Preview Datafeed API

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The Preview Datafeed API provides the ability to preview a machine learning datafeed’s data in the cluster. It accepts a PreviewDatafeedRequest object and responds with a PreviewDatafeedResponse object.

Preview Datafeed Request

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A PreviewDatafeedRequest object is created referencing a non-null datafeedId.

PreviewDatafeedRequest request = new PreviewDatafeedRequest(datafeedId); 

Constructing a new request referencing an existing datafeedId

Preview Datafeed Response

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BytesReference rawPreview = response.getPreview(); 
List<Map<String, Object>> semiParsedPreview = response.getDataList(); 

The raw BytesReference of the data preview

A List<Map<String,Object>> that represents the previewed data

Synchronous Execution

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When executing a PreviewDatafeedRequest in the following manner, the client waits for the PreviewDatafeedResponse to be returned before continuing with code execution:

PreviewDatafeedResponse response = client.machineLearning().previewDatafeed(request, RequestOptions.DEFAULT);

Asynchronous Execution

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Executing a PreviewDatafeedRequest can also be done in an asynchronous fashion so that the client can return directly. Users need to specify how the response or potential failures will be handled by passing the request and a listener to the asynchronous preview-datafeed method:

client.machineLearning().previewDatafeedAsync(request, RequestOptions.DEFAULT, listener); 

The PreviewDatafeedRequest to execute and the ActionListener to use when the execution completes

The asynchronous method does not block and returns immediately. Once it is completed the ActionListener is called back using the onResponse method if the execution successfully completed or using the onFailure method if it failed.

A typical listener for preview-datafeed looks like:

ActionListener<PreviewDatafeedResponse> listener = new ActionListener<PreviewDatafeedResponse>() {
    @Override
    public void onResponse(PreviewDatafeedResponse response) {
        
    }

    @Override
    public void onFailure(Exception e) {
        
    }
};

Called when the execution is successfully completed.

Called when the whole PreviewDatafeedRequest fails.