A service system for managing a transaction in an Internet of things, loT, environment, comprising: a cloud-based virtual object transaction manager, comprising a plurality of virtual objects, wherein the virtual object transaction manager comprises: an application program interface, API, registering unit, configured to register, when a virtual object of an loT device is generated, an interface provided from the virtual object as an API format, the registering including information about a data generation period, and a type of the loT device in an loT profile of the virtual object; wherein the type is classified as a periodic type indicating that the loT device periodically generates data or a non-periodic type indicating that the loT device non-periodically generates data; and an API use permission managing unit, configured to manage use permission of APIs according to virtual objects of loT devices registered on the cloud service, and to verify use permission of an API and provide the registered API according to a call of a callback type generated through at least one of a service or an application; wherein the virtual objects of the virtual object transaction manager are configured to analyze API request information of several high-level services and applications and to provide a communication function with loT devices. a cloud-based virtual object transaction manager, comprising a plurality of virtual objects, wherein the virtual object transaction manager comprises: an application program interface, API, registering unit, configured to register, when a virtual object of an loT device is generated, an interface provided from the virtual object as an API format, the registering including information about a data generation period, and a type of the loT device in an loT profile of the virtual object; wherein the type is classified as a periodic type indicating that the loT device periodically generates data or a non-periodic type indicating that the loT device non-periodically generates data; and an API use permission managing unit, configured to manage use permission of APIs according to virtual objects of loT devices registered on the cloud service, and to verify use permission of an API and provide the registered API according to a call of a callback type generated through at least one of a service or an application; wherein the virtual objects of the virtual object transaction manager are configured to analyze API request information of several high-level services and applications and to provide a communication function with loT devices. an application program interface, API, registering unit, configured to register, when a virtual object of an loT device is generated, an interface provided from the virtual object as an API format, the registering including information about a data generation period, and a type of the loT device in an loT profile of the virtual object; wherein the type is classified as a periodic type indicating that the loT device periodically generates data or a non-periodic type indicating that the loT device non-periodically generates data; and an API use permission managing unit, configured to manage use permission of APIs according to virtual objects of loT devices registered on the cloud service, and to verify use permission of an API and provide the registered API according to a call of a callback type generated through at least one of a service or an application; wherein the virtual objects of the virtual object transaction manager are configured to analyze API request information of several high-level services and applications and to provide a communication function with loT devices.