Introduction to Developer Documentation
Meter is a DeFi infrastructure with a built-in, crypto-native, metastable currency called MTR. You can use Meter as a Layer 1 blockchain to build DeFi apps on top of, or as a highly-decentralized, high-performance side chain for Ethereum and other public chains.
The current Ethereum version on Meter is 1.10.17
There are two primary methods of interacting with Meter: Ethereum compatible RPC or Meter Native Restful APIs. This section describes the Ethereum compatible RPC interface and native Restful APIs are detailed here.
1. Ethereum RPC
In order to better support existing Ethereum dApp developers, we developed an Ethereum emulation mode for Meter. Through an addon module called webgear Meter nodes are able to understand Ethereum transaction format and support the standard Ethereum RPC interface. It is like using the Apple M1 silicon to run x86 applications with a 100x performance improvement. Developers are even able to use their preferred Ethereum development tools like Remix, ethers.js and web3.js to interact with Meter. Due to the limitations of the Ethereum RPC, not all Meter functionality is available in Ethereum emulation mode. In this mode, MTRG must be treated as a special ERC20 token via a system contract.
The other difference between Meter and Ethereum is that Meter removed the sequential nonce concept in Ethereum and uses a random number as nonce instead. The Ethereum emulation layer will automatically generate the random nonce, you will not be able to replace a transaction with the same nonce.
When interacting with Meter you must use "Injected Web3" in Remix alongside Metamask.
Testnet:
Warringstakes Testnet Endpoints:
Websocket: wss://wstest.meter.io
ChainID: 83
Currency Symbol: MTR
Explorer: https://scan-warringstakes.meter.io
ERC20 System Interface:
MTRG: 0x8a419ef4941355476cf04933e90bf3bbf2f73814
MTR: 0x4cb6cef87d8cadf966b455e8bd58fff32aba49d1
Useful Contracts:
Multi-call3(Official Deployment): 0xcA11bde05977b3631167028862bE2a173976CA11
WMTR: 0xfAC315d105E5A7fe2174B3EB1f95C257A9A5e271
Faucet for Testnet:
https://faucet-warringstakes.meter.io/
Mainnet:
RPC Endpoint:
RPC:
Providers with high quality API key access:
https://blockpi.io/ (https://meter.blockpi.network/v1/rpc/public)
Free rate limited access:
https://rpc.meter.io (port 8545 on the mainnet docker)
https://rpc-meter.jellypool.xyz (community maintained)
Websocket:
wss://ws.meter.io (port 8546 on the mainnet docker)
ChainID: 82
Currency Symbol: MTR
Explorer: https://scan.meter.io
ERC20 System Interface:
-MTRG: 0x228ebBeE999c6a7ad74A6130E81b12f9Fe237Ba3
-MTR (Optional): 0x687A6294D0D6d63e751A059bf1ca68E4AE7B13E2
Useful Contracts:
Multi-call3 (Official Deployment): 0xcA11bde05977b3631167028862bE2a173976CA11
WMTR: 0x160361ce13ec33C993b5cCA8f62B6864943eb083
List of Common ERC20 Tokens on Meter mainnet:
https://github.com/meterio/token-list/blob/master/generated/meter-tokens.json
2. Source Code Verification
Meter explorer uses Sourcify to verify the onchain contracts' byte code is exactly the same as the source code. Verifying contracts also allows the explorer to properly decode smart contract transactions. There are various tools (for example Remix plugins) that help developers to verify on Sourcify.
The submission for source code can be either done through Meter Explorer or Sourcify Portal.
Typically the fastest way to verify a solidity project build with Hardhat is to zip all the json files under the artifacts/build-info/ directory, upload the zip files to the Sourcify Portal, and select all the contracts to be verified. If a contract is verified through the Sourcify Portal, you may have to interact with the contract tab on the explorer under the contract address page to force the Meter explorer to sync the verification status from Sourcify, otherwise it may take a few hours for the explorer to automatically pick up the information.
There are two levels of verification: 1. source code match and 2. both source code, metadata match. Source code match is considered the minimum for contract verification purposes.
