[08/13] incubator-beam git commit: [flink] restructure and cleanup Maven layout

[mx...@apache.org]

http://git-wip-us.apache.org/repos/asf/incubator-beam/blob/071e4dd6/runners/flink/runner/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/state/FlinkStateInternals.java
----------------------------------------------------------------------
diff --git a/runners/flink/runner/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/state/FlinkStateInternals.java b/runners/flink/runner/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/state/FlinkStateInternals.java
new file mode 100644
index 0000000..6cf46e5
--- /dev/null
+++ b/runners/flink/runner/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/state/FlinkStateInternals.java
@@ -0,0 +1,715 @@
+/*
+ * 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.beam.runners.flink.translation.wrappers.streaming.state;
+
+import com.google.cloud.dataflow.sdk.coders.Coder;
+import com.google.cloud.dataflow.sdk.options.PipelineOptions;
+import com.google.cloud.dataflow.sdk.transforms.Combine;
+import com.google.cloud.dataflow.sdk.transforms.CombineWithContext;
+import com.google.cloud.dataflow.sdk.transforms.windowing.BoundedWindow;
+import com.google.cloud.dataflow.sdk.transforms.windowing.OutputTimeFn;
+import com.google.cloud.dataflow.sdk.util.state.*;
+import com.google.cloud.dataflow.sdk.values.PCollectionView;
+import com.google.common.base.Preconditions;
+import com.google.protobuf.ByteString;
+import org.apache.flink.util.InstantiationUtil;
+import org.joda.time.Instant;
+
+import java.io.ByteArrayInputStream;
+import java.io.IOException;
+import java.util.*;
+
+/**
+ * An implementation of the Beam {@link StateInternals}. This implementation simply keeps elements in memory.
+ * This state is periodically checkpointed by Flink, for fault-tolerance.
+ *
+ * TODO: State should be rewritten to redirect to Flink per-key state so that coders and combiners don't need
+ * to be serialized along with encoded values when snapshotting.
+ */
+public class FlinkStateInternals<K> implements StateInternals<K> {
+
+  private final K key;
+
+  private final Coder<K> keyCoder;
+
+  private final Coder<? extends BoundedWindow> windowCoder;
+
+  private final OutputTimeFn<? super BoundedWindow> outputTimeFn;
+
+  private Instant watermarkHoldAccessor;
+
+  public FlinkStateInternals(K key,
+                             Coder<K> keyCoder,
+                             Coder<? extends BoundedWindow> windowCoder,
+                             OutputTimeFn<? super BoundedWindow> outputTimeFn) {
+    this.key = key;
+    this.keyCoder = keyCoder;
+    this.windowCoder = windowCoder;
+    this.outputTimeFn = outputTimeFn;
+  }
+
+  public Instant getWatermarkHold() {
+    return watermarkHoldAccessor;
+  }
+
+  /**
+   * This is the interface state has to implement in order for it to be fault tolerant when
+   * executed by the FlinkPipelineRunner.
+   */
+  private interface CheckpointableIF {
+
+    boolean shouldPersist();
+
+    void persistState(StateCheckpointWriter checkpointBuilder) throws IOException;
+  }
+
+  protected final StateTable<K> inMemoryState = new StateTable<K>() {
+    @Override
+    protected StateTag.StateBinder binderForNamespace(final StateNamespace namespace, final StateContext<?> c) {
+      return new StateTag.StateBinder<K>() {
+
+        @Override
+        public <T> ValueState<T> bindValue(StateTag<? super K, ValueState<T>> address, Coder<T> coder) {
+          return new FlinkInMemoryValue<>(encodeKey(namespace, address), coder);
+        }
+
+        @Override
+        public <T> BagState<T> bindBag(StateTag<? super K, BagState<T>> address, Coder<T> elemCoder) {
+          return new FlinkInMemoryBag<>(encodeKey(namespace, address), elemCoder);
+        }
+
+        @Override
+        public <InputT, AccumT, OutputT> AccumulatorCombiningState<InputT, AccumT, OutputT> bindCombiningValue(
+            StateTag<? super K, AccumulatorCombiningState<InputT, AccumT, OutputT>> address,
+            Coder<AccumT> accumCoder, Combine.CombineFn<InputT, AccumT, OutputT> combineFn) {
+          return new FlinkInMemoryKeyedCombiningValue<>(encodeKey(namespace, address), combineFn, accumCoder, c);
+        }
+
+        @Override
+        public <InputT, AccumT, OutputT> AccumulatorCombiningState<InputT, AccumT, OutputT> bindKeyedCombiningValue(
+            StateTag<? super K, AccumulatorCombiningState<InputT, AccumT, OutputT>> address,
+            Coder<AccumT> accumCoder,
+            Combine.KeyedCombineFn<? super K, InputT, AccumT, OutputT> combineFn) {
+          return new FlinkInMemoryKeyedCombiningValue<>(encodeKey(namespace, address), combineFn, accumCoder, c);
+        }
+
+        @Override
+        public <InputT, AccumT, OutputT> AccumulatorCombiningState<InputT, AccumT, OutputT> bindKeyedCombiningValueWithContext(
+            StateTag<? super K, AccumulatorCombiningState<InputT, AccumT, OutputT>> address,
+            Coder<AccumT> accumCoder,
+            CombineWithContext.KeyedCombineFnWithContext<? super K, InputT, AccumT, OutputT> combineFn) {
+          return new FlinkInMemoryKeyedCombiningValue<>(encodeKey(namespace, address), combineFn, accumCoder, c);
+        }
+
+        @Override
+        public <W extends BoundedWindow> WatermarkHoldState<W> bindWatermark(StateTag<? super K, WatermarkHoldState<W>> address, OutputTimeFn<? super W> outputTimeFn) {
+          return new FlinkWatermarkHoldStateImpl<>(encodeKey(namespace, address), outputTimeFn);
+        }
+      };
+    }
+  };
+
+  @Override
+  public K getKey() {
+    return key;
+  }
+
+  @Override
+  public <StateT extends State> StateT state(StateNamespace namespace, StateTag<? super K, StateT> address) {
+    return inMemoryState.get(namespace, address, null);
+  }
+
+  @Override
+  public <T extends State> T state(StateNamespace namespace, StateTag<? super K, T> address, StateContext<?> c) {
+    return inMemoryState.get(namespace, address, c);
+  }
+
+  public void persistState(StateCheckpointWriter checkpointBuilder) throws IOException {
+    checkpointBuilder.writeInt(getNoOfElements());
+
+    for (State location : inMemoryState.values()) {
+      if (!(location instanceof CheckpointableIF)) {
+        throw new IllegalStateException(String.format(
+            "%s wasn't created by %s -- unable to persist it",
+            location.getClass().getSimpleName(),
+            getClass().getSimpleName()));
+      }
+      ((CheckpointableIF) location).persistState(checkpointBuilder);
+    }
+  }
+
+  public void restoreState(StateCheckpointReader checkpointReader, ClassLoader loader)
+      throws IOException, ClassNotFoundException {
+
+    // the number of elements to read.
+    int noOfElements = checkpointReader.getInt();
+    for (int i = 0; i < noOfElements; i++) {
+      decodeState(checkpointReader, loader);
+    }
+  }
+
+  /**
+   * We remove the first character which encodes the type of the stateTag ('s' for system
+   * and 'u' for user). For more details check out the source of
+   * {@link StateTags.StateTagBase#getId()}.
+   */
+  private void decodeState(StateCheckpointReader reader, ClassLoader loader)
+      throws IOException, ClassNotFoundException {
+
+    StateType stateItemType = StateType.deserialize(reader);
+    ByteString stateKey = reader.getTag();
+
+    // first decode the namespace and the tagId...
+    String[] namespaceAndTag = stateKey.toStringUtf8().split("\\+");
+    if (namespaceAndTag.length != 2) {
+      throw new IllegalArgumentException("Invalid stateKey " + stateKey.toString() + ".");
+    }
+    StateNamespace namespace = StateNamespaces.fromString(namespaceAndTag[0], windowCoder);
+
+    // ... decide if it is a system or user stateTag...
+    char ownerTag = namespaceAndTag[1].charAt(0);
+    if (ownerTag != 's' && ownerTag != 'u') {
+      throw new RuntimeException("Invalid StateTag name.");
+    }
+    boolean isSystemTag = ownerTag == 's';
+    String tagId = namespaceAndTag[1].substring(1);
+
+    // ...then decode the coder (if there is one)...
+    Coder<?> coder = null;
+    switch (stateItemType) {
+      case VALUE:
+      case LIST:
+      case ACCUMULATOR:
+        ByteString coderBytes = reader.getData();
+        coder = InstantiationUtil.deserializeObject(coderBytes.toByteArray(), loader);
+        break;
+      case WATERMARK:
+        break;
+    }
+
+    // ...then decode the combiner function (if there is one)...
+    CombineWithContext.KeyedCombineFnWithContext<? super K, ?, ?, ?> combineFn = null;
+    switch (stateItemType) {
+      case ACCUMULATOR:
+        ByteString combinerBytes = reader.getData();
+        combineFn = InstantiationUtil.deserializeObject(combinerBytes.toByteArray(), loader);
+        break;
+      case VALUE:
+      case LIST:
+      case WATERMARK:
+        break;
+    }
+
+    //... and finally, depending on the type of the state being decoded,
+    // 1) create the adequate stateTag,
+    // 2) create the state container,
+    // 3) restore the actual content.
+    switch (stateItemType) {
+      case VALUE: {
+        StateTag stateTag = StateTags.value(tagId, coder);
+        stateTag = isSystemTag ? StateTags.makeSystemTagInternal(stateTag) : stateTag;
+        @SuppressWarnings("unchecked")
+        FlinkInMemoryValue<?> value = (FlinkInMemoryValue<?>) inMemoryState.get(namespace, stateTag, null);
+        value.restoreState(reader);
+        break;
+      }
+      case WATERMARK: {
+        @SuppressWarnings("unchecked")
+        StateTag<Object, WatermarkHoldState<BoundedWindow>> stateTag = StateTags.watermarkStateInternal(tagId, outputTimeFn);
+        stateTag = isSystemTag ? StateTags.makeSystemTagInternal(stateTag) : stateTag;
+        @SuppressWarnings("unchecked")
+        FlinkWatermarkHoldStateImpl<?> watermark = (FlinkWatermarkHoldStateImpl<?>) inMemoryState.get(namespace, stateTag, null);
+        watermark.restoreState(reader);
+        break;
+      }
+      case LIST: {
+        StateTag stateTag = StateTags.bag(tagId, coder);
+        stateTag = isSystemTag ? StateTags.makeSystemTagInternal(stateTag) : stateTag;
+        FlinkInMemoryBag<?> bag = (FlinkInMemoryBag<?>) inMemoryState.get(namespace, stateTag, null);
+        bag.restoreState(reader);
+        break;
+      }
+      case ACCUMULATOR: {
+        @SuppressWarnings("unchecked")
+        StateTag<K, AccumulatorCombiningState<?, ?, ?>> stateTag = StateTags.keyedCombiningValueWithContext(tagId, (Coder) coder, combineFn);
+        stateTag = isSystemTag ? StateTags.makeSystemTagInternal(stateTag) : stateTag;
+        @SuppressWarnings("unchecked")
+        FlinkInMemoryKeyedCombiningValue<?, ?, ?> combiningValue =
+            (FlinkInMemoryKeyedCombiningValue<?, ?, ?>) inMemoryState.get(namespace, stateTag, null);
+        combiningValue.restoreState(reader);
+        break;
+      }
+      default:
+        throw new RuntimeException("Unknown State Type " + stateItemType + ".");
+    }
+  }
+
+  private ByteString encodeKey(StateNamespace namespace, StateTag<? super K, ?> address) {
+    StringBuilder sb = new StringBuilder();
+    try {
+      namespace.appendTo(sb);
+      sb.append('+');
+      address.appendTo(sb);
+    } catch (IOException e) {
+      throw new RuntimeException(e);
+    }
+    return ByteString.copyFromUtf8(sb.toString());
+  }
+
+  private int getNoOfElements() {
+    int noOfElements = 0;
+    for (State state : inMemoryState.values()) {
+      if (!(state instanceof CheckpointableIF)) {
+        throw new RuntimeException("State Implementations used by the " +
+            "Flink Dataflow Runner should implement the CheckpointableIF interface.");
+      }
+
+      if (((CheckpointableIF) state).shouldPersist()) {
+        noOfElements++;
+      }
+    }
+    return noOfElements;
+  }
+
+  private final class FlinkInMemoryValue<T> implements ValueState<T>, CheckpointableIF {
+
+    private final ByteString stateKey;
+    private final Coder<T> elemCoder;
+
+    private T value = null;
+
+    public FlinkInMemoryValue(ByteString stateKey, Coder<T> elemCoder) {
+      this.stateKey = stateKey;
+      this.elemCoder = elemCoder;
+    }
+
+    @Override
+    public void clear() {
+      value = null;
+    }
+
+    @Override
+    public void write(T input) {
+      this.value = input;
+    }
+
+    @Override
+    public T read() {
+      return value;
+    }
+
+    @Override
+    public ValueState<T> readLater() {
+      // Ignore
+      return this;
+    }
+
+    @Override
