Moonbeam: The EVM of Polkadot
Deploying and onboarding users to Moonbeam or Moonriver
We've covered several Layer 2 sidechains before:
But Moonbeam is unique since it's a parachain of the Polkadot ecosystem. It only just launched which means you are now able to deploy smart contracts to the chain. Being able to deploy EVM contracts to the Polkadot world comes with unique features.
What is Moonbeam?
Moonbeam is a Polkadot parachain. Rather than regular sidechains, a parachain in Polkadot has unique security benefits. It can take advantage of the Polkadot chain's security. This shared security mechanism can greatly decrease the risk for 51% attacks like happened for Ethereum Classic attack on January 10. Parachains can also make use of Cross-Consensus Message Format (XCM) which allows to send messages from one parachain to another one. And yes you can use tokens transferred via XCM in your smart contracts!
And you can send regular Ethereum transactions to Moonbeam. Moonbeam has implemented a fully functioning EVM as part of a Polkadot parachain. The EVM is fully functioning with most precompiles and all opcodes available. But since Moonbeam itself is a Proof of Stake chain, some opcodes have no meaning in Moonbeam. If you are reading things like the block hash or difficulty, it will only return some default values.
The available precompiles and additionally deployed helper contracts can be found here. In particular Moonbeam specific features include:
- Parachain Staking: You can interact with the parachain staking directly by (un-)-delegating and retrieving rewards.
- Crowdloan Rewards: You can retrieve crowdloan information as well as claim rewards.
- Wrapped GLMR as ERC-20: 0xAcc15dC74880C9944775448304B263D191c6077F
All code for Moonbeam can be found here. And block explorers either with Moonbeam Blockscout or Moonscan.
Why choose Moonbeam?
Since Moonbeam is a Polkadot parachain, deploying smart contracts to it will have a much higher security than deploying to other sidechains. The Polkadot relay chain has a very large market cap currently being in the Top 10 of all chains. And with Moonbeam you can take full advantage of the speed, Proof of Stake and low gas fees without having to compromise on the security aspect.
And you can make use of new features!
Parachain Staking
You can directly access staking features using the ParachainStaking interface contract at address 0x0000000000000000000000000000000000000800.
This will allow you to delegate funds directly to the Moonbeam parachain staking from Proof of Stake within your smart contract.
- You can use the
delegatefunction to start a delegation to parachain node (called collator). - You can use
schedule_leave_delegatorsto stop a delegation.
There are a few other functions in the interface which you can see here, but the ones on the right will be the most important ones.
// SPDX-License-Identifier: GPL-3.0-only
pragma solidity >=0.8.0;
interface ParachainStaking {
function is_delegator(
address delegator
) external view returns (bool);
function is_candidate(
address candidate
) external view returns (bool);
function delegate(
address candidate,
uint256 amount,
uint256 candidateDelegationCount,
uint256 delegatorDelegationCount
) external;
function schedule_leave_delegators() external;
}Crowdloan Rewards
And you can also access crowdloan rewards to get info or to claim rewards for any crowdloan participant. The interface is available at address 0x0000000000000000000000000000000000000801.
If you're wondering what the heck is a crowdloan? The short answer is there is a limited amount of parachain slots available since every parachain increases the computational complexity of nodes in the Polkadot chain. That's why there are auctions for the slots as 2-year leasings. Whoever bids the most DOT will receive the slot for two years, while having their DOT locked during this time. A crowdloan then is a mechanism that most projects are using to collectively use DOT together and participants will receive the project's token as reward.
In the case of Moonbeam crowdloan participants received 30% initially and the rest is vested of a two year time with rewards being able to be claimed continuously.
You can see past, current and future auctions here. As you can see Moonbeam actually won the second auction right after Acala.
interface CrowdloanRewards {
function is_contributor(
address contributor
) external view returns (bool);
function reward_info(
address contributor
) external view returns (uint256, uint256);
function claim() external;
function update_reward_address(
address new_address
) external;
}XCM Tokens
Since Moonbeam is a parachain in Polkadot, you can make use of the cross-chain transfers. Inside your contracts you cannot directly transfer send XCM messages, because the EVM has no functionality for this. (although I imagine the Moonbeam EVM could get an upgrade to support this later?)
