diff --git a/.travis.yml b/.travis.yml
index 7402e6fb6e78..2266833f8414 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -148,6 +148,9 @@ install:
   - ./ci/suppress_output bazel build //:stats_test -c opt
   - ./bazel-bin/stats_test
 
+  # core worker test.
+  - ./ci/suppress_output bash src/ray/test/run_core_worker_tests.sh
+
   # Raylet tests.
   - ./ci/suppress_output bash src/ray/test/run_object_manager_tests.sh
   - ./ci/suppress_output bazel test --build_tests_only --test_lang_filters=cc //:all
diff --git a/BUILD.bazel b/BUILD.bazel
index 0bdbe5741cf8..2b75d5d04e77 100644
--- a/BUILD.bazel
+++ b/BUILD.bazel
@@ -77,6 +77,7 @@ cc_library(
             "src/ray/raylet/mock_gcs_client.cc",
             "src/ray/raylet/monitor_main.cc",
             "src/ray/raylet/*_test.cc",
+            "src/ray/raylet/main.cc",
         ],
     ),
     hdrs = glob([
@@ -122,15 +123,18 @@ cc_library(
     deps = [
         ":ray_common",
         ":ray_util",
+        ":raylet_lib",
     ],
 )
 
-cc_test(
+# This test is run by src/ray/test/run_core_worker_tests.sh
+cc_binary(
     name = "core_worker_test",
     srcs = ["src/ray/core_worker/core_worker_test.cc"],
     copts = COPTS,
     deps = [
         ":core_worker_lib",
+        ":gcs",
         "@com_google_googletest//:gtest_main",
     ],
 )
@@ -320,6 +324,7 @@ cc_library(
         ":node_manager_fbs",
         ":ray_util",
         "@boost//:asio",
+        "@plasma//:plasma_client",
     ],
 )
 
diff --git a/src/ray/common/buffer.h b/src/ray/common/buffer.h
index 358d903799c7..4340c74a8d38 100644
--- a/src/ray/common/buffer.h
+++ b/src/ray/common/buffer.h
@@ -3,6 +3,11 @@
 
 #include <cstdint>
 #include <cstdio>
+#include "plasma/client.h"
+
+namespace arrow {
+class Buffer;
+}
 
 namespace ray {
 
@@ -15,7 +20,7 @@ class Buffer {
   /// Size of this buffer.
   virtual size_t Size() const = 0;
 
-  virtual ~Buffer() {}
+  virtual ~Buffer(){};
 
   bool operator==(const Buffer &rhs) const {
     return this->Data() == rhs.Data() && this->Size() == rhs.Size();
@@ -40,6 +45,21 @@ class LocalMemoryBuffer : public Buffer {
   size_t size_;
 };
 
+/// Represents a byte buffer for plasma object.
+class PlasmaBuffer : public Buffer {
+ public:
+  PlasmaBuffer(std::shared_ptr<arrow::Buffer> buffer) : buffer_(buffer) {}
+
+  uint8_t *Data() const override { return const_cast<uint8_t *>(buffer_->data()); }
+
+  size_t Size() const override { return buffer_->size(); }
+
+ private:
+  /// shared_ptr to arrow buffer which can potentially hold a reference
+  /// for the object (when it's a plasma::PlasmaBuffer).
+  std::shared_ptr<arrow::Buffer> buffer_;
+};
+
 }  // namespace ray
 
 #endif  // RAY_COMMON_BUFFER_H
diff --git a/src/ray/core_worker/common.h b/src/ray/core_worker/common.h
index b53c35b25fa8..ad9485e53826 100644
--- a/src/ray/core_worker/common.h
+++ b/src/ray/core_worker/common.h
@@ -45,13 +45,13 @@ class TaskArg {
   bool IsPassedByReference() const { return id_ != nullptr; }
 
   /// Get the reference object ID.
-  ObjectID &GetReference() {
+  const ObjectID &GetReference() const {
     RAY_CHECK(id_ != nullptr) << "This argument isn't passed by reference.";
     return *id_;
   }
 
