Which two actions should you perform?

You are developing a mobile instant messaging app for a company.

The mobile app must meet the following requirements:

– Support offline data sync.

– Update the latest messages during normal sync cycles.

You need to implement Offline Data Sync.

Which two actions should you perform? Each correct answer presents part of the solution.

NOTE: Each correct selection is worth one point.
A . Retrieve records from Offline Data Sync on every call to the PullAsync method.
B . Retrieve records from Offline Data Sync using an Incremental Sync.
C . Push records to Offline Data Sync using an Incremental Sync.
D . Return the updated At column from the Mobile Service Backend. Sort data based on the updated At column.
E . Return the updated At column from the Mobile Service Backend. Sort data based on the message id.

View Answer

Answer: BE

Explanation:

B: Incremental Sync: the first parameter to the pull operation is a query name that is used only on the client. If you use a non-null query name, the Azure Mobile SDK performs an incremental sync. Each time a pull operation returns a set of results, the latest updated At timestamp from that result set is stored in the SDK local system tables. Subsequent pull operations retrieve only records after that timestamp.

E (not D): To use incremental sync, your server must return meaningful updated At values and must also support sorting by this field.

However, since the SDK adds its own sort on the updated At field, you cannot use a pull query that has its own order By clause.

References: https://docs.microsoft.com/en-us/azure/app-service-mobile/app-service-mobile-offline-data-sync