diff --git a/sentinel-cluster/sentinel-cluster-client-default/README.md b/sentinel-cluster/sentinel-cluster-client-default/README.md
new file mode 100644
index 00000000..d09d8263
--- /dev/null
+++ b/sentinel-cluster/sentinel-cluster-client-default/README.md
@@ -0,0 +1 @@
+# Sentinel Cluster Client (Default)
\ No newline at end of file
diff --git a/sentinel-cluster/sentinel-cluster-client-default/src/main/java/com/alibaba/csp/sentinel/cluster/client/ClientConstants.java b/sentinel-cluster/sentinel-cluster-client-default/src/main/java/com/alibaba/csp/sentinel/cluster/client/ClientConstants.java
new file mode 100644
index 00000000..9645feb5
--- /dev/null
+++ b/sentinel-cluster/sentinel-cluster-client-default/src/main/java/com/alibaba/csp/sentinel/cluster/client/ClientConstants.java
@@ -0,0 +1,32 @@
+/*
+ * Copyright 1999-2018 Alibaba Group Holding Ltd.
+ *
+ * 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.alibaba.csp.sentinel.cluster.client;
+
+/**
+ * @author Eric Zhao
+ */
+public final class ClientConstants {
+
+    public static final int TYPE_PING = 0;
+    public static final int TYPE_FLOW = 1;
+    public static final int TYPE_PARAM_FLOW = 2;
+
+    public static final int CLIENT_STATUS_OFF = 0;
+    public static final int CLIENT_STATUS_PENDING = 1;
+    public static final int CLIENT_STATUS_STARTED = 2;
+
+    private ClientConstants() {}
+}
diff --git a/sentinel-cluster/sentinel-cluster-client-default/src/main/java/com/alibaba/csp/sentinel/cluster/client/DefaultClusterTokenClient.java b/sentinel-cluster/sentinel-cluster-client-default/src/main/java/com/alibaba/csp/sentinel/cluster/client/DefaultClusterTokenClient.java
new file mode 100644
index 00000000..668f43bd
--- /dev/null
+++ b/sentinel-cluster/sentinel-cluster-client-default/src/main/java/com/alibaba/csp/sentinel/cluster/client/DefaultClusterTokenClient.java
@@ -0,0 +1,105 @@
+/*
+ * Copyright 1999-2018 Alibaba Group Holding Ltd.
+ *
+ * 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.alibaba.csp.sentinel.cluster.client;
+
+import java.util.Collection;
+
+import com.alibaba.csp.sentinel.cluster.ClusterConstants;
+import com.alibaba.csp.sentinel.cluster.ClusterTokenClient;
+import com.alibaba.csp.sentinel.cluster.ClusterTransportClient;
+import com.alibaba.csp.sentinel.cluster.TokenResult;
+import com.alibaba.csp.sentinel.cluster.TokenResultStatus;
+import com.alibaba.csp.sentinel.cluster.TokenServerDescriptor;
+import com.alibaba.csp.sentinel.cluster.client.config.ClusterClientConfig;
+import com.alibaba.csp.sentinel.cluster.log.ClusterStatLogUtil;
+import com.alibaba.csp.sentinel.cluster.request.ClusterRequest;
+import com.alibaba.csp.sentinel.cluster.request.data.FlowRequestData;
+import com.alibaba.csp.sentinel.cluster.request.data.ParamFlowRequestData;
+import com.alibaba.csp.sentinel.cluster.response.ClusterResponse;
+import com.alibaba.csp.sentinel.cluster.response.data.FlowTokenResponseData;
+
+/**
+ * @author Eric Zhao
+ * @since 1.4.0
+ */
+public class DefaultClusterTokenClient implements ClusterTokenClient {
+
+    private ClusterTransportClient transportClient;
+
+    public DefaultClusterTokenClient() {
+        // TODO: load and create transport client here.
+    }
+
+    public DefaultClusterTokenClient(ClusterTransportClient transportClient) {
+        this.transportClient = transportClient;
+    }
+
+    @Override
+    public TokenServerDescriptor currentServer() {
+        return new TokenServerDescriptor();
+    }
+
+    @Override
+    public TokenResult requestToken(Long flowId, int acquireCount, boolean prioritized) {
+        if (notValidRequest(flowId, acquireCount)) {
+            return badRequest();
+        }
+        FlowRequestData data = new FlowRequestData().setCount(acquireCount)
+            .setFlowId(flowId).setPriority(prioritized);
+        ClusterRequest<FlowRequestData> request = new ClusterRequest<>(ClusterConstants.MSG_TYPE_FLOW, data);
+        try {
+            return sendTokenRequest(request);
+        } catch (Exception ex) {
+            ClusterStatLogUtil.log(ex.getMessage());
+            return new TokenResult(TokenResultStatus.FAIL);
+        }
+    }
+
+    @Override
+    public TokenResult requestParamToken(Long flowId, int acquireCount, Collection<Object> params) {
+        if (notValidRequest(flowId, acquireCount) || params == null || params.isEmpty()) {
+            return badRequest();
+        }
+        ParamFlowRequestData data = new ParamFlowRequestData().setCount(acquireCount)
+            .setFlowId(flowId).setParams(params);
+        ClusterRequest<ParamFlowRequestData> request = new ClusterRequest<>(ClusterConstants.MSG_TYPE_PARAM_FLOW, data);
+        try {
+            return sendTokenRequest(request);
+        } catch (Exception ex) {
+            ClusterStatLogUtil.log(ex.getMessage());
+            return new TokenResult(TokenResultStatus.FAIL);
+        }
+    }
+
+    private boolean notValidRequest(Long id, int count) {
+        return id == null || id <= 0 || count <= 0;
+    }
+
+    private TokenResult badRequest() {
+        return new TokenResult(TokenResultStatus.BAD_REQUEST);
+    }
+
+    private TokenResult sendTokenRequest(ClusterRequest request) throws Exception {
+        ClusterResponse response = transportClient.sendRequest(request);
+        TokenResult result = new TokenResult(response.getStatus());
+        if (response.getData() != null) {
+            FlowTokenResponseData responseData = (FlowTokenResponseData)response.getData();
+            result.setRemaining(responseData.getRemainingCount())
+                .setWaitInMs(responseData.getWaitInMs());
+        }
+        return result;
+    }
+}
diff --git a/sentinel-cluster/sentinel-cluster-client-default/src/main/java/com/alibaba/csp/sentinel/cluster/client/NettyTransportClient.java b/sentinel-cluster/sentinel-cluster-client-default/src/main/java/com/alibaba/csp/sentinel/cluster/client/NettyTransportClient.java
new file mode 100644
index 00000000..676f4d44
--- /dev/null
+++ b/sentinel-cluster/sentinel-cluster-client-default/src/main/java/com/alibaba/csp/sentinel/cluster/client/NettyTransportClient.java
@@ -0,0 +1,208 @@
+/*
+ * Copyright 1999-2018 Alibaba Group Holding Ltd.
