Java-based connector that bridges FIWARE (via FIROS) and the public DLT network Hedera Hashgraph

Abstract This software implements a Java-based connector that bridges FIWARE (via FIROS) and the public Distributed Ledger Technology (DLT) network Hedera Hashgraph, enabling secure, immutable anchoring of ROS/ROS2 AGV events. The connector receives NGSI notifications generated by FIROS (which maps ROS/ROS2 topics to NGSI entities) and anchors cryptographic digests of those events to the Hedera Consensus Service (HCS). This implementation follows the hybrid on-chain/off-chain architecture described in the referenced paper, where operational data remains off-chain while verifiable proofs are recorded on-chain for auditability and integrity guarantees. 1. System architecture Components: ROS / ROS2 — AGV event generation FIROS — ROS-to-NGSI bridge FIWARE Context Broker — entity management and notification engine Java Connector (this implementation) — digest computation and DLT anchoring Hedera Consensus Service (HCS) — immutable public consensus layer Event flow: ROS/ROS2 publishes AGV events. FIROS translates ROS topics into NGSI entities. The FIWARE Context Broker triggers HTTP notifications to the connector. The connector: Parses NGSI JSON. Computes a SHA-256 digest of the payload. Constructs a reduced anchoring message. Submits the message to Hedera HCS. Hedera provides: Consensus timestamp Sequence number Immutable public verifiability This architecture ensures: Data integrity Tamper evidence Public auditability Scalable off-chain storage 2. Anchored message structure Example message stored on Hedera: { "entityId": "AGV-001", "entityType": "AGV", "eventTimestamp": "2026-02-15T10:23:45Z", "digest": "3f786850e387550fdab836ed7e6dc881de23001b", "source": "fiware-context-broker", "rawLength": 1234 } Only the digest and metadata are anchored.Full event data remains stored off-chain in FIWARE/MongoDB. 3. Security & Operational Considerations Hedera credentials must be provided via environment variables. The HTTP endpoint must be deployed behind TLS (reverse proxy recommended). For production: Add authentication (JWT or mTLS). Implement retry logic. Enable batching for cost efficiency. Add structured logging and monitoring. 4. Java Implementation Requirements Java 17+ Maven 3.8+ Hedera Testnet/Mainnet credentials