igalshilman commented on a change in pull request #19:
URL:
https://github.com/apache/flink-statefun-playground/pull/19#discussion_r796789576
##########
File path:
java/connected-components/src/main/java/org/apache/flink/statefun/playground/java/connectedcomponents/types/JavaType.java
##########
@@ -0,0 +1,70 @@
+package org.apache.flink.statefun.playground.java.connectedcomponents.types;
+
+import org.apache.flink.statefun.sdk.java.TypeName;
+import org.apache.flink.statefun.sdk.java.slice.Slice;
+import org.apache.flink.statefun.sdk.java.slice.Slices;
+import org.apache.flink.statefun.sdk.java.types.Type;
+import org.apache.flink.statefun.sdk.java.types.TypeCharacteristics;
+import org.apache.flink.statefun.sdk.java.types.TypeSerializer;
+
+import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.io.ObjectInputStream;
+import java.io.ObjectOutputStream;
+import java.util.Collections;
+import java.util.EnumSet;
+import java.util.Set;
+
+/**
+ * Simple type that uses Java serialization to serialize values.
+ *
+ * @param <T> type to hold
+ */
+final class JavaType<T> implements Type<T> {
+ private static final JavaSerializer INSTANCE = new JavaSerializer();
+ private final TypeName typeName;
+
+ JavaType(TypeName typeName) {
+ this.typeName = typeName;
+ }
+
+ @Override
+ public TypeName typeName() {
+ return typeName;
+ }
+
+ @Override
+ public TypeSerializer<T> typeSerializer() {
+ return INSTANCE;
+ }
+
+ @Override
+ public Set<TypeCharacteristics> typeCharacteristics() {
+ return
Collections.unmodifiableSet(EnumSet.of(TypeCharacteristics.IMMUTABLE_VALUES));
+ }
+
+ private static final class JavaSerializer<T> implements TypeSerializer<T> {
+ @Override
+ public Slice serialize(T value) {
+ final ByteArrayOutputStream baos = new ByteArrayOutputStream();
Review comment:
@tillrohrmann, I'm a bit reluctant of having Java serialization here as
an example, because we've learned that whatever we put in the examples folks
tend to copy as-is.
I've seen that you are using `Jackson` at `Types` do you mind using this
instead?
I think that you can use the `ObjectMapper` to serialize and deserialize the
set directly.
##########
File path:
java/connected-components/src/main/java/org/apache/flink/statefun/playground/java/connectedcomponents/types/Types.java
##########
@@ -0,0 +1,38 @@
+package org.apache.flink.statefun.playground.java.connectedcomponents.types;
+
+import
org.apache.flink.statefun.playground.java.connectedcomponents.types.generated.VertexComponentChange;
+import org.apache.flink.statefun.sdk.java.TypeName;
+import org.apache.flink.statefun.sdk.java.types.SimpleType;
+import org.apache.flink.statefun.sdk.java.types.Type;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+
+import java.util.Set;
+
+public final class Types {
+
+ private Types() {}
+
+ private static final ObjectMapper JSON_OBJ_MAPPER = new ObjectMapper();
+ private static final String TYPES_NAMESPACE = "connected-components.types";
+
+ /**
+ * Type denoting a new vertex coming from the input source.
+ */
+ public static final Type<Vertex> VERTEX_INIT_TYPE =
+ SimpleType.simpleImmutableTypeFrom(
+ TypeName.typeNameOf(TYPES_NAMESPACE, Vertex.class.getName()),
Review comment:
I think that we shouldn't encourage using `class.getName()` as this can
be bit fragile if the Vertex class moves to a different package.
How about using a logical name like `vertex`?
##########
File path: java/connected-components/src/main/protobuf/messages.proto
##########
@@ -0,0 +1,30 @@
+/*
+ * 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.
+ */
+
+syntax = "proto3";
+
+package org.apache.flink.statefun.playground.java.connectedcomponents.types;
+
+option java_package =
"org.apache.flink.statefun.playground.java.connectedcomponents.types.generated";
+option java_multiple_files = true;
+
+message VertexComponentChange {
Review comment:
I think that we can get away without Protobuf here, it seems like you
are already using JSON, what do you think about simplifying this a bit (and
removing the protobuf dependency altogether) ?
##########
File path:
java/connected-components/src/main/java/org/apache/flink/statefun/playground/java/connectedcomponents/ConnectedComponentsFn.java
##########
@@ -0,0 +1,133 @@
+package org.apache.flink.statefun.playground.java.connectedcomponents;
+
+import
org.apache.flink.statefun.playground.java.connectedcomponents.types.Types;
+import
org.apache.flink.statefun.playground.java.connectedcomponents.types.Vertex;
+import
org.apache.flink.statefun.playground.java.connectedcomponents.types.generated.VertexComponentChange;
+import org.apache.flink.statefun.sdk.java.Context;
+import org.apache.flink.statefun.sdk.java.StatefulFunction;
+import org.apache.flink.statefun.sdk.java.StatefulFunctionSpec;
+import org.apache.flink.statefun.sdk.java.TypeName;
+import org.apache.flink.statefun.sdk.java.ValueSpec;
+import org.apache.flink.statefun.sdk.java.io.KafkaEgressMessage;
+import org.apache.flink.statefun.sdk.java.message.Message;
+import org.apache.flink.statefun.sdk.java.message.MessageBuilder;
+
+import java.util.Collections;
+import java.util.HashSet;
+import java.util.Set;
+import java.util.concurrent.CompletableFuture;
+
+/**
+ * A stateful function that computes the connected component for a stream of
vertices.
Review comment:
👍 really nice that you have added the algorithm description!
Do you think that folks might find it useful if you will add a link to the
algorithm, or cite it's name?
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