+ *
+ * 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.alibaba.csp.sentinel.cluster.client;
+
+import java.util.AbstractMap.SimpleEntry;
+import java.util.concurrent.atomic.AtomicInteger;
+
+import com.alibaba.csp.sentinel.cluster.ClusterErrorMessages;
+import com.alibaba.csp.sentinel.cluster.ClusterTransportClient;
+import com.alibaba.csp.sentinel.cluster.client.codec.netty.NettyRequestEncoder;
+import com.alibaba.csp.sentinel.cluster.client.codec.netty.NettyResponseDecoder;
+import com.alibaba.csp.sentinel.cluster.client.config.ClusterClientConfig;
+import com.alibaba.csp.sentinel.cluster.client.handler.TokenClientHandler;
+import com.alibaba.csp.sentinel.cluster.client.handler.TokenClientPromiseHolder;
+import com.alibaba.csp.sentinel.cluster.exception.SentinelClusterException;
+import com.alibaba.csp.sentinel.cluster.request.ClusterRequest;
+import com.alibaba.csp.sentinel.cluster.request.Request;
+import com.alibaba.csp.sentinel.cluster.response.ClusterResponse;
+import com.alibaba.csp.sentinel.log.RecordLog;
+import com.alibaba.csp.sentinel.util.AssertUtil;
+
+import io.netty.bootstrap.Bootstrap;
+import io.netty.buffer.PooledByteBufAllocator;
+import io.netty.channel.Channel;
+import io.netty.channel.ChannelFuture;
+import io.netty.channel.ChannelInitializer;
+import io.netty.channel.ChannelOption;
+import io.netty.channel.ChannelPipeline;
+import io.netty.channel.ChannelPromise;
+import io.netty.channel.nio.NioEventLoopGroup;
+import io.netty.channel.socket.SocketChannel;
+import io.netty.channel.socket.nio.NioSocketChannel;
+import io.netty.handler.codec.LengthFieldBasedFrameDecoder;
+import io.netty.handler.codec.LengthFieldPrepender;
+import io.netty.util.concurrent.GenericFutureListener;
+
+/**
+ * Netty transport client implementation for Sentinel cluster transport.
+ *
+ * @author Eric Zhao
+ * @since 1.4.0
+ */
+public class NettyTransportClient implements ClusterTransportClient {
+
+    private ClusterClientConfig clientConfig;
+    private String host;
+    private int port;
+
+    private Channel channel;
+    private NioEventLoopGroup eventLoopGroup;
+    private TokenClientHandler clientHandler;
+
+    private AtomicInteger idGenerator = new AtomicInteger(0);
+
+    private AtomicInteger failConnectedTime = new AtomicInteger(0);
+
+    public NettyTransportClient(ClusterClientConfig clientConfig, String host, int port) {
+        this.clientConfig = clientConfig;
+        this.host = host;
+        this.port = port;
+    }
+
+    private Bootstrap initClientBootstrap() {
+        Bootstrap b = new Bootstrap();
+        eventLoopGroup = new NioEventLoopGroup();
+        b.group(eventLoopGroup)
+            .channel(NioSocketChannel.class)
+            .option(ChannelOption.SO_TIMEOUT, 20)
+            .option(ChannelOption.TCP_NODELAY, true)
+            .option(ChannelOption.ALLOCATOR, PooledByteBufAllocator.DEFAULT)
+            .option(ChannelOption.CONNECT_TIMEOUT_MILLIS, 10000)
+            .handler(new ChannelInitializer<SocketChannel>() {
+                @Override
+                public void initChannel(SocketChannel ch) throws Exception {
+                    clientHandler = new TokenClientHandler();
+                    ChannelPipeline pipeline = ch.pipeline();
+                    pipeline.addLast(new LengthFieldBasedFrameDecoder(1024, 0, 2, 0, 2));
+                    pipeline.addLast(new NettyResponseDecoder());
+                    pipeline.addLast(new LengthFieldPrepender(2));
+                    pipeline.addLast(new NettyRequestEncoder());
+                    pipeline.addLast(clientHandler);
+                }
+            });
+
+        return b;
+    }
+
+    private void connect(Bootstrap b) {
+        b.connect(host, port).addListener(new GenericFutureListener<ChannelFuture>() {
+            @Override
+            public void operationComplete(ChannelFuture future) {
+                if (future.cause() != null) {
+                    RecordLog.warn(
+                        "[NettyTransportClient] Could not connect after " + failConnectedTime.get() + " times",
+                        future.cause());
+                    failConnectedTime.incrementAndGet();
+                    channel = null;
+                } else {
+                    failConnectedTime.set(0);
+                    channel = future.channel();
+                    RecordLog.info("[NettyTransportClient] Successfully connect to server " + host + ":" + port);
+                }
+            }
+        });
+    }
+
+    public void start() {
+        connect(initClientBootstrap());
+    }
+
+    public void stop() {
+        if (channel != null) {
+            channel.close();
+            channel = null;
+        }
+        if (eventLoopGroup != null) {
+            eventLoopGroup.shutdownGracefully();
+        }
+        failConnectedTime.set(0);
+
+        RecordLog.info("[NettyTransportClient] Token client stopped");
+    }
+
+    private boolean validRequest(Request request) {
+        return request != null && request.getType() >= 0;
+    }
+
+    public boolean isReady() {
+        return channel != null && clientHandler != null && clientHandler.hasStarted();
+    }
+
+    @Override
+    public ClusterResponse sendRequest(ClusterRequest request) throws Exception {
+        if (!isReady()) {
+            throw new SentinelClusterException(ClusterErrorMessages.CLIENT_NOT_READY);
+        }
+        if (!validRequest(request)) {
+            throw new SentinelClusterException(ClusterErrorMessages.BAD_REQUEST);
+        }
+        int xid = getCurrentId();
+        try {
+            request.setId(xid);
+
+            channel.writeAndFlush(request);
+
+            ChannelPromise promise = channel.newPromise();
+            TokenClientPromiseHolder.putPromise(xid, promise);
+
+            // TODO: timeout
+            if (!promise.await(20)) {
+                throw new SentinelClusterException(ClusterErrorMessages.REQUEST_TIME_OUT);
+            }
+
+            SimpleEntry<ChannelPromise, ClusterResponse> entry = TokenClientPromiseHolder.getEntry(xid);
+            if (entry == null || entry.getValue() == null) {
+                // Should not go through here.
