Although it is widely believed that blockchain, DLT and smart contracts cannot retrieve information from external sources directly, for example, getting information such as the current temperature, new research published by Dr Joshua Ellul, Director of the Centre for Distributed Ledger Technologies, and Prof. Gordon Pace proves that this is a misconception.

In a new entry on Medium.com, titled ‘Contrary to widespread misconception, Blockchain, DLTs and Smart Contracts CAN make calls to external web services’, by making use of digitally signed responses when either a miner or validator needs to undertake an external call, and it will then record the response and the digital signature received by the external service.

What is important in understanding this, Prof. Pace and Dr Ellul say, is to do away with the preconceived belief that decentralised logic and the requirement for code to be deterministic in nature, actually means that all nodes must execute the same code. 

Whilst it is true that given some input in the system, we must be able to determine its output, not all nodes must execute the same code to reach this deterministic state. Only one node is needed to make the external call.

This revelation opens up many possibilities for new applications and allows for existing ones to become more efficient.

The preprint of the paper is available online.