Service-oriented architecture (SOA) is the application development stage or integration stage of IoT-based systems. The SOA is a software design pattern, and it is responsible for services to the other components via a communication protocol over IoT architecture. The SOA permits the IoT users to consolidate several facilities from the conventional available network to form a new one. The SOA structures the development of IoT systems by encompassing a set of designing rules. It also provides and integrates the specific components to the decentralized IoT architecture. Further, the computing packages of SOA are used to divide the business domains, which can be adapted to different software systems. The two main roles of SOA are the service provider and the service consumer. The main advantages of SOA are service reusability, ease of maintenance, independent platform design, availability, reliability, and scalability. Beyond the benefits of SoA over IoT, there are several challenges faced during the integration of SoA and IoT-based systems. The challenges are related to configurability, interoperability, and manageability. The overhead, high investment, and complex service management are the disadvantages of SOA.