diff --git a/etcd/Client.hpp b/etcd/Client.hpp
index 11e7ceb..c1dddca 100644
--- a/etcd/Client.hpp
+++ b/etcd/Client.hpp
@@ -1,278 +1,616 @@
-#ifndef __ETCD_CLIENT_HPP__
-#define __ETCD_CLIENT_HPP__
-
-#include "etcd/Response.hpp"
-
-#include <map>
-#include <mutex>
-#include <string>
-
-#include <grpc++/grpc++.h>
-#include "proto/rpc.grpc.pb.h"
-#include "proto/v3lock.grpc.pb.h"
-
-using etcdserverpb::Auth;
-using etcdserverpb::KV;
-using etcdserverpb::Watch;
-using etcdserverpb::Lease;
-using v3lockpb::Lock;
-
-namespace etcdv3 {
-  class Transaction;
-}
-
-namespace etcd
-{
-  class KeepAlive;
-  class Watcher;
-
-  /**
-   * Client is responsible for maintaining a connection towards an etcd server.
-   * Etcd operations can be reached via the methods of the client.
-   */
-  class Client
-  {
-  public:
-    /**
-     * Constructs an etcd client object.
-     *
-     * @param etcd_url is the url of the etcd server to connect to, like "http://127.0.0.1:2379",
-     *                 or multiple url, seperated by ',' or ';'.
-     * @param load_balancer is the load balance strategy, can be one of round_robin/pick_first/grpclb/xds.
-     */
-    Client(std::string const & etcd_url,
-           std::string const & load_balancer = "round_robin");
-
-    /**
-     * Constructs an etcd client object.
-     *
-     * @param etcd_url is the url of the etcd server to connect to, like "http://127.0.0.1:2379",
-     *                 or multiple url, seperated by ',' or ';'.
-     * @param username username of etcd auth
-     * @param password password of etcd auth
-     * @param load_balancer is the load balance strategy, can be one of round_robin/pick_first/grpclb/xds.
-     */
-    Client(std::string const & etcd_url,
-           std::string const & username,
-           std::string const & password,
-           std::string const & load_balancer = "round_robin");
-
-    /**
-     * Sends a get request to the etcd server
-     * @param key is the key to be read
-     */
-    pplx::task<Response> get(std::string const & key);
-
-    /**
-     * Sets the value of a key. The key will be modified if already exists or created
-     * if it does not exists.
-     * @param key is the key to be created or modified
-     * @param value is the new value to be set
-     */
-    pplx::task<Response> set(std::string const & key, std::string const & value, int ttl = 0);
-
-    /**
-     * Sets the value of a key. The key will be modified if already exists or created
-     * if it does not exists.
-     * @param key is the key to be created or modified
-     * @param value is the new value to be set
-     * @param leaseId is the lease attached to the key
-     */
-    pplx::task<Response> set(std::string const & key, std::string const & value, int64_t leaseId);
-
-
-    /**
-     * Creates a new key and sets it's value. Fails if the key already exists.
-     * @param key is the key to be created
-     * @param value is the value to be set
-     */
-    pplx::task<Response> add(std::string const & key, std::string const & value, int ttl = 0);
-
-    /**
-     * Creates a new key and sets it's value. Fails if the key already exists.
-     * @param key is the key to be created
-     * @param value is the value to be set
-     * @param leaseId is the lease attached to the key
-     */
-    pplx::task<Response> add(std::string const & key, std::string const & value, int64_t leaseId);
-
-    /**
-     * Modifies an existing key. Fails if the key does not exists.
-     * @param key is the key to be modified
-     * @param value is the new value to be set
-     */
-    pplx::task<Response> modify(std::string const & key, std::string const & value, int ttl = 0);
-
-    /**
-     * Modifies an existing key. Fails if the key does not exists.
-     * @param key is the key to be modified
-     * @param value is the new value to be set
-     * @param leaseId is the lease attached to the key
-     */
-    pplx::task<Response> modify(std::string const & key, std::string const & value, int64_t leaseId);
-
-    /**
-     * Modifies an existing key only if it has a specific value. Fails if the key does not exists
-     * or the original value differs from the expected one.
-     * @param key is the key to be modified
-     * @param value is the new value to be set
-     * @param old_value is the value to be replaced
-     */
-    pplx::task<Response> modify_if(std::string const & key, std::string const & value, std::string const & old_value, int ttl = 0);
-
-    /**
-     * Modifies an existing key only if it has a specific value. Fails if the key does not exists
-     * or the original value differs from the expected one.
-     * @param key is the key to be modified
-     * @param value is the new value to be set
-     * @param old_value is the value to be replaced
-     * @param leaseId is the lease attached to the key
-     */
-    pplx::task<Response> modify_if(std::string const & key, std::string const & value, std::string const & old_value, int64_t leaseId);
-
-    /**
-     * Modifies an existing key only if it has a specific modification index value. Fails if the key
-     * does not exists or the modification index of the previous value differs from the expected one.
-     * @param key is the key to be modified
-     * @param value is the new value to be set
-     * @param old_index is the expected index of the original value
-     */
-    pplx::task<Response> modify_if(std::string const & key, std::string const & value, int old_index, int ttl = 0);
-
-    /**
-     * Modifies an existing key only if it has a specific modification index value. Fails if the key
-     * does not exists or the modification index of the previous value differs from the expected one.
-     * @param key is the key to be modified
-     * @param value is the new value to be set
-     * @param old_index is the expected index of the original value
-     * @param leaseId is the lease attached to the key
-     */
-    pplx::task<Response> modify_if(std::string const & key, std::string const & value, int old_index, int64_t leaseId);
-
-    /**
-     * Removes a single key. The key has to point to a plain, non directory entry.
-     * @param key is the key to be deleted
-     */
-    pplx::task<Response> rm(std::string const & key);
-
-    /**
-     * Removes a single key but only if it has a specific value. Fails if the key does not exists
-     * or the its value differs from the expected one.
-     * @param key is the key to be deleted
-     */
-    pplx::task<Response> rm_if(std::string const & key, std::string const & old_value);
-
-    /**
-     * Removes an existing key only if it has a specific modification index value. Fails if the key
-     * does not exists or the modification index of it differs from the expected one.
-     * @param key is the key to be deleted
-     * @param old_index is the expected index of the existing value
-     */
-    pplx::task<Response> rm_if(std::string const & key, int old_index);
-
-    /**
-     * Gets a directory listing of the directory identified by the key.
-     * @param key is the key to be listed
-     */
-    pplx::task<Response> ls(std::string const & key);
-
-
-    /**
-     * Gets a directory listing of the directory identified by the key.
-     * @param key is the key to be listed
-     * @param limit is the size limit of results to be listed, we don't use default parameters
-     *        to ensure backwards binary compatibility.
-     */
-    pplx::task<Response> ls(std::string const & key, size_t const limit);
-
-
-    /**
-     * Removes a directory node. Fails if the parent directory dos not exists or not a directory.
-     * @param key is the directory to be created to be listed
-     * @param recursive if true then delete a whole subtree, otherwise deletes only an empty directory.
-     */
-    pplx::task<Response> rmdir(std::string const & key, bool recursive = false);
-
-    /**
-     * Watches for changes of a key or a subtree. Please note that if you watch e.g. "/testdir" and
-     * a new key is created, like "/testdir/newkey" then no change happened in the value of
-     * "/testdir" so your watch will not detect this. If you want to detect addition and deletion of
-     * directory entries then you have to do a recursive watch.
-     * @param key is the value or directory to be watched
-     * @param recursive if true watch a whole subtree
-     */
-    pplx::task<Response> watch(std::string const & key, bool recursive = false);
-
-    /**
-     * Watches for changes of a key or a subtree from a specific index. The index value can be in the "past".
-     * @param key is the value or directory to be watched
-     * @param fromIndex the first index we are interested in
-     * @param recursive if true watch a whole subtree
-     */
-    pplx::task<Response> watch(std::string const & key, int fromIndex, bool recursive = false);
-
-    /**
-     * Grants a lease.
-     * @param ttl is the time to live of the lease
-     */
-    pplx::task<Response> leasegrant(int ttl);
-
-    /**
-     * Revoke a lease.
-     * @param lease_id is the id the lease
-     */
-    pplx::task<Response> leaserevoke(int64_t lease_id);
-
-    /**
-     * Get time-to-live of a lease.
-     * @param lease_id is the id the lease
-     */
-    pplx::task<Response> leasetimetolive(int64_t lease_id);
-
-    /**
-     * Gains a lock at a key, using a default created lease, using the default lease (60 seconds), with
-     * keeping alive has already been taken care of by the library.
-     * @param key is the key to be used to request the lock.
-     */
-    pplx::task<Response> lock(std::string const &key);
-
-    /**
-     * Gains a lock at a key, using a user-provided lease, the lifetime of the lease won't be taken care
-     * of by the library.
-     * @param key is the key to be used to request the lock.
-     */
-    pplx::task<Response> lock(std::string const &key, int64_t lease_id);
-
-    /**
-     * Releases a lock at a key.
-     * @param key is the lock key to release.
-     */
-    pplx::task<Response> unlock(std::string const &lock_key);
-
-     /**
-      * Execute a etcd transaction.
-      * @param txn is the transaction object to be executed.
-      */
-    pplx::task<Response> txn(etcdv3::Transaction const &txn);
-
-  private:
-    std::shared_ptr<grpc::Channel> channel;
-    std::string auth_token;
-    std::unique_ptr<KV::Stub> kvServiceStub;
-    std::unique_ptr<Watch::Stub> watchServiceStub;
-    std::unique_ptr<Lease::Stub> leaseServiceStub;
-    std::unique_ptr<Lock::Stub> lockServiceStub;
-
-    std::mutex mutex_for_keepalives;
-    std::map<std::string, int64_t> leases_for_locks;
-    std::map<int64_t, std::shared_ptr<KeepAlive>> keep_alive_for_locks;
-
-    friend class KeepAlive;
-    friend class Watcher;
-};
-
-
-
-}
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/types.h>
 
