I. Create a new Data source to get the list of users who have sent messages to your page
1. Access the "DATAFLOWS" app and go to the "Data source" menu
2. Click "+" to create new a Data source
3. Select "Facebook Messenger" connector
4. Login your Facebook account
5. Select the page that you want
II. Set up "Dataflow" to push Facebook User ID data to "Visitor" Business Object in the CDP system
1. Access the "DATAFLOWS" app and go to the "Dataflows" menu
2. Click + Blank Dataflow
3. Select the "Facebook Page" data source that you created, then click the "Create dataflow" button
4. Select the field you want to get the data
Note:
"User ID" is the ID of the Facebook account who have sent message to your page
Facebook only returns a list of User id that have sent message to your page within 24 hours
5. Add "Destination channel" node
You can see how to create a destination channel for a Business Object here
Select "Visitor" Business Object, then map facebook's User id with Visitor's User ID on CDP system
You need to create a "Custom attribute" in the "Visitor" Business Object to know it's the Facebook user ID pushed from the dataflow
You can see how to create a "Custom attribute" here
For example: Create a Custom attribute of "Is Facebook user_id" with data type of Number
If the value of this attribute is 1, it is the User ID of Facebook
Set value pushed from dataflow to 1 for this Customer attribute
Select write mode is Insert all
6. Save Dataflow
7. REVIEW & TURN ON
Used to view setup information in dataflows and setup execution time
Force Run: Used to run immediately without timeout in dataflows
After the dataflow has finished running, you can go to the Visitor menu in Personas App to check the creation of Facebook User ID in CDP:
III. Create a new Visitor Segment to get a list of Facebook User IDs
The conditions you set in the segment are as follows:
Note: You can see how to create a new segment here
IV. Create a "Messenger" destination
1. Access the "MARKETING HUB" app and go to the "Destinations" menu
3. Select "Destination catalog": "Messenger"
User ID Facebook of the recipient of the message
You can click 
icon to add Personalization
Access token of your page on Facebook.
Note: Currently, please share your page with us with the following permission: "Send and respond to message as the Page"
-> We will help you set up the necessary information in destination
V. Sending "Messenger" via Customer Journey
Log into CDP system, access "MARKETING HUB" app and go to "Customer Journeys" menu
We have 2 channels that supporting to send:
At the "Schedule trigger" node, select the segment containing the Facebook user id that you created
Click "+" button to Create Journey, add "Destination" node and select "Messenger" destination
Fill out necessary information
Click "Save change" button to finish setting journey
After finishing the setting of the Journey, we can activate and send message to customer
