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When the app gets added to a channel the first time, an inital process starts, that will crawl over all already existing messages in the channel. The messages are called from the MS Graph API starting with the oldest message. This process can take a while, depeding on the amount of messages and links our app has to extract. The link URLs are saved in our database during the process. The client will then call our service, which responds the links saved in the database.
Synchronization process
After the app finished its initialization process, it will get informed by the MS Graph API supscription endpoint. The Link Spotter app gets a notification when a message or reply was added or changed. Then the app adds or updates the data in the database.