   /// Get the value.
-  std::shared_ptr<Buffer> GetValue() {
+  std::shared_ptr<Buffer> GetValue() const {
     RAY_CHECK(data_ != nullptr) << "This argument isn't passed by value.";
     return data_;
   }
diff --git a/src/ray/core_worker/context.cc b/src/ray/core_worker/context.cc
new file mode 100644
index 000000000000..fedcfc6625d9
--- /dev/null
+++ b/src/ray/core_worker/context.cc
@@ -0,0 +1,81 @@
+
+#include "context.h"
+
+namespace ray {
+
+/// per-thread context for core worker.
+struct WorkerThreadContext {
+  WorkerThreadContext()
+      : current_task_id(TaskID::FromRandom()), task_index(0), put_index(0) {}
+
+  int GetNextTaskIndex() { return ++task_index; }
+
+  int GetNextPutIndex() { return ++put_index; }
+
+  const TaskID &GetCurrentTaskID() const { return current_task_id; }
+
+  void SetCurrentTask(const TaskID &task_id) {
+    current_task_id = task_id;
+    task_index = 0;
+    put_index = 0;
+  }
+
+  void SetCurrentTask(const raylet::TaskSpecification &spec) {
+    SetCurrentTask(spec.TaskId());
+  }
+
+ private:
+  /// The task ID for current task.
+  TaskID current_task_id;
+
+  /// Number of tasks that have been submitted from current task.
+  int task_index;
+
+  /// Number of objects that have been put from current task.
+  int put_index;
+};
+
+thread_local std::unique_ptr<WorkerThreadContext> WorkerContext::thread_context_ =
+    nullptr;
+
+WorkerContext::WorkerContext(WorkerType worker_type, const DriverID &driver_id)
+    : worker_type(worker_type),
+      worker_id(worker_type == WorkerType::DRIVER
+                    ? ClientID::FromBinary(driver_id.Binary())
+                    : ClientID::FromRandom()),
+      current_driver_id(worker_type == WorkerType::DRIVER ? driver_id : DriverID::Nil()) {
+  // For worker main thread which initializes the WorkerContext,
+  // set task_id according to whether current worker is a driver.
+  // (For other threads it's set to randmom ID via GetThreadContext).
+  GetThreadContext().SetCurrentTask(
+      (worker_type == WorkerType::DRIVER) ? TaskID::FromRandom() : TaskID::Nil());
+}
+
+const WorkerType WorkerContext::GetWorkerType() const { return worker_type; }
+
+const ClientID &WorkerContext::GetWorkerID() const { return worker_id; }
+
+int WorkerContext::GetNextTaskIndex() { return GetThreadContext().GetNextTaskIndex(); }
+
+int WorkerContext::GetNextPutIndex() { return GetThreadContext().GetNextPutIndex(); }
+
+const DriverID &WorkerContext::GetCurrentDriverID() const { return current_driver_id; }
+
+const TaskID &WorkerContext::GetCurrentTaskID() const {
+  return GetThreadContext().GetCurrentTaskID();
+}
+
+void WorkerContext::SetCurrentTask(const raylet::TaskSpecification &spec) {
+  current_driver_id = spec.DriverId();
+  GetThreadContext().SetCurrentTask(spec);
+}
+
+WorkerThreadContext &WorkerContext::GetThreadContext() {
+  if (thread_context_ == nullptr) {
+    thread_context_ = std::unique_ptr<WorkerThreadContext>(new WorkerThreadContext());
+  }
+
+  return *thread_context_;
+}
+
+}  // namespace ray
diff --git a/src/ray/core_worker/context.h b/src/ray/core_worker/context.h
new file mode 100644
index 000000000000..6e0cf3f9f2cf
--- /dev/null
+++ b/src/ray/core_worker/context.h
@@ -0,0 +1,48 @@
+#ifndef RAY_CORE_WORKER_CONTEXT_H
+#define RAY_CORE_WORKER_CONTEXT_H
+
+#include "common.h"
+#include "ray/raylet/task_spec.h"
+
+namespace ray {
+
+struct WorkerThreadContext;
+
+class WorkerContext {
+ public:
+  WorkerContext(WorkerType worker_type, const DriverID &driver_id);
+
+  const WorkerType GetWorkerType() const;
+
+  const ClientID &GetWorkerID() const;
+
+  const DriverID &GetCurrentDriverID() const;
+
+  const TaskID &GetCurrentTaskID() const;
+
+  void SetCurrentTask(const raylet::TaskSpecification &spec);
+
+  int GetNextTaskIndex();
+
+  int GetNextPutIndex();
+
+ private:
+  /// Type of the worker.
+  const WorkerType worker_type;
+
+  /// ID for this worker.
+  const ClientID worker_id;
+
+  /// Driver ID for this worker.
+  DriverID current_driver_id;
+
+ private:
+  static WorkerThreadContext &GetThreadContext();
+
+  /// Per-thread worker context.
+  static thread_local std::unique_ptr<WorkerThreadContext> thread_context_;
+};
+
+}  // namespace ray
+
+#endif  // RAY_CORE_WORKER_CONTEXT_H
diff --git a/src/ray/core_worker/core_worker.cc b/src/ray/core_worker/core_worker.cc
new file mode 100644
index 000000000000..82f2d885ec58
--- /dev/null
+++ b/src/ray/core_worker/core_worker.cc
@@ -0,0 +1,39 @@
+#include "core_worker.h"
+#include "context.h"
+
+namespace ray {
+
+CoreWorker::CoreWorker(const enum WorkerType worker_type, const enum Language language,
+                       const std::string &store_socket, const std::string &raylet_socket,
+                       DriverID driver_id)
+    : worker_type_(worker_type),
+      language_(language),
+      worker_context_(worker_type, driver_id),
+      store_socket_(store_socket),
+      raylet_socket_(raylet_socket),
+      task_interface_(*this),
+      object_interface_(*this),
+      task_execution_interface_(*this) {}
+
+Status CoreWorker::Connect() {
+  // connect to plasma.
+  RAY_ARROW_RETURN_NOT_OK(store_client_.Connect(store_socket_));
+
+  // connect to raylet.
+  ::Language lang = ::Language::PYTHON;
+  if (language_ == ray::Language::JAVA) {
+    lang = ::Language::JAVA;
+  }
+
+  // TODO: currently RayletClient would crash in its constructor if it cannot
+  // connect to Raylet after a number of retries, this needs to be changed
+  // so that the worker (java/python .etc) can retrieve and handle the error
+  // instead of crashing.
+  raylet_client_ = std::unique_ptr<RayletClient>(
+      new RayletClient(raylet_socket_, worker_context_.GetWorkerID(),
+                       (worker_type_ == ray::WorkerType::WORKER),
+                       worker_context_.GetCurrentDriverID(), lang));
+  return Status::OK();
+}
+
+}  // namespace ray
diff --git a/src/ray/core_worker/core_worker.h b/src/ray/core_worker/core_worker.h
index 96e51dbc4532..951b55451f09 100644
--- a/src/ray/core_worker/core_worker.h
+++ b/src/ray/core_worker/core_worker.h
@@ -2,8 +2,10 @@
 #define RAY_CORE_WORKER_CORE_WORKER_H
 
