A data processing system connected to a plurality of applications and a plurality of device drivers/protocol converters, the data processing system comprising: a setting information generation function section, wherein the setting information generation function section includes: a first interface generator configured to generate a REST API as an application-specific API for the applications; a second interface generator configured to generate an MQTT API as a device-side API for the device drivers/protocol converters; and a storage to store common data structure generation source information which is common information based on which the first and second interfaces are generated, and when the common data structure generation source information is updated, the first interface generator and the second interface generator automatically generate the application-specific API and the device-side API, respectively, based on the updated common data structure generation source information, wherein the first and second interface generators (22, 24) are configured to symmetrically generate the application-specific API and the device-side API thereby maintaining consistency between the application-specific API and the device-side API as: endpoint of REST API/class name/instance ID/time stamp, and topic name of MQTT API/class name/instance ID/time stamp. a setting information generation function section, wherein the setting information generation function section includes: a first interface generator configured to generate a REST API as an application-specific API for the applications; a second interface generator configured to generate an MQTT API as a device-side API for the device drivers/protocol converters; and a storage to store common data structure generation source information which is common information based on which the first and second interfaces are generated, and when the common data structure generation source information is updated, the first interface generator and the second interface generator automatically generate the application-specific API and the device-side API, respectively, based on the updated common data structure generation source information, wherein the first and second interface generators (22, 24) are configured to symmetrically generate the application-specific API and the device-side API thereby maintaining consistency between the application-specific API and the device-side API as: endpoint of REST API/class name/instance ID/time stamp, and topic name of MQTT API/class name/instance ID/time stamp. a first interface generator configured to generate a REST API as an application-specific API for the applications; a second interface generator configured to generate an MQTT API as a device-side API for the device drivers/protocol converters; and a storage to store common data structure generation source information which is common information based on which the first and second interfaces are generated, and when the common data structure generation source information is updated, the first interface generator and the second interface generator automatically generate the application-specific API and the device-side API, respectively, based on the updated common data structure generation source information, wherein the first and second interface generators (22, 24) are configured to symmetrically generate the application-specific API and the device-side API thereby maintaining consistency between the application-specific API and the device-side API as: endpoint of REST API/class name/instance ID/time stamp, and topic name of MQTT API/class name/instance ID/time stamp. endpoint of REST API/class name/instance ID/time stamp, and topic name of MQTT API/class name/instance ID/time stamp.