+    public boolean shouldPersist() {
+      return value != null;
+    }
+
+    @Override
+    public void persistState(StateCheckpointWriter checkpointBuilder) throws IOException {
+      if (value != null) {
+        // serialize the coder.
+        byte[] coder = InstantiationUtil.serializeObject(elemCoder);
+
+        // encode the value into a ByteString
+        ByteString.Output stream = ByteString.newOutput();
+        elemCoder.encode(value, stream, Coder.Context.OUTER);
+        ByteString data = stream.toByteString();
+
+        checkpointBuilder.addValueBuilder()
+          .setTag(stateKey)
+          .setData(coder)
+          .setData(data);
+      }
+    }
+
+    public void restoreState(StateCheckpointReader checkpointReader) throws IOException {
+      ByteString valueContent = checkpointReader.getData();
+      T outValue = elemCoder.decode(new ByteArrayInputStream(valueContent.toByteArray()), Coder.Context.OUTER);
+      write(outValue);
+    }
+  }
+
+  private final class FlinkWatermarkHoldStateImpl<W extends BoundedWindow>
+      implements WatermarkHoldState<W>, CheckpointableIF {
+
+    private final ByteString stateKey;
+
+    private Instant minimumHold = null;
+
+    private OutputTimeFn<? super W> outputTimeFn;
+
+    public FlinkWatermarkHoldStateImpl(ByteString stateKey, OutputTimeFn<? super W> outputTimeFn) {
+      this.stateKey = stateKey;
+      this.outputTimeFn = outputTimeFn;
+    }
+
+    @Override
+    public void clear() {
+      // Even though we're clearing we can't remove this from the in-memory state map, since
+      // other users may already have a handle on this WatermarkBagInternal.
+      minimumHold = null;
+      watermarkHoldAccessor = null;
+    }
+
+    @Override
+    public void add(Instant watermarkHold) {
+      if (minimumHold == null || minimumHold.isAfter(watermarkHold)) {
+        watermarkHoldAccessor = watermarkHold;
+        minimumHold = watermarkHold;
+      }
+    }
+
+    @Override
+    public ReadableState<Boolean> isEmpty() {
+      return new ReadableState<Boolean>() {
+        @Override
+        public Boolean read() {
+          return minimumHold == null;
+        }
+
+        @Override
+        public ReadableState<Boolean> readLater() {
+          // Ignore
+          return this;
+        }
+      };
+    }
+
+    @Override
+    public OutputTimeFn<? super W> getOutputTimeFn() {
+      return outputTimeFn;
+    }
+
+    @Override
+    public Instant read() {
+      return minimumHold;
+    }
+
+    @Override
+    public WatermarkHoldState<W> readLater() {
+      // Ignore
+      return this;
+    }
+
+    @Override
+    public String toString() {
+      return Objects.toString(minimumHold);
+    }
+
+    @Override
+    public boolean shouldPersist() {
+      return minimumHold != null;
+    }
+
+    @Override
+    public void persistState(StateCheckpointWriter checkpointBuilder) throws IOException {
+      if (minimumHold != null) {
+        checkpointBuilder.addWatermarkHoldsBuilder()
+            .setTag(stateKey)
+            .setTimestamp(minimumHold);
+      }
+    }
+
+    public void restoreState(StateCheckpointReader checkpointReader) throws IOException {
+      Instant watermark = checkpointReader.getTimestamp();
+      add(watermark);
+    }
+  }
+
+
+  private static <K, InputT, AccumT, OutputT> CombineWithContext.KeyedCombineFnWithContext<K, InputT, AccumT, OutputT> withContext(
+      final Combine.KeyedCombineFn<K, InputT, AccumT, OutputT> combineFn) {
+    return new CombineWithContext.KeyedCombineFnWithContext<K, InputT, AccumT, OutputT>() {
+      @Override
+      public AccumT createAccumulator(K key, CombineWithContext.Context c) {
+        return combineFn.createAccumulator(key);
+      }
+
+      @Override
+      public AccumT addInput(K key, AccumT accumulator, InputT value, CombineWithContext.Context c) {
+        return combineFn.addInput(key, accumulator, value);
+      }
+
+      @Override
+      public AccumT mergeAccumulators(K key, Iterable<AccumT> accumulators, CombineWithContext.Context c) {
+        return combineFn.mergeAccumulators(key, accumulators);
+      }
+
+      @Override
+      public OutputT extractOutput(K key, AccumT accumulator, CombineWithContext.Context c) {
+        return combineFn.extractOutput(key, accumulator);
+      }
+    };
+  }
+
+  private static <K, InputT, AccumT, OutputT> CombineWithContext.KeyedCombineFnWithContext<K, InputT, AccumT, OutputT> withKeyAndContext(
+      final Combine.CombineFn<InputT, AccumT, OutputT> combineFn) {
+    return new CombineWithContext.KeyedCombineFnWithContext<K, InputT, AccumT, OutputT>() {
+      @Override
+      public AccumT createAccumulator(K key, CombineWithContext.Context c) {
+        return combineFn.createAccumulator();
+      }
+
+      @Override
+      public AccumT addInput(K key, AccumT accumulator, InputT value, CombineWithContext.Context c) {
+        return combineFn.addInput(accumulator, value);
+      }
+
+      @Override
+      public AccumT mergeAccumulators(K key, Iterable<AccumT> accumulators, CombineWithContext.Context c) {
+        return combineFn.mergeAccumulators(accumulators);
+      }
+
+      @Override
+      public OutputT extractOutput(K key, AccumT accumulator, CombineWithContext.Context c) {
+        return combineFn.extractOutput(accumulator);
+      }
+    };
+  }
+
+  private final class FlinkInMemoryKeyedCombiningValue<InputT, AccumT, OutputT>
+      implements AccumulatorCombiningState<InputT, AccumT, OutputT>, CheckpointableIF {
+
+    private final ByteString stateKey;
+    private final CombineWithContext.KeyedCombineFnWithContext<? super K, InputT, AccumT, OutputT> combineFn;
+    private final Coder<AccumT> accumCoder;
+    private final CombineWithContext.Context context;
+
+    private AccumT accum = null;
+    private boolean isClear = true;
+
+    private FlinkInMemoryKeyedCombiningValue(ByteString stateKey,
+                                             Combine.CombineFn<InputT, AccumT, OutputT> combineFn,
+                                             Coder<AccumT> accumCoder,
+                                             final StateContext<?> stateContext) {
+      this(stateKey, withKeyAndContext(combineFn), accumCoder, stateContext);
+    }
+
+
+    private FlinkInMemoryKeyedCombiningValue(ByteString stateKey,
+                                             Combine.KeyedCombineFn<? super K, InputT, AccumT, OutputT> combineFn,
+                                             Coder<AccumT> accumCoder,
+                                             final StateContext<?> stateContext) {
+      this(stateKey, withContext(combineFn), accumCoder, stateContext);
+    }
+
+    private FlinkInMemoryKeyedCombiningValue(ByteString stateKey,
+                                             CombineWithContext.KeyedCombineFnWithContext<? super K, InputT, AccumT, OutputT> combineFn,
+                                             Coder<AccumT> accumCoder,
+                                             final StateContext<?> stateContext) {
+      Preconditions.checkNotNull(combineFn);
+      Preconditions.checkNotNull(accumCoder);
+
+      this.stateKey = stateKey;
+      this.combineFn = combineFn;
+      this.accumCoder = accumCoder;
+      this.context = new CombineWithContext.Context() {
+        @Override
+        public PipelineOptions getPipelineOptions() {
+          return stateContext.getPipelineOptions();
+        }
+
+        @Override
+        public <T> T sideInput(PCollectionView<T> view) {
+          return stateContext.sideInput(view);
+        }
+      };
+      accum = combineFn.createAccumulator(key, context);
+    }
+
+    @Override
+    public void clear() {
+      accum = combineFn.createAccumulator(key, context);
+      isClear = true;
+    }
+
+    @Override
+    public void add(InputT input) {
+      isClear = false;
+      accum = combineFn.addInput(key, accum, input, context);
+    }
+
+    @Override
+    public AccumT getAccum() {
+      return accum;
+    }
+
+    @Override
+    public ReadableState<Boolean> isEmpty() {
+      return new ReadableState<Boolean>() {
+        @Override
+        public ReadableState<Boolean> readLater() {
+          // Ignore
+          return this;
+        }
+
+        @Override
+        public Boolean read() {
+          return isClear;
+        }
+      };
+    }
+
+    @Override
+    public void addAccum(AccumT accum) {
+      isClear = false;
+      this.accum = combineFn.mergeAccumulators(key, Arrays.asList(this.accum, accum), context);
+    }
+
+    @Override
+    public AccumT mergeAccumulators(Iterable<AccumT> accumulators) {
+      return combineFn.mergeAccumulators(key, accumulators, context);
+    }
+
+    @Override
+    public OutputT read() {
+      return combineFn.extractOutput(key, accum, context);
+    }
+
+    @Override
+    public AccumulatorCombiningState<InputT, AccumT, OutputT> readLater() {
+      // Ignore
+      return this;
+    }
+
+    @Override
+    public boolean shouldPersist() {
+      return !isClear;
+    }
+
+    @Override
+    public void persistState(StateCheckpointWriter checkpointBuilder) throws IOException {
+      if (!isClear) {
+        // serialize the coder.
+        byte[] coder = InstantiationUtil.serializeObject(accumCoder);
+
+        // serialize the combiner.
+        byte[] combiner = InstantiationUtil.serializeObject(combineFn);
+
+        // encode the accumulator into a ByteString
+        ByteString.Output stream = ByteString.newOutput();
+        accumCoder.encode(accum, stream, Coder.Context.OUTER);
+        ByteString data = stream.toByteString();
+
+        // put the flag that the next serialized element is an accumulator
+        checkpointBuilder.addAccumulatorBuilder()
+          .setTag(stateKey)
+          .setData(coder)
+          .setData(combiner)
+          .setData(data);
+      }
+    }
+
+    public void restoreState(StateCheckpointReader checkpointReader) throws IOException {
+      ByteString valueContent = checkpointReader.getData();
+      AccumT accum = this.accumCoder.decode(new ByteArrayInputStream(valueContent.toByteArray()), Coder.Context.OUTER);
+      addAccum(accum);
+    }
+  }
+
+  private static final class FlinkInMemoryBag<T> implements BagState<T>, CheckpointableIF {
+    private final List<T> contents = new ArrayList<>();
+
+    private final ByteString stateKey;
+    private final Coder<T> elemCoder;
+
+    public FlinkInMemoryBag(ByteString stateKey, Coder<T> elemCoder) {
+      this.stateKey = stateKey;
+      this.elemCoder = elemCoder;
+    }
+
+    @Override
+    public void clear() {
+      contents.clear();
+    }
+
+    @Override
+    public Iterable<T> read() {
+      return contents;
+    }
+
+    @Override
+    public BagState<T> readLater() {
+      // Ignore
+      return this;
+    }
+
+    @Override
+    public void add(T input) {
+      contents.add(input);
+    }
+
+    @Override
+    public ReadableState<Boolean> isEmpty() {
+      return new ReadableState<Boolean>() {
+        @Override
+        public ReadableState<Boolean> readLater() {
+          // Ignore
+          return this;
+        }
+
+        @Override
+        public Boolean read() {
+          return contents.isEmpty();
+        }
+      };
+    }
+
+    @Override
+    public boolean shouldPersist() {
+      return !contents.isEmpty();
+    }
+
+    @Override
+    public void persistState(StateCheckpointWriter checkpointBuilder) throws IOException {
+      if (!contents.isEmpty()) {
+        // serialize the coder.
+        byte[] coder = InstantiationUtil.serializeObject(elemCoder);
+
+        checkpointBuilder.addListUpdatesBuilder()
+            .setTag(stateKey)
+            .setData(coder)
+            .writeInt(contents.size());
+
+        for (T item : contents) {
+          // encode the element
+          ByteString.Output stream = ByteString.newOutput();
+          elemCoder.encode(item, stream, Coder.Context.OUTER);
+          ByteString data = stream.toByteString();
+
+          // add the data to the checkpoint.
+          checkpointBuilder.setData(data);
+        }
+      }
+    }
+
+    public void restoreState(StateCheckpointReader checkpointReader) throws IOException {
+      int noOfValues = checkpointReader.getInt();
+      for (int j = 0; j < noOfValues; j++) {
+        ByteString valueContent = checkpointReader.getData();
+        T outValue = elemCoder.decode(new ByteArrayInputStream(valueContent.toByteArray()), Coder.Context.OUTER);
+        add(outValue);
+      }
+    }
+  }
+}