 #include "common.h"
+#include "context.h"
 #include "object_interface.h"
 #include "ray/common/buffer.h"
+#include "ray/raylet/raylet_client.h"
 #include "task_execution.h"
 #include "task_interface.h"
 
@@ -18,15 +20,12 @@ class CoreWorker {
   ///
   /// \param[in] worker_type Type of this worker.
   /// \param[in] langauge Language of this worker.
-  CoreWorker(const WorkerType worker_type, const Language language)
-      : worker_type_(worker_type),
-        language_(language),
-        task_interface_(*this),
-        object_interface_(*this),
-        task_execution_interface_(*this) {}
+  CoreWorker(const WorkerType worker_type, const Language language,
+             const std::string &store_socket, const std::string &raylet_socket,
+             DriverID driver_id = DriverID::Nil());
 
-  /// Connect this worker to Raylet.
-  Status Connect() { return Status::OK(); }
+  /// Connect to raylet.
+  Status Connect();
 
   /// Type of this worker.
   enum WorkerType WorkerType() const { return worker_type_; }
@@ -53,6 +52,21 @@ class CoreWorker {
   /// Language of this worker.
   const enum Language language_;
 
+  /// Worker context per thread.
+  WorkerContext worker_context_;
+
+  /// Plasma store socket name.
+  std::string store_socket_;
+
+  /// raylet socket name.
+  std::string raylet_socket_;
+
+  /// Plasma store client.
+  plasma::PlasmaClient store_client_;
+
+  /// Raylet client.
+  std::unique_ptr<RayletClient> raylet_client_;
+
   /// The `CoreWorkerTaskInterface` instance.
   CoreWorkerTaskInterface task_interface_;
 
@@ -61,6 +75,10 @@ class CoreWorker {
 
   /// The `CoreWorkerTaskExecutionInterface` instance.
   CoreWorkerTaskExecutionInterface task_execution_interface_;
+
+  friend class CoreWorkerTaskInterface;
+  friend class CoreWorkerObjectInterface;
+  friend class CoreWorkerTaskExecutionInterface;
 };
 
 }  // namespace ray
diff --git a/src/ray/core_worker/core_worker_test.cc b/src/ray/core_worker/core_worker_test.cc
index 6711c874a973..e440aae24d67 100644
--- a/src/ray/core_worker/core_worker_test.cc
+++ b/src/ray/core_worker/core_worker_test.cc
@@ -1,20 +1,137 @@
+#include <thread>
 #include "gmock/gmock.h"
 #include "gtest/gtest.h"
 