+                throw new SentinelClusterException(ClusterErrorMessages.UNEXPECTED_STATUS);
+            }
+            return entry.getValue();
+        } finally {
+            TokenClientPromiseHolder.remove(xid);
+        }
+    }
+
+    private int getCurrentId() {
+        if (idGenerator.get() > MAX_ID) {
+            idGenerator.set(0);
+        }
+        return idGenerator.incrementAndGet();
+    }
+
+    /*public CompletableFuture<ClusterResponse> sendRequestAsync(ClusterRequest request) {
+        // Uncomment this when min target JDK is 1.8.
+        if (!validRequest(request)) {
+            return CompletableFuture.failedFuture(new IllegalArgumentException("Bad request"));
+        }
+        int xid = getCurrentId();
+        request.setId(xid);
+
+        CompletableFuture<ClusterResponse> future = new CompletableFuture<>();
+        channel.writeAndFlush(request)
+            .addListener(f -> {
+                if (f.isSuccess()) {
+                    future.complete(someResult);
+                } else if (f.cause() != null) {
+                    future.completeExceptionally(f.cause());
+                } else {
+                    future.cancel(false);
+                }
+            });
+        return future;
+    }*/
+
+    private static final int MAX_ID = 999_999_999;
+}
diff --git a/sentinel-cluster/sentinel-cluster-client-default/src/main/java/com/alibaba/csp/sentinel/cluster/client/codec/ClientEntityCodecProvider.java b/sentinel-cluster/sentinel-cluster-client-default/src/main/java/com/alibaba/csp/sentinel/cluster/client/codec/ClientEntityCodecProvider.java
new file mode 100644
index 00000000..6cb0ebda
--- /dev/null
+++ b/sentinel-cluster/sentinel-cluster-client-default/src/main/java/com/alibaba/csp/sentinel/cluster/client/codec/ClientEntityCodecProvider.java
@@ -0,0 +1,62 @@
+/*
+ * Copyright 1999-2018 Alibaba Group Holding Ltd.
+ *
+ * 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.alibaba.csp.sentinel.cluster.client.codec;
+
+import com.alibaba.csp.sentinel.util.SpiLoader;
+import com.alibaba.csp.sentinel.cluster.codec.request.RequestEntityWriter;
+import com.alibaba.csp.sentinel.cluster.codec.response.ResponseEntityDecoder;
+import com.alibaba.csp.sentinel.log.RecordLog;
+
+/**
+ * @author Eric Zhao
+ * @since 1.4.0
+ */
+public final class ClientEntityCodecProvider {
+
+    private static RequestEntityWriter requestEntityWriter = null;
+    private static ResponseEntityDecoder responseEntityDecoder = null;
+
+    static {
+        resolveInstance();
+    }
+
+    private static void resolveInstance() {
+        RequestEntityWriter writer = SpiLoader.loadFirstInstance(RequestEntityWriter.class);
+        if (writer == null) {
+            RecordLog.warn("[ClientEntityCodecProvider] No existing request entity writer, resolve failed");
+        } else {
+            requestEntityWriter = writer;
+            RecordLog.info("[ClientEntityCodecProvider] Request entity writer resolved: " + requestEntityWriter.getClass().getCanonicalName());
+        }
+        ResponseEntityDecoder decoder = SpiLoader.loadFirstInstance(ResponseEntityDecoder.class);
+        if (decoder == null) {
+            RecordLog.warn("[ClientEntityCodecProvider] No existing response entity decoder, resolve failed");
+        } else {
+            responseEntityDecoder = decoder;
+            RecordLog.info("[ClientEntityCodecProvider] Response entity decoder resolved: " + responseEntityDecoder.getClass().getCanonicalName());
+        }
+    }
+
+    public static RequestEntityWriter getRequestEntityWriter() {
+        return requestEntityWriter;
+    }
+
+    public static ResponseEntityDecoder getResponseEntityDecoder() {
+        return responseEntityDecoder;
+    }
+
+    private ClientEntityCodecProvider() {}
+}
diff --git a/sentinel-cluster/sentinel-cluster-client-default/src/main/java/com/alibaba/csp/sentinel/cluster/client/codec/DefaultRequestEntityWriter.java b/sentinel-cluster/sentinel-cluster-client-default/src/main/java/com/alibaba/csp/sentinel/cluster/client/codec/DefaultRequestEntityWriter.java
new file mode 100644
index 00000000..c4a3ce91
--- /dev/null
+++ b/sentinel-cluster/sentinel-cluster-client-default/src/main/java/com/alibaba/csp/sentinel/cluster/client/codec/DefaultRequestEntityWriter.java
@@ -0,0 +1,54 @@
+/*
+ * Copyright 1999-2018 Alibaba Group Holding Ltd.