But you can still use cross-chain tokens. Moonbeam makes them automatically available as fully compatible ERC-20 tokens. If you wanted to do cross-chain transfers yourself, you will need to use the Moonbeam Substrate API. What is Substrate you may ask?
Substrate is a framework for developing your own blockchain as part of the Polkadot ecosystem. So Moonbeam itself was developed using this framework. And while Moonbeam provides an abstraction layer to be EVM compatible, under the hood the blockchain is managed in Substrate. So to use native Substrate features, you need to move out of the EVM abstraction. You can find a block explorer for the Substrate part of Moonbeam here.
Moonbeam vs. Moonriver: Which one to choose?
One unique feature of the Polkadot ecosystem is that they have a so-called canary chain: Kusama. It's the same chain as Polkadot except that they are more experimental (hence the name canary) by doing everything faster. For example governance time is shorter, unstaking period is shorter and the parachain auctions for Kusama started already half a year ago. And that's why some projects have two parachains, one on Kusama and one on Polkadot. In the case of Moonbeam, there is also the Moonriver parachain with the connection to Kusama. So which one should you use?
Moonriver will be the faster upgrading, more experimental chain with less security. For your own Dapp on Moonbeam you have three options:
- Deploy only to Moonbeam: higher security, more stable, longer time for upgrades
- Deploy only to Moonriver: lower security, less stable, faster time for upgrades
- Deploy to Moonbeam and Moonriver: highest security, since you will have your own canary Dapp this way, but more effort to maintain
Which option you choose is up to you. If you're unsure, you're probably best to deploy only to Moonbeam since it gives you high security without extra work.
Moonbeam Ecosystem
There is a large ecosystem evolving around Moonbeam. You can find many tools and projects currently working towards integrating Moonbeam. Many are at the time of writing still work in progress for Moonbeam. For example the Band and Chainlink oracles are not yet available, although Chainlink is available for Moonriver.
You can already use The Graph on Moonbeam. Check out my tutorial how to use it here. It's the best tool for querying blockchain data in your Dapp's frontend.
And if you're looking to integrate a DEX in your contracts like Uniswap, Solarflare is exactly that. If you want to integrate it, my previous Uniswap 2 tutorial should work just fine.
How to deploy to Moonbeam
Deploying to Moonbeam is very simple. If you're using Truffle or Hardhat, simply add the network configuration like this:
moonbeam: {
provider: () => new HDWalletProvider(mnemonic, 'https://rpc.api.moonbeam.network'),
network_id: 1284,
},
},
moonriver: {
provider: () => new HDWalletProvider(mnemonic, 'https://rpc.api.moonriver.network'),
network_id: 1285,
},
},
moonbase-alpha: {
provider: () => new HDWalletProvider(mnemonic, 'https://rpc.api.moonbase.moonbeam.network'),
network_id: 1287,
},
},You'll also need funds in the chain of course. For the testnet you can use the faucet via the faucet channel at the Moonbeam Discord. For Moonbeam and Moonriver funds, you'll need to purchase those on an exchange.
How to onboard users to your Moonbeam Dapp
1. Choice of wallet
These days you have much more than just MetaMask as possible wallets to support available. Take a look at Yearn Finance for example. They are supporting 11 different wallets alone at the time of this writing.
2. MetaMask example live in action
We'll focus on MetaMask as the biggest wallet with the most features. With MetaMask you can nowadays actually request to connect directly to a custom network.
If you want to see this live, just go to the Moonbeam docs. Unless you already have Moonbeam Network added, it will request to add this network.
3. How to add Moonbeam automatically for users
You can see on the right how to add the Moonbeam automatically to the wallet for the user. This will show the popup you see above. If the user confirms, the network is added and automatically switched to.
