```
public interface DataSource
```
Interface for an object that receives updates to feature flags from LaunchDarkly.
This component uses a push model. When it is created, the SDK will provide a reference to a DataSourceUpdateSink component (as part of ClientContext, which is a write-only abstraction of the SDK state. The SDK never requests feature flag data from the DataSource-- it only looks at the last known data that was pushed into the state.
Each LDClient instance maintains exactly one active data source instance. It stops and discards the active data source whenever it needs to create a new one due to a significant state change, such as if the evaluation context is changed with identify(), or if the SDK goes online after previously being offline, or if the foreground/background state changes.

Since:

3.3.0

See Also:

Components.streamingDataSource(), Components.pollingDataSource(), LDConfig.Builder.dataSource(ComponentConfigurer)

Method Summary

All Methods Instance Methods Abstract Methods Default Methods
Modifier and Type	Method	Description
`default boolean`	`needsRefresh(boolean newInBackground, LDContext newEvaluationContext)`	The SDK calls this method to determine whether it needs to stop the current data source and start a new one after a state transition.
`void`	`start(Callback<java.lang.Boolean> resultCallback)`	Initializes the data source.
`void`	`stop(Callback<java.lang.Void> completionCallback)`	Tells the data source to stop.

- Method Detail
  - start
```
void start(@NonNull
           Callback<java.lang.Boolean> resultCallback)
```
    Initializes the data source. This is called only once per instance.
    
    Parameters:
    
    resultCallback - called when the data source has successfully acquired the initial data, or if an error has occurred
  - stop
```
void stop(@NonNull
          Callback<java.lang.Void> completionCallback)
```
    Tells the data source to stop.
    
    Parameters:
    
    completionCallback - called once it has completely stopped (this is allowed to be asynchronous because it might involve network operations that can't be done on the main thread)
  - needsRefresh
```
default boolean needsRefresh(boolean newInBackground,
                             LDContext newEvaluationContext)
```
    The SDK calls this method to determine whether it needs to stop the current data source and start a new one after a state transition.
    State transitions include going from foreground to background or vice versa, or changing the evaluation context. The SDK will not call this method unless at least one of those types of transitions has happened.
    If this method returns true, the SDK considers the current data source to be no longer valid, stops it, and asks the ComponentConfigurer to create a new one.
    If this method returns false, the SDK retains the current data source.
    
    Parameters:
    
    newInBackground - true if the application is now in the background
    
    newEvaluationContext - the new evaluation context
    
    Returns:
    
    true if the data source should be recreated
    
    Since:
    
    4.1.0

Interface DataSource

Method Summary

Method Detail

start

stop

needsRefresh