Although the primary function of any blockchain network is to process and document transactions, metadata allows users to include extra information in these transactions. If you wish to learn more about metadata, we recommend reading this article to the end.
Types of Metadata
There are two major types of metadata. They include:
On-Chain Metadata
This type of metadata is maintained on a blockchain as it is part of a particular transaction. It may include information like notes, labels, and references to documents. Note that on-chain metadata is visible to other blockchain users.
Off-Chain Metadata
Although off-chain metadata is referenced in a transaction, it’s not directly stored on a blockchain. It usually contains links to external content like web URLs, files, and documents that provide more information about a transaction.
How Off-Chain and On-Chain Metadata Are Stored
On-chain metadata can be transaction details or smart contracts. As mentioned earlier, it is stored permanently on a blockchain. When making crypto transactions, information such as your address, the recipient’s address, and transaction amount are considered on-chain metadata. Similarly, smart contracts for cryptocurrencies are on-chain metadata, which includes details like transaction IDs, block timestamps, token name, supply, and symbol.
Off-chain metadata, on the other hand, is stored off a blockchain. There are multiple places it can be stored, including off-chain scaling solutions such as the Lightning Network, external databases, and decentralized storage systems. The goal is to free up space on the chains and reduce congestion. Blockchains use cryptographic pointers or hashes to access off-chain metadata.
Examples of Metadata in Transactions
Timestamp: This shows the exact time a particular transaction block was added to a blockchain.
Transaction details: As mentioned, transaction details include addresses of the sender and receiver as well as transaction amounts.
Smart contract data: This contains a token’s address, name, and supply.
Digital signatures: Metadata has digital signatures that verify the legitimacy of blockchain transactions.
Gas fees: This metadata is helpful to validators and miners, as they use it to prioritize blockchain transactions.
Oracles: These are third-party services that allow smart contracts to access real-world information. Data stored in oracles is considered metadata.
NFTs: Details of a particular NFT, such as its creator and description, are metadata.
How Do You Add Metadata to a Transaction?
If you want to include metadata in your blockchain transaction, you can do so using a smart contract. In this guide, we will show you how to add metadata via smart contracts on Ethereum.
Develop a Smart Contract
You need to build a smart contract before adding metadata. This contract includes instructions on how and where the metadata will be maintained. You can develop your smart contract using a programming language like Solidity.
Interact With the Smart Contract
To add metadata, interact with your smart contract by initiating a transaction using an Ethereum wallet or libraries like ethers.js.
Verify the Metadata
After validators confirm your transaction and add it to the Ethereum blockchain, you can then verify the metadata.
Use Cases of Metadata
Blockchain metadata has several use cases in various sectors, including:
Supply Chain Management
Companies can enhance transparency and traceability by putting metadata for product production, quality, and transportation on a blockchain. For example, a food production company can use blockchain metadata to track information like the location of materials and quality checks.
Digital Identity
Educational institutions and governments can use blockchain metadata to store and manage personal data. They can also limit access to authorized individuals, thus lowering the risks of identity theft.
Lenders
Players in the financial sector can use metadata to determine eligibility for loans based on borrowers’ transaction history stored on a blockchain.
Healthcare Records
Medical facilities can use blockchain metadata to keep the records of patients in a secure manner.
Cons of Metadata
One of the biggest downsides of metadata is that it limits scalability. As more data is stored on a blockchain, the architecture of that network is likely to be strained, causing scalability issues.
