azagrebin commented on a change in pull request #5996: [FLINK-9343] [Example] Add Async Example with External Rest API call URL: https://github.com/apache/flink/pull/5996#discussion_r208905291
########## File path: flink-examples/flink-examples-streaming/src/main/scala/org/apache/flink/streaming/scala/examples/async/AsyncAPIExample.scala ########## @@ -0,0 +1,93 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one + * or more contributor license agreements. See the NOTICE file + * distributed with this work for additional information + * regarding copyright ownership. The ASF licenses this file + * to you under the Apache License, Version 2.0 (the + * "License"); you may not use this file except in compliance + * with the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ + +package org.apache.flink.streaming.scala.examples.async + + +import java.io.{BufferedReader, InputStreamReader} +import java.util.concurrent.TimeUnit + +import org.apache.flink.runtime.concurrent.Executors +import org.apache.flink.streaming.api.scala.{AsyncDataStream, DataStream, StreamExecutionEnvironment, _} +import org.apache.flink.streaming.api.scala.async.{AsyncFunction, ResultFuture} +import org.apache.http.client.methods.HttpGet +import org.apache.http.impl.client.HttpClientBuilder + +import scala.concurrent.{ExecutionContext, Future} + +object AsyncAPIExample { + + def main(args: Array[String]) { + + val env = StreamExecutionEnvironment.getExecutionEnvironment + + val input : DataStream[Int] = env.addSource(new SimpleSource()) + + val quoteStream: DataStream[(Int, String)] = AsyncDataStream.unorderedWait( + input, + new AsyncQuoteRequest, + 1000, + TimeUnit.MILLISECONDS, + 10) + + quoteStream.print() + + env.execute("Async API job") + } +} + +class AsyncQuoteRequest extends AsyncFunction[Int, (Int, String)] { + + /** The API specific client that can issue concurrent requests with callbacks */ + + /** The context used for the future callbacks */ + implicit lazy val executor: ExecutionContext = ExecutionContext.global + + lazy val client = new Quote() + + override def asyncInvoke(input: Int, resultFuture: ResultFuture[(Int, String)]): Unit = { + + + // issue the asynchronous request, receive a future for the result + val resultFutureRequested: Future[String] = Future { + client.getQuote(input.toString) + } + + // set the callback to be executed once the request by the client is complete + // the callback simply forwards the result to the result future + resultFutureRequested.onSuccess { + case result: String => { + resultFuture.complete(Iterable((input, result))) + } + } + } + + +} + +class Quote { + @throws[Exception] + def getQuote(number: String) : String = { + val url = "http://gturnquist-quoters.cfapps.io/api/"; + number + val client = HttpClientBuilder.create.build + val request = new HttpGet(url) + val response = client.execute(request) + val rd = new BufferedReader(new InputStreamReader(response.getEntity.getContent)) + rd.readLine Review comment: I think it would be nice to close `client` before returning the result ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: us...@infra.apache.org With regards, Apache Git Services
