The Design And Implementation Of Device Model Management In IOT System

With the increasing application demands for IOT system, the large-scale use of devices from different vendor has resulted in the lack of device interoperability. Interoperability refers to the ability of communicating and exchanging data between different devices, as well as the accuracy interpretion for the information exchanged from the system. Different device communication protocols and customized manufacturing standards brings about problems in system integration and device interconnection. The research focus on how to exchage data with different devices in the same way, regardless of device vendors or communication protocols, together with supporting the access of new equipment.Based on object-oriented modeling,IEC62056 international standard defines a device interface model applicable to various fields of energy, brings good interoperability into device data exchange. Service-oriented architecture is preferred to achieve the seamless interoperability of heterogenous Platform in recent years. OSGi is the only Java-based modular framework which can achieve physical level modular and is suitable for implementing service-oriented applications. This thesis consults the IEC62056 technology and introduces the OSGi modularity framework to design for the interoperability between devices and automated features, by developing a standard device model and one independent component based on service oriented design patterns to meet the needs of changes with good interoperability. The work of this thesis is as follows:(1) Build the device interface model according to IEC62056 standard. In the interface model, the communication service together with device information is encapsulated using the object-oriented technology, unique object identifier is provided for each device data item and interface is defined to standardize the device data items.(2) Construct the device template file based on XML to achieve device self-describing.(3) Support for the device model plug and play. The import, analysis and issue of device template file is designed, as well as the device model validator, which can guarantee reusable validation rules and decouple the validation from business logic.(4) Design one OSGi component responsible for the access, process and output of device model, providing device model by unified service interface for other components.This thesis builds device interface model in accordance with IEC62056 international standard, establishes the consistency constraints for the description of device information and the application of communication service, shielding the differences caused by heterogeneous devices. Proposed a self-describing and standardized way to characterize devices based on object-oriented technology, which solves the lack of adaption to new needs resulted from point oriented description, avoids the scale conversion as well as the correspondence between data item and engineering quantity, and supports the access of customized device without changing the access of device data item. At last, based on the OSGi modular design, device model management bundle, which oriented for the device information integration from different vendors and a plurality of integrated automation functions, is designed to provide unified interface for the access and publishment of device model, acting as the data foundation target for the interoperability of different devices as well as the flexible and efficient integration of different automation functions.