A commercial site security system is to be designed with a number of detectors and a Gateway module.
1. Proximity Sensor
2. Shock / Vibration Sensor
3. Door/ Window magnetic sensor
The sensors/ detectors connects with Gateway (with Raspbery Pi or suggets any other) through a standard wireless interface i.e. Zigbee / Z-wave
The Camera connects with Gateway through Zigbee / Z wave or WiFi. It also connects with a cloud directly to transfer the images or visual streams
The Gateway interacts with sensors as well as the cloud through Zigbee, Wifi and 3G. The notification generated by the security events should be received in the cloud clients i.e. mobile apps and in control software in PC.
You need to come up with your suggestions for component selection.