They can also give more of an organizational feel to users, where the domain represents the organization and the subdomain resembles the structure of email addresses:. It would be great to continue playing the game with the same login from your laptop and your mobile phone as you are on the go even though both devices use different key pairs.
This is how this is achieved:. Luckily, there is no minimum length limit on ENS subdomains, either. To register a subdomain, you have to be the owner of the domain as a prerequisite. To create or update a subdomain, you have to call setSubnodeOwner on the ENS registry smart contract. Once successful, the same logic as with domains applies: The owner has to set the resolver and the target address. What if we could automate this and simplify the process for users? I have created [a smart contract that does exactly that—the aforementioned EnsSubdomainFactory.
The website must be viewed on a Ethereum-enabled browser like Mist , Parity , or the mobile app Cipher ; or by installing the MetaMask plugin. Instead of a traditional back end with a server and database, the read and write calls are made directly to the Ethereum blockchain. The calls can be done using the JSON RPC protocol, but luckily for us there is a library which wraps the calls in a developer-friendly fashion.
As of this writing, there are two relevant versions of web3. In this article we are using the latter version. The check for the web3 instance happens in the initWeb3 function. This will also work with upcoming MetaMask web3 injection changes :. We can then auto-populate the input fields for the new owner and target with the address of the current account. In our application, we do not need to interact with ether balances, but for completeness, here is how to check an account balance:.
Note that you have to specify the from and to fields as Ethereum addresses and also the value of ether you want to send. This is represented in wei—e. In order to interact with a smart contract, we first have to create a proxy object.
To do this, we need its application binary interface ABI , which specifies the available operations. In the application, we are interacting with one smart contract, which is our EnsSubdomainFactory :. After this setup, we are finally ready to make some calls. For our use case, we need to know who the current owner of a particular domain and subdomain is, so this is how our checkSubdomainOwner function looks:.
Note that this is a read-only operation: We are using call function, which is free to execute—i. The final blockchain call we need to make is to create or update the subdomain. We do it inside of the newSubdomain function:.
This time, we are passing four parameters to the function: subdomain , domain , owner , and target. They are self explanatory. Note that we are using send instead of call. An additional parameter that we include is gas which represents the gas limit for the transaction. If the transaction costs more than the limit to execute we want it to get reverted.
We would like to know when our transaction completes successfully and notify the user that their subdomain is ready to use. The factory smart contract defines an event which gets emitted when the subdomain is created or updated:.
Following the web3. Where we specify the event we want to listen to SubdomainCreated and pass the filter parameter to only listen to events where the creator is specified as our DApp. Unfortunately, the current version of MetaMask does not yet support web sockets , which are required by web3. This works in older version of web3. For the full source code, feel free to dig in here. If you want to play with the code locally, simply check it out and make sure you have the following npm packages installed:.
Finally, repoint the factory smart contract to your local node by uncommenting a line in dapp. To start the web server, simply execute npm run dev , which should launch your browser on localhost The contract is deployed to 0xbddeca64eec3d8cca68fcd6. Disclaimer: This is running on the main network, not testnet, so you are operating with real money.
Use at your own risk. Best of luck! A smart contract is a computer program that gets executed on the blockchain's nodes. Smart contracts can perform any calculation, persist data, define business rules, and also send and accept native currency like ether. Contracts are immutable in nature, unless programmed otherwise.
ENS domains currently end with. They can be bought in an auction and can have hierarchical subdomains. This can be any amount, but frontends are free to set criteria for inclusion or prioritisation based on the fee paid. There is no functionality in the contract for listing or querying domains that are registered with it, though events are emitted when new domains are registered.
To avoid spamming with low-quality domains, we recommend that frontend operators maintain a whitelist of domains to offer subdomain registrations on. For the security of customers, once you have transferred your domain to the subdomain registrar, you cannot claim it back except under very limited circumstances see below.
In the event of a bug or issue with the subdomain registrar being found, a migration path to a new implementation is provided. The owner of the subdomain registrar may halt new registrations, followed by setting a migration address to a new implementation. Afterwards, domain owners may call migrate to transfer ownership of their domain to the new implementation. Only domain owners may do this, so as to prevent the owner of the subdomain registrar from being able to sieze ownership of the names.
The current. This is likely to be accompanied by a change in API, which makes catering to this in existing contracts difficult. To avoid this, the subdomain registrar implements a precommitment strategy. At any point, the owner of a domain may specify a 'transfer address' for their domain. Once a transfer address is set, it may not be changed or unset. At the point at which the. See also the list of contributors who participated in this project.
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Additionally, ENS is an interesting way to try and create some profits as you can register. You can register our own. As we are using Trust Wallet , it will automatically establish a web3 connection. We will be redirected to ens. Unfortunately, Binance Smart Chain is not yet integrated so make sure that Ethereum is selected. Then, enter desired name on the box and enter. Select the lifespan of your domain name.
The lifespan is the time you have ownership or access to the ENS domain. Remember that you can renew lifespan anytime. You can own a. This is alot cheaper than the 2-year premium plans from regular DNS providers. Finally, click register, wait for the confirmation window from Trust wallet and confirm the payment.
You now have your own. ENS domains are useful in our interactions with the Ethereum network. They save us the time typing in long addresses without compromising the security of our funds. ENS domains also allow us to show ownership of the address and can even be used as our website domains through IPFS as our host.
Each app must have one or more domains they control which they can create immediate subdomains on demand. The app therefore will make these actions on the background:. All those steps can be designed to be set up in a single ethereum transaction. Instead, have an indicator somewhere on the app the shows the progress and then allow the user to interact with your app normally. Implementation note: in order to save gas, some of these steps can be done in advance.
Manager the higher level, allows the key to initiate or sign transactions that change the identity itself, like adding or removing keys. An app should only require this level if it integrates an identity manager.
Depending on how the identity is set up, it might require signature from more keys before these transactions can be deployed. Action this level allows the key to initiate or sign transactions on address other than itself. It can move funds, ether, assets etc. Encryption the lower level has no right to initiate any transactions, but it can be used to represent the user in specific instances or off-chain signed messages. If adding the new key requires multiple signatures, or if the app receiving that request exclusiveky deals with executable signed messages and has no ether on itself, then it should follow the steps in the next section on how to request transactions.
After step 2, the end result should be that your app should have the identity address of the user, their main ens name and a private key, whose public account is listed on the identity as one of their keys, with roles being either manager, action or encryption. Now it can start using that information to sign and execute transactions. Not all transactions need to be on chain , actually most common uses of signed messages should be off chain.
If you have a chat app, for instance, you can use the local key for signing messages and sending it to the other parties, and they can just query the identity contract to see if that key actually comes from the user. If you have a game with funds at stake, only the first transaction moving funds and setting up the initial game needs to be executed by the identity: at each turn the players can sign a hash of the current state of the board and at the end, the last two plays can be used to determine the winner.
Notice that keys can be revoked at any time, so your app should take that in consideration, for instance saving all keys at the start of the game.
An Ethereum Name Service (ENS) domain is equivalent to a DNS domain and offers a decentralized and secure way to translate human-memorable text into Ethereum. The Ethereum Name Service (ENS) is a distributed, open, and extensible naming system based on the Ethereum blockchain. ENS's job is to map human-readable. The owner of any domain can configure subdomains as desired. This is achieved by creating a subdomain and setting its owner to the desired address - this can be.