diff --git a/src/main/java/com/uber/cadence/serviceclient/CallMetaData.java b/src/main/java/com/uber/cadence/serviceclient/CallMetaData.java
new file mode 100644
index 00000000..8dd7a870
--- /dev/null
+++ b/src/main/java/com/uber/cadence/serviceclient/CallMetaData.java
@@ -0,0 +1,38 @@
+/*
+ *  Copyright 2012-2016 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ *  Modifications copyright (C) 2017 Uber Technologies, Inc.
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License"). You may not
+ *  use this file except in compliance with the License. A copy of the License is
+ *  located at
+ *
+ *  http://aws.amazon.com/apache2.0
+ *
+ *  or in the "license" file accompanying this file. This file 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.uber.cadence.serviceclient;
+
+import java.time.Duration;
+import java.util.Optional;
+
+public class CallMetaData {
+  private Duration timeout;
+
+  public CallMetaData(Duration timeout) {
+    this.timeout = timeout;
+  }
+
+  public CallMetaData withTimeout(Duration timeout) {
+    this.timeout = timeout;
+    return this;
+  }
+
+  public Optional<Duration> getTimeout() {
+    return timeout == null ? Optional.empty() : Optional.of(timeout);
+  }
+}
diff --git a/src/main/java/com/uber/cadence/serviceclient/IWorkflowServiceV4.java b/src/main/java/com/uber/cadence/serviceclient/IWorkflowServiceV4.java
new file mode 100644
index 00000000..9d240193
--- /dev/null
+++ b/src/main/java/com/uber/cadence/serviceclient/IWorkflowServiceV4.java
@@ -0,0 +1,103 @@
+/*
+ *  Copyright 2012-2016 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ *  Modifications copyright (C) 2017 Uber Technologies, Inc.
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License"). You may not
+ *  use this file except in compliance with the License. A copy of the License is
+ *  located at
+ *
+ *  http://aws.amazon.com/apache2.0
+ *
+ *  or in the "license" file accompanying this file. This file 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.uber.cadence.serviceclient;
+
+import com.uber.cadence.api.v1.*;
+import java.util.concurrent.CompletableFuture;
+import javax.annotation.Nullable;
+
+public interface IWorkflowServiceV4 {
+  CompletableFuture<StartWorkflowExecutionResponse> startWorkflowExecution(
+      StartWorkflowExecutionRequest request, @Nullable CallMetaData meta);
+
+  CompletableFuture<StartWorkflowExecutionAsyncResponse> startWorkflowExecutionAsync(
+      StartWorkflowExecutionAsyncRequest request, @Nullable CallMetaData meta);
+
+  CompletableFuture<SignalWorkflowExecutionResponse> signalWorkflowExecution(
+      SignalWorkflowExecutionRequest request, @Nullable CallMetaData meta);
+
+  CompletableFuture<SignalWithStartWorkflowExecutionResponse> signalWithStartWorkflowExecution(
+      SignalWithStartWorkflowExecutionRequest request, @Nullable CallMetaData meta);
+
+  CompletableFuture<SignalWithStartWorkflowExecutionAsyncResponse>
+      signalWithStartWorkflowExecutionAsync(
+          SignalWithStartWorkflowExecutionAsyncRequest request, @Nullable CallMetaData meta);
+
+  CompletableFuture<GetWorkflowExecutionHistoryResponse> getWorkflowExecutionHistory(
+      GetWorkflowExecutionHistoryRequest request, @Nullable CallMetaData meta);
+
+  CompletableFuture<QueryWorkflowResponse> queryWorkflow(
+      QueryWorkflowRequest request, @Nullable CallMetaData meta);
+
+  CompletableFuture<RequestCancelWorkflowExecutionResponse> requestCancelWorkflowExecution(
