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_r233588545
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File path:
heron/api/src/java/org/apache/heron/streamlet/impl/StreamletImpl.java
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@@ -205,11 +207,37 @@ public int getNumPartitions() {
return nPartitions;
}
+ /**
+ * 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
+ */
+ @SuppressWarnings("HiddenField")
+ @Override
+ public Streamlet<R> withStream(String streamId) {
Review comment:
Agreed. Failfast is desirable for sure.
Validation is an option question for now. Currently all streamlet operators
receive and emit tuples to default stream.
The stream ids are in run time information now. So we need to be careful
about where the validation should be done and how to apply it.
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