+#include "context.h"
 #include "core_worker.h"
 #include "ray/common/buffer.h"
+#include "ray/raylet/raylet_client.h"
+
+#include <boost/asio.hpp>
+#include <boost/asio/error.hpp>
+#include <boost/bind.hpp>
+
+#include "ray/thirdparty/hiredis/async.h"
+#include "ray/thirdparty/hiredis/hiredis.h"
 
 namespace ray {
 
+std::string store_executable;
+std::string raylet_executable;
+
+ray::ObjectID RandomObjectID() { return ObjectID::FromRandom(); }
+
+static void flushall_redis(void) {
+  redisContext *context = redisConnect("127.0.0.1", 6379);
+  freeReplyObject(redisCommand(context, "FLUSHALL"));
+  freeReplyObject(redisCommand(context, "SET NumRedisShards 1"));
+  freeReplyObject(redisCommand(context, "LPUSH RedisShards 127.0.0.1:6380"));
+  redisFree(context);
+}
+
 class CoreWorkerTest : public ::testing::Test {
  public:
-  CoreWorkerTest() : core_worker_(WorkerType::WORKER, Language::PYTHON) {}
+  CoreWorkerTest(int num_nodes) {
+    RAY_CHECK(num_nodes >= 0);
+    if (num_nodes > 0) {
+      raylet_socket_names_.resize(num_nodes);
+      raylet_store_socket_names_.resize(num_nodes);
+    }
+
+    // start plasma store.
+    for (auto &store_socket : raylet_store_socket_names_) {
+      store_socket = StartStore();
+    }
+
+    // start raylet on each node
+    for (int i = 0; i < num_nodes; i++) {
+      raylet_socket_names_[i] = StartRaylet(raylet_store_socket_names_[i], "127.0.0.1",
+                                            "127.0.0.1", "\"CPU,4.0\"");
+    }
+  }
+
+  ~CoreWorkerTest() {
+    for (const auto &raylet_socket : raylet_socket_names_) {
+      StopRaylet(raylet_socket);
+    }
+
+    for (const auto &store_socket : raylet_store_socket_names_) {
+      StopStore(store_socket);
+    }
+  }
+
+  std::string StartStore() {
+    std::string store_socket_name = "/tmp/store" + RandomObjectID().Hex();
+    std::string store_pid = store_socket_name + ".pid";
+    std::string plasma_command = store_executable + " -m 10000000 -s " +
+                                 store_socket_name +
+                                 " 1> /dev/null 2> /dev/null & echo $! > " + store_pid;
+    RAY_LOG(INFO) << plasma_command;
+    RAY_CHECK(system(plasma_command.c_str()) == 0);
+    usleep(200 * 1000);
+    return store_socket_name;
+  }
+
+  void StopStore(std::string store_socket_name) {
+    std::string store_pid = store_socket_name + ".pid";
+    std::string kill_9 = "kill -9 `cat " + store_pid + "`";
+    RAY_LOG(INFO) << kill_9;
+    ASSERT_TRUE(system(kill_9.c_str()) == 0);
+    ASSERT_TRUE(system(("rm -rf " + store_socket_name).c_str()) == 0);
+    ASSERT_TRUE(system(("rm -rf " + store_socket_name + ".pid").c_str()) == 0);
+  }
+
+  std::string StartRaylet(std::string store_socket_name, std::string node_ip_address,
+                          std::string redis_address, std::string resource) {
+    std::string raylet_socket_name = "/tmp/raylet" + RandomObjectID().Hex();
+    std::string ray_start_cmd = raylet_executable;
+    ray_start_cmd.append(" --raylet_socket_name=" + raylet_socket_name)
+        .append(" --store_socket_name=" + store_socket_name)
+        .append(" --object_manager_port=0 --node_manager_port=0")
+        .append(" --node_ip_address=" + node_ip_address)
+        .append(" --redis_address=" + redis_address)
+        .append(" --redis_port=6379")
+        .append(" --num_initial_workers=0")
+        .append(" --maximum_startup_concurrency=10")
+        .append(" --static_resource_list=" + resource)
+        .append(" --python_worker_command=NoneCmd")
+        .append(" & echo $! > " + raylet_socket_name + ".pid");
+
+    RAY_LOG(INFO) << "Ray Start command: " << ray_start_cmd;
+    RAY_CHECK(system(ray_start_cmd.c_str()) == 0);
+    usleep(200 * 1000);
+    return raylet_socket_name;
+  }
+
+  void StopRaylet(std::string raylet_socket_name) {
+    std::string raylet_pid = raylet_socket_name + ".pid";
+    std::string kill_9 = "kill -9 `cat " + raylet_pid + "`";
+    RAY_LOG(INFO) << kill_9;
+    ASSERT_TRUE(system(kill_9.c_str()) == 0);
+    ASSERT_TRUE(system(("rm -rf " + raylet_socket_name).c_str()) == 0);
+    ASSERT_TRUE(system(("rm -rf " + raylet_socket_name + ".pid").c_str()) == 0);
+  }
+
+  void SetUp() { flushall_redis(); }
+
+  void TearDown() {}
 
  protected:
-  CoreWorker core_worker_;
+  std::vector<std::string> raylet_socket_names_;
+  std::vector<std::string> raylet_store_socket_names_;
 };
 