+#if defined(_WIN32)
+#include <winsock2.h>
+#include <ws2tcpip.h>
+#else
+#include <netdb.h>
+#include <sys/socket.h>
 #endif
+
+#include <limits>
+#include <memory>
+#include "etcd/Client.hpp"
+#include "etcd/KeepAlive.hpp"
+#include "etcd/v3/action_constants.hpp"
+#include "etcd/v3/Action.hpp"
+#include "etcd/v3/AsyncTxnResponse.hpp"
+#include "etcd/v3/AsyncRangeResponse.hpp"
+#include "etcd/v3/AsyncWatchResponse.hpp"
+#include "etcd/v3/AsyncDeleteRangeResponse.hpp"
+#include "etcd/v3/AsyncLockResponse.hpp"
+#include "etcd/v3/Transaction.hpp"
+#include <iostream>
+
+#include "etcd/v3/AsyncSetAction.hpp"
+#include "etcd/v3/AsyncCompareAndSwapAction.hpp"
+#include "etcd/v3/AsyncCompareAndDeleteAction.hpp"
+#include "etcd/v3/AsyncUpdateAction.hpp"
+#include "etcd/v3/AsyncGetAction.hpp"
+#include "etcd/v3/AsyncDeleteAction.hpp"
+#include "etcd/v3/AsyncWatchAction.hpp"
+#include "etcd/v3/AsyncLeaseAction.hpp"
+#include "etcd/v3/AsyncLockAction.hpp"
+#include "etcd/v3/AsyncTxnAction.hpp"
+
+#include <boost/algorithm/string.hpp>
+
+using grpc::Channel;
+
+namespace etcd {
+namespace detail {
+
+static bool dns_resolve(std::string const &target, std::vector<std::string> &endpoints) {
+  struct addrinfo hints = {}, *addrs;
+  hints.ai_family = AF_INET;
+  hints.ai_socktype = SOCK_STREAM;
+  hints.ai_protocol = IPPROTO_TCP;
+
+  std::vector<std::string> target_parts;
+  boost::split(target_parts, target, boost::is_any_of(":"));
+  if (target_parts.size() != 2) {
+    std::cerr << "warn: invalid URL: " << target << std::endl;
+    return false;
+  }
+
+#if defined(_WIN32)
+  {
+    // Use the MAKEWORD(lowbyte, highbyte) macro declared in Windef.h.
+    WORD wVersionRequested = MAKEWORD(2, 2);
+    WSADATA wsaData;
+
+    int err = WSAStartup(wVersionRequested, &wsaData);
+    if (err != 0) {
+      // Tell the user that we could not find a usable Winsock DLL.                                  */
+      std::cerr << "WSAStartup failed with error: %d" << err << std::endl;
+      return false;
+    }
+  }
+#endif
+
+  int r = getaddrinfo(target_parts[0].c_str(), target_parts[1].c_str(), &hints, &addrs);
+  if (r != 0) {
+    std::cerr << "warn: getaddrinfo() failed for endpoint " << target
+              << " with error: " << r << std::endl;
+    return false;
+  }
+
+  char host[16] = {'\0'};
+  for (struct addrinfo* addr = addrs; addr != nullptr; addr = addr->ai_next) {
+    memset(host, '\0', sizeof(host));
+    getnameinfo(addr->ai_addr, addr->ai_addrlen, host, sizeof(host), NULL, 0, NI_NUMERICHOST);
+    endpoints.emplace_back(std::string(host) + ":" + target_parts[1]);
+  }
+  freeaddrinfo(addrs);
+  return true;
+}
+
+const std::string strip_and_resolve_addresses(std::string const &address) {
+  std::vector<std::string> addresses;
+  boost::algorithm::split(addresses, address, boost::algorithm::is_any_of(",;"));
+  std::string stripped_address;
+  {
+    std::vector<std::string> stripped_addresses;
+    std::string substr("://");
+    for (auto const &addr: addresses) {
+      std::string::size_type idx = addr.find(substr);
+      std::string target = idx == std::string::npos ? addr : addr.substr(idx + substr.length());
+      etcd::detail::dns_resolve(target, stripped_addresses);
+    }
+    stripped_address = boost::algorithm::join(stripped_addresses, ",");
+  }
+  return "ipv4:///" + stripped_address;
+}
+
+const bool authenticate(std::shared_ptr<grpc::Channel> const &channel,
+                        std::string const &username,
+                        std::string const &password,
+                        std::string &token_or_message) {
+  // run a round of auth
+  auto auth_stub = Auth::NewStub(channel);
+  ClientContext context;
+  etcdserverpb::AuthenticateRequest auth_request;
+  etcdserverpb::AuthenticateResponse auth_response;
+  auth_request.set_name(username);
+  auth_request.set_password(password);
+  auto status = auth_stub->Authenticate(&context, auth_request, &auth_response);
+  if (status.ok()) {
+    token_or_message = auth_response.token();
+    return true;
+  } else {
+    token_or_message = status.error_message();
+    return false;
+  }
+}
+
+}
+}
+
+etcd::Client::Client(std::string const & address,
+                     const unsigned int& timeout, 
+                     std::string const & load_balancer)
+{
+  // create channels
+  std::string const addresses = etcd::detail::strip_and_resolve_addresses(address);
+  grpc::ChannelArguments grpc_args;
+  grpc_args.SetMaxSendMessageSize(std::numeric_limits<int>::max());
+  grpc_args.SetMaxReceiveMessageSize(std::numeric_limits<int>::max());
+  std::shared_ptr<grpc::ChannelCredentials> creds = grpc::InsecureChannelCredentials();
+  grpc_args.SetLoadBalancingPolicyName(load_balancer);
+  this->channel = grpc::CreateCustomChannel(addresses, creds, grpc_args);
+
+  // create stubs
+  kvServiceStub = KV::NewStub(this->channel);
+  watchServiceStub= Watch::NewStub(this->channel);
+  leaseServiceStub= Lease::NewStub(this->channel);
+  lockServiceStub = Lock::NewStub(this->channel);
+  this->timeout = timeout;
+}
+
+etcd::Client::Client(std::string const & address,
+                     std::string const & username,
+                     std::string const & password,
+                     const unsigned int& timeout,
+                     std::string const & load_balancer)
+{
+  // create channels
+  std::string const addresses = etcd::detail::strip_and_resolve_addresses(address);
+  grpc::ChannelArguments grpc_args;
+  grpc_args.SetMaxSendMessageSize(std::numeric_limits<int>::max());
+  grpc_args.SetMaxReceiveMessageSize(std::numeric_limits<int>::max());
