Whisper and Swarm

Whisper and Swarm are a decentralized communication protocol and a decentralized storage platform respectively, being developed by Ethereum developers. Whisper is a decentralized communication protocol, whereas Swarm is a decentralized filesystem.

Whisper lets nodes in the network communicate with each other. It supports broadcasting, user-to-user, encrypted messages, and so on. It's not designed to transfer bulk data. You can learn more about Whisper at https://github.com/ethereum/wiki/wiki/Whisper, and you can see a code example overview at https://github.com/ethereum/wiki/wiki/Whisper-Overview.

Swarm is similar to Filecoin, that is, it differs mostly in terms of technicalities and incentives. Filecoin doesn't penalize stores, whereas Swarm penalizes stores; therefore, this increases the file availability further. You must be wondering how incentive works in swarm. Does it have an internal currency? Actually, Swarm doesn't have an internal currency, rather it uses ether for incentives. There is a smart contract in Ethereum, which keeps track of incentives. Obviously, the smart contract cannot communicate with Swarm; instead, swarm communicates with the smart contract. So basically, you pay the stores via the smart contract, and the payment is released to the stores after the expiry date. You can also report file missing to the smart contract, in which case it can penalize the respective stores. You can learn more about the difference between Swarm and IPFS/Filecoin at https://github.com/ethersphere/go-ethereum/wiki/IPFS-&-SWARM  and see the smart contract code at https://github.com/ethersphere/go-ethereum/blob/bzz-config/bzz/bzzcontract/swarm.sol.

At the time of writing this book, Whisper and Swarm are still under development; so, many things are still not clear.