-TEST_F(CoreWorkerTest, TestTaskArg) {
+class ZeroNodeTest : public CoreWorkerTest {
+ public:
+  ZeroNodeTest() : CoreWorkerTest(0) {}
+};
+
+class SingleNodeTest : public CoreWorkerTest {
+ public:
+  SingleNodeTest() : CoreWorkerTest(1) {}
+};
+
+TEST_F(ZeroNodeTest, TestTaskArg) {
   // Test by-reference argument.
   ObjectID id = ObjectID::FromRandom();
   TaskArg by_ref = TaskArg::PassByReference(id);
@@ -30,9 +147,100 @@ TEST_F(CoreWorkerTest, TestTaskArg) {
   ASSERT_EQ(*data, *buffer);
 }
 
-TEST_F(CoreWorkerTest, TestAttributeGetters) {
-  ASSERT_EQ(core_worker_.WorkerType(), WorkerType::WORKER);
-  ASSERT_EQ(core_worker_.Language(), Language::PYTHON);
+TEST_F(ZeroNodeTest, TestAttributeGetters) {
+  CoreWorker core_worker(WorkerType::DRIVER, Language::PYTHON, "", "",
+                         DriverID::FromRandom());
+  ASSERT_EQ(core_worker.WorkerType(), WorkerType::DRIVER);
+  ASSERT_EQ(core_worker.Language(), Language::PYTHON);
+}
+
+TEST_F(ZeroNodeTest, TestWorkerContext) {
+  auto driver_id = DriverID::FromRandom();
+
+  WorkerContext context(WorkerType::WORKER, driver_id);
+  ASSERT_TRUE(context.GetCurrentTaskID().IsNil());
+  ASSERT_EQ(context.GetNextTaskIndex(), 1);
+  ASSERT_EQ(context.GetNextTaskIndex(), 2);
+  ASSERT_EQ(context.GetNextPutIndex(), 1);
+  ASSERT_EQ(context.GetNextPutIndex(), 2);
+
+  auto thread_func = [&context]() {
+    // Verify that task_index, put_index are thread-local.
+    ASSERT_TRUE(!context.GetCurrentTaskID().IsNil());
+    ASSERT_EQ(context.GetNextTaskIndex(), 1);
+    ASSERT_EQ(context.GetNextPutIndex(), 1);
+  };
+
+  std::thread async_thread(thread_func);
+  async_thread.join();
+
+  // Verify that these fields are thread-local.
+  ASSERT_EQ(context.GetNextTaskIndex(), 3);
+  ASSERT_EQ(context.GetNextPutIndex(), 3);
+}
+
+TEST_F(SingleNodeTest, TestObjectInterface) {
+  CoreWorker core_worker(WorkerType::DRIVER, Language::PYTHON,
+                         raylet_store_socket_names_[0], raylet_socket_names_[0],
+                         DriverID::FromRandom());
+  RAY_CHECK_OK(core_worker.Connect());
+
+  uint8_t array1[] = {1, 2, 3, 4, 5, 6, 7, 8};
+  uint8_t array2[] = {10, 11, 12, 13, 14, 15};
+
+  std::vector<LocalMemoryBuffer> buffers;
+  buffers.emplace_back(array1, sizeof(array1));
+  buffers.emplace_back(array2, sizeof(array2));
+
+  std::vector<ObjectID> ids(buffers.size());
+  for (int i = 0; i < ids.size(); i++) {
+    core_worker.Objects().Put(buffers[i], &ids[i]);
+  }
+
+  // Test Get().
+  std::vector<std::shared_ptr<Buffer>> results;
+  core_worker.Objects().Get(ids, 0, &results);
+
+  ASSERT_EQ(results.size(), 2);
+  for (int i = 0; i < ids.size(); i++) {
+    ASSERT_EQ(results[i]->Size(), buffers[i].Size());
+    ASSERT_EQ(memcmp(results[i]->Data(), buffers[i].Data(), buffers[i].Size()), 0);
+  }
+
+  // Test Wait().
+  ObjectID non_existent_id = ObjectID::FromRandom();
+  std::vector<ObjectID> all_ids(ids);
+  all_ids.push_back(non_existent_id);
+
+  std::vector<bool> wait_results;
+  core_worker.Objects().Wait(all_ids, 2, -1, &wait_results);
+  ASSERT_EQ(wait_results.size(), 3);
+  ASSERT_EQ(wait_results, std::vector<bool>({true, true, false}));
+
+  core_worker.Objects().Wait(all_ids, 3, 100, &wait_results);
+  ASSERT_EQ(wait_results.size(), 3);
+  ASSERT_EQ(wait_results, std::vector<bool>({true, true, false}));
+
+  // Test Delete().
+  // clear the reference held by PlasmaBuffer.
+  results.clear();
+  core_worker.Objects().Delete(ids, true, false);
+
+  // Note that Delete() calls RayletClient::FreeObjects and would not
+  // wait for objects being deleted, so wait a while for plasma store
+  // to process the command.
+  usleep(200 * 1000);
+  core_worker.Objects().Get(ids, 0, &results);
+  ASSERT_EQ(results.size(), 2);
+  ASSERT_TRUE(!results[0]);
+  ASSERT_TRUE(!results[1]);
 }
 
