260 lines
6.8 KiB
Markdown
260 lines
6.8 KiB
Markdown
What is embark
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======
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[](https://gitter.im/iurimatias/embark-framework?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
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Embark is a framework that allows you to easily develop and deploy DApps.
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With Embark you can:
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* 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.
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* Do Test Driven Development with Contracts using Javascript.
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* Easily deploy to & use decentralized systems such as IPFS.
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* Quickly create advanced DApps using multiple contracts.
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See the [Wiki](https://github.com/iurimatias/embark-framework/wiki) for more details.
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Installation
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======
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Requirements: geth (0.9.38), solc (0.9.23), node (0.12.2) and npm
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For specs: pyethereum, ethertdd.py
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```Bash
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$ npm install -g embark-framework grunt-cli
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```
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See [Complete Installation Instructions](https://github.com/iurimatias/embark-framework/wiki/Installation).
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Usage - Demo
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======
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You can easily create a sample working DApp with the following:
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```Bash
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$ embark demo
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$ cd embark_demo
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```
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To run the ethereum node for development purposes simply run:
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```Bash
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$ embark blockchain
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```
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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
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Then, in another command line:
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```Bash
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$ embark run
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```
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This will automatically deploy the contracts, update their JS bindings and deploy your DApp to a local server at http://localhost:8000
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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.
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Creating a new DApp
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======
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```Bash
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$ embark new AppName
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$ cd AppName
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```
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DApp Structure
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======
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```Bash
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app/
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|___ contracts/ #solidity contracts
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|___ html/
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|___ css/
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|___ js/
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config/
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|___ blockchain.yml #environments configuration
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|___ contracts.yml #contracts configuration
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|___ server.yml #server configuration
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spec/
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|___ contracts/ #contracts tests
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```
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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
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Using Contracts
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======
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Embark will automatically take care of deployment for you and set all needed JS bindings. For example, the contract below:
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```Javascript
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# app/contracts/simple_storage.sol
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contract SimpleStorage {
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uint public storedData;
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function SimpleStorage(uint initialValue) {
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storedData = initialValue;
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}
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function set(uint x) {
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storedData = x;
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}
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function get() constant returns (uint retVal) {
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return storedData;
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}
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}
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```
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Will automatically be available in Javascript as:
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```Javascript
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# app/js/index.js
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SimpleStorage.set(100);
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SimpleStorage.get();
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SimpleStorage.storedData();
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```
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You can specify for each contract and environment its gas costs and arguments:
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```Yaml
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# config/contracts.yml
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development:
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SimpleStorage:
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gas_limit: 500000
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gas_price: 10000000000000
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args:
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- 100
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...
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```
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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.
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```Yaml
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# config/contracts.yml
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development:
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SimpleStorage:
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args:
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- 100
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- $MyStorage
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MyStorage:
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args:
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- "initial string"
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MyMainContract:
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args:
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- $SimpleStorage
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...
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```
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You can now deploy many instances of the same contract. e.g
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```Yaml
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# config/contracts.yml
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development:
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Currency:
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args:
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- 100
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Usd:
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instanceOf: Currency
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args:
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- "initial string"
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MyCoin:
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instanceOf: Currency
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args:
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- $SimpleStorage
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...
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```
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Contracts addresses can be defined, If an address is defined the contract wouldn't be deployed but its defined address will be used instead.
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```Yaml
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development:
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UserStorage:
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address: 0x123456
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UserManagement:
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args:
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- $UserStorage
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...
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```
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Tests
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======
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You can run specs with ```embark spec```, it will run any files ending *_spec.js under ```spec/```.
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Embark includes a testing lib to fastly run & test your contracts in a EVM.
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```Javascript
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# spec/contracts/simple_storage_spec.js
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EmbarkSpec = require('embark-framework').Tests;
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describe("SimpleStorage", function() {
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beforeAll(function() {
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// equivalent to initializing SimpleStorage with param 150
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SimpleStorage = EmbarkSpec.request("SimpleStorage", [150]);
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});
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it("should set constructor value", function() {
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expect(SimpleStorage.storedData()).toEqual('150');
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});
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it("set storage value", function() {
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SimpleStorage.set(100);
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expect(SimpleStorage.get()).toEqual('100');
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});
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})
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```
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Embark uses [Jasmine](https://jasmine.github.io/2.3/introduction.html) by default, but you can use any testing framework you want.
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Working with different chains
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======
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You can specify which environment to deploy to:
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```$ embark blockchain staging```
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```$ embark run staging```
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The environment is a specific blockchain configuration that can be managed at config/blockchain.yml
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```Yaml
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# config/blockchain.yml
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...
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staging:
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rpc_host: localhost
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rpc_port: 8101
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rpc_whitelist: "*"
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datadir: default
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network_id: 0
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console: true
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account:
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init: false
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address: 0x123
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```
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See [Configuration](https://github.com/iurimatias/embark-framework/wiki/Configuration).
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Deploying only contracts
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======
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Although embark run will automatically deploy contracts, you can choose to only deploy the contracts to a specific environment
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```Bash
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$ embark deploy privatenet
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```
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embark deploy will deploy all contracts at app/contracts and return the resulting addresses
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LiveReload Plugin
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======
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Embark works quite well with the LiveReload Plugin
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Debugging embark
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======
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Because embark is internally using grunt tasks, debugging is not straightforward. Example
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- you want to debug `embark deploy`
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- normally you would write something like `node-debug -p 7000 embark -- deploy`
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- 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]`
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- with this knowledge we can prepare proper command to start debugging
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- `node-debug -p 7000 grunt -- deploy_contracts:development`
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- [here](https://github.com/iurimatias/embark-framework/blob/develop/tasks/tasks.coffee) is list of all debuggable grunt tasks
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