Initial code-base of stream events to Kafka topic
Publish Gerrit stream events to a Kafka topic called 'gerrit'.
Change-Id: I8c15dea904bcbcffaae38254ceb5beac61661c40
diff --git a/BUCK b/BUCK
new file mode 100644
index 0000000..cb6da4d
--- /dev/null
+++ b/BUCK
@@ -0,0 +1,37 @@
+include_defs('//bucklets/gerrit_plugin.bucklet')
+include_defs('//bucklets/maven_jar.bucklet')
+
+gerrit_plugin(
+ name = 'kafka-events',
+ srcs = glob(['src/main/java/**/*.java']),
+ resources = glob(['src/main/resources/**/*']),
+ manifest_entries = [
+ 'Gerrit-PluginName: kafka-events',
+ 'Gerrit-Module: com.googlesource.gerrit.plugins.kafka.Module',
+ 'Implementation-Title: Gerrit Apache Kafka plugin',
+ 'Implementation-URL: https://gerrit.googlesource.com/plugins/kafka-events',
+ 'Implementation-Vendor: GerritForge',
+ ],
+ deps = [
+ ':kafka-client',
+ ],
+ provided_deps = [
+ '//lib:gson',
+ '//lib/commons:codec',
+ '//lib/commons:lang',
+ ],
+)
+
+java_library(
+ name = 'classpath',
+ deps = [':kafka__plugin'],
+)
+
+maven_jar(
+ name = 'kafka-client',
+ id = 'org.apache.kafka:kafka-clients:0.10.0.1',
+ license = 'Apache2.0',
+ exclude_java_sources = True,
+ visibility = [],
+)
+
diff --git a/LICENSE b/LICENSE
new file mode 100644
index 0000000..11069ed
--- /dev/null
+++ b/LICENSE
@@ -0,0 +1,201 @@
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diff --git a/README.md b/README.md
new file mode 100644
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--- /dev/null
+++ b/README.md
@@ -0,0 +1,49 @@
+Kafka: Gerrit event producer for Apache Kafka
+=======================
+
+* Author: GerritForge
+* Repository: https://gerrit.googlesource.com/plugins/kafka
+* CI/Release: https://gerrit-ci.gerritforge.com/search/?q=kafka
+
+Synopsis
+----------------------
+
+This plugins allows to define a distributed stream of events
+published by Gerrit.
+
+Events can be anything, from the traditional stream events
+to the Gerrit metrics.
+
+This plugin requires Gerrit 2.13 or laster.
+
+Environments
+---------------------
+
+* `linux`
+* `java-1.8`
+* `Buck`
+
+Build
+---------------------
+
+Clone or link this plugin to the plugins directory of Gerrit's source
+tree, and issue the command:
+
+
+ buck build plugins/kafka
+
+The output is created in
+
+ buck-out/gen/plugins/kafka/kafka.jar
+
+Minimum Configuration
+---------------------
+Assuming a running Kafka broker on the same Gerrit host, add the following
+settings to gerrit.config:
+
+```
+ [plugin "kafka"]
+ server = localhost:9092
+ topic = gerrit-events
+```
+
diff --git a/lib/gerrit/BUCK b/lib/gerrit/BUCK
new file mode 100644
index 0000000..42d492c
--- /dev/null
+++ b/lib/gerrit/BUCK
@@ -0,0 +1,13 @@
+include_defs('//bucklets/maven_jar.bucklet')
+
+VER = '2.13.1'
+REPO = MAVEN_CENTRAL
+
+maven_jar(
+ name = 'plugin-api',
+ id = 'com.google.gerrit:gerrit-plugin-api:' + VER,
+ sha1 = '8e12346dbb677d70987afdbec5352ff6e889a181',
+ license = 'Apache2.0',
+ attach_source = False,
+ repository = REPO,
+)
diff --git a/src/main/java/com/googlesource/gerrit/plugins/kafka/Manager.java b/src/main/java/com/googlesource/gerrit/plugins/kafka/Manager.java
new file mode 100644
index 0000000..bdbe81b
--- /dev/null
+++ b/src/main/java/com/googlesource/gerrit/plugins/kafka/Manager.java
@@ -0,0 +1,63 @@
+// Copyright (C) 2016 The Android Open Source Project
+//
+// Licensed 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 com.googlesource.gerrit.plugins.kafka;
+
+import com.google.gerrit.extensions.events.LifecycleListener;
+import com.google.inject.Inject;
+import com.google.inject.Singleton;
+
+import com.googlesource.gerrit.plugins.kafka.config.KafkaProperties;
+import com.googlesource.gerrit.plugins.kafka.message.Publisher;
+import com.googlesource.gerrit.plugins.kafka.message.PublisherFactory;
+import com.googlesource.gerrit.plugins.kafka.worker.DefaultEventWorker;
+import com.googlesource.gerrit.plugins.kafka.worker.EventWorker;
+
+import java.util.ArrayList;