+  std::shared_ptr<grpc::ChannelCredentials> creds = grpc::InsecureChannelCredentials();
+  grpc_args.SetLoadBalancingPolicyName(load_balancer);
+  this->channel = grpc::CreateCustomChannel(addresses, creds, grpc_args);
+
+  // auth
+  std::string token_or_message;
+  if (!etcd::detail::authenticate(this->channel, username, password, token_or_message)) {
+    throw std::invalid_argument("Etcd authentication failed: " + token_or_message);
+  }
+  this->auth_token = token_or_message;
+
+  // setup stubs
+  kvServiceStub = KV::NewStub(this->channel);
+  watchServiceStub= Watch::NewStub(this->channel);
+  leaseServiceStub= Lease::NewStub(this->channel);
+  lockServiceStub = Lock::NewStub(this->channel);
+  this->timeout = timeout;
+}
+
+pplx::task<etcd::Response> etcd::Client::get(std::string const & key)
+{
+  etcdv3::ActionParameters params;
+  params.auth_token.assign(this->auth_token);
+  params.key.assign(key);
+  params.withPrefix = false;
+  params.kv_stub = kvServiceStub .get();
+  params.timeout = this->timeout;
+  std::shared_ptr<etcdv3::AsyncGetAction> call(new etcdv3::AsyncGetAction(params));
+  return Response::create(call);
+}
+
+pplx::task<etcd::Response> etcd::Client::set(std::string const & key, std::string const & value, int ttl)
+{
+  etcdv3::ActionParameters params;
+  params.auth_token.assign(this->auth_token);
+  params.key.assign(key);
+  params.value.assign(value);
+  params.kv_stub = kvServiceStub .get();
+  params.timeout = this->timeout;
+  if(ttl > 0)
+  {
+    auto res = leasegrant(ttl).get();
+    if(!res.is_ok()) 
+    {
+      return pplx::task<etcd::Response>([res]()
+      {
+        return etcd::Response(res.error_code(), res.error_message().c_str());    
+      });
+    }
+    else
+    {
+      params.lease_id = res.value().lease();
+    }
+  }
+
+  std::shared_ptr<etcdv3::AsyncSetAction> call(new etcdv3::AsyncSetAction(params));
+  return Response::create(call);
+}
+
+pplx::task<etcd::Response> etcd::Client::set(std::string const & key, std::string const & value, int64_t leaseid)
+{
+  etcdv3::ActionParameters params;
+  params.auth_token.assign(this->auth_token);
+  params.key.assign(key);
+  params.value.assign(value);
+  params.lease_id = leaseid;
+  params.kv_stub = kvServiceStub .get();
+  params.timeout = this->timeout;
+  std::shared_ptr<etcdv3::AsyncSetAction> call(new etcdv3::AsyncSetAction(params));
+  return Response::create(call);
+}
+
+
+pplx::task<etcd::Response> etcd::Client::add(std::string const & key, std::string const & value, int ttl)
+{
+  etcdv3::ActionParameters params;
+  params.auth_token.assign(this->auth_token);
+  params.key.assign(key);
+  params.value.assign(value);
+  params.kv_stub = kvServiceStub .get();
+  params.timeout = this->timeout;
+  if(ttl > 0)
+  {
+    auto res = leasegrant(ttl).get();
+    if(!res.is_ok()) 
+    {
+      return pplx::task<etcd::Response>([res]()
+      {
+        return etcd::Response(res.error_code(), res.error_message().c_str());    
+      });
+    }
+    else
+    {
+      params.lease_id = res.value().lease();
+    }
+  }
+  std::shared_ptr<etcdv3::AsyncSetAction> call(new etcdv3::AsyncSetAction(params,true));
+  return Response::create(call);
+}
+
+pplx::task<etcd::Response> etcd::Client::add(std::string const & key, std::string const & value, int64_t leaseid)
+{
+  etcdv3::ActionParameters params;
+  params.auth_token.assign(this->auth_token);
+  params.key.assign(key);
+  params.value.assign(value);
+  params.lease_id = leaseid;
+  params.kv_stub = kvServiceStub .get();
+  params.timeout = this->timeout;
+  std::shared_ptr<etcdv3::AsyncSetAction> call(new etcdv3::AsyncSetAction(params,true));
+  return Response::create(call);
+}
+
+
+pplx::task<etcd::Response> etcd::Client::modify(std::string const & key, std::string const & value, int ttl)
+{
+  etcdv3::ActionParameters params;
+  params.auth_token.assign(this->auth_token);
+  params.key.assign(key);
+  params.value.assign(value);
+  params.kv_stub = kvServiceStub .get();
+  params.timeout = this->timeout;
+  if(ttl > 0)
+  {
+    auto res = leasegrant(ttl).get();
+    if(!res.is_ok()) 
+    {
+      return pplx::task<etcd::Response>([res]()
+      {
+        return etcd::Response(res.error_code(), res.error_message().c_str());    
+      });
+    }
+    else
+    {
+      params.lease_id = res.value().lease();
+    }
+  }
+  std::shared_ptr<etcdv3::AsyncUpdateAction> call(new etcdv3::AsyncUpdateAction(params));
+  return Response::create(call);
+}
+
+pplx::task<etcd::Response> etcd::Client::modify(std::string const & key, std::string const & value, int64_t leaseid)
+{
+  etcdv3::ActionParameters params;
+  params.auth_token.assign(this->auth_token);
+  params.key.assign(key);
+  params.value.assign(value);
+  params.lease_id = leaseid;
+  params.kv_stub = kvServiceStub .get();
+  params.timeout = this->timeout;
+  std::shared_ptr<etcdv3::AsyncUpdateAction> call(new etcdv3::AsyncUpdateAction(params));
+  return Response::create(call);
+}
+
+
+pplx::task<etcd::Response> etcd::Client::modify_if(std::string const & key, std::string const & value, std::string const & old_value, int ttl)
+{
+  etcdv3::ActionParameters params;
+  params.auth_token.assign(this->auth_token);
+  params.key.assign(key);
+  params.value.assign(value);
+  params.old_value.assign(old_value);
+  params.kv_stub = kvServiceStub .get();
+  params.timeout = this->timeout;
+  if(ttl > 0)
+  {
+    auto res = leasegrant(ttl).get();
+    if(!res.is_ok()) 
+    {
+      return pplx::task<etcd::Response>([res]()
+      {
+        return etcd::Response(res.error_code(), res.error_message().c_str());    
