Я окончательно определил простое чтение из функции ElasticSearch
public static class ElasticsearchFunction
extends ProcessFunction<MetricMeasurement, MetricPrediction> {
public ElasticsearchFunction() throws UnknownHostException {
client = new PreBuiltTransportClient(settings)
.addTransportAddress(new TransportAddress(InetAddress.getByName("YOUR_IP"), PORT_NUMBER));
}
@Override
public void processElement(MetricMeasurement in, Context context, Collector<MetricPrediction> out) throws Exception {
MetricPrediction metricPrediction = new MetricPrediction();
metricPrediction.setMetricId(in.getMetricId());
metricPrediction.setGroupId(in.getGroupId());
metricPrediction.setBucket(in.getBucket());
// Get the metric measurement from Elasticsearch
SearchResponse response = client.prepareSearch("YOUR_INDEX_NAME")
.setSearchType(SearchType.DFS_QUERY_THEN_FETCH)
.setQuery(QueryBuilders.termQuery("YOUR_TERM", in.getMetricId())) // Query
.setPostFilter(QueryBuilders.rangeQuery("value").from(0L).to(50L)) // Filter
.setFrom(0).setSize(1).setExplain(true)
.get();
SearchHit[] results = response.getHits().getHits();
for(SearchHit hit : results){
String sourceAsString = hit.getSourceAsString();
if (sourceAsString != null) {
ObjectMapper mapper = new ObjectMapper();
MetricMeasurement obj = mapper.readValue(sourceAsString, MetricMeasurement.class);
obj.getMetricId();
metricPrediction.setPredictionValue(obj.getValue());
}
}
out.collect(metricPrediction);
}
}