+ *
+ * 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.alibaba.csp.sentinel.cluster.client.codec;
+
+import com.alibaba.csp.sentinel.cluster.client.codec.registry.RequestDataWriterRegistry;
+import com.alibaba.csp.sentinel.cluster.codec.EntityWriter;
+import com.alibaba.csp.sentinel.cluster.codec.request.RequestEntityWriter;
+import com.alibaba.csp.sentinel.cluster.request.ClusterRequest;
+import com.alibaba.csp.sentinel.cluster.request.Request;
+import com.alibaba.csp.sentinel.log.RecordLog;
+
+import io.netty.buffer.ByteBuf;
+
+/**
+ * @author Eric Zhao
+ * @since 1.4.0
+ */
+public class DefaultRequestEntityWriter implements RequestEntityWriter<ClusterRequest, ByteBuf> {
+
+    @Override
+    public void writeTo(ClusterRequest request, ByteBuf target) {
+        int type = request.getType();
+        EntityWriter<Object, ByteBuf> requestDataWriter = RequestDataWriterRegistry.getWriter(type);
+
+        if (requestDataWriter == null) {
+            // TODO: may need to throw exception?
+            RecordLog.warn(
+                "[NettyRequestEncoder] Cannot find matching request writer for type <{0}>, dropping the request", type);
+            return;
+        }
+        // Write head part of request.
+        writeHead(request, target);
+        // Write data part.
+        requestDataWriter.writeTo(request.getData(), target);
+    }
+
+    private void writeHead(Request request, ByteBuf out) {
+        out.writeInt(request.getId());
+        out.writeByte(request.getType());
+    }
+}
diff --git a/sentinel-cluster/sentinel-cluster-client-default/src/main/java/com/alibaba/csp/sentinel/cluster/client/codec/DefaultResponseEntityDecoder.java b/sentinel-cluster/sentinel-cluster-client-default/src/main/java/com/alibaba/csp/sentinel/cluster/client/codec/DefaultResponseEntityDecoder.java
new file mode 100644
index 00000000..4c1ad34e
--- /dev/null
+++ b/sentinel-cluster/sentinel-cluster-client-default/src/main/java/com/alibaba/csp/sentinel/cluster/client/codec/DefaultResponseEntityDecoder.java
@@ -0,0 +1,66 @@
+/*
+ * Copyright 1999-2018 Alibaba Group Holding Ltd.
+ *
+ * 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.alibaba.csp.sentinel.cluster.client.codec;
+
+import com.alibaba.csp.sentinel.cluster.client.codec.registry.ResponseDataDecodeRegistry;
+import com.alibaba.csp.sentinel.cluster.codec.EntityDecoder;
+import com.alibaba.csp.sentinel.cluster.codec.response.ResponseEntityDecoder;
+import com.alibaba.csp.sentinel.cluster.response.ClusterResponse;
+import com.alibaba.csp.sentinel.log.RecordLog;
+
+import io.netty.buffer.ByteBuf;
+
+/**
+ * <p>Default entity decoder for any {@link ClusterResponse} entity.</p>
+ *
+ * <p>Decode format:</p>
+ * <pre>
+ * +--------+---------+-----------+---------+
+ * | xid(4) | type(1) | status(1) | data... |
+ * +--------+---------+-----------+---------+
+ * </pre>
+ *
+ * @author Eric Zhao
+ * @since 1.4.0
+ */
+public class DefaultResponseEntityDecoder implements ResponseEntityDecoder<ByteBuf, ClusterResponse> {
+
+    @Override
+    public ClusterResponse decode(ByteBuf source) {
+        if (source.readableBytes() >= 6) {
+            int xid = source.readInt();
+            int type = source.readByte();
+            int status = source.readByte();
+
+            EntityDecoder<ByteBuf, ?> decoder = ResponseDataDecodeRegistry.getDecoder(type);
+            if (decoder == null) {
+                RecordLog.warn("Unknown type of response data decoder: {0}", type);
+                return null;
+            }
+
+            Object data;
+            if (source.readableBytes() == 0) {
+                data = null;
+            } else {
+                // TODO: handle decode error here.
+                data = decoder.decode(source);
+            }
+
+            return new ClusterResponse<>(xid, type, status, data);
+        }
+        return null;
+    }
+}
diff --git a/sentinel-cluster/sentinel-cluster-client-default/src/main/java/com/alibaba/csp/sentinel/cluster/client/codec/data/FlowRequestDataWriter.java b/sentinel-cluster/sentinel-cluster-client-default/src/main/java/com/alibaba/csp/sentinel/cluster/client/codec/data/FlowRequestDataWriter.java
new file mode 100644
index 00000000..2683a925
--- /dev/null
+++ b/sentinel-cluster/sentinel-cluster-client-default/src/main/java/com/alibaba/csp/sentinel/cluster/client/codec/data/FlowRequestDataWriter.java
@@ -0,0 +1,39 @@
+/*
+ * Copyright 1999-2018 Alibaba Group Holding Ltd.
+ *
+ * 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.alibaba.csp.sentinel.cluster.client.codec.data;
+
+import com.alibaba.csp.sentinel.cluster.codec.EntityWriter;
+import com.alibaba.csp.sentinel.cluster.request.data.FlowRequestData;
+
+import io.netty.buffer.ByteBuf;
+
+/**
+ * +-------------------+--------------+----------------+---------------+------------------+
+ * | RequestID(4 byte) | Type(1 byte) | FlowID(4 byte) | Count(4 byte) | PriorityFlag (1) |
+ * +-------------------+--------------+----------------+---------------+------------------+
+ *
+ * @author Eric Zhao
+ * @since 1.4.0
+ */
+public class FlowRequestDataWriter implements EntityWriter<FlowRequestData, ByteBuf> {
+
+    @Override
+    public void writeTo(FlowRequestData entity, ByteBuf target) {
+        target.writeLong(entity.getFlowId());
+        target.writeInt(entity.getCount());
+        target.writeBoolean(entity.isPriority());
+    }
+}
diff --git a/sentinel-cluster/sentinel-cluster-client-default/src/main/java/com/alibaba/csp/sentinel/cluster/client/codec/data/FlowResponseDataDecoder.java b/sentinel-cluster/sentinel-cluster-client-default/src/main/java/com/alibaba/csp/sentinel/cluster/client/codec/data/FlowResponseDataDecoder.java
new file mode 100644
index 00000000..c15355fe
--- /dev/null
+++ b/sentinel-cluster/sentinel-cluster-client-default/src/main/java/com/alibaba/csp/sentinel/cluster/client/codec/data/FlowResponseDataDecoder.java
@@ -0,0 +1,39 @@
+/*
+ * Copyright 1999-2018 Alibaba Group Holding Ltd.
