  To promote the benefits of the Internet of Things (IoT) in smart communities
and smart cities, a real-time data marketplace middleware platform, called the
Intelligent IoT Integrator (I3), has been recently proposed. While facilitating
the easy exchanges of real-time IoT data streams between device owners and
third-party applications through the marketplace, I3 is presently a monolithic,
centralized platform for a single community. Although the service oriented
architecture (SOA) has been widely adopted in the IoT and cyber-physical
systems (CPS), it is difficult for a monolithic architecture to provide
scalable, inter-operable and extensible services for large numbers of
distributed IoT devices and different application vendors. Traditional security
solutions rely on a centralized authority, which can be a performance
bottleneck or susceptible to a single point of failure. Inspired by
containerized microservices and blockchain technology, this paper proposed a
BLockchain-ENabled Secure Microservices for Decentralized Data Marketplaces
(BlendSM-DDM). Within a permissioned blockchain network, a microservices based
security mechanism is introduced to secure data exchange and payment among
participants in the marketplace. BlendSM-DDM is able to offer a decentralized,
scalable and auditable data exchanges for the data marketplace.
