diff --git a/kmip/core/exceptions.py b/kmip/core/exceptions.py
index 00ae0b9..0b4f42e 100644
--- a/kmip/core/exceptions.py
+++ b/kmip/core/exceptions.py
@@ -53,7 +53,8 @@ class CryptographicFailure(KmipError):
         """
         super(CryptographicFailure, self).__init__(
             reason=enums.ResultReason.CRYPTOGRAPHIC_FAILURE,
-            message=message)
+            message=message
+        )
 
 
 class InvalidField(KmipError):
@@ -70,7 +71,44 @@ class InvalidField(KmipError):
         """
         super(InvalidField, self).__init__(
             reason=enums.ResultReason.INVALID_FIELD,
-            message=message)
+            message=message
+        )
+
+
+class InvalidMessage(KmipError):
+    """
+    An error generated when an invalid message is processed.
+    """
+
+    def __init__(self, message):
+        """
+        Create an InvalidMessage exception.
+
+        Args:
+            message (string): A string containing information about the error.
+        """
+        super(InvalidMessage, self).__init__(
+            reason=enums.ResultReason.INVALID_MESSAGE,
+            message=message
+        )
+
+
+class OperationNotSupported(KmipError):
+    """
+    An error generated when an unsupported operation is invoked.
+    """
+
+    def __init__(self, message):
+        """
+        Create an OperationNotSupported exception.
+
+        Args:
+            message (string): A string containing information about the error.
+        """
+        super(OperationNotSupported, self).__init__(
+            reason=enums.ResultReason.OPERATION_NOT_SUPPORTED,
+            message=message
+        )
 
 
 class InvalidKmipEncoding(Exception):
diff --git a/kmip/services/server/engine.py b/kmip/services/server/engine.py
new file mode 100644
index 0000000..9443a9e
--- /dev/null
+++ b/kmip/services/server/engine.py
@@ -0,0 +1,420 @@
+# Copyright (c) 2016 The Johns Hopkins University/Applied Physics Laboratory
+# All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License. You may obtain
+# a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+
+import logging
+import threading
+import time
+
+import kmip
+
+from kmip.core import enums
+from kmip.core import exceptions
+
+from kmip.core.messages import contents
+from kmip.core.messages import messages
+
+from kmip.core.messages.payloads import discover_versions
+from kmip.core.messages.payloads import query
+
+from kmip.core import misc
+
+from kmip.services.server.crypto import engine
+
+
+class KmipEngine(object):
+    """
+    A KMIP request processor that acts as the core of the KmipServer.
+
+    The KmipEngine contains the core application logic for the KmipServer.
+    It processes all KMIP requests and maintains consistent state across
+    client connections.
+
+    Features that are not supported:
+        * KMIP versions > 1.1
+        * Numerous operations, objects, and attributes.
+        * User authentication
+        * Batch processing options: UNDO
+        * Asynchronous operations
+    """
+
+    def __init__(self):
+        """
+        Create a KmipEngine.
+        """
+        self._logger = logging.getLogger(__name__)
+
+        self._cryptography_engine = engine.CryptographyEngine()
+        self._lock = threading.RLock()
+
+        self._id_placeholder = None
+
+        self._protocol_versions = [
+            contents.ProtocolVersion.create(1, 2),
+            contents.ProtocolVersion.create(1, 1),
+            contents.ProtocolVersion.create(1, 0)
+        ]
+
+        self._protocol_version = self._protocol_versions[0]
+
+    def _kmip_version_supported(supported):
+        def decorator(function):
+            def wrapper(self, *args, **kwargs):
+                if float(str(self._protocol_version)) < float(supported):
+                    name = function.__name__
+                    operation = ''.join(
+                        [x.capitalize() for x in name[9:].split('_')]
+                    )
+                    raise exceptions.OperationNotSupported(
+                        "{0} is not supported by KMIP {1}".format(
+                            operation,
+                            self._protocol_version
+                        )
+                    )
+                else:
+                    return function(self, *args, **kwargs)
+            return wrapper
+        return decorator
+
+    def _synchronize(function):
+        def decorator(self, *args, **kwargs):
+            with self._lock:
+                return function(self, *args, **kwargs)
+        return decorator
+
+    def _set_protocol_version(self, protocol_version):
+        if protocol_version in self._protocol_versions:
+            self._protocol_version = protocol_version
+        else:
+            raise exceptions.InvalidMessage(
+                "KMIP {0} is not supported by the server.".format(
+                    protocol_version
+                )
+            )
+
+    def _verify_credential(self, request_credential, connection_credential):
+        # TODO (peterhamilton) Add authentication support
+        # 1. If present, verify user ID of connection_credential is valid user.
