This is not my first time to create an app with barcode scan function, but it's my first time to using Firebase Cloud Messaging for single device communication.

So, I decide to have 2 apps. One for client use, another for manager use:

1. CLIENT SIDE FUNCTIONS:

• receive notification from firebase messaging.
• show news data from firebase database.
• register device token to firebase database.
• others: make a phone call, FB share....

2. MANAGER SIDE FUNCTIONS:

• can scan QR code.
• can make a notification to a group or single device.
• can publish news and saved it to firebase database, included images.

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Workflow:

1. user installed client app -> register Token and SID to database

2. while manager scan the QR code content with SID -> database return device's token -> app call clouding messaging to make new notification.

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Part code:

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