software

Installing the Software

There is some software that you will need to install:

• The main development node/javascript packages
• The parity ethereum client
• The solc compiler (optional)
• A Solidity flattener (optional)

Javascript Packages

The core software components can be installed simply by npm in the root directory of the repository:

npm install

This will install several packages, including:

• web3. This is the main ethereum javascript library. It provides an API into the ethereum blockchain. Most tools use this at their base.
• Truffle. A development/testing framework for smart contract development.
• testrpc. testrpc is a node-based testing and development library for ethereum. With it you can test and deploy code on your local machine, which drastically reduces the time for iteration cycles, as compared to deploying to one of the public testing networks, such as ropsten.
• Open Zeppelin, a "framework of reusable and secure smart contracts in the Solidity language."

The Open Zeppelin project is an ambitious project meant to bring reliable components to the development of smart contracts -- kind of like a boost for solidity. It's still early in its life-cycle, but its initial appearance is promising. The example in this tutorial will be based upon that framework.

The above command (npm install) will install the software locally, so you will not need root or sudo access, but you will need to add the installed scripts to your path, such as:

npm install
cd node_modules/.bin
export PATH=`pwd`:$PATH

(and adding the path to any terminal in which you're developing).

Parity

Once the parity client is installed, you'll want to download the testing blockchain. In it's most basic terms, this can be done with the command:

parity --chain ropsten

This will download the blockchain, which could take a little while depending upon the speed of your connection, the speed of your hard disk, etc. Note, however, they parity client will conflict with the testrpc client (they default to the same port), so it's probably a good idea to get in the habit of using the --ports-shift keyword, which will shift all the ports the client listens on, including its main port (8545 -> 8546), as well as the port the GUI listens on (8180 -> 8181).

parity --chain ropsten --ports-shift 1

After you've started the client you can access the GUI through a web browser:

http://localhost:8180/ # The default
http://localhost:8181/ # with --ports-shift 1

The first time though you will be guided through the process of setting up an account on the blockchain. Of course, you can have an many accounts and/or wallets as you want, and you'll probably want at least two for testing purposes. For example, this client shows two accounts and one multi-signature wallet:

Once you've synchronized the blockchain and created an account, you'll need some ether to work on it. On the production chain ether is acquired through mining or purchase; on the test networks there are "drips" or "faucets" that will transfer some ether to your account. Currently the faucet at http://faucet.ropsten.be:3001/ will transfer 3 ropsten ether to an account you specify. I think there are daily limits, but 3 ether is plenty for doing a little work on the public chain.

The solc Solidity compiler

As mentioned in the repository README, it is useful to install The solc compiler, although it is not strictly necessary as the solcjs version installed with the node modules will work for development.

Information for installing the compiler (should you decide to do so) can be found here.

The solidity_flattener

You can also install the solidity flattener if you have python installed:

pip install solidity_flattener

This, along with solc can be used to publish source code in a way that allows it to be associated with the contract code that is deployed on the blockchain.

An Editor

You'll want to deck out your favorite editor for solidity. The atom editor seems have reasonable Solidity support with the appropriate plugins (but is a little buggy, in that the plugins sometime crash).

Next

• Creating a Project.