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# IAsyncProcessingCallback Interface

<Note>
  This interface is implemented in FRE for Linux and Windows.
</Note>

This is a callback interface that is used for managing the work of the [BatchProcessor](/fine-reader/engine/api-reference/batch-processor/batchprocessor) object and reporting errors, occurred during processing. This interface is implemented on the client-side.

An object receiving notifications through this interface's methods may do the following inside the methods' implementation:

* Report processing errors to the user.
* Cancel processing.
* It can also process any system messages to help prevent the application from appearing unresponsive during long operations. This can be helpful in applications with a user interface.

## Methods

| Name                                                                                                       | Description                                                                   |
| ---------------------------------------------------------------------------------------------------------- | ----------------------------------------------------------------------------- |
| [OnError](/fine-reader/engine/api-reference/batch-processor/iasyncprocessingcallback/onerror-method)       | Delivers to the client descriptions of the errors appeared during processing. |
| [OnProgress](/fine-reader/engine/api-reference/batch-processor/iasyncprocessingcallback/onprogress-method) | Allows the client to cancel processing.                                       |

## Input parameter

The [IBatchProcessor::Start](/fine-reader/engine/api-reference/batch-processor/batchprocessor/start-method) method receives a pointer to this interface as an input parameter.

## Remarks

In Linux, this interface does not work if the Engine object is loaded as an out-of-process server.

## See also

[BatchProcessor](/fine-reader/engine/api-reference/batch-processor/batchprocessor)