+import java.util.List;
+
+@Singleton
+public class Manager implements LifecycleListener {
+
+ private final EventWorker defaultEventWorker;
+ private final PublisherFactory publisherFactory;
+ private final KafkaProperties properties;
+ private final List<Publisher> publisherList = new ArrayList<>();
+
+ @Inject
+ public Manager(DefaultEventWorker defaultEventWorker,
+ PublisherFactory publisherFactory,
+ KafkaProperties properties) {
+ this.defaultEventWorker = defaultEventWorker;
+ this.publisherFactory = publisherFactory;
+ this.properties = properties;
+ }
+
+ @Override
+ public void start() {
+ Publisher publisher = publisherFactory.create(properties);
+ publisher.start();
+ defaultEventWorker.addPublisher(publisher);
+ publisherList.add(publisher);
+ }
+
+ @Override
+ public void stop() {
+ for (Publisher publisher : publisherList) {
+ publisher.stop();
+ defaultEventWorker.removePublisher(publisher);
+ }
+ publisherList.clear();
+ }
+}
diff --git a/src/main/java/com/googlesource/gerrit/plugins/kafka/Module.java b/src/main/java/com/googlesource/gerrit/plugins/kafka/Module.java
new file mode 100644
index 0000000..00b22ef
--- /dev/null
+++ b/src/main/java/com/googlesource/gerrit/plugins/kafka/Module.java
@@ -0,0 +1,50 @@
+// Copyright (C) 2016 The Android Open Source Project
+//
+// Licensed 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 com.googlesource.gerrit.plugins.kafka;
+
+import com.google.gerrit.common.EventListener;
+import com.google.gerrit.extensions.events.LifecycleListener;
+import com.google.gerrit.extensions.registration.DynamicSet;
+import com.google.gson.Gson;
+import com.google.inject.AbstractModule;
+import com.google.inject.Singleton;
+import com.google.inject.assistedinject.FactoryModuleBuilder;
+
+import com.googlesource.gerrit.plugins.kafka.config.KafkaProperties;
+import com.googlesource.gerrit.plugins.kafka.config.KafkaPropertiesProvider;
+import com.googlesource.gerrit.plugins.kafka.message.GsonProvider;
+import com.googlesource.gerrit.plugins.kafka.message.MessagePublisher;
+import com.googlesource.gerrit.plugins.kafka.message.Publisher;
+import com.googlesource.gerrit.plugins.kafka.message.PublisherFactory;
+import com.googlesource.gerrit.plugins.kafka.session.KafkaSessionFactory;
+import com.googlesource.gerrit.plugins.kafka.session.SessionFactoryProvider;
+import com.googlesource.gerrit.plugins.kafka.worker.DefaultEventWorker;
+
+class Module extends AbstractModule {
+
+ @Override
+ protected void configure() {
+ bind(KafkaSessionFactory.class).toProvider(SessionFactoryProvider.class);
+
+ install(new FactoryModuleBuilder().implement(Publisher.class,
+ MessagePublisher.class).build(PublisherFactory.class));
+ bind(KafkaProperties.class).toProvider(KafkaPropertiesProvider.class)
+ .in(Singleton.class);
+ bind(Gson.class).toProvider(GsonProvider.class).in(Singleton.class);
+
+ DynamicSet.bind(binder(), LifecycleListener.class).to(Manager.class);
+ DynamicSet.bind(binder(), EventListener.class).to(DefaultEventWorker.class);
+ }
+}
diff --git a/src/main/java/com/googlesource/gerrit/plugins/kafka/config/KafkaProperties.java b/src/main/java/com/googlesource/gerrit/plugins/kafka/config/KafkaProperties.java
new file mode 100644
index 0000000..d519e03
--- /dev/null
+++ b/src/main/java/com/googlesource/gerrit/plugins/kafka/config/KafkaProperties.java
@@ -0,0 +1,58 @@
+// Copyright (C) 2016 The Android Open Source Project
+//
+// Licensed 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 com.googlesource.gerrit.plugins.kafka.config;
+
+import com.google.common.base.CaseFormat;
+import com.google.gerrit.server.config.PluginConfig;
+
+public class KafkaProperties extends java.util.Properties {
+ private static final long serialVersionUID = 0L;
+
+ private final String topic;
+
+ public KafkaProperties(PluginConfig config) {
+ super();
+ setDefaults();
+ applyConfig(config);
+
+ topic = config.getString("topic", "gerrit");
+ }
+
+ private void setDefaults() {
