## Appendix A System Components
In BLE technology, data exchange occurs in the following two modes: active and passive. SKK Smart Logistics Unit utilizes both modes for data transmission with the receiving device. In the case of the broadcast mode, called Advertisement, these devices do not use any popular beacon-type protocol standards. Instead, a custom standard was designed that uses BLE mechanisms to transmit measurement data and additional information required by the system. Dedicated BLE protocol-defined services were not used. As a result, some universal scanners may report errors or provide incomplete encoded data from the SKK SLU Sensor. There are currently many popular data encoding standards for Beacon Advertisement, which define appropriate values and positions in the broadcasted byte array. The most commonly used ones are presented in the diagram--Figure 15.  
Each BLE device typically has a profile that includes service groups composed of characteristics. Services are described and defined in the Bluetooth Low Energy specification in the GATT (General Attribute Profile) section. They constitute the protocol and framework for data exchange between two devices in this standard. The SKK SLU Sensor profile consists of the SLU Service, which enables the following operations through appropriate characteristics and data encoding:  
* Changing sensor operation parameters (activating sensors, changing measurement intervals);
* Controlling the transmission of sensor measurement data;
* Managing the transmission of the current sensor configuration. Additionally, the manufacturer's module CC2640R2F service is used, allowing remote programming of the device. The profile also includes a standard profile describing basic device information, such as hardware or software version, as shown in the table below. Data collections--Server  
The Hive Server is a distributed application that runs in a Docker environment. It includes microservices designated to manage Hive Sensors and Hive Gateway devices and to collect, store, and manage measurement data received from Hive Gateway devices. The application allows the following:  
* Saving measurement data in real-time;
* Access to historical data;
* Tracking Hive Sensor location;
* Measurement and technical data visualization;
* the possibility of creating designated dashboards;
* Management of the Hive Sensor;
* Access and management of Hive Gateway devices;
* Configuration of system actions (e.g., an alert) after meeting defined conditions;
* Exporting measurement data to an external database or other data source;
* Provide data for external software to integrate with other Big Data solutions. The Hive Web is a web application module allowing for real-time browsing and historical measurement data from Hive Sensors stored in the Hive Sensors system including the following:  
* The possibility to create customizable dashboards;
* Visualization of temperature, light, humidity, and acceleration measurements in graph and table form for the selected Hive Sensor for the last 7 days with information about the minimum, maximum and average value for a given time range;
* Real-time value for selected sensors;
* Information about the last known location of the Hive Sensor;
* Information about the number of sensors within the range of a given Hive Gateway device;
* List of Hive Sensors with the date of adding to the system and the date of the last update.