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.
The website must be viewed on an Ethereum-enabled browser like Mist, Parity, or the mobile app Cipher; or by installing the MetaMask plugin. All blockchains are distributed in nature as they have separate nodes working together in a distributed manner. Not all blockchains are decentralized, though. Some are centralized if there is a company that can censor, change, or stop the operation of the blockchain.
Author Radek Ostrowski. Radek is a blockchain engineer with an interest in Ethereum smart contracts. He also has extensive experience in machine learning. What about subdomains? Are they any simpler? ENS Subdomains What use is there of a subdomain in the first place?
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: radek freedomain. This will also work with upcoming MetaMask web3 injection changes : window. In our application, we do not need to interact with ether balances, but for completeness, here is how to check an account balance: web3.
Interacting with Smart Contracts In order to interact with a smart contract, we first have to create a proxy object. The significance of owning a domain like Nike. In the early days of the internet, websites had IP addresses which made it difficult to easily visit a website. As the age of the internet continues and Web 2. With the progression of web 3. Otherwise known as Ethereum Name Service, the ENS offers a secure way to translate the Ethereum addresses a user has into a text that is easily searchable from human memory.
When creating an Ethereum wallet, users are given a long string of generated numbers and letters that they are able to send their Ethereum assets to and from. The difficulty with this is that these addresses are too difficult to memorize and use consistently.
When registered, the ENS resolves the address and becomes the identifier for the specific address that the wallet is registered to. You will need an Ethereum-enabled browser to access your crypto wallet. If you do not have a crypto wallet, you can set up yours by following this guide here.
If you are registering through mobile you can use Trustwallet , Coinbase Wallet , or MetaMask mobile apps. In order to access the ENS registration application, you must be signed in to your Ethereum browser with the same wallet that you want to have the ENS name registered to. Note: If you register the ENS name to one address and you want to transfer it in the future, you can do that. When searching for a name, you will get one of two prompts: Available or Unavailable.
If the name is unavailable you will be able to see the address that registered it and when the expiration date is. If the address is available you will be prompted with a way to register the domain and pay for the number of years that you would like to register the domain for.
You can always log back into the ENS provider to extend the time that you have the ENS registered for so that it does not expire. This is the step that you will need to use your crypto wallet to sign the transaction.
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