Github user bijanfahimi commented on a diff in the pull request:
https://github.com/apache/storm/pull/2282#discussion_r134977497
--- Diff:
external/storm-kafka-client/src/main/java/org/apache/storm/kafka/spout/KafkaTupleListener.java
---
@@ -0,0 +1,78 @@
+/*
+ * 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.kafka.spout;
+
+import java.io.Serializable;
+import java.util.Collection;
+import java.util.List;
+import java.util.Map;
+
+import org.apache.kafka.common.TopicPartition;
+import org.apache.storm.spout.SpoutOutputCollector;
+import org.apache.storm.task.TopologyContext;
+
+
+/**
+ * The KafkaTupleListener handles state changes of a kafka tuple inside a
KafkaSpout.
+ */
+public interface KafkaTupleListener extends Serializable {
+
+
+ void open(Map<String, Object> conf, TopologyContext context,
SpoutOutputCollector collector);
--- End diff --
Thats a good point. So how I see it there are two options. First, add a
hook for declareOutputFields to allow streaming to an error stream or, as you
suggested, removing the SpoutOutputcollector from the open parameters.
I tend to your suggestion. I think when this interface is capable of
emitting it acts like a spout Itself and not like a simple listener.
If more people need to emit to an user specific error stream the interface
can be expanded afterwards, i guess.
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