[],\"payable\":false,\"type\":\"function\"},{\"constant\":true,\"inputs\":[],\"name\":\"greet\",\"outputs\":[{\"name\":\"\",\"type\":\"string\"}],\"payable\":false,\"type\":\"function\"},{\"inputs\":[{\"name\":\"_greeting\",\"type\":\"string\"}],\"payable\":false,\"type\":\"constructor\"}]",
     "contractParamsJson" : "[\"Hello World\"]"
   }
   

   The user must send an ark transaction to the serviceArkAddress with at least estimatedArkCost ark. Any un-used ark will be returned to returnArkAddress in a ark transaction created by the service.

3. Create an Ark Transaction

   Using the Ark javascript API, the user sends a transaction to the serviceArkAddress with the message token in the VendorField parameter. The listener service will match the ark transaction with the corresponding contract for processing.

   var serviceArkAddress = "AewU1vEmPrtQNjdVo33cX84bfovY3jNAkV";
   var messageToken = "abe05cd7-40c2-4fb0-a4a7-8d2f76e74978";
   var amount = 1.0000000;
   var transaction = ark.transaction.createTransaction(serviceArkAddress, amount, messageToken, "passphrase", "secondPassphrase");
   

4. Check the Status of Ethereum Contract Message

   curl -X GET 'localhost:8080/contracts/abe05cd7-40c2-4fb0-a4a7-8d2f76e74978'
   

   {
     "token" : "abe05cd7-40c2-4fb0-a4a7-8d2f76e74978",
     "createdAt" : "2017-07-04T21:59:38.129Z",
     "estimatedGasCost" : "214411.00",
     "estimatedArkCost" : "1.00",
     "serviceArkAddress": "AewU1vEmPrtQNjdVo33cX84bfovY3jNAkV", 
     "returnArkAddress" : "ARNJJruY6RcuYCXcwWsu4bx9kyZtntqeAx",
     "contractCode" : "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",
     "contractAbiJson" : "[{\"constant\":false,\"inputs\":[],\"name\":\"kill\",\"outputs\":[],\"payable\":false,\"type\":\"function\"},{\"constant\":true,\"inputs\":[],\"name\":\"greet\",\"outputs\":[{\"name\":\"\",\"type\":\"string\"}],\"payable\":false,\"type\":\"function\"},{\"inputs\":[{\"name\":\"_greeting\",\"type\":\"string\"}],\"payable\":false,\"type\":\"constructor\"}]",
     "contractParamsJson" : "[\"Hello World\"]"
     "actualArkCost": "0.80000000",
     "returnArkAmount": "0.2000000",
     "returnArkTransactionId": "49f55381c5c3c70f96d848df53ab7f9ae9881dbb8eb43e8f91f642018bf1258f",
     "contractTransactionHash": "500224999259823996",
     "contractAddress": "0xdaa24d02bad7e9d6a80106db164bad9399a0423e",
     "createdAt":"2017-07-01T22:35:57.695Z"
   }
   

5. Running the Ethereum Contract

   Load the generated Ethereum contract using the contract address in the eth console:

   geth --dev attach
   > var contractAddress = "0xdaa24d02bad7e9d6a80106db164bad9399a0423e"
   > var contractInfo = admin.getContractInfo(contractAddress)
   > var contract = eth.contract(contractInfo.info.abiDefinition);
   > var instance = contract.at(contractAddress);
   > instance.greet()
   "Hello World"
   

Deploying your Node

These steps help you get set up a Ubuntu 16.04 linux server running ACES. You'll need at least 50GB of disk space to sync the ethereum blockchain (might not be necessary for light syncing).

These instructions use systemd to supervise applications running in the background and nginx to serve web traffic.