http://git-wip-us.apache.org/repos/asf/incubator-beam/blob/071e4dd6/runners/flink/runner/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/state/StateCheckpointReader.java
----------------------------------------------------------------------
diff --git a/runners/flink/runner/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/state/StateCheckpointReader.java b/runners/flink/runner/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/state/StateCheckpointReader.java
new file mode 100644
index 0000000..5aadccd
--- /dev/null
+++ b/runners/flink/runner/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/state/StateCheckpointReader.java
@@ -0,0 +1,91 @@
+/*
+ * 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.beam.runners.flink.translation.wrappers.streaming.state;
+
+import org.apache.beam.runners.flink.translation.types.CoderTypeSerializer;
+import com.google.protobuf.ByteString;
+import org.apache.flink.core.memory.DataInputView;
+import org.joda.time.Instant;
+
+import java.io.IOException;
+import java.util.concurrent.TimeUnit;
+
+public class StateCheckpointReader {
+
+  private final DataInputView input;
+
+  public StateCheckpointReader(DataInputView in) {
+    this.input = in;
+  }
+
+  public ByteString getTag() throws IOException {
+    return ByteString.copyFrom(readRawData());
+  }
+
+  public String getTagToString() throws IOException {
+    return input.readUTF();
+  }
+
+  public ByteString getData() throws IOException {
+    return ByteString.copyFrom(readRawData());
+  }
+
+  public int getInt() throws IOException {
+    validate();
+    return input.readInt();
+  }
+
+  public byte getByte() throws IOException {
+    validate();
+    return input.readByte();
+  }
+
+  public Instant getTimestamp() throws IOException {
+    validate();
+    Long watermarkMillis = input.readLong();
+    return new Instant(TimeUnit.MICROSECONDS.toMillis(watermarkMillis));
+  }
+
+  public <K> K deserializeKey(CoderTypeSerializer<K> keySerializer) throws IOException {
+    return deserializeObject(keySerializer);
+  }
+
+  public <T> T deserializeObject(CoderTypeSerializer<T> objectSerializer) throws IOException {
+    return objectSerializer.deserialize(input);
+  }
+
+  /////////      Helper Methods      ///////
+
+  private byte[] readRawData() throws IOException {
+    validate();
+    int size = input.readInt();
+
+    byte[] serData = new byte[size];
+    int bytesRead = input.read(serData);
+    if (bytesRead != size) {
+      throw new RuntimeException("Error while deserializing checkpoint. Not enough bytes in the input stream.");
+    }
+    return serData;
+  }
+
+  private void validate() {
+    if (this.input == null) {
+      throw new RuntimeException("StateBackend not initialized yet.");
+    }
+  }
+}