+      });
+    }
+    else
+    {
+      params.lease_id = res.value().lease();
+    }
+  }
+  std::shared_ptr<etcdv3::AsyncCompareAndSwapAction> call(new etcdv3::AsyncCompareAndSwapAction(params,etcdv3::Atomicity_Type::PREV_VALUE));
+  return Response::create(call);
+}
+
+pplx::task<etcd::Response> etcd::Client::modify_if(std::string const & key, std::string const & value, std::string const & old_value, int64_t leaseid)
+{
+  etcdv3::ActionParameters params;
+  params.auth_token.assign(this->auth_token);
+  params.key.assign(key);
+  params.value.assign(value);
+  params.old_value.assign(old_value);
+  params.lease_id = leaseid;
+  params.kv_stub = kvServiceStub .get();
+  params.timeout = this->timeout;
+  std::shared_ptr<etcdv3::AsyncCompareAndSwapAction> call(new etcdv3::AsyncCompareAndSwapAction(params,etcdv3::Atomicity_Type::PREV_VALUE));
+  return Response::create(call);
+}
+
+pplx::task<etcd::Response> etcd::Client::modify_if(std::string const & key, std::string const & value, int old_index, int ttl)
+{
+  etcdv3::ActionParameters params;
+  params.auth_token.assign(this->auth_token);
+  params.key.assign(key);
+  params.value.assign(value);
+  params.old_revision = old_index;
+  params.kv_stub = kvServiceStub.get();
+  params.timeout = this->timeout;
+  if(ttl > 0)
+  {
+    auto res = leasegrant(ttl).get();
+    if(!res.is_ok()) 
+    {
+      return pplx::task<etcd::Response>([res]()
+      {
+        return etcd::Response(res.error_code(), res.error_message().c_str());    
+      });
+    }
+    else
+    {
+      params.lease_id = res.value().lease();
+    }
+  }
+  std::shared_ptr<etcdv3::AsyncCompareAndSwapAction> call(new etcdv3::AsyncCompareAndSwapAction(params,etcdv3::Atomicity_Type::PREV_INDEX));
+  return Response::create(call);
+}
+
+pplx::task<etcd::Response> etcd::Client::modify_if(std::string const & key, std::string const & value, int old_index, int64_t leaseid)
+{
+  etcdv3::ActionParameters params;
+  params.auth_token.assign(this->auth_token);
+  params.key.assign(key);
+  params.value.assign(value);
+  params.lease_id = leaseid;
+  params.old_revision = old_index;
+  params.kv_stub = kvServiceStub .get();
+  params.timeout = this->timeout;
+  std::shared_ptr<etcdv3::AsyncCompareAndSwapAction> call(new etcdv3::AsyncCompareAndSwapAction(params,etcdv3::Atomicity_Type::PREV_INDEX));
+  return Response::create(call);
+}
+
+
+pplx::task<etcd::Response> etcd::Client::rm(std::string const & key)
+{
+  etcdv3::ActionParameters params;
+  params.auth_token.assign(this->auth_token);
+  params.key.assign(key);
+  params.withPrefix = false;
+  params.kv_stub = kvServiceStub.get();
+  params.timeout = this->timeout;
+  std::shared_ptr<etcdv3::AsyncDeleteAction> call(new etcdv3::AsyncDeleteAction(params));
+  return Response::create(call);
+}
+
+
+pplx::task<etcd::Response> etcd::Client::rm_if(std::string const & key, std::string const & old_value)
+{
+  etcdv3::ActionParameters params;
+  params.auth_token.assign(this->auth_token);
+  params.key.assign(key);
+  params.old_value.assign(old_value);
+  params.kv_stub = kvServiceStub.get();
+  params.timeout = this->timeout;
+  std::shared_ptr<etcdv3::AsyncCompareAndDeleteAction> call(new etcdv3::AsyncCompareAndDeleteAction(params,etcdv3::Atomicity_Type::PREV_VALUE));
+  return Response::create(call);
+}
+
+pplx::task<etcd::Response> etcd::Client::rm_if(std::string const & key, int old_index)
+{
+  etcdv3::ActionParameters params;
+  params.auth_token.assign(this->auth_token);
+  params.key.assign(key);
+  params.old_revision = old_index;
+  params.kv_stub = kvServiceStub.get();
+  params.timeout = this->timeout;
+  std::shared_ptr<etcdv3::AsyncCompareAndDeleteAction> call(new etcdv3::AsyncCompareAndDeleteAction(params, etcdv3::Atomicity_Type::PREV_INDEX));;
+  return Response::create(call);
+
+}
+
+pplx::task<etcd::Response> etcd::Client::rmdir(std::string const & key, bool recursive)
+{
+  etcdv3::ActionParameters params;
+  params.auth_token.assign(this->auth_token);
+  params.key.assign(key);
+  params.withPrefix = recursive;
+  params.kv_stub = kvServiceStub .get();
+  params.timeout = this->timeout;
+  std::shared_ptr<etcdv3::AsyncDeleteAction> call(new etcdv3::AsyncDeleteAction(params));
+  return Response::create(call);
+}
+
+pplx::task<etcd::Response> etcd::Client::ls(std::string const & key)
+{
+  etcdv3::ActionParameters params;
+  params.auth_token.assign(this->auth_token);
+  params.key.assign(key);
+  params.withPrefix = true;
+  params.limit = 0;  // default no limit.
+  params.kv_stub = kvServiceStub .get();
+  params.timeout = this->timeout;
+  std::shared_ptr<etcdv3::AsyncGetAction> call(new etcdv3::AsyncGetAction(params));
+  return Response::create(call);
+}
+
+pplx::task<etcd::Response> etcd::Client::ls(std::string const & key, size_t const limit)
+{
+  etcdv3::ActionParameters params;
+  params.auth_token.assign(this->auth_token);
+  params.key.assign(key);
+  params.withPrefix = true;
+  params.limit = limit;
+  params.kv_stub = kvServiceStub .get();
+  params.timeout = this->timeout;
+  std::shared_ptr<etcdv3::AsyncGetAction> call(new etcdv3::AsyncGetAction(params));
+  return Response::create(call);
+}
+
+pplx::task<etcd::Response> etcd::Client::watch(std::string const & key, bool recursive)
+{
+  etcdv3::ActionParameters params;
+  params.auth_token.assign(this->auth_token);
+  params.key.assign(key);
+  params.withPrefix = recursive;
+  params.watch_stub = watchServiceStub.get();
+  params.timeout = this->timeout;
+  std::shared_ptr<etcdv3::AsyncWatchAction> call(new etcdv3::AsyncWatchAction(params));
+  return Response::create(call);