The main difference between Sourcify and Etherscan verification is that Sourcify requires metadata to be uploaded for verification in addition to source code and byte code. Information on finding the metadata file is available in Sourcify Documents. Both the Meter Explorer and Sourcify website allow uploading zip file. If your file is too large, we recommend directly using the Sourcify website to upload multiple files. If you are using Truffle, sometimes after you upload the json file, Sourcify complains not able to find the corresponding find .sol files in your local file path. You could try zip all the contract source code in a file and upload to Sourcify website. It will typically resolve the issue. From time to time, Sourcify may have problem recognizing files uploaded from Windows computers. You could try using a Mac to upload the files.
3. Multisig Wallet
Meter team has deployed a forked UI of Gnosis Safe multsig wallet on the Meter mainnet. The smart contracts for the multsig were officially deployed by the Gnosis team. It can be found at:
4. Graph Node
The meter foundation maintains two separate graph nodes for the Meter Testnet and mainnet for dApp developers. They are for testing purposes only. If you need production-level graph nodes on Meter mainnet, please reach out to the team on Discord or Telegram. We are happy to host the subgraph on our production graph nodes.
On testnet:
In the package.json file for your subgraph:
In the subgraph.yaml file for your subgraph:
On Mainnet:
In the package.json file for your subgraph:
In the subgraph.yaml file for your subgraph:
5. APIs and Indexers
Thirdweb.com provides RPC endpoints, tools, smart contract libraries, and APIs for developers to launch dApp quickly:
covalenthq.com provides data analytics APIs on the Meter mainnet.
SubQuery is a leading blockchain data indexer that provides developers with fast, flexible, universal, open source and decentralised APIs for web3 projects. Another one of SubQuery's competitive advantages is the ability to aggregate data not only within a chain but across multiple blockchains all within a single project.
6. Bridges
Layer 0 connects Meter Mainnet and Testnet to more than 20 other chains. The documentation can be found at https://layerzero.gitbook.io/docs/technical-reference/mainnet/supported-chain-ids and https://layerzero.gitbook.io/docs/technical-reference/testnet/testnet-addresses
Meter Passport provides connection to 8 different chains. To add ERC20 or NFT tokens to the supported list, please make a pull request based on the instructions here: https://github.com/meterio/token-list
7. Oracles
Band Protocol and Witnet are providing price feeds to the Meter mainnet and testnet. Detailed documentation can be found on their respective websites.
Pyth Network provides real-time data in an on-demand-based push model. Meter Foundation is currently running a price pusher for USDC/USDT/ETH/MTRG/MTR/BTC/WBTC on the Meter mainnet and testnet. In addition, Pyth network allows any developer to run additional price pushers permissionlessly.
Supra provides decentralized oracle price feeds that can be used for on-chain and off-chain use-cases such as spot and perpetual DEXes, lending protocols, and payments protocols. Supra’s oracle chain and consensus algorithm makes it the fastest-to-finality oracle provider, with layer-1 security guarantees. The pull oracle has a sub-second response time. The list of push based data available on Meter can be found here. The developer docs are available here.
8. Important Things to Pay Attention to:
Currently, there is a limitation that MTR and MTRG can only be sent to a contract address through smart contract interactions. For example, if you want to send MTR to a contract address manually, you will have to use the above ERC20 system interface.
Meter network now requires all transactions to contain chainID. Please make sure to configure your deployment script properly.
The minimum gas price on Meter is currently 100gwei (Use eth_estimateGas to obtain the gas price). Even if a lower gas price is specified, the network will still charge 100gwei silently. Make sure you have enough MTR in the account.
Meter network is front-running resistant. It does not order transactions by the gas price specified. Transactions are ordered by the time the proposing node receives them. By default, if a transaction is not processed within 320 blocks after the network receives it, it will automatically expire.
Meter does not require sequential nonce for each account. If you want to deploy your contract to a specified address, please use the deterministic deployment method for Ethereum. If you want to use an EOA address and specific nonce to create a deterministic contract address, you will have to force the nonce of your transaction (for example in MetaMask) instead of relying on the random nonce returned from the RPC. As long as the nonce has not been used, the transaction will be processed and the same contract address can be created.
If you use Ethereum RPC to obtain the next nonce, you will receive a random number. In fact, you could use any nonce when sending a transaction on Meter. However, transactions from the same account with duplicated nonce will not be executed. Precomputed Ethereum tx hash is also guaranteed to be the same as on-chain hash.
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