With the rapid spread of smart contracts (SCs), the potential for automated execution of distributed systems increased. These systems, often involve complex business processes workflows, and interactions between various SCs. Nonetheless, executing workflows on the Blockchain (BC) is a daunting undertaking due to the inflexibility of SCs, interoperability challenges, and the complexity of implementing workflow logic. In this paper, we present a new BC service-oriented architecture (SoBcA) along with a smart contracts orchestration approach (SCs-ORCHA). The proposed approach employs the Orcha language to the specification to model the workflow. Event handling is carried out using an event-driven method, while inter-contracts communication is performed based on a message-driven approach. To validate our proposals and demonstrate their effectiveness, a validation case study is implemented using Orcha Proto-language and Solidity SCs.