+        # 2. If present, verify request_credential is valid credential.
+        # 3. If both present, verify that they are compliant with each other.
+        # 4. If neither present, set server to only allow Query operations.
+        pass
+
+    @_synchronize
+    def process_request(self, request, credential=None):
+        """
+        Process a KMIP request message.
+
+        This routine is the main driver of the KmipEngine. It breaks apart and
+        processes the request header, handles any message errors that may
+        result, and then passes the set of request batch items on for
+        processing. This routine is thread-safe, allowing multiple client
+        connections to use the same KmipEngine.
+
+        Args:
+            request (RequestMessage): The request message containing the batch
+                items to be processed.
+            credential (Credential): A credential containing any identifying
+                information about the client obtained from the client
+                certificate. Optional, defaults to None.
+
+        Returns:
+            ResponseMessage: The response containing all of the results from
+                the request batch items.
+        """
+        header = request.request_header
+
+        # Process the protocol version
+        self._set_protocol_version(header.protocol_version)
+
+        # Process the maximum response size
+        max_response_size = None
+        if header.maximum_response_size:
+            max_response_size = header.maximum_response_size.value
+
+        # Process the time stamp
+        now = int(time.time())
+        if header.time_stamp:
+            then = header.time_stamp.value
+
+            if (now >= then) and ((now - then) < 60):
+                self._logger.info("Received request at time: {0}".format(
+                    time.strftime(
+                        "%Y-%m-%d %H:%M:%S",
+                        time.gmtime(then)
+                    )
+                ))
+            else:
+                if now < then:
+                    self._logger.warning(
+                        "Received request with future timestamp. Received "
+                        "timestamp: {0}, Current timestamp: {1}".format(
+                            then,
+                            now
+                        )
+                    )
+
+                    raise exceptions.InvalidMessage(
+                        "Future request rejected by server."
+                    )
+                else:
+                    self._logger.warning(
+                        "Received request with old timestamp. Possible "
+                        "replay attack. Received timestamp: {0}, Current "
+                        "timestamp: {1}".format(then, now)
+                    )
+
+                    raise exceptions.InvalidMessage(
+                        "Stale request rejected by server."
+                    )
+        else:
+            self._logger.info("Received request at time: {0}".format(
+                time.strftime(
+                    "%Y-%m-%d %H:%M:%S",
+                    time.gmtime(now)
+                )
+            ))
+
+        # Process the asynchronous indicator
+        self.is_asynchronous = False
+        if header.asynchronous_indicator is not None:
+            self.is_asynchronous = header.asynchronous_indicator.value
+
+        if self.is_asynchronous:
+            raise exceptions.InvalidMessage(
+                "Asynchronous operations are not supported."
+            )
+
+        # Process the authentication credentials
+        auth_credentials = header.authentication.credential
+        self._verify_credential(auth_credentials, credential)
+
+        # Process the batch error continuation option
+        batch_error_option = enums.BatchErrorContinuationOption.STOP
+        if header.batch_error_cont_option is not None:
+            batch_error_option = header.batch_error_cont_option.value
+
+        if batch_error_option == enums.BatchErrorContinuationOption.UNDO:
+            raise exceptions.InvalidMessage(
+                "Undo option for batch handling is not supported."
