democoin/

README

Democoin

This is the "Democoin" example application built on the Cosmos-Sdk. This "Democoin" is not affiliated with Coinbase, nor the stable coin.

Assuming you've run make get_tools && make get_vendor_deps from the root of this repository, run make build here to build the democoind and basecli binaries.

If you want to create a new application, start by copying the Democoin app.

Building your own Blockchain

Democoin is the equivalent of an ERC20 token contract for blockchains. In order to deploy your own application all you need to do is clone examples/democoin and run it. Now you are already running your own blockchain. In the following I will explain how to add functionality to your blockchain. This is akin to defining your own vesting schedule within a contract or setting a specific multisig. You are just extending the base layer with extra functionality here and there.

Structure of Democoin

Democoin is build with the cosmos-sdk. It is a sample application that works with any engine that implements the ABCI protocol. Democoin defines multiple unique modules as well as uses modules directly from the sdk. If you want to modify Democoin, you either remove or add modules according to your wishes.

Modules

A module is a fundamental unit in the cosmos-sdk. A module defines its own transaction, handles its own state as well as its own state transition logic. Globally, in the app/app.go file you just have to define a key for that module to access some parts of the state, as well as initialise the module object and finally add it to the transaction router. The router ensures that every module only gets its own messages.

Transactions

A user can send a transaction to the running blockchain application. This transaction can be of any of the ones that are supported by any of the registered modules.

CheckTx

Once a user has submitted their transaction to the engine, the engine will first run checkTx to confirm that it is a valid transaction. The module has to define a handler that knows how to handle every transaction type. The corresponding handler gets invoked with the checkTx flag set to true. This means that the handler shouldn't do any expensive operations, but it can and should write to the checkTx state.

DeliverTx

The engine calls deliverTx when a new block has been agreed upon in consensus. Again, the corresponding module will have its handler invoked and the state and context is passed in. During deliverTx execution the transaction needs to be processed fully and the results are written to the application state.

CLI

The cosmos-sdk contains a number of helper libraries in clients/ to build cli and RPC interfaces for your specific application.