 }  // namespace ray
+
+int main(int argc, char **argv) {
+  ::testing::InitGoogleTest(&argc, argv);
+  ray::store_executable = std::string(argv[1]);
+  ray::raylet_executable = std::string(argv[2]);
+  return RUN_ALL_TESTS();
+}
diff --git a/src/ray/core_worker/object_interface.cc b/src/ray/core_worker/object_interface.cc
index d5d5d6f883f6..c966192610c7 100644
--- a/src/ray/core_worker/object_interface.cc
+++ b/src/ray/core_worker/object_interface.cc
@@ -1,25 +1,128 @@
 #include "object_interface.h"
+#include "context.h"
+#include "core_worker.h"
+#include "ray/ray_config.h"
 
 namespace ray {
 
-Status CoreWorkerObjectInterface::Put(const Buffer &buffer, const ObjectID *object_id) {
+CoreWorkerObjectInterface::CoreWorkerObjectInterface(CoreWorker &core_worker)
+    : core_worker_(core_worker) {}
+
+Status CoreWorkerObjectInterface::Put(const Buffer &buffer, ObjectID *object_id) {
+  ObjectID put_id = ObjectID::ForPut(core_worker_.worker_context_.GetCurrentTaskID(),
+                                     core_worker_.worker_context_.GetNextPutIndex());
+  *object_id = put_id;
+
+  auto plasma_id = put_id.ToPlasmaId();
+  std::shared_ptr<arrow::Buffer> data;
+  RAY_ARROW_RETURN_NOT_OK(
+      core_worker_.store_client_.Create(plasma_id, buffer.Size(), nullptr, 0, &data));
+  memcpy(data->mutable_data(), buffer.Data(), buffer.Size());
+  RAY_ARROW_RETURN_NOT_OK(core_worker_.store_client_.Seal(plasma_id));
+  RAY_ARROW_RETURN_NOT_OK(core_worker_.store_client_.Release(plasma_id));
   return Status::OK();
 }
 
