Getting started

Create and deploy a blockchain in 10 minutes

This document describes how to get started with application development on the Second State DevChain. The Second State DevChain features a powerful and easy-to-use virtual machine that can quickly get you started with smart contract and DApp development.

With the Second State Blockchain as a Service (BaaS), you can start a new Second State blockchain with its innovative virtual machines and smart contract search engines with one click of the mouse.

In this document, we will explain how to create and run the Second State blockchain. You can then connect and test basic features such as coin transactions and smart contract functions.

The easiest way to get started is to use our pre-build Docker images. Please make sure that you have Docker installed and that your Docker can work without sudo.

For example, on Ubuntu, you can use the following commands.

$ sudo apt install docker.io
$ sudo usermod -a -G docker $USER
$ docker pull secondstate/devchain:devchain

Initialize

Let’s initialize the DevChain configuration and genesis settings.

$ docker run --rm -v $HOME/.devchain:/devchain secondstate/devchain:devchain node init --home /devchain

Note: If you are running a cluster, you should now copy over the cluster wide genesis.json and config.toml files to the $HOME/.devchain/config directory.

Run

Now you can start the DevChain node in docker.

$ docker run --rm -v $HOME/.devchain:/devchain -p 26657:26657 -p 8545:8545 secondstate/devchain:devchain node start --home /devchain

You should see blocks like the following in the log.

INFO [07-14|07:23:05] Imported new chain segment               blocks=1 txs=0 mgas=0.000 elapsed=431.085µs mgasps=0.000 number=163 hash=05e16c…a06228
INFO [07-14|07:23:15] Imported new chain segment               blocks=1 txs=0 mgas=0.000 elapsed=461.465µs mgasps=0.000 number=164 hash=933b97…0c340c

Connect

Next, open another terminal window to interact with the running node.

You can get the ID of the running Docker container.

$ docker container ls
CONTAINER ID        IMAGE                   COMMAND                  CREATED             STATUS              PORTS                                                         NAMES
0bcd9da5bf05        secondstate/devchain   "./devchain node sta…"   4 minutes ago       Up 4 minutes        0.0.0.0:8545->8545/tcp, 0.0.0.0:26657->26657/tcp, 26656/tcp   pedantic_mendeleev

Next, log into that container.

$ docker exec -i -t 0bcd9da5bf05 bash
root@0bcd9da5bf05:/app# ls
devchain  devchain.sha256  lib

Finally, you can attach a console to the node to run web3 commands.

root@0bcd9da5bf05:/app# ./devchain attach http://localhost:8545
...
> cmt.syncing
{
  catching_up: false,
  latest_app_hash: "C7D8AECE081DF06FFC9BF6144A50B37CA5DD8A8E",
  latest_block_hash: "B592D63AB78C571E0FB695A052681E65F6DFE15B",
  latest_block_height: 35,
  latest_block_time: "2019-05-04T02:59:30.542783017Z"
}

Test accounts

If you go with the default setup, the chain starts with two accounts that already have CMT balances (CMT is the native currency here).

• 0x77beb894fc9b0ed41231e51f128a347043960a9d is the coinbase account with 10,000,000,000,000,000 CMTs.

• 0x7eff122b94897ea5b0e2a9abf47b86337fafebdc is a validator account with 10,000,000,000,000,000 CMTs.

You MUST NOT use those two addresses in your production systems. Their private keys are well known and anyone could move fund from them!!! To create a new blockchain with your own genesis accounts, you will need to use this tool to create new config files.

We already put keystore files for the two default genesis accounts in your .devchain/keystore directory. The passphrase to both keystores are 1234.

$ ls .devchain/keystore
UTC--2016-10-21T22-30-03.071787745Z--7eff122b94897ea5b0e2a9abf47b86337fafebdc
UTC--2018-04-09T09-48-47.241470000Z--77beb894fc9b0ed41231e51f128a347043960a9d

Next, you can paste the following script into the client console, at the > prompt.

function checkAllBalances() {
  var totalBal = 0;
  for (var acctNum in cmt.accounts) {
      var acct = cmt.accounts[acctNum];
      var acctBal = web3.fromWei(cmt.getBalance(acct), "cmt");
      totalBal += parseFloat(acctBal);
      console.log("  cmt.accounts[" + acctNum + "]: \t" + acct + " \tbalance: " + acctBal + " CMT");
  }
  console.log("  Total balance: " + totalBal + "CMT");
};

You can now run the script in the console, and see the results.

> checkAllBalances();
  cmt.accounts[0]: 	0x7eff122b94897ea5b0e2a9abf47b86337fafebdc 	balance: 10000000000000000 CMT
  cmt.accounts[1]: 	0x77beb894fc9b0ed41231e51f128a347043960a9d 	balance: 10000000000000000 CMT
  Total balance: 20000000000000000CMT

Aside from the default public (UNSECURE) accounts, you can create your own accounts like the following. The keystore for the newly created accounts will be in your local .devchain/keystore folder.

> personal.newAccount("mypass")
"0x6fa1f61bfb38b204d1b44b0116a166155bb4a161"

Those accounts start from 0 CMT balance, and you will need to transfer CMTs from the genesis accounts for them to be useful.

Test transactions

You can now send a transaction between accounts like the following. Again, the passphrase is 1234 for the unsecure public keystores.

personal.unlockAccount("from_address")
Passphrase:
cmt.sendTransaction({"from": "from_address", "to": "to_address", "value": web3.toWei(0.001, "cmt")})

Next, run the checkAllBalances() script in the console, and see the results.

> checkAllBalances();
cmt.accounts[0]:      0x6....................................230      balance: 466.798526 CMT
cmt.accounts[1]:      0x6....................................244      balance: 1531 CMT
Total balance: 1997.798526CMT