+            )
+
+        # Process the batch order option
+        batch_order_option = False
+        if header.batch_order_option:
+            batch_order_option = header.batch_order_option.value
+
+        response_batch = self._process_batch(
+            request.batch_items,
+            batch_error_option,
+            batch_order_option
+        )
+        response = self._build_response(
+            header.protocol_version,
+            response_batch
+        )
+
+        return response, max_response_size
+
+    def _build_response(self, version, batch_items):
+        header = messages.ResponseHeader(
+            protocol_version=version,
+            time_stamp=contents.TimeStamp(int(time.time())),
+            batch_count=contents.BatchCount(len(batch_items))
+        )
+        message = messages.ResponseMessage(
+            response_header=header,
+            batch_items=batch_items
+        )
+        return message
+
+    def build_error_response(self, version, reason, message):
+        """
+        Build a simple ResponseMessage with a single error result.
+
+        Args:
+            version (ProtocolVersion): The protocol version the response
+                should be addressed with.
+            reason (ResultReason): An enumeration classifying the type of
+                error occurred.
+            message (str): A string providing additional information about
+                the error.
+
+        Returns:
+            ResponseMessage: The simple ResponseMessage containing a
+                single error result.
+        """
+        batch_item = messages.ResponseBatchItem(
+            result_status=contents.ResultStatus(
+                enums.ResultStatus.OPERATION_FAILED
+            ),
+            result_reason=contents.ResultReason(reason),
+            result_message=contents.ResultMessage(message)
+        )
+        return self._build_response(version, [batch_item])
+
+    def _process_batch(self, request_batch, batch_handling, batch_order):
+        response_batch = list()
+        for batch_item in request_batch:
+            error_occurred = False
+
+            response_payload = None
+            result_status = None
+            result_reason = None
+            result_message = None
+
+            operation = batch_item.operation
+            request_payload = batch_item.request_payload
+
+            # Process batch item ID.
+            if len(request_batch) > 1:
+                if not batch_item.unique_batch_item_id:
+                    raise exceptions.InvalidMessage(
+                        "Batch item ID is undefined."
+                    )
+
+            # Process batch message extension.
+            # TODO (peterhamilton) Add support for message extension handling.
+            # 1. Extract the vendor identification and criticality indicator.
+            # 2. If the indicator is True, raise an error.
+            # 3. If the indicator is False, ignore the extension.
+
+            # Process batch payload.
+            try:
+                response_payload = self._process_operation(
+                    operation.value,
+                    request_payload
+                )
+
+                result_status = enums.ResultStatus.SUCCESS
+            except exceptions.KmipError as e:
+                error_occurred = True
+                result_status = e.status
+                result_reason = e.reason
+                result_message = str(e)
+            except Exception as e:
+                self._logger.warning(
+                    "Error occurred while processing operation."
+                )
+                self._logger.exception(e)
+
+                error_occurred = True
+                result_status = enums.ResultStatus.OPERATION_FAILED
+                result_reason = enums.ResultReason.GENERAL_FAILURE
+                result_message = (
+                    "Operation failed. See the server logs for more "
+                    "information."
+                )
+
+            # Compose operation result.
+            result_status = contents.ResultStatus(result_status)
+            if result_reason:
+                result_reason = contents.ResultReason(result_reason)
+            if result_message:
+                result_message = contents.ResultMessage(result_message)
+
+            batch_item = messages.ResponseBatchItem(
+                operation=batch_item.operation,
+                unique_batch_item_id=batch_item.unique_batch_item_id,
+                result_status=result_status,
+                result_reason=result_reason,
+                result_message=result_message,
+                response_payload=response_payload
+            )
+            response_batch.append(batch_item)
+
+            # Handle batch error if necessary.
