Contracts enable mutually suspicious parties to cooperate safely through the exchange of rights. Smart contracts are programs whose behavior enforces the terms of the contract.
Contract Host
Smart Contract in Dr.SES
# The Contract Host Once Alice and Bob agree on a contract, how do they arrange for it to be run in a mutually trusted manner? To engage in the escrow exchange contract, Alice and Bob had to agree on the issuers, which is unsurprising since they need to agree on the nature of rights exchanged by the contract. And they had to agree on an escrow exchange agent to honestly run this specific escrow exchange contract. For a contract as reusable as this, perhaps that is not a problem. But if Alice and Bob negotiate a custom contract specialized to their needs, they should not expect to find a mutually trusted third party specializing in running this particular contract. Rather, it should be sufficient for them to agree on: - The issuers of each of the rights at stake. - The source code of the contract. - Who is to play which side of the contract. - A third party they mutually trust to run their agreed code, whatever it is, honestly
This paper shows how such contracts can be specified elegantly and executed safely, given an appropriate distributed, secure, persistent, and ubiquitous computational fabric. JavaScript provides the ubiquity but must be significantly extended to deal with the other aspects. The first part of this paper is a progress report on our efforts to turn JavaScript into this fabric. To demonstrate the suitability of this design, we describe an escrow exchange contract implemented in 42 lines of JavaScript code. page 
Smart Contract code ported to Node and Q github