embark/README.md

What is embark
======

[![Join the chat at https://gitter.im/iurimatias/embark-framework](https://badges.gitter.im/Join%20Chat.svg)](https://gitter.im/iurimatias/embark-framework?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)

Embark is a framework that allows you to easily develop and deploy DApps.

With Embark you can:
* Automatically deploy contracts and make them available in your JS code. Embark watches for changes, and if you update a contract, Embark will automatically redeploy the contracts (if needed) and the dapp.
* Do Test Driven Development with Contracts using Javascript.
* Easily deploy to & use decentralized systems such as IPFS.
* Quickly create advanced DApps using multiple contracts.

See the [Wiki](https://github.com/iurimatias/embark-framework/wiki) for more details.

Installation
======
Requirements: geth (1.0.0), solc (0.9.23), node (0.12.2) and npm

For specs: pyethereum, ethertdd.py

```Bash
$ npm install -g embark-framework grunt-cli
```

If you get EACCES (access denied) errors, it is not recommended to use sudo, please try this:

```Bash
$ mkdir ~/npm-global
$ npm config set prefix ~/npm-global
$ echo 'export PATH="$PATH:$HOME/npm-global/bin"' >>~/.bashrc
$ source ~/.bashrc
$ npm install -g embark-framework grunt-cli
```

See [Complete Installation Instructions](https://github.com/iurimatias/embark-framework/wiki/Installation).

Usage - Demo
======
You can easily create a sample working DApp with the following:

```Bash
$ embark demo
$ cd embark_demo
```
To run the ethereum node for development purposes simply run:

```Bash
$ embark blockchain
```
By default embark blockchain will mine a minimum amount of ether and will only mine when new transactions come in. This is quite usefull to keep a low CPU. The option can be configured at config/blockchain.yml

Then, in another command line:

```Bash
$ embark run
```
This will automatically deploy the contracts, update their JS bindings and deploy your DApp to a local server at http://localhost:8000

Note that if you update your code it will automatically be re-deployed, contracts included. There is no need to restart embark, refreshing the page on the browser will do.

Creating a new DApp
======

```Bash
$ embark new AppName
$ cd AppName
```

DApp Structure
======

```Bash
  app/
    |___ contracts/ #solidity contracts
    |___ html/
    |___ css/
    |___ js/
  config/
    |___ blockchain.yml #environments configuration
    |___ contracts.yml  #contracts configuration
    |___ server.yml     #server configuration
  spec/
    |___ contracts/ #contracts tests
```

Solidity files in the contracts directory will automatically be deployed with embark run. Changes in any files will automatically be reflected in app, changes to contracts will result in a redeployment and update of their JS Bindings

Using Contracts
======
Embark will automatically take care of deployment for you and set all needed JS bindings. For example, the contract below:

```Javascript
# app/contracts/simple_storage.sol
contract SimpleStorage {
  uint public storedData;

  function SimpleStorage(uint initialValue) {
    storedData = initialValue;
  }

  function set(uint x) {
    storedData = x;
  }
  function get() constant returns (uint retVal) {
    return storedData;
  }
}
```
Will automatically be available in Javascript as:

```Javascript
# app/js/index.js
SimpleStorage.set(100);
SimpleStorage.get();
SimpleStorage.storedData();
```

You can specify for each contract and environment its gas costs and arguments:

```Yaml
# config/contracts.yml
  development:
    SimpleStorage:
      gas_limit: 500000
      gas_price: 10000000000000
      args:
        - 100
  ...
```

If you are using multiple contracts, you can pass a reference to another contract as ```$ContractName```, Embark will automatically replace this with the correct address for the contract.


```Yaml
# config/contracts.yml
  development:
    SimpleStorage:
      args:
        - 100
        - $MyStorage
    MyStorage:
       args:
         - "initial string"
    MyMainContract:
      args:
        - $SimpleStorage
  ...
```

You can now deploy many instances of the same contract. e.g


```Yaml
# config/contracts.yml
  development:
    Currency:
      args:
        - 100
    Usd:
      instanceOf: Currency
      args:
        - "initial string"
    MyCoin:
      instanceOf: Currency
      args:
        - $SimpleStorage
  ...
```

Contracts addresses can be defined, If an address is defined the contract wouldn't be deployed but its defined address will be used instead.


```Yaml
  development:
    UserStorage:
      address: 0x123456
    UserManagement:
       args:
         - $UserStorage
  ...
```

Tests
======

You can run specs with ```embark spec```, it will run any files ending *_spec.js under ```spec/```.

Embark includes a testing lib to fastly run & test your contracts in a EVM. 

```Javascript
# spec/contracts/simple_storage_spec.js
EmbarkSpec = require('embark-framework').Tests;

describe("SimpleStorage", function() {
  beforeAll(function() {
    // equivalent to initializing SimpleStorage with param 150
    SimpleStorage = EmbarkSpec.request("SimpleStorage", [150]);
  });

  it("should set constructor value", function() {
    expect(SimpleStorage.storedData()).toEqual('150');
  });

  it("set storage value", function() {
    SimpleStorage.set(100);
    expect(SimpleStorage.get()).toEqual('100');
  });

})
```

Embark uses [Jasmine](https://jasmine.github.io/2.3/introduction.html) by default, but you can use any testing framework you want.


Working with different chains
======
You can specify which environment to deploy to:


```$ embark blockchain staging```

```$ embark run staging```

The environment is a specific blockchain configuration that can be managed at config/blockchain.yml

```Yaml
# config/blockchain.yml
  ...
  staging:
    rpc_host: localhost
    rpc_port: 8101
    rpc_whitelist: "*"
    datadir: default
    network_id: 0
    console: true
    account:
      init: false
      address: 0x123
```

See [Configuration](https://github.com/iurimatias/embark-framework/wiki/Configuration).


Deploying only contracts
======
Although embark run will automatically deploy contracts, you can choose to only deploy the contracts to a specific environment

```Bash
$ embark deploy privatenet
```

embark deploy will deploy all contracts at app/contracts and return the resulting addresses

LiveReload Plugin
======

Embark works quite well with the LiveReload Plugin

Debugging embark
======
Because embark is internally using grunt tasks, debugging is not straightforward. Example

- you want to debug `embark deploy`
- normally you would write something like `node-debug -p 7000 embark -- deploy`
- This gives you nothing with embark. If you look at `deploy` command in [`./bin/embark`](https://github.com/iurimatias/embark-framework/blob/develop/bin/embark#L32-L35) you will notice that it internally runs grunt task `grunt deploy_contracts:[env]`
- with this knowledge we can prepare proper command to start debugging
- `node-debug -p 7000 grunt -- deploy_contracts:development`
- [here](https://github.com/iurimatias/embark-framework/blob/develop/tasks/tasks.coffee) is list of all debuggable grunt tasks