# Package org.apache.olingo.odata2.api.ep.callback

Entity Provider Callbacks These callbacks will be used to support the $expand query option.

See: Description

- Interface Summary
  Interface | Description
  --- | ---
  OnReadInlineContent | Callback interface for the deep insert read calls (read of `` content).
  OnWriteEntryContent | Callback interface for the $expand query option.
  OnWriteFeedContent | Callback interface for the $expand query option.
  TombstoneCallback | Interface that must be implemented in order to provide tombstone support.

- Class Summary
  Class | Description
  --- | ---
  ReadEntryResult | A `ReadEntryResult` represents an inlined navigation property which points to an entry.
  ReadFeedResult | A `ReadFeedResult` represents an inlined navigation property which points to a feed (in the form of a list of `ODataEntry` instances).
  ReadResult | A `ReadResult` represents an inlined navigation property which points to an entry or feed.
  TombstoneCallbackResult | Objects of this class are a container for the result of the `TombstoneCallback`.
  WriteCallbackContext | Wrapper for `WriteEntryCallbackContext` and `WriteFeedCallbackContext`.
  WriteEntryCallbackContext | Context given if the target of an expand is an entry.
  WriteEntryCallbackResult | Result of a callback.
  WriteFeedCallbackContext | Context given if the target of an expand is a feed.
  WriteFeedCallbackResult | Result of a callback.

## Package org.apache.olingo.odata2.api.ep.callback Description

Entity Provider Callbacks

These callbacks will be used to support the $expand query option. Callbacks have to implement the `ODataCallback` as a marker.
To support an expanded entry the `OnWriteEntryContent` interface has to be implemented.
To support an expanded feed the `OnWriteFeedContent` interface has to be implemented.

All callbacks are registered for a navigation property in a HashMap and will only be called if a matching $expand clause is found.

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