The emergence of blockchain interoperability is reducing the risk of investing in blockchain by avoiding vendor lock-in, leveraging interoperation, and providing migration capabilities. However, to fully unlock the internet of blockchains, it is necessary to provide enterprise interoperability mechanisms that allow service providers to comply with different regulations, e.g., data privacy regulations. Each blockchain can be reached via a gateway, allowing to interconnect value, to provide different services, and to enable self-sovereignty. To realize this vision, we propose Hermes, a fault-tolerant middleware that connects blockchain networks and is based on the Open Digital Asset Protocol (ODAP). Hermes is crash fault-tolerant by allying a new protocol, ODAP-2PC, with a log storage API that can leverage blockchain to secure logs, providing them transparency, auditability, availability, and non-repudiation. We introduce a use case benefiting from Hermes, digital cross-jurisdiction promissory notes. We show that cross-chain transactions can be achieved securely with Hermes, given that gateways are complying with legal frameworks.