Unspent output notifications

The old model

How ElectrumX allows a wallet to find existing transactions and hear about new transactions in both the mempool and in blocks, is by monitoring script hashes. The wallet has to know how coins were spent to find them. And the server has to index all relevant transactions in the blockchain, so it can provide any data the user is asking for.

The new model

We will no have longer a full index of the blockchain. It will be an expensive action to ask “look back through the blockchain and find me this”. The user needs to know what has already happened, and keep that data, and provision services to monitor ongoing usage to add to their existing data and react to.

Examining applications

This is not intended to be a definitive list of the applications that could be made of APIs that provide unspent output functionality, but just the ones we know we are more than likely going to make use of.


The highest priority is to get this working in our sample indexer, it does not have to be long term implementation. As long as it serves our needs, we can integrate it and hook it up. If at a later time it is apparent there is a better way, we’ll just implement it and change the reference server API.



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