Mirror nodes are newly available in beta as a developer preview as of August 29th.
Mirror nodes provide a way to store and cost-effectively query historical data from the public ledger while minimizing the use of Hedera network resources. Mirror nodes support the Hedera network services currently available and can be used to retrieve the following information:
Transactions and records
A beta version of mirror node code is available on GitHub.
Hedera mirror nodes receive information from Hedera network consensus nodes, either mainnet or testnet, and provide a more effective means to perform:
While mirror nodes receive information from the consensus nodes, they do not contribute to consensus themselves. The trust of Hedera is derived based on the the consensus reached by the consensus nodes. That trust is transferred to the mirror nodes using signatures, chain of hashes and state proofs.
At version 1.0, mirror nodes will run the same code as consensus nodes.
To make the initial deployments easier, the beta version of mirror nodes strive to take away the burden of running a full Hedera node through creation of periodic files that contain processed information (such as account balances or transaction records), and have the full trust of the Hedera consensus nodes. The beta mirror node software reduces the processing burden by receiving pre-constructed files from the network, validating those, populating a database and providing REST APIs
Beta mirror nodes work by validating the signature files associated with the record, balance, and event files from the consensus nodes that were uploaded to a cloud storage solution from the network.
As transactions reach consensus on the Hedera network, either mainnet or testnet, Hedera consensus nodes add the transaction and its associated records to a record file. A record file contains a series of ordered transactions and their associated records. After a given amount of time, a record file is closed and a new one is created. This process repeats as the network continues to receive transactions.
Once a record file is closed, the consensus nodes generate a signature file. The signature file contains a signature for the corresponding record file’s hash. Along with the signature file of the consensus node, the record file also contains the hash of the previous record file. The former record file can now be verified by matching the hash of the previous record file.
Hedera consensus nodes push new record files and signature files to the cloud storage provider – currently AWS S3 and Google File Storage are supported, but not yet available. Mirror nodes download these files, verify their signatures based upon their hashes, and only then make them available to be processed.
Hedera will provide a REST API to easily query a mirror node that is hosted by Hedera, removing the complexity of having to run your own. This is actively being tested by a limited group of partners and will look to be expanded soon.
Anyone can run a Hedera mirror node by downloading and configuring the software on their computer. By running a beta mirror node, you are able to connect to the appropriate cloud storage and store account balance files, record files, and event files as described above.