Architecture Modeling - SPES 2020
Architecture Modeling - SPES 2020
Architecture Modeling - SPES 2020
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<strong>Architecture</strong> <strong>Modeling</strong><br />
Unit Level: Logical and Technical Perspectives We start with an overview<br />
on the logical perspective on Unit Level depicted in Figure 5.16. Here, the<br />
BrakingSystemControlUnit is shown as the top level component containing subcomponents<br />
that realize the two channels of the BSCU each consisting of a command<br />
(Command1/2) and a monitor (Monitor1/2) unit. Because command and monitor has<br />
to communicate, there exists a further logical component that realizes the communication<br />
named Com1ToMon1 and Com2ToMo2, respectively. The top level component is annotated<br />
with two contracts specifying deadlines between certain signals. There exists one<br />
contract for each channel saying that under the strong assumption that the input signal<br />
cmd in1/2.cmdFlow occurs each 5 milliseconds, it is guaranteed that the output signal<br />
control out1/2.controlFlow occurs within 3 milliseconds.<br />
Figure 5.17: Logical Perspective – Unit Level – Contracts<br />
The subcomponents of the BSCU each have a contract as well, as shown in Figure 5.17.<br />
These contracts divide the channel deadlines of 3 milliseconds specified for the BSCU into<br />
local deadlines for the three subcomponents of each channel. The deadline for each command<br />
unit is 1200 microseconds, the deadline for communication via the respective component is 400<br />
microseconds and the deadline for the monitor is defined as 1400 microseconds. How these<br />
local deadlines are chosen is a design decision and may be refined e.g. because analysis results<br />
show that some components violate their deadlines while others would satisfy also smaller<br />
deadlines. Whether these subcontracts are valid with respect to the contracts of the top level<br />
component has to be shown by a virtual integration test.<br />
Next, we have a look at the top level component of the technical perspective as depicted<br />
in Figure 5.18. Here, the BSCU as the top level component is composed of two computing<br />
resources namely ECU1 and ECU2, and a communication resource named CANBus. Each ECU<br />
component has input and output ports to the bus component to send and receive messages and<br />
interfaces to the top level component to communicate with the environment. In this perspective<br />
we have again contracts talking about the deadlines of the top level component specifying the<br />
same deadlines as in the logical perspective.<br />
To be able to specify contracts for the local deadlines, we need to consider the interna of<br />
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