http://git-wip-us.apache.org/repos/asf/incubator-beam/blob/071e4dd6/runners/flink/runner/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/state/StateCheckpointUtils.java
----------------------------------------------------------------------
diff --git a/runners/flink/runner/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/state/StateCheckpointUtils.java b/runners/flink/runner/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/state/StateCheckpointUtils.java
new file mode 100644
index 0000000..b2dc33c
--- /dev/null
+++ b/runners/flink/runner/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/state/StateCheckpointUtils.java
@@ -0,0 +1,155 @@
+/*
+ * 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.beam.runners.flink.translation.wrappers.streaming.state;
+
+import org.apache.beam.runners.flink.translation.types.CoderTypeSerializer;
+import com.google.cloud.dataflow.sdk.coders.Coder;
+import com.google.cloud.dataflow.sdk.transforms.Combine;
+import com.google.cloud.dataflow.sdk.transforms.windowing.BoundedWindow;
+import com.google.cloud.dataflow.sdk.transforms.windowing.OutputTimeFn;
+import com.google.cloud.dataflow.sdk.util.TimeDomain;
+import com.google.cloud.dataflow.sdk.util.TimerInternals;
+import com.google.cloud.dataflow.sdk.util.state.StateNamespace;
+import com.google.cloud.dataflow.sdk.util.state.StateNamespaces;
+import org.joda.time.Instant;
+
+import java.io.IOException;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.Map;
+import java.util.Set;
+
+public class StateCheckpointUtils {
+
+  public static <K> void encodeState(Map<K, FlinkStateInternals<K>> perKeyStateInternals,
+               StateCheckpointWriter writer, Coder<K> keyCoder) throws IOException {
+    CoderTypeSerializer<K> keySerializer = new CoderTypeSerializer<>(keyCoder);
+
+    int noOfKeys = perKeyStateInternals.size();
+    writer.writeInt(noOfKeys);
+    for (Map.Entry<K, FlinkStateInternals<K>> keyStatePair : perKeyStateInternals.entrySet()) {
+      K key = keyStatePair.getKey();
+      FlinkStateInternals<K> state = keyStatePair.getValue();
+
+      // encode the key
+      writer.serializeKey(key, keySerializer);
+
+      // write the associated state
+      state.persistState(writer);
+    }
+  }
+
+  public static <K> Map<K, FlinkStateInternals<K>> decodeState(
+      StateCheckpointReader reader,
+      OutputTimeFn<? super BoundedWindow> outputTimeFn,
+      Coder<K> keyCoder,
+      Coder<? extends BoundedWindow> windowCoder,
+      ClassLoader classLoader) throws IOException, ClassNotFoundException {
+
+    int noOfKeys = reader.getInt();
+    Map<K, FlinkStateInternals<K>> perKeyStateInternals = new HashMap<>(noOfKeys);
+    perKeyStateInternals.clear();
+
+    CoderTypeSerializer<K> keySerializer = new CoderTypeSerializer<>(keyCoder);
+    for (int i = 0; i < noOfKeys; i++) {
+
+      // decode the key.
+      K key = reader.deserializeKey(keySerializer);
+
+      //decode the state associated to the key.
+      FlinkStateInternals<K> stateForKey =
+          new FlinkStateInternals<>(key, keyCoder, windowCoder, outputTimeFn);
+      stateForKey.restoreState(reader, classLoader);
+      perKeyStateInternals.put(key, stateForKey);
+    }
+    return perKeyStateInternals;
+  }
+
+  //////////////        Encoding/Decoding the Timers        ////////////////
+
+
+  public static <K> void encodeTimers(Map<K, Set<TimerInternals.TimerData>> allTimers,
+                StateCheckpointWriter writer,
+                Coder<K> keyCoder) throws IOException {
+    CoderTypeSerializer<K> keySerializer = new CoderTypeSerializer<>(keyCoder);
+
+    int noOfKeys = allTimers.size();
+    writer.writeInt(noOfKeys);
+    for (Map.Entry<K, Set<TimerInternals.TimerData>> timersPerKey : allTimers.entrySet()) {
+      K key = timersPerKey.getKey();
+
+      // encode the key
+      writer.serializeKey(key, keySerializer);
+
+      // write the associated timers
+      Set<TimerInternals.TimerData> timers = timersPerKey.getValue();
+      encodeTimerDataForKey(writer, timers);
+    }
+  }
+
+  public static <K> Map<K, Set<TimerInternals.TimerData>> decodeTimers(
+      StateCheckpointReader reader,
+      Coder<? extends BoundedWindow> windowCoder,
+      Coder<K> keyCoder) throws IOException {
+
+    int noOfKeys = reader.getInt();
+    Map<K, Set<TimerInternals.TimerData>> activeTimers = new HashMap<>(noOfKeys);
+    activeTimers.clear();
+
+    CoderTypeSerializer<K> keySerializer = new CoderTypeSerializer<>(keyCoder);
+    for (int i = 0; i < noOfKeys; i++) {
+
+      // decode the key.
+      K key = reader.deserializeKey(keySerializer);
+
+      // decode the associated timers.
+      Set<TimerInternals.TimerData> timers = decodeTimerDataForKey(reader, windowCoder);
+      activeTimers.put(key, timers);
+    }
+    return activeTimers;
+  }
+
+  private static void encodeTimerDataForKey(StateCheckpointWriter writer, Set<TimerInternals.TimerData> timers) throws IOException {
+    // encode timers
+    writer.writeInt(timers.size());
+    for (TimerInternals.TimerData timer : timers) {
+      String stringKey = timer.getNamespace().stringKey();
+
+      writer.setTag(stringKey);
+      writer.setTimestamp(timer.getTimestamp());
+      writer.writeInt(timer.getDomain().ordinal());
+    }
+  }
+
+  private static Set<TimerInternals.TimerData> decodeTimerDataForKey(
+      StateCheckpointReader reader, Coder<? extends BoundedWindow> windowCoder) throws IOException {
+
+    // decode the timers: first their number and then the content itself.
+    int noOfTimers = reader.getInt();
+    Set<TimerInternals.TimerData> timers = new HashSet<>(noOfTimers);
+    for (int i = 0; i < noOfTimers; i++) {
+      String stringKey = reader.getTagToString();
+      Instant instant = reader.getTimestamp();
+      TimeDomain domain = TimeDomain.values()[reader.getInt()];
+
+      StateNamespace namespace = StateNamespaces.fromString(stringKey, windowCoder);
+      timers.add(TimerInternals.TimerData.of(namespace, instant, domain));
+    }
+    return timers;
+  }
+}

http://git-wip-us.apache.org/repos/asf/incubator-beam/blob/071e4dd6/runners/flink/runner/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/state/StateCheckpointWriter.java
----------------------------------------------------------------------
diff --git a/runners/flink/runner/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/state/StateCheckpointWriter.java b/runners/flink/runner/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/state/StateCheckpointWriter.java
new file mode 100644
index 0000000..18e118a
--- /dev/null
+++ b/runners/flink/runner/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/state/StateCheckpointWriter.java
@@ -0,0 +1,129 @@
+/*
+ * 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.beam.runners.flink.translation.wrappers.streaming.state;
+
+import org.apache.beam.runners.flink.translation.types.CoderTypeSerializer;
+import com.google.protobuf.ByteString;
+import org.apache.flink.runtime.state.AbstractStateBackend;
+import org.joda.time.Instant;
+
+import java.io.IOException;
+import java.util.concurrent.TimeUnit;
+
+public class StateCheckpointWriter {
+
+  private final AbstractStateBackend.CheckpointStateOutputView output;
+
+  public static StateCheckpointWriter create(AbstractStateBackend.CheckpointStateOutputView output) {
+    return new StateCheckpointWriter(output);
+  }
+
+  private StateCheckpointWriter(AbstractStateBackend.CheckpointStateOutputView output) {
+    this.output = output;
+  }
+
+  /////////      Creating the serialized versions of the different types of state held by dataflow      ///////
+
+  public StateCheckpointWriter addValueBuilder() throws IOException {
+    validate();
+    StateType.serialize(StateType.VALUE, this);
+    return this;
+  }
+
+  public StateCheckpointWriter addWatermarkHoldsBuilder() throws IOException {
+    validate();
+    StateType.serialize(StateType.WATERMARK, this);
+    return this;
+  }
+
+  public StateCheckpointWriter addListUpdatesBuilder() throws IOException {
+    validate();
+    StateType.serialize(StateType.LIST, this);
+    return this;
+  }
+
+  public StateCheckpointWriter addAccumulatorBuilder() throws IOException {
+    validate();
+    StateType.serialize(StateType.ACCUMULATOR, this);
+    return this;
+  }
+
+  /////////      Setting the tag for a given state element      ///////
+
+  public StateCheckpointWriter setTag(ByteString stateKey) throws IOException {
+    return writeData(stateKey.toByteArray());
+  }
+
+  public StateCheckpointWriter setTag(String stateKey) throws IOException {
+    output.writeUTF(stateKey);
+    return this;
+  }
+
+
+  public <K> StateCheckpointWriter serializeKey(K key, CoderTypeSerializer<K> keySerializer) throws IOException {
+    return serializeObject(key, keySerializer);
+  }
+
+  public <T> StateCheckpointWriter serializeObject(T object, CoderTypeSerializer<T> objectSerializer) throws IOException {
+    objectSerializer.serialize(object, output);
+    return this;
+  }
+
+  /////////      Write the actual serialized data      //////////
+
+  public StateCheckpointWriter setData(ByteString data) throws IOException {
+    return writeData(data.toByteArray());
+  }
+
+  public StateCheckpointWriter setData(byte[] data) throws IOException {
+    return writeData(data);
+  }
+
+  public StateCheckpointWriter setTimestamp(Instant timestamp) throws IOException {
+    validate();
+    output.writeLong(TimeUnit.MILLISECONDS.toMicros(timestamp.getMillis()));
+    return this;
+  }
+
+  public StateCheckpointWriter writeInt(int number) throws IOException {
+    validate();
+    output.writeInt(number);
+    return this;
+  }
+
+  public StateCheckpointWriter writeByte(byte b) throws IOException {
+    validate();
+    output.writeByte(b);
+    return this;
+  }
+
+  /////////      Helper Methods      ///////
+
+  private StateCheckpointWriter writeData(byte[] data) throws IOException {
+    validate();
+    output.writeInt(data.length);
+    output.write(data);
+    return this;
+  }
+
+  private void validate() {
+    if (this.output == null) {
+      throw new RuntimeException("StateBackend not initialized yet.");
+    }
+  }
+}
\ No newline at end of file