This is all thanks to EIP-3085 with the new RPC method wallet_addEthereumChain . See also the MetaMask docs here.
const params = [{
"chainId": "1284",
// Moonriver: "chainId": "1285",
// Testnet: "chainId": "1287",
"chainName": "Moonbeam",
// or "Moonriver" or "Moonbase Alpha"
"rpcUrls": [
"https://rpc.api.moonbeam.network"
// or "https://rpc.moonriver.moonbeam.network"
// or "https://rpc.api.moonbase.moonbeam.network"
],
"nativeCurrency": {
"name": "Glimmer", // or Moonriver or Dev
"symbol": "GLMR", // or MOVR or DEV
"decimals": 18
},
"blockExplorerUrls": [
"https://moonscan.io"
// or "https://moonriver.moonscan.io/"
// or "https://moonbase.moonscan.io/"
]
}]
try {
await ethereum.request({
method: 'wallet_addEthereumChain',
params,
})
} catch (error) {
// something failed, e.g., user denied request
}Solidity Developer
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Using the new Uniswap v2 in your contracts
What's new in Uniswap v2 and how to integrate Uniswap v2
Note : For Uniswap 3 check out the tutorial here. What is UniSwap? If you're not familiar with Uniswap yet, it's a fully decentralized protocol for automated liquidity provision on Ethereum. An easier-to-understand description would be that it's a decentralized exchange (DEX) relying on external...
Solidity and Truffle Continuous Integration Setup
How to setup Travis or Circle CI for Truffle testing along with useful plugins.
Continuous integration (CI) with Truffle is great for developing once you have a basic set of tests implemented. It allows you to run very long tests, ensure all tests pass before merging a pull request and to keep track of various statistics using additional tools. We will use the Truffle...
Upcoming Devcon 2021 and other events
The Ethereum Foundation just announced the next Devcon in 2021 in Colombia
Biggest virtual hackathon almost finished First of all, the current HackMoney event has come to an end and it has been a massive success. One can only imagine what kind of cool projects people have built in a 30 days hackathon. All final projects can be seen at:...
The Year of the 20: Creating an ERC20 in 2020
How to use the latest and best tools to create an ERC-20 token contract
You know what an ERC-20 is, you probably have created your own versions of it several times (if not, have a look at: ERC-20). But how would you start in 2020 using the latest tools? Let's create a new ERC-2020 token contract with some basic functionality which focuses on simplicity and latest...
How to get a Solidity developer job?
There are many ways to get a Solidity job and it might be easier than you think!
You have mastered the basics of Solidity, created your first few useful projects and now want to get your hands on some real-world projects. Getting a Solidity developer job might be easier than you think. There are generally plenty of options to choose from and often times not a lot of...
Design Pattern Solidity: Mock contracts for testing
Why you should make fun of your contracts
Mock objects are a common design pattern in object-oriented programming. Coming from the old French word 'mocquer' with the meaning of 'making fun of', it evolved to 'imitating something real' which is actually what we are doing in programming. Please only make fun of your smart contracts if you...
Kickstart your Dapp frontend development with create-eth-app
An overview on how to use the app and its features
Last time we looked at the big picture of Solidity and already mentioned the create-eth-app. Now you will find out how to use it, what features are integrated and additional ideas on how to expand on it. Started by Paul Razvan Berg, the founder of sablier, this app will kickstart your frontend...
The big picture of Solidity and Blockchain development in 2020
Overview of the most important technologies, services and tools that you need to know
Now, I do not know about you, but I remember when I first started with Solidity development being very confused by all the tools and services and how they work in connection with one another. If you are like me, this overview will help you understand the big picture of Solidity development. As I...
Design Pattern Solidity: Free up unused storage
Why you should clean up after yourself
You may or may not be used to a garbage collectors in your previous programming language. There is no such thing in Solidity and even if there was a similar concept, you would still be better off managing state data yourself. Only you as a programmer can know exactly which data will not be used...
How to setup Solidity Developer Environment on Windows
What you need to know about developing on Windows
Using Windows for development, especially for Solidity development, can be a pain sometimes, but it does not have to be. Once you have configured your environment properly, it can actually be extremely efficient and Windows is a very, very stable OS, so your overall experience can be amazing. The...