 Status CoreWorkerObjectInterface::Get(const std::vector<ObjectID> &ids,
-                                      int64_t timeout_ms, std::vector<Buffer> *results) {
+                                      int64_t timeout_ms,
+                                      std::vector<std::shared_ptr<Buffer>> *results) {
+  (*results).resize(ids.size(), nullptr);
+
+  bool was_blocked = false;
+
+  std::unordered_map<ObjectID, int> unready;
+  for (int i = 0; i < ids.size(); i++) {
+    unready.insert({ids[i], i});
+  }
+
+  int num_attempts = 0;
+  bool should_break = false;
+  int64_t remaining_timeout = timeout_ms;
+  // Repeat until we get all objects.
+  while (!unready.empty() && !should_break) {
+    std::vector<ObjectID> unready_ids;
+    for (const auto &entry : unready) {
+      unready_ids.push_back(entry.first);
+    }
+
+    // For the initial fetch, we only fetch the objects, do not reconstruct them.
+    bool fetch_only = num_attempts == 0;
+    if (!fetch_only) {
+      // If fetch_only is false, this worker will be blocked.
+      was_blocked = true;
+    }
+
+    // TODO: can call `fetchOrReconstruct` in batches as an optimization.
+    RAY_CHECK_OK(core_worker_.raylet_client_->FetchOrReconstruct(
+        unready_ids, fetch_only, core_worker_.worker_context_.GetCurrentTaskID()));
+
+    // Get the objects from the object store, and parse the result.
+    int64_t get_timeout;
+    if (remaining_timeout >= 0) {
+      get_timeout =
+          std::min(remaining_timeout, RayConfig::instance().get_timeout_milliseconds());
+      remaining_timeout -= get_timeout;
+      should_break = remaining_timeout <= 0;
+    } else {
+      get_timeout = RayConfig::instance().get_timeout_milliseconds();
+    }
+
+    std::vector<plasma::ObjectID> plasma_ids;
+    for (const auto &id : unready_ids) {
+      plasma_ids.push_back(id.ToPlasmaId());
+    }
+
+    std::vector<plasma::ObjectBuffer> object_buffers;
+    auto status =
+        core_worker_.store_client_.Get(plasma_ids, get_timeout, &object_buffers);
+
+    for (int i = 0; i < object_buffers.size(); i++) {
+      if (object_buffers[i].data != nullptr) {
+        const auto &object_id = unready_ids[i];
+        (*results)[unready[object_id]] =
+            std::make_shared<PlasmaBuffer>(object_buffers[i].data);
+        unready.erase(object_id);
+      }
+    }
+
+    num_attempts += 1;
+    // TODO: log a message if attempted too many times.
+  }
+
+  if (was_blocked) {
+    RAY_CHECK_OK(core_worker_.raylet_client_->NotifyUnblocked(
+        core_worker_.worker_context_.GetCurrentTaskID()));
+  }
+
   return Status::OK();
 }
 
 Status CoreWorkerObjectInterface::Wait(const std::vector<ObjectID> &object_ids,
                                        int num_objects, int64_t timeout_ms,
                                        std::vector<bool> *results) {
-  return Status::OK();
+  WaitResultPair result_pair;
+  auto status = core_worker_.raylet_client_->Wait(
+      object_ids, num_objects, timeout_ms, false,
+      core_worker_.worker_context_.GetCurrentTaskID(), &result_pair);
+  std::unordered_set<ObjectID> ready_ids;
+  for (const auto &entry : result_pair.first) {
+    ready_ids.insert(entry);
+  }
+
+  // TODO: change RayletClient::Wait() to return a bit set, so that we don't need
+  // to do this translation.
+  (*results).resize(object_ids.size());
+  for (int i = 0; i < object_ids.size(); i++) {
+    (*results)[i] = ready_ids.count(object_ids[i]) > 0;
+  }
+
+  return status;
 }
 
 Status CoreWorkerObjectInterface::Delete(const std::vector<ObjectID> &object_ids,
                                          bool local_only, bool delete_creating_tasks) {
-  return Status::OK();
+  return core_worker_.raylet_client_->FreeObjects(object_ids, local_only,
+                                                  delete_creating_tasks);
 }
 
 }  // namespace ray
diff --git a/src/ray/core_worker/object_interface.h b/src/ray/core_worker/object_interface.h
index 424c123ee543..f14c5297c456 100644
--- a/src/ray/core_worker/object_interface.h
+++ b/src/ray/core_worker/object_interface.h
@@ -2,6 +2,7 @@
 #define RAY_CORE_WORKER_OBJECT_INTERFACE_H
 
 #include "common.h"
+#include "plasma/client.h"
 #include "ray/common/buffer.h"
 #include "ray/id.h"
 #include "ray/status.h"
@@ -13,14 +14,14 @@ class CoreWorker;
 /// The interface that contains all `CoreWorker` methods that are related to object store.
 class CoreWorkerObjectInterface {
  public:
-  CoreWorkerObjectInterface(CoreWorker &core_worker) : core_worker_(core_worker) {}
+  CoreWorkerObjectInterface(CoreWorker &core_worker);
 
   /// Put an object into object store.
   ///
   /// \param[in] buffer Data buffer of the object.
   /// \param[out] object_id Generated ID of the object.
   /// \return Status.
-  Status Put(const Buffer &buffer, const ObjectID *object_id);
+  Status Put(const Buffer &buffer, ObjectID *object_id);
 
   /// Get a list of objects from the object store.
   ///
@@ -29,7 +30,7 @@ class CoreWorkerObjectInterface {
   /// \param[out] results Result list of objects data.
   /// \return Status.
   Status Get(const std::vector<ObjectID> &ids, int64_t timeout_ms,
-             std::vector<Buffer> *results);
+             std::vector<std::shared_ptr<Buffer>> *results);
 