http://git-wip-us.apache.org/repos/asf/incubator-beam/blob/071e4dd6/runners/flink/runner/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/state/StateType.java
----------------------------------------------------------------------
diff --git a/runners/flink/runner/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/state/StateType.java b/runners/flink/runner/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/state/StateType.java
new file mode 100644
index 0000000..5849773
--- /dev/null
+++ b/runners/flink/runner/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/state/StateType.java
@@ -0,0 +1,73 @@
+/*
+ * 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.beam.runners.flink.translation.wrappers.streaming.state;
+
+import java.io.IOException;
+
+/**
+ * The available types of state, as provided by the Beam SDK. This class is used for serialization/deserialization
+ * purposes.
+ * */
+public enum StateType {
+
+  VALUE(0),
+
+  WATERMARK(1),
+
+  LIST(2),
+
+  ACCUMULATOR(3);
+
+  private final int numVal;
+
+  StateType(int value) {
+    this.numVal = value;
+  }
+
+  public static void serialize(StateType type, StateCheckpointWriter output) throws IOException {
+    if (output == null) {
+      throw new IllegalArgumentException("Cannot write to a null output.");
+    }
+
+    if(type.numVal < 0 || type.numVal > 3) {
+      throw new RuntimeException("Unknown State Type " + type + ".");
+    }
+
+    output.writeByte((byte) type.numVal);
+  }
+
+  public static StateType deserialize(StateCheckpointReader input) throws IOException {
+    if (input == null) {
+      throw new IllegalArgumentException("Cannot read from a null input.");
+    }
+
+    int typeInt = (int) input.getByte();
+    if(typeInt < 0 || typeInt > 3) {
+      throw new RuntimeException("Unknown State Type " + typeInt + ".");
+    }
+
+    StateType resultType = null;
+    for(StateType st: values()) {
+      if(st.numVal == typeInt) {
+        resultType = st;
+        break;
+      }
+    }
+    return resultType;
+  }
+}

http://git-wip-us.apache.org/repos/asf/incubator-beam/blob/071e4dd6/runners/flink/runner/src/main/resources/log4j.properties
----------------------------------------------------------------------
diff --git a/runners/flink/runner/src/main/resources/log4j.properties b/runners/flink/runner/src/main/resources/log4j.properties
new file mode 100644
index 0000000..4daaad1
--- /dev/null
+++ b/runners/flink/runner/src/main/resources/log4j.properties
@@ -0,0 +1,23 @@
+################################################################################
+#  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.
+################################################################################
+
+log4j.rootLogger=INFO,console
+log4j.appender.console=org.apache.log4j.ConsoleAppender
+log4j.appender.console.target=System.err
+log4j.appender.console.layout=org.apache.log4j.PatternLayout
+log4j.appender.console.layout.ConversionPattern=%d{yy/MM/dd HH:mm:ss} %p %c{2}: %m%n

http://git-wip-us.apache.org/repos/asf/incubator-beam/blob/071e4dd6/runners/flink/runner/src/test/java/org/apache/beam/runners/flink/AvroITCase.java
----------------------------------------------------------------------
diff --git a/runners/flink/runner/src/test/java/org/apache/beam/runners/flink/AvroITCase.java b/runners/flink/runner/src/test/java/org/apache/beam/runners/flink/AvroITCase.java
new file mode 100644
index 0000000..3536f87
--- /dev/null
+++ b/runners/flink/runner/src/test/java/org/apache/beam/runners/flink/AvroITCase.java
@@ -0,0 +1,127 @@
+/*
+ * 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.beam.runners.flink;
+
+import com.google.cloud.dataflow.sdk.Pipeline;
+import com.google.cloud.dataflow.sdk.coders.AvroCoder;
+import com.google.cloud.dataflow.sdk.io.AvroIO;
+import com.google.cloud.dataflow.sdk.io.TextIO;
+import com.google.cloud.dataflow.sdk.transforms.Create;
+import com.google.cloud.dataflow.sdk.transforms.DoFn;
+import com.google.cloud.dataflow.sdk.transforms.ParDo;
+import com.google.common.base.Joiner;
+import org.apache.flink.test.util.JavaProgramTestBase;
+
+
+public class AvroITCase extends JavaProgramTestBase {
+
+  protected String resultPath;
+  protected String tmpPath;
+
+  public AvroITCase(){
+  }
+
+  static final String[] EXPECTED_RESULT = new String[] {
+      "Joe red 3",
+      "Mary blue 4",
+      "Mark green 1",
+      "Julia purple 5"
+  };
+
+  @Override
+  protected void preSubmit() throws Exception {
+    resultPath = getTempDirPath("result");
+    tmpPath = getTempDirPath("tmp");
+
+  }
+
+  @Override
+  protected void postSubmit() throws Exception {
+    compareResultsByLinesInMemory(Joiner.on('\n').join(EXPECTED_RESULT), resultPath);
+  }
+
+  @Override
+  protected void testProgram() throws Exception {
+    runProgram(tmpPath, resultPath);
+  }
+
+  private static void runProgram(String tmpPath, String resultPath) {
+    Pipeline p = FlinkTestPipeline.createForBatch();
+
+    p
+      .apply(Create.of(
+          new User("Joe", 3, "red"),
+          new User("Mary", 4, "blue"),
+          new User("Mark", 1, "green"),
+          new User("Julia", 5, "purple"))
+        .withCoder(AvroCoder.of(User.class)))
+
+      .apply(AvroIO.Write.to(tmpPath)
+        .withSchema(User.class));
+
+    p.run();
+
+    p = FlinkTestPipeline.createForBatch();
+
+    p
+      .apply(AvroIO.Read.from(tmpPath).withSchema(User.class).withoutValidation())
+
+        .apply(ParDo.of(new DoFn<User, String>() {
+          @Override
+          public void processElement(ProcessContext c) throws Exception {
+            User u = c.element();
+            String result = u.getName() + " " + u.getFavoriteColor() + " " + u.getFavoriteNumber();
+            c.output(result);
+          }
+        }))
+
+      .apply(TextIO.Write.to(resultPath));
+
+    p.run();
+  }
+
+  private static class User {
+
+    private String name;
+    private int favoriteNumber;
+    private String favoriteColor;
+
+    public User() {}
+
+    public User(String name, int favoriteNumber, String favoriteColor) {
+      this.name = name;
+      this.favoriteNumber = favoriteNumber;
+      this.favoriteColor = favoriteColor;
+    }
+
+    public String getName() {
+      return name;
+    }
+
+    public String getFavoriteColor() {
+      return favoriteColor;
+    }
+
+    public int getFavoriteNumber() {
+      return favoriteNumber;
+    }
+  }
+
+}
+

http://git-wip-us.apache.org/repos/asf/incubator-beam/blob/071e4dd6/runners/flink/runner/src/test/java/org/apache/beam/runners/flink/FlattenizeITCase.java
----------------------------------------------------------------------
diff --git a/runners/flink/runner/src/test/java/org/apache/beam/runners/flink/FlattenizeITCase.java b/runners/flink/runner/src/test/java/org/apache/beam/runners/flink/FlattenizeITCase.java
new file mode 100644
index 0000000..5ae0e83
--- /dev/null
+++ b/runners/flink/runner/src/test/java/org/apache/beam/runners/flink/FlattenizeITCase.java
@@ -0,0 +1,74 @@
+/*
+ * 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.beam.runners.flink;
+
+import com.google.cloud.dataflow.sdk.Pipeline;
+import com.google.cloud.dataflow.sdk.io.TextIO;
+import com.google.cloud.dataflow.sdk.transforms.Create;
+import com.google.cloud.dataflow.sdk.transforms.Flatten;
+import com.google.cloud.dataflow.sdk.values.PCollection;
+import com.google.cloud.dataflow.sdk.values.PCollectionList;
+import com.google.common.base.Joiner;
+import org.apache.flink.test.util.JavaProgramTestBase;
+
+public class FlattenizeITCase extends JavaProgramTestBase {
+
+  private String resultPath;
+  private String resultPath2;
+
+  private static final String[] words = {"hello", "this", "is", "a", "DataSet!"};
+  private static final String[] words2 = {"hello", "this", "is", "another", "DataSet!"};
+  private static final String[] words3 = {"hello", "this", "is", "yet", "another", "DataSet!"};
+
+  @Override
+  protected void preSubmit() throws Exception {
+    resultPath = getTempDirPath("result");
+    resultPath2 = getTempDirPath("result2");
+  }
+
+  @Override
+  protected void postSubmit() throws Exception {
+    String join = Joiner.on('\n').join(words);
+    String join2 = Joiner.on('\n').join(words2);
+    String join3 = Joiner.on('\n').join(words3);
+    compareResultsByLinesInMemory(join + "\n" + join2, resultPath);
+    compareResultsByLinesInMemory(join + "\n" + join2 + "\n" + join3, resultPath2);
+  }
+
+
+  @Override
+  protected void testProgram() throws Exception {
+    Pipeline p = FlinkTestPipeline.createForBatch();
+
+    PCollection<String> p1 = p.apply(Create.of(words));
+    PCollection<String> p2 = p.apply(Create.of(words2));
+
+    PCollectionList<String> list = PCollectionList.of(p1).and(p2);
+
+    list.apply(Flatten.<String>pCollections()).apply(TextIO.Write.to(resultPath));
+
+    PCollection<String> p3 = p.apply(Create.of(words3));
+
+    PCollectionList<String> list2 = list.and(p3);
+
+    list2.apply(Flatten.<String>pCollections()).apply(TextIO.Write.to(resultPath2));
+
+    p.run();
+  }
+
+}