+      RequestCancelWorkflowExecutionRequest request, @Nullable CallMetaData meta);
+
+  CompletableFuture<TerminateWorkflowExecutionResponse> terminateWorkflowExecution(
+      TerminateWorkflowExecutionRequest request, @Nullable CallMetaData meta);
+
+  CompletableFuture<RestartWorkflowExecutionResponse> restartWorkflowExecution(
+      RestartWorkflowExecutionRequest request, @Nullable CallMetaData meta);
+
+  CompletableFuture<ListWorkflowExecutionsResponse> listWorkflowExecutions(
+      ListWorkflowExecutionsRequest request, @Nullable CallMetaData meta);
+
+  CompletableFuture<ScanWorkflowExecutionsResponse> scanWorkflowExecutions(
+      ScanWorkflowExecutionsRequest request, @Nullable CallMetaData meta);
+
+  CompletableFuture<ListOpenWorkflowExecutionsResponse> listOpenWorkflowExecutions(
+      ListOpenWorkflowExecutionsRequest request, @Nullable CallMetaData meta);
+
+  CompletableFuture<ListClosedWorkflowExecutionsResponse> listClosedWorkflowExecutions(
+      ListClosedWorkflowExecutionsRequest request, @Nullable CallMetaData meta);
+
+  CompletableFuture<CountWorkflowExecutionsResponse> countWorkflowExecutions(
+      CountWorkflowExecutionsRequest request, @Nullable CallMetaData meta);
+
+  CompletableFuture<PollForActivityTaskResponse> pollForActivityTask(
+      PollForActivityTaskRequest request, @Nullable CallMetaData meta);
+
+  CompletableFuture<RecordActivityTaskHeartbeatResponse> recordActivityTaskHeartbeat(
+      RecordActivityTaskHeartbeatRequest request, @Nullable CallMetaData meta);
+
+  CompletableFuture<RespondActivityTaskCanceledResponse> respondActivityTaskCanceled(
+      RespondActivityTaskCanceledRequest request, @Nullable CallMetaData meta);
+
+  CompletableFuture<RespondActivityTaskCanceledByIDResponse> respondActivityTaskCanceledByID(
+      RespondActivityTaskCanceledByIDRequest request, @Nullable CallMetaData meta);
+
+  CompletableFuture<RespondActivityTaskFailedResponse> respondActivityTaskFailed(
+      RespondActivityTaskFailedRequest request, @Nullable CallMetaData meta);
+
+  CompletableFuture<RespondActivityTaskFailedByIDResponse> respondActivityTaskFailedByID(
+      RespondActivityTaskFailedByIDRequest request, @Nullable CallMetaData meta);
+
+  CompletableFuture<RespondActivityTaskCompletedResponse> respondActivityTaskCompleted(
+      RespondActivityTaskCompletedRequest request, @Nullable CallMetaData meta);
+
+  CompletableFuture<RespondActivityTaskCompletedByIDResponse> respondActivityTaskCompletedByID(
+      RespondActivityTaskCompletedByIDRequest request, @Nullable CallMetaData meta);
+
+  CompletableFuture<PollForDecisionTaskResponse> pollForDecisionTask(
+      PollForDecisionTaskRequest request, @Nullable CallMetaData meta);
+
+  CompletableFuture<RespondDecisionTaskFailedResponse> respondDecisionTaskFailed(
+      RespondDecisionTaskFailedRequest request, @Nullable CallMetaData meta);
+
+  CompletableFuture<RespondDecisionTaskCompletedResponse> respondDecisionTaskCompleted(
+      RespondDecisionTaskCompletedRequest request, @Nullable CallMetaData meta);
+}
diff --git a/src/main/java/com/uber/cadence/serviceclient/WorkflowServiceGrpc.java b/src/main/java/com/uber/cadence/serviceclient/WorkflowServiceGrpc.java
new file mode 100644
index 00000000..8520cbab
--- /dev/null
+++ b/src/main/java/com/uber/cadence/serviceclient/WorkflowServiceGrpc.java
@@ -0,0 +1,339 @@
+/*
+ *  Copyright 2012-2016 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ *  Modifications copyright (C) 2017 Uber Technologies, Inc.