+}
+
+pplx::task<etcd::Response> etcd::Client::watch(std::string const & key, int fromIndex, bool recursive)
+{
+  etcdv3::ActionParameters params;
+  params.auth_token.assign(this->auth_token);
+  params.key.assign(key);
+  params.withPrefix = recursive;
+  params.revision = fromIndex;
+  params.watch_stub = watchServiceStub.get();
+  params.timeout = this->timeout;
+  std::shared_ptr<etcdv3::AsyncWatchAction> call(new etcdv3::AsyncWatchAction(params));
+  return Response::create(call);
+}
+
+pplx::task<etcd::Response> etcd::Client::leasegrant(int ttl)
+{
+  etcdv3::ActionParameters params;
+  params.auth_token.assign(this->auth_token);
+  params.ttl = ttl;
+  params.lease_stub = leaseServiceStub.get();
+  params.timeout = this->timeout;
+  std::shared_ptr<etcdv3::AsyncLeaseGrantAction> call(new etcdv3::AsyncLeaseGrantAction(params));
+  return Response::create(call);
+}
+
+pplx::task<etcd::Response> etcd::Client::leaserevoke(int64_t lease_id)
+{
+  etcdv3::ActionParameters params;
+  params.auth_token.assign(this->auth_token);
+  params.lease_id = lease_id;
+  params.lease_stub = leaseServiceStub.get();
+  params.timeout = this->timeout;
+  std::shared_ptr<etcdv3::AsyncLeaseRevokeAction> call(new etcdv3::AsyncLeaseRevokeAction(params));
+  return Response::create(call);
+}
+
+pplx::task<etcd::Response> etcd::Client::leasetimetolive(int64_t lease_id)
+{
+  etcdv3::ActionParameters params;
+  params.auth_token.assign(this->auth_token);
+  params.lease_id = lease_id;
+  params.lease_stub = leaseServiceStub.get();
+  params.timeout = this->timeout;
+  std::shared_ptr<etcdv3::AsyncLeaseTimeToLiveAction> call(new etcdv3::AsyncLeaseTimeToLiveAction(params));
+  return Response::create(call);
+}
+
+pplx::task<etcd::Response> etcd::Client::lock(std::string const &key) {
+  etcdv3::ActionParameters params;
+  params.auth_token.assign(this->auth_token);
+  params.timeout = this->timeout;
+  static const int DEFAULT_LEASE_TTL_FOR_LOCK = 10;
+
+  // routines in lock usually will be fast, less than 10 seconds.
+  //
+  // (base on our experiences in vineyard and GraphScope).
+  auto resp = this->leasegrant(DEFAULT_LEASE_TTL_FOR_LOCK).get();
+  int64_t lease_id = resp.value().lease();
+  {
+    std::lock_guard<std::mutex> lexical_scope_lock(mutex_for_keepalives);
+    this->keep_alive_for_locks[lease_id].reset(
+      new KeepAlive(*this, DEFAULT_LEASE_TTL_FOR_LOCK, lease_id));
+  }
+  params.key = key;
+  params.lease_id = lease_id;
+  params.lock_stub = lockServiceStub.get();
+  std::shared_ptr<etcdv3::AsyncLockAction> call(new etcdv3::AsyncLockAction(params));
+  return Response::create(call).then(
+    [this, lease_id](pplx::task<etcd::Response> const &resp_task) -> etcd::Response {
+      auto const& resp = resp_task.get();
+      {
+        std::lock_guard<std::mutex> lexical_scope_lock(mutex_for_keepalives);
+        if (resp.is_ok()) {
+          this->leases_for_locks[resp.lock_key()] = lease_id;
+        } else {
+          this->keep_alive_for_locks.erase(lease_id);
+        }
+      }
+      return resp;
+    }
+  );
+}
+
+pplx::task<etcd::Response> etcd::Client::lock(std::string const &key,
+                                              int64_t lease_id) {
+  etcdv3::ActionParameters params;
+  params.auth_token.assign(this->auth_token);
+  params.key = key;
+  params.lease_id = lease_id;
+  params.lock_stub = lockServiceStub.get();
+  params.timeout = this->timeout;
+  std::shared_ptr<etcdv3::AsyncLockAction> call(new etcdv3::AsyncLockAction(params));
+  return Response::create(call);
+}
+
+pplx::task<etcd::Response> etcd::Client::unlock(std::string const &lock_key) {
+  // cancel the KeepAlive first, it exists
+  {
+    std::lock_guard<std::mutex> lexical_scope_lock(mutex_for_keepalives);
+    auto p_leases = this->leases_for_locks.find(lock_key);
+    if (p_leases != this->leases_for_locks.end()) {
+      auto p_keeps_alive = this->keep_alive_for_locks.find(p_leases->second);
+      if (p_keeps_alive != this->keep_alive_for_locks.end()) {
+        this->keep_alive_for_locks.erase(p_keeps_alive);
+      }
+      this->leases_for_locks.erase(p_leases);
+    }
+  }
+
+  // issue a "unlock" request
+  etcdv3::ActionParameters params;
+  params.auth_token.assign(this->auth_token);
+  params.key = lock_key;
+  params.lock_stub = lockServiceStub.get();
+  params.timeout = this->timeout;
+  std::shared_ptr<etcdv3::AsyncUnlockAction> call(new etcdv3::AsyncUnlockAction(params));
+  return Response::create(call);
+}
+
+pplx::task<etcd::Response> etcd::Client::txn(etcdv3::Transaction const &txn) {
+  etcdv3::ActionParameters params;
+  params.auth_token.assign(this->auth_token);
+  params.kv_stub = kvServiceStub .get();
+  params.timeout = this->timeout;
+  std::shared_ptr<etcdv3::AsyncTxnAction> call(new etcdv3::AsyncTxnAction(params, txn));
+  return Response::create(call);
+}
diff --git a/etcd/SyncClient.hpp b/etcd/SyncClient.hpp
index a90dc2e..b50bf39 100644
--- a/etcd/SyncClient.hpp
+++ b/etcd/SyncClient.hpp
@@ -21,9 +21,11 @@ namespace etcd
      *
      * @param etcd_url is the url of the etcd server to connect to, like "http://127.0.0.1:2379",
      *                 or multiple url, seperated by ',' or ';'.
+     * @param timeout timeout duration for each operation in terms of milliseconds
      * @param load_balancer is the load balance strategy, can be one of round_robin/pick_first/grpclb/xds.
      */
     SyncClient(std::string const & etcd_url,
+               const unsigned int& timeout = std::numeric_limits<unsigned int>::max(),
                std::string const & load_balancer = "round_robin");
 
