Читать книгу Service Level Management in Emerging Environments - Nader Mbarek - Страница 50

The IoT-SP establishes a service level contract called iSLA with the IoT-C using a set of subcontracts such as cSLA and nSLA, implemented with various NSPs and CSPs. The global iSLA type agreement makes it possible to identify the IoT service using the “Service Identification” attribute. At the client’s end, this attribute is based on a list of IP addresses used by the IoT-C. At the supplier’s end, an application identifier, the IP address of the application interface, the port number as well as the identifiers of the HL-Gw and LL-Gw are used. In addition, the iSLA-type agreement includes an attribute for “IoT Service Performance Parameters” that describes the characteristics of the IoT service using three subattributes: “IoT Sensing Characteristics”, “IoT Application Characteristics” and “IoT QoS Parameters”. Thus, the “IoT Sensing Characteristics” section includes the characteristics of the gateways (HL-Gw and LL-Gw) and of the group of IoT objects (i.e. inter- and intragateway communication technology, number of objects connected by LL-Gw, number of LL-Gws per HL-Gw, etc.). The “IoT Application Characteristics” section includes parameters related to cSLA such as the application identifier, the maximum number of users, the average number of requests per second per user, the support time and the storage parameters. Finally, the “IoT QoS Parameters” section includes qualitative and quantitative QoS parameters. The qualitative parameters define the type of application by specifying the QoS class of the data generated. We can cite the example of the category of services called Real-Time Mission Critical (RTMC), those called Real-Time Non Mission Critical (RTNMC), the category of Streaming services and the category of Non-Real-Time (NRT) services. The quantitative parameters depend on the type of service covered by the iSLA and include the end-to-end delay, availability, the lifespan of the objects and the quality of the data (standard deviation, frequency of detection and error ratio of the data, etc.). The iSLA-type agreement also includes a “Business Parameters” attribute specifying the cost of the IoT service and the methodology for managing violations and resulting penalties through thresholds and monitoring intervals for each quantitative QoS parameter.