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License"). You may not
+ *  use this file except in compliance with the License. A copy of the License is
+ *  located at
+ *
+ *  http://aws.amazon.com/apache2.0
+ *
+ *  or in the "license" file accompanying this file. This file 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.uber.cadence.serviceclient;
+
+import com.google.common.util.concurrent.FutureCallback;
+import com.google.common.util.concurrent.Futures;
+import com.google.common.util.concurrent.ListenableFuture;
+import com.google.common.util.concurrent.MoreExecutors;
+import com.uber.cadence.api.v1.*;
+import com.uber.cadence.internal.compatibility.proto.serviceclient.IGrpcServiceStubs;
+import io.grpc.*;
+import java.time.Duration;
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.TimeUnit;
+import javax.annotation.Nullable;
+
+public class WorkflowServiceGrpc implements IWorkflowServiceV4 {
+
+  private final IGrpcServiceStubs grpcServiceStubs;
+
+  WorkflowServiceGrpc(ClientOptions options) {
+    this.grpcServiceStubs = IGrpcServiceStubs.newInstance(options);
+  }
+
+  @Override
+  public CompletableFuture<StartWorkflowExecutionResponse> startWorkflowExecution(
+      StartWorkflowExecutionRequest request, @Nullable CallMetaData meta) {
+    return toCompletableFuture(
+        grpcServiceStubs
+            .workflowFutureStub()
+            .withInterceptors(new CallMetadataClientInterceptor(meta))
+            .startWorkflowExecution(request));
+  }
+
+  @Override
+  public CompletableFuture<StartWorkflowExecutionAsyncResponse> startWorkflowExecutionAsync(
+      StartWorkflowExecutionAsyncRequest request, @Nullable CallMetaData meta) {
+    return toCompletableFuture(
+        grpcServiceStubs
+            .workflowFutureStub()
+            .withInterceptors(new CallMetadataClientInterceptor(meta))
+            .startWorkflowExecutionAsync(request));
+  }
+
+  @Override
+  public CompletableFuture<SignalWorkflowExecutionResponse> signalWorkflowExecution(
+      SignalWorkflowExecutionRequest request, @Nullable CallMetaData meta) {
+    return toCompletableFuture(
+        grpcServiceStubs
+            .workflowFutureStub()
+            .withInterceptors(new CallMetadataClientInterceptor(meta))
+            .signalWorkflowExecution(request));
+  }
+
+  @Override
+  public CompletableFuture<SignalWithStartWorkflowExecutionResponse>
+      signalWithStartWorkflowExecution(
+          SignalWithStartWorkflowExecutionRequest request, @Nullable CallMetaData meta) {
+    return toCompletableFuture(
+        grpcServiceStubs
+            .workflowFutureStub()
+            .withInterceptors(new CallMetadataClientInterceptor(meta))
+            .signalWithStartWorkflowExecution(request));
+  }
+
+  @Override
+  public CompletableFuture<SignalWithStartWorkflowExecutionAsyncResponse>
+      signalWithStartWorkflowExecutionAsync(
+          SignalWithStartWorkflowExecutionAsyncRequest request, @Nullable CallMetaData meta) {
+    return toCompletableFuture(
+        grpcServiceStubs
+            .workflowFutureStub()
+            .withInterceptors(new CallMetadataClientInterceptor(meta))
+            .signalWithStartWorkflowExecutionAsync(request));
+  }
+
+  @Override
+  public CompletableFuture<GetWorkflowExecutionHistoryResponse> getWorkflowExecutionHistory(
+      GetWorkflowExecutionHistoryRequest request, @Nullable CallMetaData meta) {
+    return toCompletableFuture(
+        grpcServiceStubs
+            .workflowFutureStub()
+            .withInterceptors(new CallMetadataClientInterceptor(meta))
+            .getWorkflowExecutionHistory(request));
+  }
+
+  @Override
+  public CompletableFuture<QueryWorkflowResponse> queryWorkflow(
+      QueryWorkflowRequest request, @Nullable CallMetaData meta) {
+    return toCompletableFuture(
+        grpcServiceStubs
+            .workflowFutureStub()
+            .withInterceptors(new CallMetadataClientInterceptor(meta))
+            .queryWorkflow(request));
+  }
+
+  @Override
+  public CompletableFuture<RequestCancelWorkflowExecutionResponse> requestCancelWorkflowExecution(
+      RequestCancelWorkflowExecutionRequest request, @Nullable CallMetaData meta) {
+    return toCompletableFuture(
+        grpcServiceStubs
+            .workflowFutureStub()
+            .withInterceptors(new CallMetadataClientInterceptor(meta))
