Github user aljoscha commented on a diff in the pull request:
https://github.com/apache/flink/pull/5230#discussion_r165394684
--- Diff:
flink-streaming-java/src/main/java/org/apache/flink/streaming/api/functions/co/BaseBroadcastProcessFunction.java
---
@@ -0,0 +1,105 @@
+/*
+ * 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.api.functions.co;
+
+import org.apache.flink.annotation.PublicEvolving;
+import org.apache.flink.api.common.functions.AbstractRichFunction;
+import org.apache.flink.api.common.state.MapStateDescriptor;
+import org.apache.flink.api.common.state.ReadOnlyBroadcastState;
+import org.apache.flink.api.common.state.ReadWriteBroadcastState;
+import org.apache.flink.util.OutputTag;
+
+/**
+ * The base class containing the functionality available to all broadcast
process function.
+ * These include the {@link BroadcastProcessFunction} and the {@link
KeyedBroadcastProcessFunction}.
+ */
+@PublicEvolving
+public abstract class BaseBroadcastProcessFunction extends
AbstractRichFunction {
+
+ private static final long serialVersionUID = -131631008887478610L;
+
+ /**
+ * The base context available to all methods in a broadcast process
function. This
+ * include {@link BroadcastProcessFunction BroadcastProcessFunctions}
and
+ * {@link KeyedBroadcastProcessFunction KeyedBroadcastProcessFunctions}.
+ */
+ abstract class Context {
+
+ /**
+ * Timestamp of the element currently being processed or
timestamp of a firing timer.
+ *
+ * <p>This might be {@code null}, for example if the time
characteristic of your program
+ * is set to {@link
org.apache.flink.streaming.api.TimeCharacteristic#ProcessingTime}.
+ */
+ public abstract Long timestamp();
+
+ /**
+ * Emits a record to the side output identified by the {@link
OutputTag}.
+ *
+ * @param outputTag the {@code OutputTag} that identifies the
side output to emit to.
+ * @param value The record to emit.
+ */
+ public abstract <X> void output(OutputTag<X> outputTag, X
value);
+
+ /** Returns the current processing time. */
+ public abstract long currentProcessingTime();
+
+ /** Returns the current event-time watermark. */
+ public abstract long currentWatermark();
+ }
+
+ /**
+ * A base {@link Context context} available to the broadcasted stream
side of
+ * a {@link
org.apache.flink.streaming.api.datastream.BroadcastConnectedStream
BroadcastConnectedStream}.
+ *
+ * <p>Apart from the basic functionality of a {@link Context context},
+ * this also allows to get and update the elements stored in the
+ * {@link ReadWriteBroadcastState broadcast state}.
+ * In other words, it gives read/write access to the broadcast state.
+ */
+ public abstract class ReadWriteContext extends Context {
--- End diff --
I think this could be called `Context`, similar to my comment on
`ReadWriteBroadcastState`.
---