+ put("acks", "all");
+ put("retries", 0);
+ put("batch.size", 16384);
+ put("linger.ms", 1);
+ put("buffer.memory", 33554432);
+ put("key.serializer",
+ "org.apache.kafka.common.serialization.StringSerializer");
+ put("value.serializer",
+ "org.apache.kafka.common.serialization.StringSerializer");
+ }
+
+ private void applyConfig(PluginConfig config) {
+ for (String name : config.getNames()) {
+ Object value = config.getString(name);
+ String propName =
+ CaseFormat.LOWER_CAMEL.to(CaseFormat.LOWER_HYPHEN, name).replaceAll(
+ "-", ".");
+ put(propName, value);
+ }
+ }
+
+ public String getTopic() {
+ return topic;
+ }
+}
diff --git a/src/main/java/com/googlesource/gerrit/plugins/kafka/config/KafkaPropertiesProvider.java b/src/main/java/com/googlesource/gerrit/plugins/kafka/config/KafkaPropertiesProvider.java
new file mode 100644
index 0000000..dd16963
--- /dev/null
+++ b/src/main/java/com/googlesource/gerrit/plugins/kafka/config/KafkaPropertiesProvider.java
@@ -0,0 +1,40 @@
+// Copyright (C) 2016 The Android Open Source Project
+//
+// Licensed 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 com.googlesource.gerrit.plugins.kafka.config;
+
+import com.google.gerrit.extensions.annotations.PluginName;
+import com.google.gerrit.server.config.PluginConfig;
+import com.google.gerrit.server.config.PluginConfigFactory;
+import com.google.inject.Inject;
+import com.google.inject.Provider;
+
+
+public class KafkaPropertiesProvider implements Provider<KafkaProperties> {
+
+ private final PluginConfigFactory configFactory;
+ private final String pluginName;
+
+ @Inject
+ public KafkaPropertiesProvider(PluginConfigFactory configFactory,
+ @PluginName String pluginName) {
+ this.configFactory = configFactory;
+ this.pluginName = pluginName;
+ }
+
+ @Override
+ public KafkaProperties get() {
+ return new KafkaProperties(configFactory.getFromGerritConfig(pluginName));
+ }
+}
diff --git a/src/main/java/com/googlesource/gerrit/plugins/kafka/message/GsonProvider.java b/src/main/java/com/googlesource/gerrit/plugins/kafka/message/GsonProvider.java
new file mode 100644
index 0000000..40080cf
--- /dev/null
+++ b/src/main/java/com/googlesource/gerrit/plugins/kafka/message/GsonProvider.java
@@ -0,0 +1,30 @@
+// Copyright (C) 2016 The Android Open Source Project
+//
+// Licensed 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 com.googlesource.gerrit.plugins.kafka.message;
+
+import com.google.common.base.Supplier;
+import com.google.gerrit.server.events.SupplierSerializer;
+import com.google.gson.Gson;
+import com.google.gson.GsonBuilder;
+import com.google.inject.Provider;
+
+public class GsonProvider implements Provider<Gson> {
+
+ @Override
+ public Gson get() {
+ return new GsonBuilder().registerTypeAdapter(Supplier.class,
+ new SupplierSerializer()).create();
+ }
+}
diff --git a/src/main/java/com/googlesource/gerrit/plugins/kafka/message/MessagePublisher.java b/src/main/java/com/googlesource/gerrit/plugins/kafka/message/MessagePublisher.java
new file mode 100644
index 0000000..9f235a1
--- /dev/null
+++ b/src/main/java/com/googlesource/gerrit/plugins/kafka/message/MessagePublisher.java
@@ -0,0 +1,94 @@
+// Copyright (C) 2016 The Android Open Source Project
+//
+// Licensed 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 com.googlesource.gerrit.plugins.kafka.message;
+
+import com.google.gerrit.extensions.events.LifecycleListener;
+import com.google.gerrit.server.events.Event;
+import com.google.gson.Gson;
+import com.google.inject.Inject;
+import com.google.inject.assistedinject.Assisted;
+
+import com.googlesource.gerrit.plugins.kafka.config.KafkaProperties;
+import com.googlesource.gerrit.plugins.kafka.session.Session;
+import com.googlesource.gerrit.plugins.kafka.session.SessionFactoryProvider;
+
+public class MessagePublisher implements Publisher, LifecycleListener {
+
+ private final Session session;
+ private final KafkaProperties properties;
+ private final Gson gson;