+            .requestCancelWorkflowExecution(request));
+  }
+
+  @Override
+  public CompletableFuture<TerminateWorkflowExecutionResponse> terminateWorkflowExecution(
+      TerminateWorkflowExecutionRequest request, @Nullable CallMetaData meta) {
+    return toCompletableFuture(
+        grpcServiceStubs
+            .workflowFutureStub()
+            .withInterceptors(new CallMetadataClientInterceptor(meta))
+            .terminateWorkflowExecution(request));
+  }
+
+  @Override
+  public CompletableFuture<RestartWorkflowExecutionResponse> restartWorkflowExecution(
+      RestartWorkflowExecutionRequest request, @Nullable CallMetaData meta) {
+    return toCompletableFuture(
+        grpcServiceStubs
+            .workflowFutureStub()
+            .withInterceptors(new CallMetadataClientInterceptor(meta))
+            .restartWorkflowExecution(request));
+  }
+
+  @Override
+  public CompletableFuture<ListWorkflowExecutionsResponse> listWorkflowExecutions(
+      ListWorkflowExecutionsRequest request, @Nullable CallMetaData meta) {
+    return toCompletableFuture(
+        grpcServiceStubs
+            .visibilityFutureStub()
+            .withInterceptors(new CallMetadataClientInterceptor(meta))
+            .listWorkflowExecutions(request));
+  }
+
+  @Override
+  public CompletableFuture<ScanWorkflowExecutionsResponse> scanWorkflowExecutions(
+      ScanWorkflowExecutionsRequest request, @Nullable CallMetaData meta) {
+    return toCompletableFuture(
+        grpcServiceStubs
+            .visibilityFutureStub()
+            .withInterceptors(new CallMetadataClientInterceptor(meta))
+            .scanWorkflowExecutions(request));
+  }
+
+  @Override
+  public CompletableFuture<ListOpenWorkflowExecutionsResponse> listOpenWorkflowExecutions(
+      ListOpenWorkflowExecutionsRequest request, @Nullable CallMetaData meta) {
+    return toCompletableFuture(
+        grpcServiceStubs
+            .visibilityFutureStub()
+            .withInterceptors(new CallMetadataClientInterceptor(meta))
+            .listOpenWorkflowExecutions(request));
+  }
+
+  @Override
+  public CompletableFuture<ListClosedWorkflowExecutionsResponse> listClosedWorkflowExecutions(
+      ListClosedWorkflowExecutionsRequest request, @Nullable CallMetaData meta) {
+    return toCompletableFuture(
+        grpcServiceStubs
+            .visibilityFutureStub()
+            .withInterceptors(new CallMetadataClientInterceptor(meta))
+            .listClosedWorkflowExecutions(request));
+  }
+
+  @Override
+  public CompletableFuture<CountWorkflowExecutionsResponse> countWorkflowExecutions(
+      CountWorkflowExecutionsRequest request, @Nullable CallMetaData meta) {
+    return toCompletableFuture(
+        grpcServiceStubs
+            .visibilityFutureStub()
+            .withInterceptors(new CallMetadataClientInterceptor(meta))
+            .countWorkflowExecutions(request));
+  }
+
+  @Override
+  public CompletableFuture<PollForActivityTaskResponse> pollForActivityTask(
+      PollForActivityTaskRequest request, @Nullable CallMetaData meta) {
+    return toCompletableFuture(
+        grpcServiceStubs
+            .workerFutureStub()
+            .withInterceptors(new CallMetadataClientInterceptor(meta))
+            .pollForActivityTask(request));
+  }
+
+  @Override
+  public CompletableFuture<RecordActivityTaskHeartbeatResponse> recordActivityTaskHeartbeat(
+      RecordActivityTaskHeartbeatRequest request, @Nullable CallMetaData meta) {
+    return toCompletableFuture(
+        grpcServiceStubs
+            .workerFutureStub()
+            .withInterceptors(new CallMetadataClientInterceptor(meta))
+            .recordActivityTaskHeartbeat(request));
+  }
+
+  @Override
+  public CompletableFuture<RespondActivityTaskCanceledResponse> respondActivityTaskCanceled(
+      RespondActivityTaskCanceledRequest request, @Nullable CallMetaData meta) {
+    return toCompletableFuture(
+        grpcServiceStubs
+            .workerFutureStub()
+            .withInterceptors(new CallMetadataClientInterceptor(meta))
+            .respondActivityTaskCanceled(request));
+  }
+
+  @Override
+  public CompletableFuture<RespondActivityTaskCanceledByIDResponse> respondActivityTaskCanceledByID(
+      RespondActivityTaskCanceledByIDRequest request, @Nullable CallMetaData meta) {
+    return toCompletableFuture(
