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From "ASF GitHub Bot (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (FLINK-9343) Add Async Example with External Rest API call
Date Thu, 09 Aug 2018 12:22:00 GMT

    [ https://issues.apache.org/jira/browse/FLINK-9343?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16574763#comment-16574763
] 

ASF GitHub Bot commented on FLINK-9343:
---------------------------------------

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_r208905065
 
 

 ##########
 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)
+    }
 
 Review comment:
   It can be a bit shorter as in `AsyncIOExample`:
   ```
   Future {
         val result = client.getQuote(input.toString)
         resultFuture.complete(Iterable((input, result)))
   } (ExecutionContext.global)
   ```
   then no need for `implicit lazy val executor`

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> Add Async Example with External Rest API call
> ---------------------------------------------
>
>                 Key: FLINK-9343
>                 URL: https://issues.apache.org/jira/browse/FLINK-9343
>             Project: Flink
>          Issue Type: Improvement
>          Components: Examples
>    Affects Versions: 1.4.0, 1.4.1, 1.4.2
>            Reporter: Yazdan Shirvany
>            Assignee: Yazdan Shirvany
>            Priority: Minor
>              Labels: pull-request-available
>
> Async I/O is a good way to call External resources such as REST API and enrich the
stream with external data.
> Adding example to simulate Async GET api call on an input stream.



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