Smart Contract Locator (SCL)

Version: 1.0.0

Date: July 31, 2019

Authors:
Andrea Lamparelli
Ghareeb Falazi
Uwe Breitenbücher
Florian Daniel
Frank Leymann

Introduction

This document specifies the Smart Contract Locator (SCL) extension to the URL scheme intended for the technology-agnostic addressing of permissioned and permissionless blockchain smart contracts.

Scheme Definition

Given the IETF specification of the generic URL format:

URL = scheme ":" [userinfo "@" ] host [":" port] path ["?" query] ["#" fragment]

An SCL is defined as a specialization of a URL composed of a standard URL (up to the path element included), which identifies a gateway that provides access to the blockchain platform on which the designated smart contract is hosted, and of an SCL query, which identifies the target smart contract inside the blockchain network:

 SCL = scheme ":" [userinfo "@" ] host [":" port] path "?" scl_query
 scl_query = "blockchain=" bc "&blockchain-id=" id "&address=" addr

 bc = "ethereum" | "bitcoin" | "fabric" | "eosio" | ...

 id = NetworkIdentifier                    // not further detailed here

 addr = eth_addr | bit_addr | fab_addr | eos_addr | ...
 eth_addr = 40ByteHexString                // not further detailed here
 bit_addr = Bech32Address                  // not further detailed here
 fab_addr = PathString                     // not further detailed here
 eos_addr = 12CharacterString              // not further detailed here
 ...

Therefore, an SCL identifies:

1. Which type of blockchain is addressed via the blockchain query parameter
2. Which exact blockchain network is addressed (especially useful for permissioned blockchains where a gateway could connect to multiple instances of the same type).
3. The blockchain-internal smart contract address (technology-specific)

Examples

In the following, we list example SCL addresses for a set of the supported blockchains that are accessed using the https scheme via a hypothetical gateway hosted at mygateway.com

Ethereum

https://mygateway.com?blockchain=ethereum&blockchain-id=eth-mainnet
        &address=0xa0b73e1ff0b80914ab6fe0444e65848c4c34450b

Bitcoin

https://mygateway.com?blockchain=bitcoin&blockchain-id=btc-mainnet
        &address=1Mbk53DzVKCz6MHiBd8ZHkPhsZETo7PtZR

Hyperledger Fabric

https://mygateway.com?blockchain=fabric&blockchain-id=part-vendors
        &address=channel1%2Fchaincode1%2Fsmartcontract1

EOSIO

https://mygateway.com?blockchain=eos&blockchain-id=eos-mainnet
        &address=myfancyacc05

Notes

• The proposal of SCL is compliant with standard URLs, which makes it natively ready for the Internet. The examples here use a schema binding of http or https, but nothing prohibits the use of SMTP or any other transport protocol.