   /// Wait for a list of objects to appear in the object store.
   ///
diff --git a/src/ray/gcs/redis_module/ray_redis_module.cc b/src/ray/gcs/redis_module/ray_redis_module.cc
index 6a7742c6b5a4..13450a4b7642 100644
--- a/src/ray/gcs/redis_module/ray_redis_module.cc
+++ b/src/ray/gcs/redis_module/ray_redis_module.cc
@@ -791,7 +791,7 @@ int TableCancelNotifications_RedisCommand(RedisModuleCtx *ctx, RedisModuleString
   return REDISMODULE_OK;
 }
 
-Status is_nil(bool *out, const std::string &data) {
+Status IsNil(bool *out, const std::string &data) {
   if (data.size() != kUniqueIDSize) {
     return Status::RedisError("Size of data doesn't match size of UniqueID");
   }
@@ -836,7 +836,7 @@ int TableTestAndUpdate_RedisCommand(RedisModuleCtx *ctx, RedisModuleString **arg
                    static_cast<int>(update->test_state_bitmask());
 
   bool is_nil_result;
-  REPLY_AND_RETURN_IF_NOT_OK(is_nil(&is_nil_result, update->test_raylet_id()->str()));
+  REPLY_AND_RETURN_IF_NOT_OK(IsNil(&is_nil_result, update->test_raylet_id()->str()));
   if (!is_nil_result) {
     do_update = do_update && update->test_raylet_id()->str() == data->raylet_id()->str();
   }
diff --git a/src/ray/status.h b/src/ray/status.h
index fb6252b34667..340ffb3112cc 100644
--- a/src/ray/status.h
+++ b/src/ray/status.h
@@ -54,6 +54,17 @@
 // This macro is used to replace the "ARROW_CHECK_OK" macro.
 #define RAY_ARROW_CHECK_OK(s) RAY_ARROW_CHECK_OK_PREPEND(s, "Bad status")
 
+// If arrow status is not ok, return a ray IOError status
+// with the error message.
+#define RAY_ARROW_RETURN_NOT_OK(s)               \
+  do {                                           \
+    ::arrow::Status _s = (s);                    \
+    if (RAY_PREDICT_FALSE(!_s.ok())) {           \
+      return ray::Status::IOError(_s.message()); \
+      ;                                          \
+    }                                            \
+  } while (0)
+
 namespace ray {
 
 enum class StatusCode : char {
diff --git a/src/ray/test/run_core_worker_tests.sh b/src/ray/test/run_core_worker_tests.sh
new file mode 100644
index 000000000000..5f1dd2eda69f
--- /dev/null
+++ b/src/ray/test/run_core_worker_tests.sh
@@ -0,0 +1,47 @@
+#!/usr/bin/env bash
+
+# This needs to be run in the root directory.
+
+# Cause the script to exit if a single command fails.
+set -e
+set -x
+
+bazel build "//:core_worker_test" "//:raylet" "//:libray_redis_module.so" "@plasma//:plasma_store_server"
+
+# Get the directory in which this script is executing.
+SCRIPT_DIR="`dirname \"$0\"`"
+RAY_ROOT="$SCRIPT_DIR/../../.."
+# Makes $RAY_ROOT an absolute path.
+RAY_ROOT="`( cd \"$RAY_ROOT\" && pwd )`"
+if [ -z "$RAY_ROOT" ] ; then
+  exit 1
+fi
+# Ensure we're in the right directory.
+if [ ! -d "$RAY_ROOT/python" ]; then
+  echo "Unable to find root Ray directory. Has this script moved?"
+  exit 1
+fi
+
+REDIS_MODULE="./bazel-bin/libray_redis_module.so"
+LOAD_MODULE_ARGS="--loadmodule ${REDIS_MODULE}"
+STORE_EXEC="./bazel-bin/external/plasma/plasma_store_server"
+RAYLET_EXEC="./bazel-bin/raylet"
+
+# Allow cleanup commands to fail.
+bazel run //:redis-cli -- -p 6379 shutdown || true
+sleep 1s
+bazel run //:redis-cli -- -p 6380 shutdown || true
+sleep 1s
+bazel run //:redis-server -- --loglevel warning ${LOAD_MODULE_ARGS} --port 6379 &
+sleep 2s
+bazel run //:redis-server -- --loglevel warning ${LOAD_MODULE_ARGS} --port 6380 &
+sleep 2s
+# Run tests.
+./bazel-bin/core_worker_test $STORE_EXEC $RAYLET_EXEC
+sleep 1s
+bazel run //:redis-cli -- -p 6379 shutdown
+bazel run //:redis-cli -- -p 6380 shutdown
+sleep 1s
+
+# Include raylet integration test once it's ready.
+# ./bazel-bin/object_manager_integration_test $STORE_EXEC