http://git-wip-us.apache.org/repos/asf/incubator-beam/blob/071e4dd6/runners/flink/runner/src/test/java/org/apache/beam/runners/flink/FlinkTestPipeline.java
----------------------------------------------------------------------
diff --git a/runners/flink/runner/src/test/java/org/apache/beam/runners/flink/FlinkTestPipeline.java b/runners/flink/runner/src/test/java/org/apache/beam/runners/flink/FlinkTestPipeline.java
new file mode 100644
index 0000000..aadda24
--- /dev/null
+++ b/runners/flink/runner/src/test/java/org/apache/beam/runners/flink/FlinkTestPipeline.java
@@ -0,0 +1,72 @@
+/*
+ * 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.beam.runners.flink;
+
+import com.google.cloud.dataflow.sdk.Pipeline;
+import com.google.cloud.dataflow.sdk.PipelineResult;
+import com.google.cloud.dataflow.sdk.options.PipelineOptions;
+import com.google.cloud.dataflow.sdk.runners.PipelineRunner;
+
+/**
+ * {@link com.google.cloud.dataflow.sdk.Pipeline} for testing Dataflow programs on the
+ * {@link org.apache.beam.runners.flink.FlinkPipelineRunner}.
+ */
+public class FlinkTestPipeline extends Pipeline {
+
+  /**
+   * Creates and returns a new test pipeline for batch execution.
+   *
+   * <p> Use {@link com.google.cloud.dataflow.sdk.testing.DataflowAssert} to add tests, then call
+   * {@link Pipeline#run} to execute the pipeline and check the tests.
+   */
+  public static FlinkTestPipeline createForBatch() {
+    return create(false);
+  }
+
+  /**
+   * Creates and returns a new test pipeline for streaming execution.
+   *
+   * <p> Use {@link com.google.cloud.dataflow.sdk.testing.DataflowAssert} to add tests, then call
+   * {@link Pipeline#run} to execute the pipeline and check the tests.
+   *
+   * @return The Test Pipeline
+   */
+  public static FlinkTestPipeline createForStreaming() {
+    return create(true);
+  }
+
+  /**
+   * Creates and returns a new test pipeline for streaming or batch execution.
+   *
+   * <p> Use {@link com.google.cloud.dataflow.sdk.testing.DataflowAssert} to add tests, then call
+   * {@link Pipeline#run} to execute the pipeline and check the tests.
+   *
+   * @param streaming <code>True</code> for streaming mode, <code>False</code> for batch.
+   * @return The Test Pipeline.
+   */
+  private static FlinkTestPipeline create(boolean streaming) {
+    FlinkPipelineRunner flinkRunner = FlinkPipelineRunner.createForTest(streaming);
+    return new FlinkTestPipeline(flinkRunner, flinkRunner.getPipelineOptions());
+  }
+
+  private FlinkTestPipeline(PipelineRunner<? extends PipelineResult> runner,
+              PipelineOptions options) {
+    super(runner, options);
+  }
+}
+

http://git-wip-us.apache.org/repos/asf/incubator-beam/blob/071e4dd6/runners/flink/runner/src/test/java/org/apache/beam/runners/flink/JoinExamplesITCase.java
----------------------------------------------------------------------
diff --git a/runners/flink/runner/src/test/java/org/apache/beam/runners/flink/JoinExamplesITCase.java b/runners/flink/runner/src/test/java/org/apache/beam/runners/flink/JoinExamplesITCase.java
new file mode 100644
index 0000000..f60056d
--- /dev/null
+++ b/runners/flink/runner/src/test/java/org/apache/beam/runners/flink/JoinExamplesITCase.java
@@ -0,0 +1,101 @@
+/*
+ * 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.beam.runners.flink;
+
+import org.apache.beam.runners.flink.util.JoinExamples;
+import com.google.api.services.bigquery.model.TableRow;
+import com.google.cloud.dataflow.sdk.Pipeline;
+import com.google.cloud.dataflow.sdk.io.TextIO;
+import com.google.cloud.dataflow.sdk.transforms.Create;
+import com.google.cloud.dataflow.sdk.values.KV;
+import com.google.cloud.dataflow.sdk.values.PCollection;
+import com.google.common.base.Joiner;
+import org.apache.flink.test.util.JavaProgramTestBase;
+
+import java.util.Arrays;
+import java.util.List;
+
+
+/**
+ * Unfortunately we need to copy the code from the Dataflow SDK because it is not public there.
+ */
+public class JoinExamplesITCase extends JavaProgramTestBase {
+
+  protected String resultPath;
+
+  public JoinExamplesITCase(){
+  }
+
+  private static final TableRow row1 = new TableRow()
+      .set("ActionGeo_CountryCode", "VM").set("SQLDATE", "20141212")
+      .set("Actor1Name", "BANGKOK").set("SOURCEURL", "http://cnn.com");
+  private static final TableRow row2 = new TableRow()
+      .set("ActionGeo_CountryCode", "VM").set("SQLDATE", "20141212")
+      .set("Actor1Name", "LAOS").set("SOURCEURL", "http://www.chicagotribune.com");
+  private static final TableRow row3 = new TableRow()
+      .set("ActionGeo_CountryCode", "BE").set("SQLDATE", "20141213")
+      .set("Actor1Name", "AFGHANISTAN").set("SOURCEURL", "http://cnn.com");
+  static final TableRow[] EVENTS = new TableRow[] {
+      row1, row2, row3
+  };
+  static final List<TableRow> EVENT_ARRAY = Arrays.asList(EVENTS);
+
+  private static final TableRow cc1 = new TableRow()
+      .set("FIPSCC", "VM").set("HumanName", "Vietnam");
+  private static final TableRow cc2 = new TableRow()
+      .set("FIPSCC", "BE").set("HumanName", "Belgium");
+  static final TableRow[] CCS = new TableRow[] {
+      cc1, cc2
+  };
+  static final List<TableRow> CC_ARRAY = Arrays.asList(CCS);
+
+  static final String[] JOINED_EVENTS = new String[] {
+      "Country code: VM, Country name: Vietnam, Event info: Date: 20141212, Actor1: LAOS, "
+          + "url: http://www.chicagotribune.com",
+      "Country code: VM, Country name: Vietnam, Event info: Date: 20141212, Actor1: BANGKOK, "
+          + "url: http://cnn.com",
+      "Country code: BE, Country name: Belgium, Event info: Date: 20141213, Actor1: AFGHANISTAN, "
+          + "url: http://cnn.com"
+  };
+
+  @Override
+  protected void preSubmit() throws Exception {
+    resultPath = getTempDirPath("result");
+  }
+
+  @Override
+  protected void postSubmit() throws Exception {
+    compareResultsByLinesInMemory(Joiner.on('\n').join(JOINED_EVENTS), resultPath);
+  }
+
+  @Override
+  protected void testProgram() throws Exception {
+
+    Pipeline p = FlinkTestPipeline.createForBatch();
+
+    PCollection<TableRow> input1 = p.apply(Create.of(EVENT_ARRAY));
+    PCollection<TableRow> input2 = p.apply(Create.of(CC_ARRAY));
+
+    PCollection<String> output = JoinExamples.joinEvents(input1, input2);
+
+    output.apply(TextIO.Write.to(resultPath));
+
+    p.run();
+  }
+}
+

http://git-wip-us.apache.org/repos/asf/incubator-beam/blob/071e4dd6/runners/flink/runner/src/test/java/org/apache/beam/runners/flink/MaybeEmptyTestITCase.java
----------------------------------------------------------------------
diff --git a/runners/flink/runner/src/test/java/org/apache/beam/runners/flink/MaybeEmptyTestITCase.java b/runners/flink/runner/src/test/java/org/apache/beam/runners/flink/MaybeEmptyTestITCase.java
new file mode 100644
index 0000000..199602c
--- /dev/null
+++ b/runners/flink/runner/src/test/java/org/apache/beam/runners/flink/MaybeEmptyTestITCase.java
@@ -0,0 +1,65 @@
+/*
+ * 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.beam.runners.flink;
+
+import com.google.cloud.dataflow.sdk.Pipeline;
+import com.google.cloud.dataflow.sdk.coders.VoidCoder;
+import com.google.cloud.dataflow.sdk.io.TextIO;
+import com.google.cloud.dataflow.sdk.transforms.Create;
+import com.google.cloud.dataflow.sdk.transforms.DoFn;
+import com.google.cloud.dataflow.sdk.transforms.ParDo;
+import org.apache.flink.test.util.JavaProgramTestBase;
+
+import java.io.Serializable;
+
+public class MaybeEmptyTestITCase extends JavaProgramTestBase implements Serializable {
+
+  protected String resultPath;
+
+  protected final String expected = "test";
+
+  public MaybeEmptyTestITCase() {
+  }
+
+  @Override
+  protected void preSubmit() throws Exception {
+    resultPath = getTempDirPath("result");
+  }
+
+  @Override
+  protected void postSubmit() throws Exception {
+    compareResultsByLinesInMemory(expected, resultPath);
+  }
+
+  @Override
+  protected void testProgram() throws Exception {
+
+    Pipeline p = FlinkTestPipeline.createForBatch();
+
+    p.apply(Create.of((Void) null)).setCoder(VoidCoder.of())
+        .apply(ParDo.of(
+            new DoFn<Void, String>() {
+              @Override
+              public void processElement(DoFn<Void, String>.ProcessContext c) {
+                c.output(expected);
+              }
+            })).apply(TextIO.Write.to(resultPath));
+    p.run();
+  }
+
+}

