Gibbername: your first off-chain composable protocol
On-chain vs. off-chain composability
The best way of understanding off-chain composability, Mel's new paradigm for the blockchain ecosystem, is to contrast it with the way Web3 is right now. Right now, smart contracts using standard APIs like ERC-20 form a pretty nice interoperable on-chain ecosystem, enabling applications like complex DeFi instruments beyond what's possible with first-generation blockchains like Bitcoin.
But interacting with anything outside this smart contract ecosystem turns out to be really hard. For instance, let's say you heard that ENS is decentralized and trustless, so you want to use it to replace DNS in some off-chain decentralized protocol (maybe to name Tor hidden services?).
You might think that it'll be a nice drop-in replacement, since it's very easy to integrate ENS into on-chain contracts. But you would be very wrong: the names are stored "illegibly" in the ENS contract state, exposed only through an on-chain contract API. All of your options for calling this API from off-chain code are bad:
Sacrifice security: just call RPC methods on some full node (with something like Web3.js), who you end up trusting completely. Just like with DNS, a centralized third party can now arbitrarily lie to you, censor you, etc. Oops!
Sacrifice scalability: force all your clients to run their own Ethereum full node, that you then query using the same RPC methods. This is going to be impractical for almost any application.
Reverse-engineer the contract and hack together a hyper-fragile thin client: Ethereum does have some thin-client support. So you can sorta-trustlessly query ENS names by disassembling the EVM code of ENS, figuring out where exactly in the blockchain state it stores name information, then craft the exact getProof calls needed to get the data in a verifiable way. But this is horribly complex and brittle. The smallest ENS governance upgrade can require you to re-reverse-engineer the EVM code, not to mention L1 issues like consensus-breaking upgrades and block reorganizations. You'll never compete against DNS's reliability and simplicity.
Furthermore, this "on/off-chain boundary problem" persists regardless of how much blockchains scale and how far we make protocols "crypto-native". Any web3 ecosystem has components like frontends, apps, and human users that fundamentally live off-chain while needing to securely talk to on-chain.
We need to solve this problem to have a truly successful Web3, with a rich ecosystem of secure decentralized protocols and apps outside of the blockchain. This requires a new kind of blockchain — Mel — that actually supports use as an off-chain root of trust. Features like a simple-to-implement protocol, a governance-free development model, and embeddable thin clients cooperate let off-chain programs efficiently utilize on-chain security.
More interestingly, on-chain logic for decentralized protocols plays a very different role. Instead of interoperating with on-chain code, on-chain protocols are written for off-chain consumers. Mel's overall data model lacks the entire concept of smart contracts calling each other, but it is supremely suited for encoding on-chain logic in a way that is legible and usable off-chain.
What will we build?
To demonstrate that, we'll build Gibbername, a trivial DNS-like decentralized naming system that would serve as an exemplary citizen of an off-chain composable ecosystem. Gibbername allows you to
Register a short, human-readable name. You won't be able to pick the name though, it will look something like sublak-demfet. (As we'll see, this makes the implementation really simple)
Bind the name to any data you wish, like a DNS record or JSON document.
Transfer the name to another person.
Like DNS, Gibbername will be very easy to integrate into apps, with a simple Rust library that allows for looking up and managing names. Unlike DNS, though, Gibbername will have three important, blockchain-backed "superpowers":
Identity retention: without the consent of the current owner, nobody can change the name-to-data mapping or transfer the name
Censorship resistance: nobody is able to prevent from name from resolving or prevent the current owner from updating or transferring the name
Permissionlessness: nobody can stop name registrations
All the above properties will be upheld despite the fact that lookups, transfers, etc will all be initiated by off-chain code rather than on-chain contracts.