     /**
@@ -33,11 +35,13 @@ namespace etcd
      *                 or multiple url, seperated by ',' or ';'.
      * @param username username of etcd auth
      * @param password password of etcd auth
+     * @param timeout timeout duration for each operation in terms of milliseconds
      * @param load_balancer is the load balance strategy, can be one of round_robin/pick_first/grpclb/xds.
      */
     SyncClient(std::string const & etcd_url,
                std::string const & username,
                std::string const & password,
+               const unsigned int& timeout = std::numeric_limits<unsigned int>::max(),
                std::string const & load_balancer = "round_robin");
 
     Response get(std::string const & key);
diff --git a/etcd/v3/Action.hpp b/etcd/v3/Action.hpp
index 3c8f8f2..961dee8 100644
--- a/etcd/v3/Action.hpp
+++ b/etcd/v3/Action.hpp
@@ -2,6 +2,7 @@
 #define __V3_ACTION_HPP__
 
 #include <chrono>
+#include <limits>
 
 #include <grpc++/grpc++.h>
 #include "proto/rpc.grpc.pb.h"
@@ -41,6 +42,7 @@ namespace etcdv3
     Watch::Stub* watch_stub;
     Lease::Stub* lease_stub;
     Lock::Stub* lock_stub;
+    unsigned int timeout;
   };
 
   class Action
diff --git a/src/Client.cpp b/src/Client.cpp
index 70fcd52..c1dddca 100644
--- a/src/Client.cpp
+++ b/src/Client.cpp
@@ -129,6 +129,7 @@ const bool authenticate(std::shared_ptr<grpc::Channel> const &channel,
 }
 
 etcd::Client::Client(std::string const & address,
+                     const unsigned int& timeout, 
                      std::string const & load_balancer)
 {
   // create channels
@@ -145,11 +146,13 @@ etcd::Client::Client(std::string const & address,
   watchServiceStub= Watch::NewStub(this->channel);
   leaseServiceStub= Lease::NewStub(this->channel);
   lockServiceStub = Lock::NewStub(this->channel);
+  this->timeout = timeout;
 }
 
 etcd::Client::Client(std::string const & address,
                      std::string const & username,
                      std::string const & password,
+                     const unsigned int& timeout,
                      std::string const & load_balancer)
 {
   // create channels
@@ -173,6 +176,7 @@ etcd::Client::Client(std::string const & address,
   watchServiceStub= Watch::NewStub(this->channel);
   leaseServiceStub= Lease::NewStub(this->channel);
   lockServiceStub = Lock::NewStub(this->channel);
+  this->timeout = timeout;
 }
 