http://git-wip-us.apache.org/repos/asf/incubator-beam/blob/071e4dd6/runners/flink/runner/src/test/java/org/apache/beam/runners/flink/ParDoMultiOutputITCase.java
----------------------------------------------------------------------
diff --git a/runners/flink/runner/src/test/java/org/apache/beam/runners/flink/ParDoMultiOutputITCase.java b/runners/flink/runner/src/test/java/org/apache/beam/runners/flink/ParDoMultiOutputITCase.java
new file mode 100644
index 0000000..403de29
--- /dev/null
+++ b/runners/flink/runner/src/test/java/org/apache/beam/runners/flink/ParDoMultiOutputITCase.java
@@ -0,0 +1,100 @@
+/*
+ * 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.beam.runners.flink;
+
+import com.google.cloud.dataflow.sdk.Pipeline;
+import com.google.cloud.dataflow.sdk.io.TextIO;
+import com.google.cloud.dataflow.sdk.transforms.Create;
+import com.google.cloud.dataflow.sdk.transforms.DoFn;
+import com.google.cloud.dataflow.sdk.transforms.ParDo;
+import com.google.cloud.dataflow.sdk.values.PCollection;
+import com.google.cloud.dataflow.sdk.values.PCollectionTuple;
+import com.google.cloud.dataflow.sdk.values.TupleTag;
+import com.google.cloud.dataflow.sdk.values.TupleTagList;
+import com.google.common.base.Joiner;
+import org.apache.flink.test.util.JavaProgramTestBase;
+
+import java.io.Serializable;
+
+public class ParDoMultiOutputITCase extends JavaProgramTestBase implements Serializable {
+
+  private String resultPath;
+
+  private static String[] expectedWords = {"MAAA", "MAAFOOO"};
+
+  @Override
+  protected void preSubmit() throws Exception {
+    resultPath = getTempDirPath("result");
+  }
+
+  @Override
+  protected void postSubmit() throws Exception {
+    compareResultsByLinesInMemory(Joiner.on("\n").join(expectedWords), resultPath);
+  }
+
+  @Override
+  protected void testProgram() throws Exception {
+    Pipeline p = FlinkTestPipeline.createForBatch();
+
+    PCollection<String> words = p.apply(Create.of("Hello", "Whatupmyman", "hey", "SPECIALthere", "MAAA", "MAAFOOO"));
+
+    // Select words whose length is below a cut off,
+    // plus the lengths of words that are above the cut off.
+    // Also select words starting with "MARKER".
+    final int wordLengthCutOff = 3;
+    // Create tags to use for the main and side outputs.
+    final TupleTag<String> wordsBelowCutOffTag = new TupleTag<String>(){};
+    final TupleTag<Integer> wordLengthsAboveCutOffTag = new TupleTag<Integer>(){};
+    final TupleTag<String> markedWordsTag = new TupleTag<String>(){};
+
+    PCollectionTuple results =
+        words.apply(ParDo
+            .withOutputTags(wordsBelowCutOffTag, TupleTagList.of(wordLengthsAboveCutOffTag)
+                .and(markedWordsTag))
+            .of(new DoFn<String, String>() {
+              final TupleTag<String> specialWordsTag = new TupleTag<String>() {
+              };
+
+              public void processElement(ProcessContext c) {
+                String word = c.element();
+                if (word.length() <= wordLengthCutOff) {
+                  c.output(word);
+                } else {
+                  c.sideOutput(wordLengthsAboveCutOffTag, word.length());
+                }
+                if (word.startsWith("MAA")) {
+                  c.sideOutput(markedWordsTag, word);
+                }
+
+                if (word.startsWith("SPECIAL")) {
+                  c.sideOutput(specialWordsTag, word);
+                }
+              }
+            }));
+
+    // Extract the PCollection results, by tag.
+    PCollection<String> wordsBelowCutOff = results.get(wordsBelowCutOffTag);
+    PCollection<Integer> wordLengthsAboveCutOff = results.get
+        (wordLengthsAboveCutOffTag);
+    PCollection<String> markedWords = results.get(markedWordsTag);
+
+    markedWords.apply(TextIO.Write.to(resultPath));
+
+    p.run();
+  }
+}

http://git-wip-us.apache.org/repos/asf/incubator-beam/blob/071e4dd6/runners/flink/runner/src/test/java/org/apache/beam/runners/flink/ReadSourceITCase.java
----------------------------------------------------------------------
diff --git a/runners/flink/runner/src/test/java/org/apache/beam/runners/flink/ReadSourceITCase.java b/runners/flink/runner/src/test/java/org/apache/beam/runners/flink/ReadSourceITCase.java
new file mode 100644
index 0000000..323c41b
--- /dev/null
+++ b/runners/flink/runner/src/test/java/org/apache/beam/runners/flink/ReadSourceITCase.java
@@ -0,0 +1,165 @@
+/*
+ * 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.beam.runners.flink;
+
+import com.google.cloud.dataflow.sdk.Pipeline;
+import com.google.cloud.dataflow.sdk.coders.BigEndianIntegerCoder;
+import com.google.cloud.dataflow.sdk.coders.Coder;
+import com.google.cloud.dataflow.sdk.io.BoundedSource;
+import com.google.cloud.dataflow.sdk.io.Read;
+import com.google.cloud.dataflow.sdk.io.TextIO;
+import com.google.cloud.dataflow.sdk.options.PipelineOptions;
+import com.google.cloud.dataflow.sdk.transforms.DoFn;
+import com.google.cloud.dataflow.sdk.transforms.ParDo;
+import com.google.cloud.dataflow.sdk.values.PCollection;
+import com.google.common.base.Joiner;
+import com.google.common.base.Preconditions;
+import org.apache.flink.test.util.JavaProgramTestBase;
+
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.List;
+
+
+public class ReadSourceITCase extends JavaProgramTestBase {
+
+  protected String resultPath;
+
+  public ReadSourceITCase(){
+  }
+
+  static final String[] EXPECTED_RESULT = new String[] {
+      "1", "2", "3", "4", "5", "6", "7", "8", "9"};
+
+  @Override
+  protected void preSubmit() throws Exception {
+    resultPath = getTempDirPath("result");
+  }
+
+  @Override
+  protected void postSubmit() throws Exception {
+    compareResultsByLinesInMemory(Joiner.on('\n').join(EXPECTED_RESULT), resultPath);
+  }
+
+  @Override
+  protected void testProgram() throws Exception {
+    runProgram(resultPath);
+  }
+
+  private static void runProgram(String resultPath) {
+
+    Pipeline p = FlinkTestPipeline.createForBatch();
+
+    PCollection<String> result = p
+        .apply(Read.from(new ReadSource(1, 10)))
+        .apply(ParDo.of(new DoFn<Integer, String>() {
+          @Override
+          public void processElement(ProcessContext c) throws Exception {
+            c.output(c.element().toString());
+          }
+        }));
+
+    result.apply(TextIO.Write.to(resultPath));
+    p.run();
+  }
+
+
+  private static class ReadSource extends BoundedSource<Integer> {
+    final int from;
+    final int to;
+
+    ReadSource(int from, int to) {
+      this.from = from;
+      this.to = to;
+    }
+
+    @Override
+    public List<ReadSource> splitIntoBundles(long desiredShardSizeBytes, PipelineOptions options)
+        throws Exception {
+      List<ReadSource> res = new ArrayList<>();
+      FlinkPipelineOptions flinkOptions = options.as(FlinkPipelineOptions.class);
+      int numWorkers = flinkOptions.getParallelism();
+      Preconditions.checkArgument(numWorkers > 0, "Number of workers should be larger than 0.");
+
+      float step = 1.0f * (to - from) / numWorkers;
+      for (int i = 0; i < numWorkers; ++i) {
+        res.add(new ReadSource(Math.round(from + i * step), Math.round(from + (i + 1) * step)));
+      }
+      return res;
+    }
+
+    @Override
+    public long getEstimatedSizeBytes(PipelineOptions options) throws Exception {
+      return 8 * (to - from);
+    }
+
+    @Override
+    public boolean producesSortedKeys(PipelineOptions options) throws Exception {
+      return true;
+    }
+
+    @Override
+    public BoundedReader<Integer> createReader(PipelineOptions options) throws IOException {
+      return new RangeReader(this);
+    }
+
+    @Override
+    public void validate() {}
+
+    @Override
+    public Coder<Integer> getDefaultOutputCoder() {
+      return BigEndianIntegerCoder.of();
+    }
+
+    private class RangeReader extends BoundedReader<Integer> {
+      private int current;
+
+      public RangeReader(ReadSource source) {
+        this.current = source.from - 1;
+      }
+
+      @Override
+      public boolean start() throws IOException {
+        return true;
+      }
+
+      @Override
+      public boolean advance() throws IOException {
+        current++;
+        return (current < to);
+      }
+
+      @Override
+      public Integer getCurrent() {
+        return current;
+      }
+
+      @Override
+      public void close() throws IOException {
+        // Nothing
+      }
+
+      @Override
+      public BoundedSource<Integer> getCurrentSource() {
+        return ReadSource.this;
+      }
+    }
+  }
+}
+
+

http://git-wip-us.apache.org/repos/asf/incubator-beam/blob/071e4dd6/runners/flink/runner/src/test/java/org/apache/beam/runners/flink/RemoveDuplicatesEmptyITCase.java
----------------------------------------------------------------------
diff --git a/runners/flink/runner/src/test/java/org/apache/beam/runners/flink/RemoveDuplicatesEmptyITCase.java b/runners/flink/runner/src/test/java/org/apache/beam/runners/flink/RemoveDuplicatesEmptyITCase.java
new file mode 100644
index 0000000..524554a
--- /dev/null
+++ b/runners/flink/runner/src/test/java/org/apache/beam/runners/flink/RemoveDuplicatesEmptyITCase.java
@@ -0,0 +1,70 @@
+/*
+ * 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.beam.runners.flink;
+
+import com.google.cloud.dataflow.sdk.Pipeline;
+import com.google.cloud.dataflow.sdk.coders.StringUtf8Coder;
+import com.google.cloud.dataflow.sdk.io.TextIO;
+import com.google.cloud.dataflow.sdk.transforms.Create;
+import com.google.cloud.dataflow.sdk.transforms.RemoveDuplicates;
+import com.google.cloud.dataflow.sdk.values.PCollection;
+import com.google.common.base.Joiner;
+import org.apache.flink.test.util.JavaProgramTestBase;
+
+import java.util.Collections;
+import java.util.List;
+
+
+public class RemoveDuplicatesEmptyITCase extends JavaProgramTestBase {
+
+  protected String resultPath;
+
+  public RemoveDuplicatesEmptyITCase(){
+  }
+
+  static final String[] EXPECTED_RESULT = new String[] {};
+
+  @Override
+  protected void preSubmit() throws Exception {
+    resultPath = getTempDirPath("result");
+  }
+
+  @Override
+  protected void postSubmit() throws Exception {
+    compareResultsByLinesInMemory(Joiner.on('\n').join(EXPECTED_RESULT), resultPath);
+  }
+
+  @Override
+  protected void testProgram() throws Exception {
+
+    List<String> strings = Collections.emptyList();
+
+    Pipeline p = FlinkTestPipeline.createForBatch();
+
+    PCollection<String> input =
+        p.apply(Create.of(strings))
+            .setCoder(StringUtf8Coder.of());
+
+    PCollection<String> output =
+        input.apply(RemoveDuplicates.<String>create());
+
+    output.apply(TextIO.Write.to(resultPath));
+    p.run();
+  }
+}
+