+ private boolean available = true;
+
+ @Inject
+ public MessagePublisher(
+ @Assisted KafkaProperties properties,
+ SessionFactoryProvider sessionFactoryProvider,
+ Gson gson) {
+ this.session = sessionFactoryProvider.get().create(properties);
+ this.properties = properties;
+ this.gson = gson;
+ }
+
+ @Override
+ public void start() {
+ if (!session.isOpen()) {
+ session.connect();
+ available = true;
+ }
+ }
+
+ @Override
+ public void stop() {
+ session.disconnect();
+ available = false;
+ }
+
+ @Override
+ public void onEvent(Event event) {
+ if (available && session.isOpen()) {
+ session.publish(gson.toJson(event));
+ }
+ }
+
+ @Override
+ public void enable() {
+ available = true;
+ }
+
+ @Override
+ public void disable() {
+ available = false;
+ }
+
+ @Override
+ public boolean isEnabled() {
+ return available;
+ }
+
+ @Override
+ public Session getSession() {
+ return session;
+ }
+
+ @Override
+ public KafkaProperties getProperties() {
+ return properties;
+ }
+
+ @Override
+ public String getName() {
+ return "Kafka";
+ }
+}
diff --git a/src/main/java/com/googlesource/gerrit/plugins/kafka/message/Publisher.java b/src/main/java/com/googlesource/gerrit/plugins/kafka/message/Publisher.java
new file mode 100644
index 0000000..44c1aeb
--- /dev/null
+++ b/src/main/java/com/googlesource/gerrit/plugins/kafka/message/Publisher.java
@@ -0,0 +1,31 @@
+// Copyright (C) 2016 The Android Open Source Project
+//
+// Licensed 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 com.googlesource.gerrit.plugins.kafka.message;
+
+import com.google.gerrit.common.EventListener;
+
+import com.googlesource.gerrit.plugins.kafka.config.KafkaProperties;
+import com.googlesource.gerrit.plugins.kafka.session.Session;
+
+public interface Publisher extends EventListener {
+ void start();
+ void stop();
+ void enable();
+ void disable();
+ boolean isEnabled();
+ Session getSession();
+ KafkaProperties getProperties();
+ String getName();
+}
diff --git a/src/main/java/com/googlesource/gerrit/plugins/kafka/message/PublisherFactory.java b/src/main/java/com/googlesource/gerrit/plugins/kafka/message/PublisherFactory.java
new file mode 100644
index 0000000..f365416
--- /dev/null
+++ b/src/main/java/com/googlesource/gerrit/plugins/kafka/message/PublisherFactory.java
@@ -0,0 +1,21 @@
+// Copyright (C) 2016 The Android Open Source Project
+//
+// Licensed 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 com.googlesource.gerrit.plugins.kafka.message;
+
+import com.googlesource.gerrit.plugins.kafka.config.KafkaProperties;
+
+public interface PublisherFactory {
+ Publisher create(KafkaProperties properties);
+}
diff --git a/src/main/java/com/googlesource/gerrit/plugins/kafka/session/KafkaSessionFactory.java b/src/main/java/com/googlesource/gerrit/plugins/kafka/session/KafkaSessionFactory.java
new file mode 100644
index 0000000..d4b6e80
--- /dev/null
+++ b/src/main/java/com/googlesource/gerrit/plugins/kafka/session/KafkaSessionFactory.java
@@ -0,0 +1,24 @@
+// Copyright (C) 2016 The Android Open Source Project
+//
+// Licensed 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 com.googlesource.gerrit.plugins.kafka.session;
+
+import com.googlesource.gerrit.plugins.kafka.config.KafkaProperties;
+import com.googlesource.gerrit.plugins.kafka.session.type.KafkaSession;
+
+public class KafkaSessionFactory {
+ public Session create(KafkaProperties properties) {
+ return new KafkaSession(properties);
+ }
+}
diff --git a/src/main/java/com/googlesource/gerrit/plugins/kafka/session/Session.java b/src/main/java/com/googlesource/gerrit/plugins/kafka/session/Session.java
new file mode 100644
index 0000000..fc8b9ff
--- /dev/null
+++ b/src/main/java/com/googlesource/gerrit/plugins/kafka/session/Session.java
@@ -0,0 +1,22 @@
+// Copyright (C) 2016 The Android Open Source Project
+//
+// Licensed 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 com.googlesource.gerrit.plugins.kafka.session;
+
+public interface Session {