 pplx::task<etcd::Response> etcd::Client::get(std::string const & key)
@@ -182,6 +186,7 @@ pplx::task<etcd::Response> etcd::Client::get(std::string const & key)
   params.key.assign(key);
   params.withPrefix = false;
   params.kv_stub = kvServiceStub .get();
+  params.timeout = this->timeout;
   std::shared_ptr<etcdv3::AsyncGetAction> call(new etcdv3::AsyncGetAction(params));
   return Response::create(call);
 }
@@ -193,7 +198,7 @@ pplx::task<etcd::Response> etcd::Client::set(std::string const & key, std::strin
   params.key.assign(key);
   params.value.assign(value);
   params.kv_stub = kvServiceStub .get();
-
+  params.timeout = this->timeout;
   if(ttl > 0)
   {
     auto res = leasegrant(ttl).get();
@@ -222,6 +227,7 @@ pplx::task<etcd::Response> etcd::Client::set(std::string const & key, std::strin
   params.value.assign(value);
   params.lease_id = leaseid;
   params.kv_stub = kvServiceStub .get();
+  params.timeout = this->timeout;
   std::shared_ptr<etcdv3::AsyncSetAction> call(new etcdv3::AsyncSetAction(params));
   return Response::create(call);
 }
@@ -234,7 +240,7 @@ pplx::task<etcd::Response> etcd::Client::add(std::string const & key, std::strin
   params.key.assign(key);
   params.value.assign(value);
   params.kv_stub = kvServiceStub .get();
-
+  params.timeout = this->timeout;
   if(ttl > 0)
   {
     auto res = leasegrant(ttl).get();
@@ -262,6 +268,7 @@ pplx::task<etcd::Response> etcd::Client::add(std::string const & key, std::strin
   params.value.assign(value);
   params.lease_id = leaseid;
   params.kv_stub = kvServiceStub .get();
+  params.timeout = this->timeout;
   std::shared_ptr<etcdv3::AsyncSetAction> call(new etcdv3::AsyncSetAction(params,true));
   return Response::create(call);
 }
@@ -274,7 +281,7 @@ pplx::task<etcd::Response> etcd::Client::modify(std::string const & key, std::st
   params.key.assign(key);
   params.value.assign(value);
   params.kv_stub = kvServiceStub .get();
-
+  params.timeout = this->timeout;
   if(ttl > 0)
   {
     auto res = leasegrant(ttl).get();
@@ -302,6 +309,7 @@ pplx::task<etcd::Response> etcd::Client::modify(std::string const & key, std::st
   params.value.assign(value);
   params.lease_id = leaseid;
   params.kv_stub = kvServiceStub .get();
+  params.timeout = this->timeout;
   std::shared_ptr<etcdv3::AsyncUpdateAction> call(new etcdv3::AsyncUpdateAction(params));
   return Response::create(call);
 }
@@ -315,7 +323,7 @@ pplx::task<etcd::Response> etcd::Client::modify_if(std::string const & key, std:
   params.value.assign(value);
   params.old_value.assign(old_value);
   params.kv_stub = kvServiceStub .get();
-
+  params.timeout = this->timeout;
   if(ttl > 0)
   {
     auto res = leasegrant(ttl).get();
@@ -344,6 +352,7 @@ pplx::task<etcd::Response> etcd::Client::modify_if(std::string const & key, std:
   params.old_value.assign(old_value);
   params.lease_id = leaseid;
   params.kv_stub = kvServiceStub .get();
+  params.timeout = this->timeout;
   std::shared_ptr<etcdv3::AsyncCompareAndSwapAction> call(new etcdv3::AsyncCompareAndSwapAction(params,etcdv3::Atomicity_Type::PREV_VALUE));
   return Response::create(call);
 }
@@ -356,6 +365,7 @@ pplx::task<etcd::Response> etcd::Client::modify_if(std::string const & key, std:
   params.value.assign(value);
   params.old_revision = old_index;
   params.kv_stub = kvServiceStub.get();
+  params.timeout = this->timeout;
   if(ttl > 0)
   {
     auto res = leasegrant(ttl).get();
@@ -384,6 +394,7 @@ pplx::task<etcd::Response> etcd::Client::modify_if(std::string const & key, std:
   params.lease_id = leaseid;
   params.old_revision = old_index;
   params.kv_stub = kvServiceStub .get();
+  params.timeout = this->timeout;
   std::shared_ptr<etcdv3::AsyncCompareAndSwapAction> call(new etcdv3::AsyncCompareAndSwapAction(params,etcdv3::Atomicity_Type::PREV_INDEX));
   return Response::create(call);
 }
@@ -395,7 +406,8 @@ pplx::task<etcd::Response> etcd::Client::rm(std::string const & key)
   params.auth_token.assign(this->auth_token);
   params.key.assign(key);
   params.withPrefix = false;
-  params.kv_stub = kvServiceStub .get();
+  params.kv_stub = kvServiceStub.get();
+  params.timeout = this->timeout;
   std::shared_ptr<etcdv3::AsyncDeleteAction> call(new etcdv3::AsyncDeleteAction(params));
   return Response::create(call);
 }
@@ -407,7 +419,8 @@ pplx::task<etcd::Response> etcd::Client::rm_if(std::string const & key, std::str
   params.auth_token.assign(this->auth_token);
   params.key.assign(key);
   params.old_value.assign(old_value);
-  params.kv_stub = kvServiceStub .get();
+  params.kv_stub = kvServiceStub.get();
+  params.timeout = this->timeout;
   std::shared_ptr<etcdv3::AsyncCompareAndDeleteAction> call(new etcdv3::AsyncCompareAndDeleteAction(params,etcdv3::Atomicity_Type::PREV_VALUE));
   return Response::create(call);
 }
@@ -418,7 +431,8 @@ pplx::task<etcd::Response> etcd::Client::rm_if(std::string const & key, int old_
   params.auth_token.assign(this->auth_token);
   params.key.assign(key);
   params.old_revision = old_index;
-  params.kv_stub = kvServiceStub .get();
+  params.kv_stub = kvServiceStub.get();
+  params.timeout = this->timeout;
   std::shared_ptr<etcdv3::AsyncCompareAndDeleteAction> call(new etcdv3::AsyncCompareAndDeleteAction(params, etcdv3::Atomicity_Type::PREV_INDEX));;
   return Response::create(call);
 