http://git-wip-us.apache.org/repos/asf/incubator-beam/blob/071e4dd6/runners/flink/runner/src/test/java/org/apache/beam/runners/flink/RemoveDuplicatesITCase.java
----------------------------------------------------------------------
diff --git a/runners/flink/runner/src/test/java/org/apache/beam/runners/flink/RemoveDuplicatesITCase.java b/runners/flink/runner/src/test/java/org/apache/beam/runners/flink/RemoveDuplicatesITCase.java
new file mode 100644
index 0000000..54e92aa
--- /dev/null
+++ b/runners/flink/runner/src/test/java/org/apache/beam/runners/flink/RemoveDuplicatesITCase.java
@@ -0,0 +1,71 @@
+/*
+ * 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.beam.runners.flink;
+
+import com.google.cloud.dataflow.sdk.Pipeline;
+import com.google.cloud.dataflow.sdk.coders.StringUtf8Coder;
+import com.google.cloud.dataflow.sdk.io.TextIO;
+import com.google.cloud.dataflow.sdk.transforms.Create;
+import com.google.cloud.dataflow.sdk.transforms.RemoveDuplicates;
+import com.google.cloud.dataflow.sdk.values.PCollection;
+import com.google.common.base.Joiner;
+import org.apache.flink.test.util.JavaProgramTestBase;
+
+import java.util.Arrays;
+import java.util.List;
+
+
+public class RemoveDuplicatesITCase extends JavaProgramTestBase {
+
+  protected String resultPath;
+
+  public RemoveDuplicatesITCase(){
+  }
+
+  static final String[] EXPECTED_RESULT = new String[] {
+      "k1", "k5", "k2", "k3"};
+
+  @Override
+  protected void preSubmit() throws Exception {
+    resultPath = getTempDirPath("result");
+  }
+
+  @Override
+  protected void postSubmit() throws Exception {
+    compareResultsByLinesInMemory(Joiner.on('\n').join(EXPECTED_RESULT), resultPath);
+  }
+
+  @Override
+  protected void testProgram() throws Exception {
+
+    List<String> strings = Arrays.asList("k1", "k5", "k5", "k2", "k1", "k2", "k3");
+
+    Pipeline p = FlinkTestPipeline.createForBatch();
+
+    PCollection<String> input =
+        p.apply(Create.of(strings))
+            .setCoder(StringUtf8Coder.of());
+
+    PCollection<String> output =
+        input.apply(RemoveDuplicates.<String>create());
+
+    output.apply(TextIO.Write.to(resultPath));
+    p.run();
+  }
+}
+

http://git-wip-us.apache.org/repos/asf/incubator-beam/blob/071e4dd6/runners/flink/runner/src/test/java/org/apache/beam/runners/flink/SideInputITCase.java
----------------------------------------------------------------------
diff --git a/runners/flink/runner/src/test/java/org/apache/beam/runners/flink/SideInputITCase.java b/runners/flink/runner/src/test/java/org/apache/beam/runners/flink/SideInputITCase.java
new file mode 100644
index 0000000..7f73b83
--- /dev/null
+++ b/runners/flink/runner/src/test/java/org/apache/beam/runners/flink/SideInputITCase.java
@@ -0,0 +1,69 @@
+/*
+ * 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.beam.runners.flink;
+
+import com.google.cloud.dataflow.sdk.Pipeline;
+import com.google.cloud.dataflow.sdk.io.TextIO;
+import com.google.cloud.dataflow.sdk.transforms.Create;
+import com.google.cloud.dataflow.sdk.transforms.DoFn;
+import com.google.cloud.dataflow.sdk.transforms.ParDo;
+import com.google.cloud.dataflow.sdk.transforms.View;
+import com.google.cloud.dataflow.sdk.values.PCollectionView;
+import org.apache.flink.test.util.JavaProgramTestBase;
+
+import java.io.Serializable;
+
+public class SideInputITCase extends JavaProgramTestBase implements Serializable {
+
+  private static final String expected = "Hello!";
+
+  protected String resultPath;
+
+  @Override
+  protected void testProgram() throws Exception {
+
+
+    Pipeline p = FlinkTestPipeline.createForBatch();
+
+
+    final PCollectionView<String> sidesInput = p
+        .apply(Create.of(expected))
+        .apply(View.<String>asSingleton());
+
+    p.apply(Create.of("bli"))
+        .apply(ParDo.of(new DoFn<String, String>() {
+          @Override
+          public void processElement(ProcessContext c) throws Exception {
+            String s = c.sideInput(sidesInput);
+            c.output(s);
+          }
+        }).withSideInputs(sidesInput)).apply(TextIO.Write.to(resultPath));
+
+    p.run();
+  }
+
+  @Override
+  protected void preSubmit() throws Exception {
+    resultPath = getTempDirPath("result");
+  }
+
+  @Override
+  protected void postSubmit() throws Exception {
+    compareResultsByLinesInMemory(expected, resultPath);
+  }
+}

http://git-wip-us.apache.org/repos/asf/incubator-beam/blob/071e4dd6/runners/flink/runner/src/test/java/org/apache/beam/runners/flink/TfIdfITCase.java
----------------------------------------------------------------------
diff --git a/runners/flink/runner/src/test/java/org/apache/beam/runners/flink/TfIdfITCase.java b/runners/flink/runner/src/test/java/org/apache/beam/runners/flink/TfIdfITCase.java
new file mode 100644
index 0000000..b0fb7b8
--- /dev/null
+++ b/runners/flink/runner/src/test/java/org/apache/beam/runners/flink/TfIdfITCase.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.beam.runners.flink;
+
+import com.google.cloud.dataflow.examples.complete.TfIdf;
+import com.google.cloud.dataflow.sdk.Pipeline;
+import com.google.cloud.dataflow.sdk.coders.StringDelegateCoder;
+import com.google.cloud.dataflow.sdk.io.TextIO;
+import com.google.cloud.dataflow.sdk.transforms.Create;
+import com.google.cloud.dataflow.sdk.transforms.Keys;
+import com.google.cloud.dataflow.sdk.transforms.RemoveDuplicates;
+import com.google.cloud.dataflow.sdk.values.KV;
+import com.google.cloud.dataflow.sdk.values.PCollection;
+import com.google.common.base.Joiner;
+import org.apache.flink.test.util.JavaProgramTestBase;
+
+import java.net.URI;
+
+
+public class TfIdfITCase extends JavaProgramTestBase {
+
+  protected String resultPath;
+
+  public TfIdfITCase(){
+  }
+
+  static final String[] EXPECTED_RESULT = new String[] {
+      "a", "m", "n", "b", "c", "d"};
+
+  @Override
+  protected void preSubmit() throws Exception {
+    resultPath = getTempDirPath("result");
+  }
+
+  @Override
+  protected void postSubmit() throws Exception {
+    compareResultsByLinesInMemory(Joiner.on('\n').join(EXPECTED_RESULT), resultPath);
+  }
+
+  @Override
+  protected void testProgram() throws Exception {
+
+    Pipeline pipeline = FlinkTestPipeline.createForBatch();
+
+    pipeline.getCoderRegistry().registerCoder(URI.class, StringDelegateCoder.of(URI.class));
+
+    PCollection<KV<String, KV<URI, Double>>> wordToUriAndTfIdf = pipeline
+        .apply(Create.of(
+            KV.of(new URI("x"), "a b c d"),
+            KV.of(new URI("y"), "a b c"),
+            KV.of(new URI("z"), "a m n")))
+        .apply(new TfIdf.ComputeTfIdf());
+
+    PCollection<String> words = wordToUriAndTfIdf
+        .apply(Keys.<String>create())
+        .apply(RemoveDuplicates.<String>create());
+
+    words.apply(TextIO.Write.to(resultPath));
+
+    pipeline.run();
+  }
+}
+

http://git-wip-us.apache.org/repos/asf/incubator-beam/blob/071e4dd6/runners/flink/runner/src/test/java/org/apache/beam/runners/flink/WordCountITCase.java
----------------------------------------------------------------------
diff --git a/runners/flink/runner/src/test/java/org/apache/beam/runners/flink/WordCountITCase.java b/runners/flink/runner/src/test/java/org/apache/beam/runners/flink/WordCountITCase.java
new file mode 100644
index 0000000..2677c9e
--- /dev/null
+++ b/runners/flink/runner/src/test/java/org/apache/beam/runners/flink/WordCountITCase.java
@@ -0,0 +1,75 @@
+/*
+ * 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.beam.runners.flink;
+
+import com.google.cloud.dataflow.examples.WordCount;
+import com.google.cloud.dataflow.sdk.Pipeline;
+import com.google.cloud.dataflow.sdk.coders.StringUtf8Coder;
+import com.google.cloud.dataflow.sdk.io.TextIO;
+import com.google.cloud.dataflow.sdk.transforms.Create;
+import com.google.cloud.dataflow.sdk.transforms.MapElements;
+import com.google.cloud.dataflow.sdk.values.PCollection;
+import com.google.common.base.Joiner;
+import org.apache.flink.test.util.JavaProgramTestBase;
+
+import java.util.Arrays;
+import java.util.List;
+
+
+public class WordCountITCase extends JavaProgramTestBase {
+
+  protected String resultPath;
+
+  public WordCountITCase(){
+  }
+
+  static final String[] WORDS_ARRAY = new String[] {
+      "hi there", "hi", "hi sue bob",
+      "hi sue", "", "bob hi"};
+
+  static final List<String> WORDS = Arrays.asList(WORDS_ARRAY);
+
+  static final String[] COUNTS_ARRAY = new String[] {
+      "hi: 5", "there: 1", "sue: 2", "bob: 2"};
+
+  @Override
+  protected void preSubmit() throws Exception {
+    resultPath = getTempDirPath("result");
+  }
+
+  @Override
+  protected void postSubmit() throws Exception {
+    compareResultsByLinesInMemory(Joiner.on('\n').join(COUNTS_ARRAY), resultPath);
+  }
+
+  @Override
+  protected void testProgram() throws Exception {
+
+    Pipeline p = FlinkTestPipeline.createForBatch();
+
+    PCollection<String> input = p.apply(Create.of(WORDS)).setCoder(StringUtf8Coder.of());
+
+    input
+        .apply(new WordCount.CountWords())
+        .apply(MapElements.via(new WordCount.FormatAsTextFn()))
+        .apply(TextIO.Write.to(resultPath));
+
+    p.run();
+  }
+}
+