Avoiding out of gas for Truffle tests
How you do not have to worry about gas in tests anymore
You have probably seen this error message a lot of times: Error: VM Exception while processing transaction: out of gas Disclaimer : Unfortunately, this does not always actually mean what it is saying when using Truffle , especially for older versions. It can occur for various reasons and might be...
Design Pattern Solidity: Stages
How you can design stages in your contract
Closely related to the concept of finite-state machines, this pattern will help you restrict functions in your contract. You will find a lot of situations where it might be useful. Any time a contract should allow function calls only in certain stages. Let's look at an example: contract Pool {...
Web3 1.2.5: Revert reason strings
How to use the new feature
A new Web3 version was just released and it comes with a new feature that should make your life easier. With the latest version 1.2.5, you can now see the the revert reason if you use the new handleRevert option. You can activate it easily by using web3.eth.handleRevert = true . Now when you use...
Gaining back control of the internet
How Ocelot is decentralizing cloud computing
I recently came across an ambitious company that will completely redefine the way we are using the internet. Or rather, the way we are using its underlying infrastructure which ultimately is the internet. While looking at their offering, I also learned how to get anonymous cloud machines, you...
Devcon 5 - Review
Impressions from the conference
I had a lot to catch up on after Devcon. Also things didn't go quite as planned, so please excuse my delayed review! This year's Devcon was certainly stormy with a big typhoon warning already on day 1. Luckily (for us, not the people in Tokyo), it went right past Osaka. Nevertheless, a lot of...
Devcon 5 - Information, Events, Links, Telegram
What you need to know
Devcon 5 is coming up soon and there are already lots of events available, information about Osaka and more. Here is a short overview: Events Events Calendar Events Google Docs Events Kickback Most events are in all three, but if you really want to see all, you will have to look at all three...
Design Pattern Solidity: Off-chain beats on-chain
Why you should do as much as possible off-chain
As you might have realized, Ethereum transactions are anything but cheap. In particular, if you are computing complex things or storing a lot of data. That means sometimes we cannot put all logic inside Solidity. Instead, we can utilize off-chain computations to help us. A very simple example...
Design Pattern Solidity: Initialize Contract after Deployment
How to use the Initializable pattern
There are a few reasons why you might want to initialize a contract after deployment and not directly by passing constructor arguments. But first let's look at an example: contract MyCrowdsale { uint256 rate; function initialize(uint256 _rate) public { rate = _rate; } } What's the advantage over...
Consensys Blockchain Jobs Report
What the current blockchain job market looks like
Consensys published their blockchain jobs report which you can checkout in their Blockchain Developer Job Kit. The most interesting aspects are Blockchain developer jobs have been growing at a rate of 33x of the previous year according to LinkedIns jobs report Typical salary is about...
Provable — Randomness Oracle
How the Oraclize random number generator works
One particularly interesting approach by Provable is the usage of a hardware security device, namely the Ledger Nano S. It uses a trusted execution environment to generate random numbers and provides a Provable Connector Contract as interface. How to use the Provable Randomness Oracle? Use the...
Solidity Design Patterns: Multiply before Dividing
Why the correct order matters!
There has been a lot of progress since the beginning of Ethereum about best practices in Solidity. Unfortunately, I have the feeling that most of the knowledge is within the circle of experienced people and there aren’t that many online resources about it. That is why I would like to start this...
Devcon 5 Applications closing in one week
Devcon 5 Applications closing
Watch out for the Devcon 5 applications. You only have one week left to apply either as Buidler Student Scholarship Press Devcon is by far the biggest and most impressive Ethereum conference in the world. And it's full of developers! I am especially excited about the cool location this year in...
Randomness and the Blockchain
How to achieve secure randomness for Solidity smart contracts?
When we talk about randomness and blockchain, these are really two problems: 1. How to generate randomness in smart contracts? 2. How to produce randomness for proof-of-stake (POS) systems? Or more generally, how to produce trusted randomness in public distributed systems? There is some overlap...