+            if error_occurred:
+                if batch_handling == enums.BatchErrorContinuationOption.STOP:
+                    break
+
+        return response_batch
+
+    def _process_operation(self, operation, payload):
+        if operation == enums.Operation.QUERY:
+            return self._process_query(payload)
+        elif operation == enums.Operation.DISCOVER_VERSIONS:
+            return self._process_discover_versions(payload)
+        else:
+            raise exceptions.OperationNotSupported(
+                "{0} operation is not supported by the server.".format(
+                    operation.name.title()
+                )
+            )
+
+    @_kmip_version_supported('1.0')
+    def _process_query(self, payload):
+        self._logger.info("Processing operation: Query")
+
+        queries = [x.value for x in payload.query_functions]
+
+        operations = list()
+        objects = list()
+        vendor_identification = None
+        server_information = None
+        namespaces = list()
+        extensions = list()
+
+        if enums.QueryFunction.QUERY_OPERATIONS in queries:
+            operations = list([
+                contents.Operation(enums.Operation.QUERY)
+            ])
+
+            if self._protocol_version == contents.ProtocolVersion.create(1, 1):
+                operations.extend([
+                    contents.Operation(enums.Operation.DISCOVER_VERSIONS)
+                ])
+
+        if enums.QueryFunction.QUERY_OBJECTS in queries:
+            objects = list()
+        if enums.QueryFunction.QUERY_SERVER_INFORMATION in queries:
+            vendor_identification = misc.VendorIdentification(
+                "PyKMIP {0} Software Server".format(kmip.__version__)
+            )
+            server_information = None
+        if enums.QueryFunction.QUERY_APPLICATION_NAMESPACES in queries:
+            namespaces = list()
+        if enums.QueryFunction.QUERY_EXTENSION_LIST in queries:
+            extensions = list()
+        if enums.QueryFunction.QUERY_EXTENSION_MAP in queries:
+            extensions = list()
+
+        response_payload = query.QueryResponsePayload(
+            operations=operations,
+            object_types=objects,
+            vendor_identification=vendor_identification,
+            server_information=server_information,
+            application_namespaces=namespaces,
+            extension_information=extensions
+        )
+
+        return response_payload
+
+    @_kmip_version_supported('1.1')
+    def _process_discover_versions(self, payload):
+        self._logger.info("Processing operation: DiscoverVersions")
+        supported_versions = list()
+
+        if len(payload.protocol_versions) > 0:
+            for version in payload.protocol_versions:
+                if version in self._protocol_versions:
+                    supported_versions.append(version)
+        else:
+            supported_versions = self._protocol_versions
+
+        response_payload = discover_versions.DiscoverVersionsResponsePayload(
+            protocol_versions=supported_versions
+        )
+
+        return response_payload
diff --git a/kmip/tests/unit/services/server/test_engine.py b/kmip/tests/unit/services/server/test_engine.py
new file mode 100644
index 0000000..f13baed
--- /dev/null
+++ b/kmip/tests/unit/services/server/test_engine.py
@@ -0,0 +1,772 @@
+# Copyright (c) 2016 The Johns Hopkins University/Applied Physics Laboratory
+# All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License. You may obtain
+# a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+
+import mock
+import testtools
+import time
+
+import kmip
+
+from kmip.core import enums
+from kmip.core import exceptions
+from kmip.core import misc
+from kmip.core import objects
+
+from kmip.core.messages import contents
+from kmip.core.messages import messages
+
+from kmip.core.messages.payloads import discover_versions
+from kmip.core.messages.payloads import query
+
+from kmip.services.server import engine
+
+
+class MockRegexString(str):
+    """
+    A comparator string for doing simple containment regex comparisons
+    for mock asserts.
+    """
+    def __eq__(self, other):
+        return self in other
+
+
+class TestKmipEngine(testtools.TestCase):
+    """
+    A test suite for the KmipEngine.