+ *
+ * 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.alibaba.csp.sentinel.cluster.client.codec.data;
+
+import com.alibaba.csp.sentinel.cluster.codec.EntityDecoder;
+import com.alibaba.csp.sentinel.cluster.response.data.FlowTokenResponseData;
+
+import io.netty.buffer.ByteBuf;
+
+/**
+ * @author Eric Zhao
+ * @since 1.4.0
+ */
+public class FlowResponseDataDecoder implements EntityDecoder<ByteBuf, FlowTokenResponseData> {
+
+    @Override
+    public FlowTokenResponseData decode(ByteBuf source) {
+        FlowTokenResponseData data = new FlowTokenResponseData();
+
+        if (source.readableBytes() == 8) {
+            data.setRemainingCount(source.readInt());
+            data.setWaitInMs(source.readInt());
+        }
+        return data;
+    }
+}
diff --git a/sentinel-cluster/sentinel-cluster-client-default/src/main/java/com/alibaba/csp/sentinel/cluster/client/codec/data/ParamFlowRequestDataWriter.java b/sentinel-cluster/sentinel-cluster-client-default/src/main/java/com/alibaba/csp/sentinel/cluster/client/codec/data/ParamFlowRequestDataWriter.java
new file mode 100644
index 00000000..7367b6e2
--- /dev/null
+++ b/sentinel-cluster/sentinel-cluster-client-default/src/main/java/com/alibaba/csp/sentinel/cluster/client/codec/data/ParamFlowRequestDataWriter.java
@@ -0,0 +1,128 @@
+/*
+ * Copyright 1999-2018 Alibaba Group Holding Ltd.
+ *
+ * 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.alibaba.csp.sentinel.cluster.client.codec.data;
+
+import java.util.Collection;
+
+import com.alibaba.csp.sentinel.cluster.ClusterConstants;
+import com.alibaba.csp.sentinel.cluster.codec.EntityWriter;
+import com.alibaba.csp.sentinel.cluster.request.data.ParamFlowRequestData;
+
+import io.netty.buffer.ByteBuf;
+
+/**
+ * @author Eric Zhao
+ * @since 1.4.0
+ */
+public class ParamFlowRequestDataWriter implements EntityWriter<ParamFlowRequestData, ByteBuf> {
+
+    @Override
+    public void writeTo(ParamFlowRequestData entity, ByteBuf target) {
+        target.writeLong(entity.getFlowId());
+        target.writeInt(entity.getCount());
+
+        Collection<Object> params = entity.getParams();
+
+        // Write parameter amount.
+        int amount = calculateParamAmount(params);
+        target.writeInt(amount);
+
+        // Serialize parameters with type flag.
+        for (Object param : entity.getParams()) {
+            encodeValue(param, target);
+        }
+    }
+
+    private void encodeValue(Object param, ByteBuf target) {
+        // Handle primitive type.
+        if (param instanceof Integer || int.class.isInstance(param)) {
+            target.writeByte(ClusterConstants.PARAM_TYPE_INTEGER);
+            target.writeInt((Integer)param);
+        } else if (param instanceof String) {
+            encodeString((String)param, target);
+        } else if (boolean.class.isInstance(param) || param instanceof Boolean) {
+            target.writeByte(ClusterConstants.PARAM_TYPE_BOOLEAN);
+            target.writeBoolean((Boolean)param);
+        } else if (long.class.isInstance(param) || param instanceof Long) {
+            target.writeByte(ClusterConstants.PARAM_TYPE_LONG);
+            target.writeLong((Long)param);
+        } else if (double.class.isInstance(param) || param instanceof Double) {
+            target.writeByte(ClusterConstants.PARAM_TYPE_DOUBLE);
+            target.writeDouble((Double)param);
+        } else if (float.class.isInstance(param) || param instanceof Float) {
+            target.writeByte(ClusterConstants.PARAM_TYPE_FLOAT);
+            target.writeFloat((Float)param);
+        } else if (byte.class.isInstance(param) || param instanceof Byte) {
+            target.writeByte(ClusterConstants.PARAM_TYPE_BYTE);
+            target.writeByte((Byte)param);
+        } else if (short.class.isInstance(param) || param instanceof Short) {
+            target.writeByte(ClusterConstants.PARAM_TYPE_SHORT);
+            target.writeShort((Short)param);
+        } else {
+            // Unexpected type, drop.
+        }
+    }
+
+    private void encodeString(String param, ByteBuf target) {
+        target.writeByte(ClusterConstants.PARAM_TYPE_STRING);
+        byte[] tmpChars = param.getBytes();
+        target.writeInt(tmpChars.length);
+        target.writeBytes(tmpChars);
+    }
+
+    private int calculateParamAmount(/*@NonEmpty*/ Collection<Object> params) {
+        int size = 0;
+        int length = 0;
+        for (Object param : params) {
+            int s = calculateParamTransportSize(param);
+            if (size + s > PARAM_MAX_SIZE) {
+                break;
+            }
+            length++;
+        }
+        return length;
+    }
+
+    private int calculateParamTransportSize(Object value) {
+        // Layout for primitives: |type flag(1)|value|
+        // size = original size + type flag (1)
+        if (value instanceof Integer || int.class.isInstance(value)) {
+            return 5;
+        } else if (value instanceof String) {
+            // Layout for string: |type flag(1)|length(4)|string content|
+            String tmpValue = (String)value;
+            byte[] tmpChars = tmpValue.getBytes();
+            return 1 + 4 + tmpChars.length;
+        } else if (boolean.class.isInstance(value) || value instanceof Boolean) {
+            return 2;
+        } else if (long.class.isInstance(value) || value instanceof Long) {
+            return 9;
+        } else if (double.class.isInstance(value) || value instanceof Double) {
+            return 9;
+        } else if (float.class.isInstance(value) || value instanceof Float) {
+            return 5;
+        } else if (byte.class.isInstance(value) || value instanceof Byte) {
+            return 2;
+        } else if (short.class.isInstance(value) || value instanceof Short) {
+            return 3;
+        } else {
+            // Ignore unexpected type.