+        grpcServiceStubs
+            .workerFutureStub()
+            .withInterceptors(new CallMetadataClientInterceptor(meta))
+            .respondActivityTaskCanceledByID(request));
+  }
+
+  @Override
+  public CompletableFuture<RespondActivityTaskFailedResponse> respondActivityTaskFailed(
+      RespondActivityTaskFailedRequest request, @Nullable CallMetaData meta) {
+    return toCompletableFuture(
+        grpcServiceStubs
+            .workerFutureStub()
+            .withInterceptors(new CallMetadataClientInterceptor(meta))
+            .respondActivityTaskFailed(request));
+  }
+
+  @Override
+  public CompletableFuture<RespondActivityTaskFailedByIDResponse> respondActivityTaskFailedByID(
+      RespondActivityTaskFailedByIDRequest request, @Nullable CallMetaData meta) {
+    return toCompletableFuture(
+        grpcServiceStubs
+            .workerFutureStub()
+            .withInterceptors(new CallMetadataClientInterceptor(meta))
+            .respondActivityTaskFailedByID(request));
+  }
+
+  @Override
+  public CompletableFuture<RespondActivityTaskCompletedResponse> respondActivityTaskCompleted(
+      RespondActivityTaskCompletedRequest request, @Nullable CallMetaData meta) {
+    return toCompletableFuture(
+        grpcServiceStubs
+            .workerFutureStub()
+            .withInterceptors(new CallMetadataClientInterceptor(meta))
+            .respondActivityTaskCompleted(request));
+  }
+
+  @Override
+  public CompletableFuture<RespondActivityTaskCompletedByIDResponse>
+      respondActivityTaskCompletedByID(
+          RespondActivityTaskCompletedByIDRequest request, @Nullable CallMetaData meta) {
+    return toCompletableFuture(
+        grpcServiceStubs
+            .workerFutureStub()
+            .withInterceptors(new CallMetadataClientInterceptor(meta))
+            .respondActivityTaskCompletedByID(request));
+  }
+
+  @Override
+  public CompletableFuture<PollForDecisionTaskResponse> pollForDecisionTask(
+      PollForDecisionTaskRequest request, @Nullable CallMetaData meta) {
+    return toCompletableFuture(
+        grpcServiceStubs
+            .workerFutureStub()
+            .withInterceptors(new CallMetadataClientInterceptor(meta))
+            .pollForDecisionTask(request));
+  }
+
+  @Override
+  public CompletableFuture<RespondDecisionTaskFailedResponse> respondDecisionTaskFailed(
+      RespondDecisionTaskFailedRequest request, @Nullable CallMetaData meta) {
+    return toCompletableFuture(
+        grpcServiceStubs
+            .workerFutureStub()
+            .withInterceptors(new CallMetadataClientInterceptor(meta))
+            .respondDecisionTaskFailed(request));
+  }
+
+  @Override
+  public CompletableFuture<RespondDecisionTaskCompletedResponse> respondDecisionTaskCompleted(
+      RespondDecisionTaskCompletedRequest request, @Nullable CallMetaData meta) {
+    return toCompletableFuture(
+        grpcServiceStubs
+            .workerFutureStub()
+            .withInterceptors(new CallMetadataClientInterceptor(meta))
+            .respondDecisionTaskCompleted(request));
+  }
+
+  private static class CallMetadataClientInterceptor implements ClientInterceptor {
+    private final CallMetaData meta;
+
+    CallMetadataClientInterceptor(CallMetaData meta) {
+      this.meta = meta;
+    }
+
+    @Override
+    public <ReqT, RespT> ClientCall<ReqT, RespT> interceptCall(
+        MethodDescriptor<ReqT, RespT> method, CallOptions callOptions, Channel next) {
+      if (meta != null && meta.getTimeout().isPresent()) {
+        Duration timeout = meta.getTimeout().get();
+        callOptions = callOptions.withDeadlineAfter(timeout.toMillis(), TimeUnit.MILLISECONDS);
+      }
+      return next.newCall(method, callOptions);
+    }
+  }
+
+  private <T> CompletableFuture<T> toCompletableFuture(ListenableFuture<T> listenable) {
+    CompletableFuture<T> completableFuture = new CompletableFuture<>();
+    Futures.addCallback(
+        listenable,
+        new FutureCallback<T>() {
+          @Override
+          public void onSuccess(T t) {
+            completableFuture.complete(t);
+          }
+
+          @Override
+          public void onFailure(Throwable throwable) {
+            completableFuture.completeExceptionally(throwable);
+          }
+        },
+        MoreExecutors.directExecutor());
+    return completableFuture;
+  }
+}