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https://issues.apache.org/jira/browse/STORM-1505?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15120117#comment-15120117
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ASF GitHub Bot commented on STORM-1505:
---------------------------------------
Github user ptgoetz commented on a diff in the pull request:
https://github.com/apache/storm/pull/1050#discussion_r51045778
--- Diff:
storm-core/src/jvm/org/apache/storm/trident/operation/FlatMapFunction.java ---
@@ -0,0 +1,36 @@
+/**
+ * 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.storm.trident.operation;
+
+import org.apache.storm.tuple.Values;
+
+import java.io.Serializable;
+import java.util.List;
+
+/**
+ * A one to many transformation function
+ */
+public interface FlatMapFunction extends Serializable {
+ /**
+ * Invoked by the framework for each value in a stream.
+ *
+ * @param input the input value
+ * @return an iterable over the resultant values
+ */
+ Iterable<Values> execute(Values input);
--- End diff --
Why use `Values` as the input parameter and not `ITuple`? With `Values` the
user will have to know the index of the value they are after, whereas `Tuple`
has convenience methods like `getStringByField()`.
(Same question/comment applies to `MapFunction`.)
> Add map and flatMap operations in trident api
> ---------------------------------------------
>
> Key: STORM-1505
> URL: https://issues.apache.org/jira/browse/STORM-1505
> Project: Apache Storm
> Issue Type: Improvement
> Reporter: Arun Mahadevan
> Assignee: Arun Mahadevan
>
> map and flatMap are common stream operations.
> Right now in trident this has to be implemented via each() which also sends
> the input field values in addition to the mapped field values, so the map and
> flatmap should make things slightly more efficient and easy.
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