Boson Protocol enables smart contracts to perform on-chain financial transfers coordinated with the off-chain, often physical, delivery of goods and services. The ultimate goal is to do it in an atomic and autonomous manner - any other way raises security/trust issues and raises questions about why you would need a blockchain.
The base layer of Boson Protocol is implemented and enforced in smart contracts. There are also keeper services running as self-hosted scripts that offer an improved UX and can be run by anyone, e.g. scheduled transactions.
The protocol will progressively grow in complexity, as will the list of its components, and we are looking forward to finding the best paths in collaboration with other projects in the space.