Polkadot’s Messaging Scheme (XCMP)
One of the key features of Polkadot “version 1.0” is to let its otherwise isolated parachains send messages between each other with guarantees and in a secure and trust-free manner. A message refers to data coming from outside of the receiving chain, and implies and requires that the chain acts on the data following the chain’s internal logic. Allowing for some level of delay typical for real-world systems, the chain cannot reject or confound the implications of the data. The key difference between a transaction and a message is that a transaction contains a signature to prove the provenance of the data (and thus the authority of the instructions), whereas with a message the provenance is proven merely by virtue of Polkadot’s internal Byzantine-resistant cryptoeconomic validation infrastructure, in much the same way as Ethereum’s inter-contract message passing. Let's take a look how Polkadot works and enables its messaging system. What is Polkadot? Polkadot is a next-generation