cosmos-sdk/docs/guide/basecoin-basics.md

Basecoin Basics

Here we explain how to get started with a simple Basecoin blockchain, and how to send transactions between accounts using the basecoin tool.

Install

Make sure you have basecoin installed. You will also need to install Tendermint.

Note All code is on the 0.9 pre-release branch, you may have to install Tendermint from source until 0.9 is released. (Make sure to add git checkout develop to the linked install instructions)

Initialization

Basecoin is an ABCI application that runs on Tendermint, so we first need to initialize Tendermint:

tendermint init

This will create the necessary files for a single Tendermint node in ~/.tendermint. If you had previously run Tendermint, make sure you reset the chain (note this will delete all chain data, so back it up if you need it):

tendermint unsafe_reset_all

Now we need some initialization files for basecoin. We have included some defaults in the basecoin directory, under data. For purposes of convenience, change to that directory:

cd $GOPATH/src/github.com/tendermint/basecoin/data

The directory contains a genesis file and two private keys.

You can generate your own private keys with tendermint gen_validator, and construct the genesis.json as you like. Note, however, that you must be careful with the chain_id field, as every transaction must contain the correct chain_id (default is test_chain_id).

Start

Now we can start basecoin:

basecoin start --in-proc

This will initialize the chain with the genesis.json file from the current directory. If you want to specify another location, you can run:

basecoin start --in-proc --dir PATH/TO/CUSTOM/DATA

Note that --in-proc stands for "in process", which means basecoin will be started with the Tendermint node running in the same process. To start Tendermint in a separate process instead, use:

basecoin start

and in another window:

tendermint node

In either case, you should see blocks start streaming in! Note, however, that currently basecoin currently requires the develop branch of Tendermint for this to work.

Send transactions

Now we are ready to send some transactions. If you take a look at the genesis.json file, you will see one account listed there. This account corresponds to the private key in key.json. We also included the private key for another account, in key2.json.

Let's check the balance of these two accounts:

basecoin account 0x1B1BE55F969F54064628A63B9559E7C21C925165
basecoin account 0x1DA7C74F9C219229FD54CC9F7386D5A3839F0090

The first account is flush with cash, while the second account doesn't exist. Let's send funds from the first account to the second:

basecoin tx send --to 0x1DA7C74F9C219229FD54CC9F7386D5A3839F0090 --amount 10

By default, the CLI looks for a priv_validator.json to sign the transaction with, so this will only work if you are in the $GOPATH/src/github.com/tendermint/basecoin/data. To specify a different key, we can use the --from flag.

Now if we check the second account, it should have 10 coins!

basecoin account 0x1DA7C74F9C219229FD54CC9F7386D5A3839F0090

We can send some of these coins back like so:

basecoin tx send --to 0x1B1BE55F969F54064628A63B9559E7C21C925165 --from key2.json --amount 5

Note how we use the --from flag to select a different account to send from.

If we try to send too much, we'll get an error:

basecoin tx send --to 0x1B1BE55F969F54064628A63B9559E7C21C925165 --from key2.json --amount 100

See basecoin tx send --help for additional details.

Plugins

The tx send command creates and broadcasts a transaction of type SendTx, which is only useful for moving tokens around. Fortunately, Basecoin supports another transaction type, the AppTx, which can trigger code registered via a plugin system.

In the next tutorial, we demonstrate how to implement a plugin and extend the CLI to support new transaction types! But first, you may want to learn a bit more about Basecoin's design