Recognize and explain the IoT's reference model (IoT). Complete the missing pieces by using the four connection tiers provided by the reference model.

Determine and describe the IoT reference model. There are four levels of interdependence in the reference model.

Consider a conceptual schema given below. LONGER TSERVICE SHORTER TSERVICE total-days total-hours DRIVER TSERVICE dlnumber enumber first-name last-name phone[e..] ID1 ID2 BUS departure-city destination-city departure-time arrival time ID ID ID Assigned-to - - Assigned-to date-when-assigned ID rego make 1..* snumber Passes-through 0..1 date-when-discharged STOP stop-City edap larrival-time Your task is to perform a step of logical database design, i.e. to transform a conceptual schema given above into a collection of relational schemas. For each relational schema clearly list the names of attributes, primary key, candidate keys (if any), and foreign keys (if any). Assume, that a superset method must be used to implement a generalization. T0

In theory, an OSI model must always consist of at least seven levels, although in practise, this is not always the case. Why is it a good idea to reduce the total number of layers that are used? What are some potential drawbacks that might result from using a reduced number of layers?