1. Insert a message into the messages table with the corresponding `deviceID` in the `toDeviceID` field.
2. Connect by the gRPC client to the bidirectional stream with the `sessionID` corresponding to the `deviceID` in metadata.
3. The message from the database would be delivered to the client as the [[ https://github.com/CommE2E/comm/blob/efbbde6e7eb567b9a7e1e1bbf4de562a77d2e35a/shared/protos/tunnelbroker.proto#L132 | MessagesToDeliver ]].
4. Get the `messageID` identifier from the delivered message.
5. Send back to the stream a [[ https://github.com/CommE2E/comm/blob/efbbde6e7eb567b9a7e1e1bbf4de562a77d2e35a/shared/protos/tunnelbroker.proto#L112 | processedMessages ]] message with the message identifier.
6. The expected result is that the message with the corresponding messageID will be removed from the database in messages table.