+ boolean isOpen();
+ void connect();
+ void disconnect();
+ void publish(String message);
+}
diff --git a/src/main/java/com/googlesource/gerrit/plugins/kafka/session/SessionFactoryProvider.java b/src/main/java/com/googlesource/gerrit/plugins/kafka/session/SessionFactoryProvider.java
new file mode 100644
index 0000000..0a869be
--- /dev/null
+++ b/src/main/java/com/googlesource/gerrit/plugins/kafka/session/SessionFactoryProvider.java
@@ -0,0 +1,25 @@
+// Copyright (C) 2016 The Android Open Source Project
+//
+// Licensed 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 com.googlesource.gerrit.plugins.kafka.session;
+
+import com.google.inject.Provider;
+
+public class SessionFactoryProvider implements Provider<KafkaSessionFactory> {
+
+ @Override
+ public KafkaSessionFactory get() {
+ return new KafkaSessionFactory();
+ }
+}
diff --git a/src/main/java/com/googlesource/gerrit/plugins/kafka/session/type/KafkaSession.java b/src/main/java/com/googlesource/gerrit/plugins/kafka/session/type/KafkaSession.java
new file mode 100644
index 0000000..6cd9ad7
--- /dev/null
+++ b/src/main/java/com/googlesource/gerrit/plugins/kafka/session/type/KafkaSession.java
@@ -0,0 +1,73 @@
+// Copyright (C) 2016 The Android Open Source Project
+//
+// Licensed 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 com.googlesource.gerrit.plugins.kafka.session.type;
+
+import com.googlesource.gerrit.plugins.kafka.config.KafkaProperties;
+import com.googlesource.gerrit.plugins.kafka.session.Session;
+
+import org.apache.kafka.clients.producer.KafkaProducer;
+import org.apache.kafka.clients.producer.Producer;
+import org.apache.kafka.clients.producer.ProducerRecord;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+public final class KafkaSession implements Session {
+
+ private static final Logger LOGGER = LoggerFactory
+ .getLogger(KafkaSession.class);
+ private final KafkaProperties properties;
+ private volatile Producer<String, String> producer;
+
+ public KafkaSession(KafkaProperties properties) {
+ this.properties = properties;
+ }
+
+ @Override
+ public boolean isOpen() {
+ if (producer != null) {
+ return true;
+ }
+ return false;
+ }
+
+ @Override
+ public void connect() {
+ if (isOpen()) {
+ LOGGER.debug("Already connected.");
+ return;
+ }
+
+ LOGGER.info("Connect to {}...",
+ properties.getProperty("bootstrap.servers"));
+ producer = new KafkaProducer<>(properties);
+ LOGGER.info("Connection established.");
+ }
+
+ @Override
+ public void disconnect() {
+ LOGGER.info("Disconnecting...");
+ if (producer != null) {
+ LOGGER.info("Closing Producer {}...", producer);
+ producer.close();
+ }
+ producer = null;
+ }
+
+ @Override
+ public void publish(String messageBody) {
+ producer.send(new ProducerRecord<>(properties.getTopic(), "" + System.nanoTime(),
+ messageBody));
+ }
+}
diff --git a/src/main/java/com/googlesource/gerrit/plugins/kafka/worker/DefaultEventWorker.java b/src/main/java/com/googlesource/gerrit/plugins/kafka/worker/DefaultEventWorker.java
new file mode 100644
index 0000000..9e58701
--- /dev/null
+++ b/src/main/java/com/googlesource/gerrit/plugins/kafka/worker/DefaultEventWorker.java
@@ -0,0 +1,61 @@
+// Copyright (C) 2016 The Android Open Source Project
+//
+// Licensed 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 com.googlesource.gerrit.plugins.kafka.worker;
+
+import com.google.gerrit.common.EventListener;
+import com.google.gerrit.server.events.Event;
+import com.google.inject.Singleton;
+
+import com.googlesource.gerrit.plugins.kafka.message.Publisher;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.util.Set;
+import java.util.concurrent.CopyOnWriteArraySet;
+
+@Singleton
+public class DefaultEventWorker implements EventListener, EventWorker {
+ private static final Logger log = LoggerFactory
+ .getLogger(DefaultEventWorker.class);
+ private final Set<Publisher> publishers = new CopyOnWriteArraySet<>();
+
+ @Override
+ public void addPublisher(Publisher publisher) {
