Saving Data on Android

optimize battery 
usage
 and 
reduce bandwidth
. If the client app doesn't have any connection to the 
database, no active listeners, no pending requests, or similar, Firebase will 
automatically close the connection after 
60 seconds
 of inactivity. Alternatively, you 
can explicitly close the connection by using the 
goOffline
 method.
Visit the official 
documentation
 to learn more about the presence feature.
Latency
Generally speaking, 
latency
 is the time delay between the cause and the effect of 
some change. In Realtime database that would, for example, be when a user triggers 
the action to disconnect from the server until the user is actually disconnected, or 
the delay between requesting a login entry, to actual authorization response.
Firebase handles latency in a way that it stores a timestamp, that is generated on the 
server, as data, when the client disconnects, and lets you use that data to reliably 
know the exact time when the user disconnected. You can combine this feature with 
the 
onDisconnect()
 method, that you learned about earlier, to store the exact time 
when the user disconnected from the database. The timestamp is a static field in the 
ServerValue
 class and you access it by calling 
ServerValue.TIMESTAMP
.
Saving Data on Android
Chapter 14: Realtime Database Offline Capabilities
raywenderlich.com
236

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Key points
• Realtime database allows you to enable