@@ -431,6 +445,7 @@ pplx::task<etcd::Response> etcd::Client::rmdir(std::string const & key, bool rec
   params.key.assign(key);
   params.withPrefix = recursive;
   params.kv_stub = kvServiceStub .get();
+  params.timeout = this->timeout;
   std::shared_ptr<etcdv3::AsyncDeleteAction> call(new etcdv3::AsyncDeleteAction(params));
   return Response::create(call);
 }
@@ -443,6 +458,7 @@ pplx::task<etcd::Response> etcd::Client::ls(std::string const & key)
   params.withPrefix = true;
   params.limit = 0;  // default no limit.
   params.kv_stub = kvServiceStub .get();
+  params.timeout = this->timeout;
   std::shared_ptr<etcdv3::AsyncGetAction> call(new etcdv3::AsyncGetAction(params));
   return Response::create(call);
 }
@@ -455,6 +471,7 @@ pplx::task<etcd::Response> etcd::Client::ls(std::string const & key, size_t cons
   params.withPrefix = true;
   params.limit = limit;
   params.kv_stub = kvServiceStub .get();
+  params.timeout = this->timeout;
   std::shared_ptr<etcdv3::AsyncGetAction> call(new etcdv3::AsyncGetAction(params));
   return Response::create(call);
 }
@@ -466,6 +483,7 @@ pplx::task<etcd::Response> etcd::Client::watch(std::string const & key, bool rec
   params.key.assign(key);
   params.withPrefix = recursive;
   params.watch_stub = watchServiceStub.get();
+  params.timeout = this->timeout;
   std::shared_ptr<etcdv3::AsyncWatchAction> call(new etcdv3::AsyncWatchAction(params));
   return Response::create(call);
 }
@@ -478,6 +496,7 @@ pplx::task<etcd::Response> etcd::Client::watch(std::string const & key, int from
   params.withPrefix = recursive;
   params.revision = fromIndex;
   params.watch_stub = watchServiceStub.get();
+  params.timeout = this->timeout;
   std::shared_ptr<etcdv3::AsyncWatchAction> call(new etcdv3::AsyncWatchAction(params));
   return Response::create(call);
 }
@@ -488,6 +507,7 @@ pplx::task<etcd::Response> etcd::Client::leasegrant(int ttl)
   params.auth_token.assign(this->auth_token);
   params.ttl = ttl;
   params.lease_stub = leaseServiceStub.get();
+  params.timeout = this->timeout;
   std::shared_ptr<etcdv3::AsyncLeaseGrantAction> call(new etcdv3::AsyncLeaseGrantAction(params));
   return Response::create(call);
 }
@@ -498,6 +518,7 @@ pplx::task<etcd::Response> etcd::Client::leaserevoke(int64_t lease_id)
   params.auth_token.assign(this->auth_token);
   params.lease_id = lease_id;
   params.lease_stub = leaseServiceStub.get();
+  params.timeout = this->timeout;
   std::shared_ptr<etcdv3::AsyncLeaseRevokeAction> call(new etcdv3::AsyncLeaseRevokeAction(params));
   return Response::create(call);
 }
@@ -508,6 +529,7 @@ pplx::task<etcd::Response> etcd::Client::leasetimetolive(int64_t lease_id)
   params.auth_token.assign(this->auth_token);
   params.lease_id = lease_id;
   params.lease_stub = leaseServiceStub.get();
+  params.timeout = this->timeout;
   std::shared_ptr<etcdv3::AsyncLeaseTimeToLiveAction> call(new etcdv3::AsyncLeaseTimeToLiveAction(params));
   return Response::create(call);
 }
@@ -515,7 +537,7 @@ pplx::task<etcd::Response> etcd::Client::leasetimetolive(int64_t lease_id)
 pplx::task<etcd::Response> etcd::Client::lock(std::string const &key) {
   etcdv3::ActionParameters params;
   params.auth_token.assign(this->auth_token);
-
+  params.timeout = this->timeout;
   static const int DEFAULT_LEASE_TTL_FOR_LOCK = 10;
 
   // routines in lock usually will be fast, less than 10 seconds.
@@ -555,6 +577,7 @@ pplx::task<etcd::Response> etcd::Client::lock(std::string const &key,
   params.key = key;
   params.lease_id = lease_id;
   params.lock_stub = lockServiceStub.get();
+  params.timeout = this->timeout;
   std::shared_ptr<etcdv3::AsyncLockAction> call(new etcdv3::AsyncLockAction(params));
   return Response::create(call);
 }
@@ -578,6 +601,7 @@ pplx::task<etcd::Response> etcd::Client::unlock(std::string const &lock_key) {
   params.auth_token.assign(this->auth_token);
   params.key = lock_key;
   params.lock_stub = lockServiceStub.get();
+  params.timeout = this->timeout;
   std::shared_ptr<etcdv3::AsyncUnlockAction> call(new etcdv3::AsyncUnlockAction(params));
   return Response::create(call);
 }
@@ -586,6 +610,7 @@ pplx::task<etcd::Response> etcd::Client::txn(etcdv3::Transaction const &txn) {
   etcdv3::ActionParameters params;
   params.auth_token.assign(this->auth_token);
   params.kv_stub = kvServiceStub .get();
+  params.timeout = this->timeout;
   std::shared_ptr<etcdv3::AsyncTxnAction> call(new etcdv3::AsyncTxnAction(params, txn));
   return Response::create(call);
 }
diff --git a/src/SyncClient.cpp b/src/SyncClient.cpp
index 4dc267f..7f9329b 100644
--- a/src/SyncClient.cpp
+++ b/src/SyncClient.cpp
@@ -10,16 +10,17 @@
     return etcd::Response(500, ex.what());      \
   }
 
-etcd::SyncClient::SyncClient(std::string const & address, std::string const & load_balancer)
-  : client(address, load_balancer)
+etcd::SyncClient::SyncClient(std::string const & address, const unsigned int& timeout,  std::string const & load_balancer)
+  : client(address, timeout, load_balancer)
 {
 }
 
 etcd::SyncClient::SyncClient(std::string const & address,
                              std::string const & username,
                              std::string const & password,
+                             const unsigned int& timeout, 
                              std::string const & load_balancer)
-  : client(address, username, password, load_balancer)
+  : client(address, username, password, timeout, load_balancer)
 {
 }
 
diff --git a/src/v3/Action.cpp b/src/v3/Action.cpp
index 0f4c81b..e9c4ce1 100644
--- a/src/v3/Action.cpp
+++ b/src/v3/Action.cpp
@@ -23,6 +23,7 @@ etcdv3::ActionParameters::ActionParameters()
   kv_stub = NULL;
   watch_stub = NULL;
   lease_stub = NULL;
+  timeout = std::numeric_limits<unsigned int>::max();
 }
 
 void etcdv3::Action::waitForResponse() 
@@ -30,8 +31,17 @@ void etcdv3::Action::waitForResponse()
   void* got_tag;
   bool ok = false;    
 
-  cq_.Next(&got_tag, &ok);
-  GPR_ASSERT(got_tag == (void*)this);
+  auto status = cq_.AsyncNext(&got_tag, &ok, std::chrono::system_clock::now() + std::chrono::milliseconds(parameters.timeout));
+  if( status == grpc::CompletionQueue::NextStatus::TIMEOUT )
+  {
+    ok = false;
+    this->status = grpc::Status(grpc::StatusCode::DEADLINE_EXCEEDED, "Timeout");
+  }
+  else
+  {
+    GRP_ASSERT(got_tag == (void*)this);
+  }
+  
 }
 
 const std::chrono::high_resolution_clock::time_point etcdv3::Action::startTimepoint() {