[GitHub] nwangtw commented on a change in pull request #3109: Add withStream() in Streamlet to support stream selection

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nwangtw commented on a change in pull request #3109: Add withStream() in Streamlet to support stream selection
URL: https://github.com/apache/incubator-heron/pull/3109#discussion_r233266843
 
 

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 File path: heron/api/src/java/org/apache/heron/streamlet/Streamlet.java
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 @@ -71,6 +71,22 @@
    */
   int getNumPartitions();
 
+  /**
+   * Set the id of the stream to be used by the children nodes.
+   * Usage (assuming source is a Streamlet object with two output streams: stream1 and stream2):
+   *   source.withStream("stream1").filter(...).log();
+   *   source.withStream("stream2").filter(...).log();
+   * @param streamId The specified stream id
+   * @return Returns back the Streamlet with changed stream id
+   */
+  Streamlet<R> withStream(String streamId);
 
 Review comment:
   Yeah. A component can generates multiple different streams (such as 3 integer streams: odd, even, all) and the next component needs to specify which one to accept data.
   
   UI doesn't show this information currently and it could be a useful feature to add. And grouping strategy is another important information on the edges.

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