# A Modeling Method of Agents and SOA in Advanced Avionics System Based on AADL
## 4 Case Study
In the traditional software system modeling method, these three different applications need to be deployed independently in the system with fixed architecture simultaneously. However, the SOA executes the application and invokes the corresponding service upon request, so the modeling method presented in this paper better describes how SOA works and its flexibility. In this case, services with the same name in different applications refer to repeated invocation of the same service. As can be observed from the A  
Figure 7: AADL model of SOA system with agents. below, the signal reception service and signal transmission service in the intelligent path planning application and communication application are invocations to the same service rather than repeated implementation of the same function. This modeling method reflects the loose coupling and architectural flexibility of SOA. Assuming that new applications added to the model in the future contain the same service, the existing service can be invoked in the same way. Based on this model, this case will show how this modeling method works in practice by analyzing the delay time of a task path. In this path, radar1_signal in Radar1 first obtains the signal and sends it to FPGA1 for preliminary signal processing, Then, the processed data is transferred from data_switch1 to Signal_processing_FPGA for secondary data processing. The processed data is then transmitted to the SOA_System, which executes applications based on system tasks, such as path planning or equipment health monitoring. The path information is as follows: radar1_signal-FPGA1-data_Switch1-Signal_Processing_FPGA-SOA_System. The SOA_System receives control instructions from DDS and RPC to execute a specific application. For intelligent target analysis applications that include agents, the image data will trigger the agent working state transition. The task path and the components on the path model are highlighted in red, yellow, and green in Figure 8.  
The delay time of the hardware components in the task path are shown in Table 1. There are four hardware components in the task path. \begin{table}
\begin{tabular}{c c} \hline \hline
**Component Name** & **Value (ms)** \\ \hline radar1\_signal & 5 \\ FPGA1 & 10 \\ data\_switch1 & 4 \\ Signal\_processing\_FPGA & 15 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: The delay time of hardware components in the task path. Figure 8: The task path in AADL model. The delay time of the SOA_System and services inside are shown in Table 2. There are seven services in the SOA_System. For the target analysis service with agents, there are three working states, target recognition, obstacle warning, path planning. In the different working states, the delay time of the target analysis service is shown in Table 3.  
Based on the above information, the delay time of this task path in three different application execution cases is analyzed. In the first case, the avionics system sends an application request through RPC to enable the SOA system to execute the equipment health monitoring application, and Equation (9) shows the calculation process of system delay time \(T_{1}\) in this case. \[ \begin{split} T_{1}=T_{radar1\_signal}+& T_{FPGA1}+T_{ data\_switch1}+T_{Signal\_processing\_FPGA}+T_{SOA\_System}\\ +& T_{Equipment\_signal\_ acquisition\_service}+T_{Equipment\_status\_analysis\_service}\\ =& 5+10+4+15+5+3+10=52\text{ ms},\end{split}  \tag{9}\]  
In the second case, the avionics system sends an application request through RPC to make the SOA system execute intelligent target analysis application. At this time, the image information from the radar triggers the agent to transition to the obstacle warning state, and Equation (10) shows the calculation process of system delay time \(T_{2}\) in this case. \[ \begin{split} T_{2}=T_{radar1\_signal}+& T_{FPGA1}+T_{ data\_switch1}+T_{Signal\_processing\_FPGA}+T_{SOA\_System}+T_{Signal\_ reception\_service}\\ +& T_{obstacle\_warning}+T_{signal\_ transmission\_service}=5+10+4+15+5+5+5+27\\ =& 76\text{ ms},\end{split}