Store IoT device data on a blockchain, then transfer it to PostgreSQL, and finally expose API endpoints to fetch the data. This process involves multiple steps and technologies:

Storing IoT Device Data on the Blockchain

IOT devices data will be stored off-chain, in the cloud, IPFS etc. Smart Contract on a public or private blockchain (e.g., Ethereum, Hyperledger, or private blockchains) will be used to store data related to the IoT devices. These smart contracts will log each event or reading from the IoT device.

Example Workflow for Blockchain Data Storage:

• IoT devices send data (e.g., temperature readings, location, etc.) to a middleware or application.

• Middleware generates a hash of the data, adds metadata (device ID, timestamp), and stores this information on the blockchain.

• The actual data (if large) can be stored off-chain in a distributed file system or database, with the blockchain storing just the reference or hash.

Transferring Data to PostgreSQL

Once the data is recorded on the blockchain, it can be processed and transferred to a PostgreSQL database. This can be done by a backend application that listens for blockchain events (e.g., using webhooks or polling the blockchain for new blocks).

Exposing Data via API Endpoints

Once the IoT data is stored in PostgreSQL, you can expose it through an API using a web framework (e.g., Flask, FastAPI, Express.js). These API endpoints can be used to fetch the data for use in your applications or dashboards.

• You can build RESTful or GraphQL API endpoints to query the PostgreSQL database and return the data.

• API endpoints could include functionality like:

  • Fetching recent data from the database.

  • Filtering data by device ID or timestamp.

  • Retrieving the hash or reference to the blockchain for verification.