+            return 0;
+        }
+    }
+
+    private static final int PARAM_MAX_SIZE = 1000;
+}
diff --git a/sentinel-cluster/sentinel-cluster-client-default/src/main/java/com/alibaba/csp/sentinel/cluster/client/codec/netty/NettyRequestEncoder.java b/sentinel-cluster/sentinel-cluster-client-default/src/main/java/com/alibaba/csp/sentinel/cluster/client/codec/netty/NettyRequestEncoder.java
new file mode 100644
index 00000000..bc8b05cb
--- /dev/null
+++ b/sentinel-cluster/sentinel-cluster-client-default/src/main/java/com/alibaba/csp/sentinel/cluster/client/codec/netty/NettyRequestEncoder.java
@@ -0,0 +1,44 @@
+/*
+ * Copyright 1999-2018 Alibaba Group Holding Ltd.
+ *
+ * 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.alibaba.csp.sentinel.cluster.client.codec.netty;
+
+import com.alibaba.csp.sentinel.cluster.client.codec.ClientEntityCodecProvider;
+import com.alibaba.csp.sentinel.cluster.codec.request.RequestEntityWriter;
+import com.alibaba.csp.sentinel.cluster.request.ClusterRequest;
+import com.alibaba.csp.sentinel.cluster.request.Request;
+import com.alibaba.csp.sentinel.log.RecordLog;
+
+import io.netty.buffer.ByteBuf;
+import io.netty.channel.ChannelHandlerContext;
+import io.netty.handler.codec.MessageToByteEncoder;
+
+/**
+ * @author Eric Zhao
+ */
+public class NettyRequestEncoder extends MessageToByteEncoder<ClusterRequest> {
+
+    @Override
+    protected void encode(ChannelHandlerContext ctx, ClusterRequest request, ByteBuf out) throws Exception {
+        RequestEntityWriter<Request, ByteBuf> requestEntityWriter = ClientEntityCodecProvider.getRequestEntityWriter();
+        if (requestEntityWriter == null) {
+            // TODO: may need to throw exception?
+            RecordLog.warn("[NettyRequestEncoder] Cannot resolve the global request entity writer, dropping the request");
+            return;
+        }
+
+        requestEntityWriter.writeTo(request, out);
+    }
+}
diff --git a/sentinel-cluster/sentinel-cluster-client-default/src/main/java/com/alibaba/csp/sentinel/cluster/client/codec/netty/NettyResponseDecoder.java b/sentinel-cluster/sentinel-cluster-client-default/src/main/java/com/alibaba/csp/sentinel/cluster/client/codec/netty/NettyResponseDecoder.java
new file mode 100644
index 00000000..75c15a72
--- /dev/null
+++ b/sentinel-cluster/sentinel-cluster-client-default/src/main/java/com/alibaba/csp/sentinel/cluster/client/codec/netty/NettyResponseDecoder.java
@@ -0,0 +1,54 @@
+/*
+ * Copyright 1999-2018 Alibaba Group Holding Ltd.
+ *
+ * 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.alibaba.csp.sentinel.cluster.client.codec.netty;
+
+import java.util.List;
+
+import com.alibaba.csp.sentinel.cluster.client.codec.ClientEntityCodecProvider;
+import com.alibaba.csp.sentinel.cluster.client.codec.registry.ResponseDataDecodeRegistry;
+import com.alibaba.csp.sentinel.cluster.codec.EntityDecoder;
+import com.alibaba.csp.sentinel.cluster.codec.response.ResponseEntityDecoder;
+import com.alibaba.csp.sentinel.cluster.response.ClusterResponse;
+import com.alibaba.csp.sentinel.cluster.response.Response;
+import com.alibaba.csp.sentinel.log.RecordLog;
+
+import io.netty.buffer.ByteBuf;
+import io.netty.channel.ChannelHandlerContext;
+import io.netty.handler.codec.ByteToMessageDecoder;
+
+/**
+ * @author Eric Zhao
+ * @since 1.4.0
+ */
+public class NettyResponseDecoder extends ByteToMessageDecoder {
+
+    @Override
+    protected void decode(ChannelHandlerContext ctx, ByteBuf in, List<Object> out) throws Exception {
+        ResponseEntityDecoder<ByteBuf, Response> responseDecoder = ClientEntityCodecProvider.getResponseEntityDecoder();
+        if (responseDecoder == null) {
+            // TODO: may need to throw exception?
+            RecordLog.warn("[NettyResponseDecoder] Cannot resolve the global response entity decoder, "
+                + "dropping the response");
+            return;
+        }
+
+        // TODO: handle decode error here.
+        Response response = responseDecoder.decode(in);
+        if (response != null) {
+            out.add(response);
+        }
+    }
+}
diff --git a/sentinel-cluster/sentinel-cluster-client-default/src/main/java/com/alibaba/csp/sentinel/cluster/client/codec/registry/RequestDataWriterRegistry.java b/sentinel-cluster/sentinel-cluster-client-default/src/main/java/com/alibaba/csp/sentinel/cluster/client/codec/registry/RequestDataWriterRegistry.java
new file mode 100644
index 00000000..4ad9305d
--- /dev/null
+++ b/sentinel-cluster/sentinel-cluster-client-default/src/main/java/com/alibaba/csp/sentinel/cluster/client/codec/registry/RequestDataWriterRegistry.java
@@ -0,0 +1,47 @@
+/*
+ * Copyright 1999-2018 Alibaba Group Holding Ltd.