1. Install system dependencies

sudo apt-get python-software-properties
sudo add-apt-repository -y ppa:ethereum/ethereum
sudo add-apt-repository ppa:webupd8team/java -y

sudo apt-get update
sudo apt-get install software-properties-common build-essential curl git maven
sudo apt-get install ethereum solc

# install Java JVM
echo oracle-java8-installer shared/accepted-oracle-license-v1-1 select true | sudo /usr/bin/debconf-set-selections
sudo apt-get install oracle-java8-installer

# install nodejs
curl -sL https://deb.nodesource.com/setup_6.x | sudo -E bash -
sudo apt-get install nodejs

# install nginx
sudo apt-get install nginx

2. Install ethereum service

Copy the following into /etc/systemd/system/geth-network.service. There are 3 different ways to run geth to target different ethereum networks: dev, testnet, and mainnet.

Local Devnet:

[Unit]
Description=Ethereum devnet

[Service]
Restart=always
ExecStart=/usr/bin/geth --dev --rpc --rpcaddr=127.0.0.1 --rpcapi 'web3,eth,personal' --rpccorsdomain="*" \
--datadir=/eth-data
[Install]
WantedBy=multi-user.target

Ropsten Testnet:

[Unit]
Description=Ethereum testnet

[Service]
Restart=always
ExecStart=/usr/bin/geth --testnet --rpc --rpcaddr=127.0.0.1 --rpcapi 'web3,eth,personal' --rpccorsdomain="*" \
--datadir=/eth-data --fast --cache=1024 \
--bootnodes "enode://20c9ad97c081d63397d7b685a412227a40e23c8bdc6688c6f37e97cfbc22d2b4d1db1510d8f61e6a8866ad7f0e17c02b14182d37ea7c3c8b9c2683aeb6b733a1@52.169.14.227:30303,enode://6ce05930c72abc632c58e2e4324f7c7ea478cec0ed4fa2528982cf34483094e9cbc9216e7aa349691242576d552a2a56aaeae426c5303ded677ce455ba1acd9d@13.84.180.240:30303"

[Install]
WantedBy=multi-user.target

Mainnet:

[Unit]
Description=Ethereum network

[Service]
Restart=always
ExecStart=/usr/bin/geth --rpc --rpcaddr=127.0.0.1 --rpcapi 'web3,eth,personal' --rpccorsdomain="*" \
--datadir=/eth-data --fast --cache=1024 \
--bootnodes "enode://20c9ad97c081d63397d7b685a412227a40e23c8bdc6688c6f37e97cfbc22d2b4d1db1510d8f61e6a8866ad7f0e17c02b14182d37ea7c3c8b9c2683aeb6b733a1@52.169.14.227:30303,enode://6ce05930c72abc632c58e2e4324f7c7ea478cec0ed4fa2528982cf34483094e9cbc9216e7aa349691242576d552a2a56aaeae426c5303ded677ce455ba1acd9d@13.84.180.240:30303"

[Install]
WantedBy=multi-user.target

Start up ethereum service (this can take several hours to sync before transactions):

sudo chmod 655 /etc/systemd/system/geth-network.service
sudo systemctl daemon-reload
sudo service geth-network start

You can view the output of running systemd services by tailing the syslog:

sudo tail -f /var/log/syslog

3. Create Service Eth Wallet

Connect to the local geth instance and create a new eth wallet for ACES service:

geth attach ipc:/eth-data/geth.ipc

> let password = '12345';
> personal.newAccount(password);
> eth.accounts
["0x77fa2ae66ff74d99da00cdd3f82a3a50750bb95d"]

Use the eth wallet address and password in the application.yml configuration below.

4. Install ACES application

Install the application under /apps:

sudo mkdir /apps
sudo mkdir /apps/aces-backend
cd /apps/aces-backend
git clone https://github.com/bradyo/ark-java-smart-bridge-listener.git

Install application.yml configuration file under /etc/aces-backend:

mkdir /etc/aces-backend

Copy src/main/resources/application.yml file over into /etc/aces-backend and replace wallet configurations with your own Eth and Ark wallet addresses and passphrase.

