Читать книгу Fog Computing - Группа авторов - Страница 40

Application context influences the server-side performance and also the tenant-side decision regarding where the application should perform the task. In some cases, the process involves handling large amounts of sensory data locally at the tenant-side client, which could be more energy efficient than distributing the task to a fog server, because the involved data size is too large for the tenant-side client to transmit it to the fog server effectively. In summary, application context involves the following elements [28, 64]:

 Request data type and the amount of data. Determines the complexity of the request from the perspective of the computational power of the tenant-side client and the fog server.

 Deadline of the task and task priority. Determines the required time to complete the task derived from the tenant-side client. In general, it is a part of the service level agreement (SLA), which specifies that the fog server should adjust the tasks in its queue when it needs to prioritze some tasks.

 Energy consumption of the client. Which represents one of the major costs of the tenant-side client, when the tenant-side application demands that the client relay the data to its encountered fog server for processing. As mentioned previously, in some cases local processing at the tenant-side client can be more energy-efficient. Hence, the tenant needs to consider the optimal energy efficiency for the clients in the application management.