+ *
+ * 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.alibaba.csp.sentinel.cluster.client.codec.registry;
+
+import java.util.HashMap;
+import java.util.Map;
+
+import com.alibaba.csp.sentinel.cluster.codec.EntityWriter;
+
+import io.netty.buffer.ByteBuf;
+
+/**
+ * @author Eric Zhao
+ */
+public final class RequestDataWriterRegistry {
+
+    private static final Map<Integer, EntityWriter<Object, ByteBuf>> WRITER_MAP = new HashMap<>();
+
+    public static <T> boolean addWriter(int type, EntityWriter<T, ByteBuf> writer) {
+        if (WRITER_MAP.containsKey(type)) {
+            return false;
+        }
+        WRITER_MAP.put(type, (EntityWriter<Object, ByteBuf>)writer);
+        return true;
+    }
+
+    public static EntityWriter<Object, ByteBuf> getWriter(int type) {
+        return WRITER_MAP.get(type);
+    }
+
+    public static boolean remove(int type) {
+        return WRITER_MAP.remove(type) != null;
+    }
+}
diff --git a/sentinel-cluster/sentinel-cluster-client-default/src/main/java/com/alibaba/csp/sentinel/cluster/client/codec/registry/ResponseDataDecodeRegistry.java b/sentinel-cluster/sentinel-cluster-client-default/src/main/java/com/alibaba/csp/sentinel/cluster/client/codec/registry/ResponseDataDecodeRegistry.java
new file mode 100644
index 00000000..543fa774
--- /dev/null
+++ b/sentinel-cluster/sentinel-cluster-client-default/src/main/java/com/alibaba/csp/sentinel/cluster/client/codec/registry/ResponseDataDecodeRegistry.java
@@ -0,0 +1,48 @@
+/*
+ * Copyright 1999-2018 Alibaba Group Holding Ltd.
+ *
+ * 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.alibaba.csp.sentinel.cluster.client.codec.registry;
+
+import java.util.HashMap;
+import java.util.Map;
+
+import com.alibaba.csp.sentinel.cluster.codec.EntityDecoder;
+
+import io.netty.buffer.ByteBuf;
+
+/**
+ * @author Eric Zhao
+ * @since 1.4.0
+ */
+public final class ResponseDataDecodeRegistry {
+
+    private static final Map<Integer, EntityDecoder<ByteBuf, ?>> DECODER_MAP = new HashMap<>();
+
+    public static boolean addDecoder(int type, EntityDecoder<ByteBuf, ?> decoder) {
+        if (DECODER_MAP.containsKey(type)) {
+            return false;
+        }
+        DECODER_MAP.put(type, decoder);
+        return true;
+    }
+
+    public static EntityDecoder<ByteBuf, Object> getDecoder(int type) {
+        return (EntityDecoder<ByteBuf, Object>)DECODER_MAP.get(type);
+    }
+
+    public static boolean removeDecoder(int type) {
+        return DECODER_MAP.remove(type) != null;
+    }
+}
diff --git a/sentinel-cluster/sentinel-cluster-client-default/src/main/java/com/alibaba/csp/sentinel/cluster/client/config/ClusterClientConfig.java b/sentinel-cluster/sentinel-cluster-client-default/src/main/java/com/alibaba/csp/sentinel/cluster/client/config/ClusterClientConfig.java
new file mode 100644
index 00000000..81a0edf0
--- /dev/null
+++ b/sentinel-cluster/sentinel-cluster-client-default/src/main/java/com/alibaba/csp/sentinel/cluster/client/config/ClusterClientConfig.java
@@ -0,0 +1,65 @@
+/*
+ * Copyright 1999-2018 Alibaba Group Holding Ltd.
+ *
+ * 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.alibaba.csp.sentinel.cluster.client.config;
+
+/**
+ * @author Eric Zhao
+ * @since 1.4.0
+ */
+public class ClusterClientConfig {
+
+    private String serverHost;
+    private int serverPort;
+
+    private int requestTimeout;
+    private int connectTimeout;
+
+    public String getServerHost() {
+        return serverHost;
+    }
+
+    public ClusterClientConfig setServerHost(String serverHost) {
+        this.serverHost = serverHost;
+        return this;
+    }
+
+    public int getServerPort() {
+        return serverPort;
+    }
+
+    public ClusterClientConfig setServerPort(int serverPort) {
+        this.serverPort = serverPort;
+        return this;
+    }
+
+    public int getRequestTimeout() {
+        return requestTimeout;
+    }
+
+    public ClusterClientConfig setRequestTimeout(int requestTimeout) {
+        this.requestTimeout = requestTimeout;
+        return this;
+    }
+
+    public int getConnectTimeout() {
+        return connectTimeout;
+    }
+
+    public ClusterClientConfig setConnectTimeout(int connectTimeout) {
+        this.connectTimeout = connectTimeout;
+        return this;
+    }
+}
diff --git a/sentinel-cluster/sentinel-cluster-client-default/src/main/java/com/alibaba/csp/sentinel/cluster/client/config/ClusterClientConfigManager.java b/sentinel-cluster/sentinel-cluster-client-default/src/main/java/com/alibaba/csp/sentinel/cluster/client/config/ClusterClientConfigManager.java
new file mode 100644
index 00000000..94ade2d9
--- /dev/null
+++ b/sentinel-cluster/sentinel-cluster-client-default/src/main/java/com/alibaba/csp/sentinel/cluster/client/config/ClusterClientConfigManager.java
@@ -0,0 +1,30 @@
+/*
+ * Copyright 1999-2018 Alibaba Group Holding Ltd.
+ *
+ * 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.alibaba.csp.sentinel.cluster.client.config;
+
+import com.alibaba.csp.sentinel.cluster.ClusterConstants;
+
+/**
+ * @author Eric Zhao
+ */
+public final class ClusterClientConfigManager {
+
+    private static volatile String serverIp;
+    private static volatile int serverPort = ClusterConstants.DEFAULT_CLUSTER_SERVER_PORT;
+    private static volatile int requestTimeout = ClusterConstants.DEFAULT_REQUEST_TIMEOUT;
+
+    private ClusterClientConfigManager() {}
+}
diff --git a/sentinel-cluster/sentinel-cluster-client-default/src/main/java/com/alibaba/csp/sentinel/cluster/client/handler/TokenClientHandler.java b/sentinel-cluster/sentinel-cluster-client-default/src/main/java/com/alibaba/csp/sentinel/cluster/client/handler/TokenClientHandler.java
new file mode 100644
index 00000000..fc14cd35
--- /dev/null
+++ b/sentinel-cluster/sentinel-cluster-client-default/src/main/java/com/alibaba/csp/sentinel/cluster/client/handler/TokenClientHandler.java
@@ -0,0 +1,72 @@
+/*
+ * Copyright 1999-2018 Alibaba Group Holding Ltd.