spring:
  datasource:
    url: "jdbc:h2:/tmp/testdb;DB_CLOSE_ON_EXIT=FALSE;AUTO_RECONNECT=TRUE"
    driver-class-name: "org.h2.Driver"
  jpa:
    hibernate:
      ddl-auto: "update"

arkNetwork:
  name: "mainnet"

ethBridge:
  ethServerUrl: "http://localhost:8545"
  scriptPath: "./bin"
  nodeCommand: "/usr/bin/node"

  serviceArkWallet:
    address: "change me"
    passphrase: "change me"
    passphrase2:

  serviceEthAccount:
    address: "change me"
    password: "change me"
    
arkPerEthAdjustment: "100.00"

ethContractDeployService:
  arkFlatFee: "2.00"
  arkPercentFee: "2.25"
  requiredArkMultiplier: "1.2"

ethTransferService:
  arkFlatFee: "1.00"
  arkPercentFee: "1.25"
  requiredArkMultiplier: "1"

For production instances, you should configure the application to use a real database like posgresql:

spring:
  datasource:
    url: "jdbc:postgresql://{host}:{port}/{database_name}"
    username: "change me"
    password: "change me"
  jpa:
    database-platform: "org.hibernate.dialect.PostgreSQLDialect"
    generate-ddl: true
    hibernate:
      ddl-auto: "update"

Copy the following into /etc/systemd/system/aces-backend.service:

[Unit]
Description=Aces Backend

[Service]
Restart=always
WorkingDirectory=/apps/aces-backend/ark-java-smart-bridge-listener
ExecStart=/usr/bin/mvn spring-boot:run -Dspring.config.location=file:/etc/aces-backend/application.yml

[Install]
WantedBy=multi-user.target

Install npm dependencies:

cd /apps/aces-backend/ark-java-smart-bridge-listener/bin
npm install

Start the ACES backend service:

sudo chmod 655 /etc/systemd/system/aces-backend.service
sudo systemctl daemon-reload
sudo service aces-backend start

5. Installing ACES frontend

Install the application under /apps:

sudo mkdir /apps/aces-frontend
cd /apps/aces-frontend
git clone https://github.com/bradyo/aces-app.git

todo: set up api url via config and point that to the backend-api https://github.com/bradyo/aces-app/blob/master/src/app/aces-server-config.ts#L8

Copy prod configuration template into custom configuration file:

cd /apps/aces-frontend/aces-app
cp src/environments/environment.prod.ts src/environments/environment.custom.ts

If using an Ethereum Testnet, copy the following into /apps/aces-frontend/aces-app/src/environments/environment.custom.ts:

export const environment = {
  production: true,
  title: 'Custom Ark Contract Execution Services (ACES)',
  isEthTestnet: true,
  ethNetworkName: 'ropsten',
  etherscanBaseUrl: 'https://ropsten.etherscan.io',
  ethArkRateFraction: '1/100',
  arkExplorerBaseUrl: 'https://explorer.ark.io',
  acesApiBaseUrl: 'http://localhost/aces-api'
};

If using the Ethereum Mainnet, copy the following into /apps/aces-frontend/aces-app/src/environments/environment.custom.ts:

export const environment = {
  production: true,
  title: 'Custom Ark Contract Execution Services (ACES)',
  isEthTestnet: false,
  etherscanBaseUrl: 'https://etherscan.io',
  arkExplorerBaseUrl: 'https://explorer.ark.io',
  acesApiBaseUrl: 'http://localhost/aces-api'
};

Build the frontend application:

cd /apps/aces-frontend/aces-app
npm install -g @angular/cli
npm install
ng build --target=production --env=custom --base-href /aces-app/

6. Set up nginx web server

Allow backend and frontend to be served by nginx by adding the following to /etc/nginx/sites-available/default under root server directive.

location /aces-app/ {
    alias /apps/aces-frontend/aces-app/dist/;
    try_files $uri $uri/ /aces-app/;
}

location /aces-api/ {
    proxy_pass http://127.0.0.1:8080/;
}

sudo service nginx restart

7. Confirm setup

Check the backend API by making a GET request to http://localhost/aces-api/test-service-info:

curl http://localhost/aces-api/test-service-info
{
  "capacity" : "∞",
  "flatFeeArk" : "0",
  "percentFee" : "0",
  "status" : "Up"
}

Open up the aces-app frontend in your browser: https://localhost/aces-app/