+ publishers.add(publisher);
+ }
+
+ @Override
+ public void removePublisher(Publisher publisher) {
+ publishers.remove(publisher);
+ }
+
+ @Override
+ public void clear() {
+ publishers.clear();
+ }
+
+ @Override
+ public void onEvent(Event event) {
+ for (Publisher publisher : publishers) {
+ try {
+ publisher.onEvent(event);
+ } catch (Exception e) {
+ log.error("Unable to process event " + e + " through publisher "
+ + publisher, e);
+ }
+ }
+ }
+}
diff --git a/src/main/java/com/googlesource/gerrit/plugins/kafka/worker/EventWorker.java b/src/main/java/com/googlesource/gerrit/plugins/kafka/worker/EventWorker.java
new file mode 100644
index 0000000..eb7afa7
--- /dev/null
+++ b/src/main/java/com/googlesource/gerrit/plugins/kafka/worker/EventWorker.java
@@ -0,0 +1,23 @@
+// Copyright (C) 2016 The Android Open Source Project
+//
+// Licensed 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 com.googlesource.gerrit.plugins.kafka.worker;
+
+import com.googlesource.gerrit.plugins.kafka.message.Publisher;
+
+public interface EventWorker {
+ void addPublisher(Publisher publisher);
+ void removePublisher(Publisher publisher);
+ void clear();
+}
diff --git a/src/main/resources/Documentation/about.md b/src/main/resources/Documentation/about.md
new file mode 100644
index 0000000..685c195
--- /dev/null
+++ b/src/main/resources/Documentation/about.md
@@ -0,0 +1 @@
+This plugin can publish gerrit stream events to an Apache Kafka topic.
diff --git a/src/main/resources/Documentation/build.md b/src/main/resources/Documentation/build.md
new file mode 100644
index 0000000..0e292bd
--- /dev/null
+++ b/src/main/resources/Documentation/build.md
@@ -0,0 +1,29 @@
+Build
+=====
+
+This plugin is built with Buck.
+
+Build in Gerrit tree
+--------------------
+
+Clone or link this plugin to the plugins directory of Gerrit's source
+tree, and issue the command:
+
+```
+ buck build plugins/kafka-events
+```
+
+The output is created in
+
+```
+ buck-out/gen/plugins/kafka-events/kafka-events.jar
+```
+
+This project can be imported into the Eclipse IDE:
+
+```
+ ./tools/eclipse/project.py
+```
+
+How to build the Gerrit Plugin API is described in the [Gerrit
+documentation](../../../Documentation/dev-buck.html#_extension_and_plugin_api_jar_files).
diff --git a/src/main/resources/Documentation/config.md b/src/main/resources/Documentation/config.md
new file mode 100644
index 0000000..96e4b94
--- /dev/null
+++ b/src/main/resources/Documentation/config.md
@@ -0,0 +1,34 @@
+Apache Kafka Configuration
+======================
+
+Some parameters can be configured using Gerrit config file.
+
+Sample config
+---------------------
+
+```
+[plugin "kafka-events"]
+ bootstrapServers = localhost:9092
+```
+
+All the Apache Kafka properties configuration needs to
+be defined in gerrit.config using a lower camel-case notation.
+
+Example: bootstrapServers correspond to the Apache Kafka property
+bootstrap.servers.
+
+See [Apache Kafka Producer Config](http://kafka.apache.org/documentation.html#producerconfigs)
+for a full list of available settings and the values allowed.
+
+Default Values
+-----------------
+
+|name | value
+|:--------------------|:------------------
+| acks | all
+| retries | 0
+| batchSize | 16384
+| lingerMs | 1
+| bufferMemory | 33554432
+| keySerializer | org.apache.kafka.common.serialization.StringSerializer
+| valueSerializer | org.apache.kafka.common.serialization.StringSerializer
\ No newline at end of file
diff --git a/src/main/resources/Documentation/message.md b/src/main/resources/Documentation/message.md
new file mode 100644
index 0000000..47cae2b
--- /dev/null
+++ b/src/main/resources/Documentation/message.md
@@ -0,0 +1,15 @@
+Message Format
+======================
+
+This plugin publishes message like the below format to Apache Kafka.
+
+Key
+-----------------------
+
+Current time in nanoseconds.
+
+
+Payload
+-----------------------
+
+Payload is JSON string. (same as gerrit-events)