+ *
+ * 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.alibaba.csp.sentinel.cluster.client.handler;
+
+import java.util.concurrent.atomic.AtomicInteger;
+
+import com.alibaba.csp.sentinel.cluster.client.ClientConstants;
+import com.alibaba.csp.sentinel.cluster.response.ClusterResponse;
+
+import io.netty.channel.ChannelHandlerContext;
+import io.netty.channel.ChannelInboundHandlerAdapter;
+
+/**
+ * @author Eric Zhao
+ * @since 1.4.0
+ */
+public class TokenClientHandler extends ChannelInboundHandlerAdapter {
+
+    private final AtomicInteger currentState = new AtomicInteger(ClientConstants.CLIENT_STATUS_OFF);
+
+    @Override
+    public void channelActive(ChannelHandlerContext ctx) throws Exception {
+        currentState.set(ClientConstants.CLIENT_STATUS_STARTED);
+    }
+
+    @Override
+    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
+        System.out.println(String.format("[%s] Client message recv: %s", System.currentTimeMillis(), msg));
+        if (msg instanceof ClusterResponse) {
+            ClusterResponse<?> response = (ClusterResponse) msg;
+
+            TokenClientPromiseHolder.completePromise(response.getId(), response);
+        }
+    }
+
+    @Override
+    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
+        super.exceptionCaught(ctx, cause);
+        cause.printStackTrace();
+    }
+
+    @Override
+    public void channelInactive(ChannelHandlerContext ctx) throws Exception {
+        super.channelInactive(ctx);
+    }
+
+    @Override
+    public void channelUnregistered(ChannelHandlerContext ctx) throws Exception {
+        currentState.set(ClientConstants.CLIENT_STATUS_OFF);
+    }
+
+    public int getCurrentState() {
+        return currentState.get();
+    }
+
+    public boolean hasStarted() {
+        return getCurrentState() == ClientConstants.CLIENT_STATUS_STARTED;
+    }
+}
diff --git a/sentinel-cluster/sentinel-cluster-client-default/src/main/java/com/alibaba/csp/sentinel/cluster/client/handler/TokenClientPromiseHolder.java b/sentinel-cluster/sentinel-cluster-client-default/src/main/java/com/alibaba/csp/sentinel/cluster/client/handler/TokenClientPromiseHolder.java
new file mode 100644
index 00000000..033d5900
--- /dev/null
+++ b/sentinel-cluster/sentinel-cluster-client-default/src/main/java/com/alibaba/csp/sentinel/cluster/client/handler/TokenClientPromiseHolder.java
@@ -0,0 +1,60 @@
+/*
+ * Copyright 1999-2018 Alibaba Group Holding Ltd.
+ *
+ * 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.alibaba.csp.sentinel.cluster.client.handler;
+
+import java.util.AbstractMap.SimpleEntry;
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+
+import com.alibaba.csp.sentinel.cluster.response.ClusterResponse;
+
+import io.netty.channel.ChannelPromise;
+
+/**
+ * @author Eric Zhao
+ * @since 1.4.0
+ */
+public final class TokenClientPromiseHolder {
+
+    private static final Map<Integer, SimpleEntry<ChannelPromise, ClusterResponse>> PROMISE_MAP = new ConcurrentHashMap<>();
+
+    public static void putPromise(int xid, ChannelPromise promise) {
+        PROMISE_MAP.put(xid, new SimpleEntry<ChannelPromise, ClusterResponse>(promise, null));
+    }
+
+    public static SimpleEntry<ChannelPromise, ClusterResponse> getEntry(int xid) {
+        return PROMISE_MAP.get(xid);
+    }
+
+    public static void remove(int xid) {
+        PROMISE_MAP.remove(xid);
+    }
+
+    public static <T> boolean completePromise(int xid, ClusterResponse<T> response) {
+        if (!PROMISE_MAP.containsKey(xid)) {
+            return false;
+        }
+        ChannelPromise promise = PROMISE_MAP.get(xid).getKey();
+        if (promise.isDone() || promise.isCancelled()) {
+            return false;
+        }
+        PROMISE_MAP.get(xid).setValue(response);
+        promise.setSuccess();
+        return true;
+    }
+
+    private TokenClientPromiseHolder() {}
+}
diff --git a/sentinel-cluster/sentinel-cluster-client-default/src/main/resources/META-INF/services/com.alibaba.csp.sentinel.cluster.codec.request.RequestEntityWriter b/sentinel-cluster/sentinel-cluster-client-default/src/main/resources/META-INF/services/com.alibaba.csp.sentinel.cluster.codec.request.RequestEntityWriter
new file mode 100644
index 00000000..23698745
--- /dev/null
+++ b/sentinel-cluster/sentinel-cluster-client-default/src/main/resources/META-INF/services/com.alibaba.csp.sentinel.cluster.codec.request.RequestEntityWriter
@@ -0,0 +1 @@
+com.alibaba.csp.sentinel.cluster.client.codec.DefaultRequestEntityWriter
\ No newline at end of file
diff --git a/sentinel-cluster/sentinel-cluster-client-default/src/main/resources/META-INF/services/com.alibaba.csp.sentinel.cluster.codec.response.ResponseEntityDecoder b/sentinel-cluster/sentinel-cluster-client-default/src/main/resources/META-INF/services/com.alibaba.csp.sentinel.cluster.codec.response.ResponseEntityDecoder
new file mode 100644
index 00000000..cd43e7e2
--- /dev/null
+++ b/sentinel-cluster/sentinel-cluster-client-default/src/main/resources/META-INF/services/com.alibaba.csp.sentinel.cluster.codec.response.ResponseEntityDecoder
@@ -0,0 +1 @@
+com.alibaba.csp.sentinel.cluster.client.codec.DefaultResponseEntityDecoder
\ No newline at end of file