Create transform API

A PutTransformRequest requires the following argument:

PutTransformRequest request =
        new PutTransformRequest(transformConfig); 
request.setDeferValidation(false); 

The TransformConfig object contains all the details about the transform configuration and contains the following arguments:

TransformConfig transformConfig = TransformConfig
    .builder()
    .setId("reviewer-avg-rating") 
    .setSource(sourceConfig) 
    .setDest(destConfig) 
    .setFrequency(TimeValue.timeValueSeconds(15)) 
    .setPivotConfig(pivotConfig) 
    .setDescription("This is my test transform") 
    .setSettings(settings) 
    .setRetentionPolicyConfig(retentionPolicy) 
    .setSyncConfig(syncConfig) 
    .build();

The indices and the query from which to collect data. If query is not set, a match_all query is used by default.

SourceConfig sourceConfig = SourceConfig.builder()
    .setIndex("source-index")
    .setQueryConfig(queryConfig).build();

The index where to write the data and the optional pipeline through which the docs should be indexed

DestConfig destConfig = DestConfig.builder()
    .setIndex("pivot-destination")
    .setPipeline("my-pipeline").build();

QueryConfig queryConfig = new QueryConfig(new MatchAllQueryBuilder());

Defines the pivot function group by fields and the aggregation to reduce the data.

PivotConfig pivotConfig = PivotConfig.builder()
    .setGroups(groupConfig) 
    .setAggregationConfig(aggConfig) 
    .build();

GroupConfig groupConfig = GroupConfig.builder()
    .groupBy("reviewer", 
        TermsGroupSource.builder().setField("user_id").build()) 
    .build();

AggregatorFactories.Builder aggBuilder = new AggregatorFactories.Builder();
aggBuilder.addAggregator(
        AggregationBuilders.avg("avg_rating").field("stars"));  
AggregationConfig aggConfig = new AggregationConfig(aggBuilder);

RetentionPolicyConfig retentionPolicy = TimeRetentionPolicyConfig.builder()
    .setField("time-field") 
    .setMaxAge(TimeValue.timeValueDays(30)) 
    .build();

SettingsConfig settings = SettingsConfig.builder()
    .setMaxPageSearchSize(1000) 
    .build();

SyncConfig syncConfig = TimeSyncConfig.builder()
    .setField("time-field") 
    .setDelay(TimeValue.timeValueSeconds(30)) 
    .build();

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

AcknowledgedResponse response =
        client.transform().putTransform(
                request, RequestOptions.DEFAULT);

Synchronous calls may throw an IOException in case of either failing to parse the REST response in the high-level REST client, the request times out or similar cases where there is no response coming back from the server.

In cases where the server returns a 4xx or 5xx error code, the high-level client tries to parse the response body error details instead and then throws a generic ElasticsearchException and adds the original ResponseException as a suppressed exception to it.

Executing a PutTransformRequest 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 put-transform method:

client.transform().putTransformAsync(
        request, RequestOptions.DEFAULT, listener); 

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. Failure scenarios and expected exceptions are the same as in the synchronous execution case.

A typical listener for put-transform looks like:

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

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

The returned AcknowledgedResponse acknowledges the successful creation of the new transform or an error if the configuration is invalid.