+    """
+
+    def setUp(self):
+        super(TestKmipEngine, self).setUp()
+
+    def tearDown(self):
+        super(TestKmipEngine, self).tearDown()
+
+    def _build_request(self):
+        payload = discover_versions.DiscoverVersionsRequestPayload()
+        batch = [
+            messages.RequestBatchItem(
+                operation=contents.Operation(
+                    enums.Operation.DISCOVER_VERSIONS
+                ),
+                request_payload=payload
+            )
+        ]
+
+        protocol = contents.ProtocolVersion.create(1, 0)
+        max_size = contents.MaximumResponseSize(2 ** 20)
+        asynch = contents.AsynchronousIndicator(False)
+
+        # TODO (peterhamilton) Change this insanity in the substructs.
+        username = objects.Credential.UsernamePasswordCredential.Username(
+            "tester"
+        )
+        password = objects.Credential.UsernamePasswordCredential.Password(
+            "password"
+        )
+        creds = objects.Credential.UsernamePasswordCredential(
+            username=username,
+            password=password
+        )
+        auth = contents.Authentication(creds)
+
+        batch_error_option = contents.BatchErrorContinuationOption(
+            enums.BatchErrorContinuationOption.STOP
+        )
+        batch_order_option = contents.BatchOrderOption(True)
+        timestamp = contents.TimeStamp(int(time.time()))
+
+        header = messages.RequestHeader(
+            protocol_version=protocol,
+            maximum_response_size=max_size,
+            asynchronous_indicator=asynch,
+            authentication=auth,
+            batch_error_cont_option=batch_error_option,
+            batch_order_option=batch_order_option,
+            time_stamp=timestamp,
+            batch_count=contents.BatchCount(len(batch))
+        )
+
+        return messages.RequestMessage(
+            request_header=header,
+            batch_items=batch
+        )
+
+    def test_init(self):
+        """
+        Test that a KmipEngine can be instantiated without any errors.
+        """
+        engine.KmipEngine()
+
+    def test_version_operation_match(self):
+        """
+        Test that a valid response is generated when trying to invoke an
+        operation supported by a specific version of KMIP.
+        """
+        e = engine.KmipEngine()
+        e._logger = mock.MagicMock()
+
+        payload = discover_versions.DiscoverVersionsRequestPayload()
+        e._process_discover_versions(payload)
+
+    def test_version_operation_mismatch(self):
+        """
+        Test that an OperationNotSupported error is generated when trying to
+        invoke an operation unsupported by a specific version of KMIP.
+        """
+        e = engine.KmipEngine()
+        e._logger = mock.MagicMock()
+        e._protocol_version = contents.ProtocolVersion.create(1, 0)
+
+        args = (None, )
+        regex = "DiscoverVersions is not supported by KMIP {0}".format(
+            e._protocol_version
+        )
+        self.assertRaisesRegexp(
+            exceptions.OperationNotSupported,
+            regex,
+            e._process_discover_versions,
+            *args
+        )
+
+    def test_process_request(self):
+        """
+        Test that a basic request is processed correctly.
+        """
+        e = engine.KmipEngine()
+        e._logger = mock.MagicMock()
+
+        protocol = contents.ProtocolVersion.create(1, 1)
+        header = messages.RequestHeader(
+            protocol_version=protocol,
+            maximum_response_size=contents.MaximumResponseSize(2 ** 20),
+            authentication=contents.Authentication(),
+            batch_error_cont_option=contents.BatchErrorContinuationOption(
+                enums.BatchErrorContinuationOption.STOP
+            ),
+            batch_order_option=contents.BatchOrderOption(True),
+            time_stamp=contents.TimeStamp(int(time.time())),
+            batch_count=contents.BatchCount(1)
+        )
+        payload = discover_versions.DiscoverVersionsRequestPayload()
+        batch = list([
+            messages.RequestBatchItem(
+                operation=contents.Operation(
+                    enums.Operation.DISCOVER_VERSIONS
+                ),
+                request_payload=payload
+            )
+        ])
+        request = messages.RequestMessage(
+            request_header=header,
+            batch_items=batch
+        )
+
+        response, max_size = e.process_request(request)
+
+        e._logger.info.assert_any_call(
+            MockRegexString("Received request at time:")
+        )
+        e._logger.info.assert_any_call(
+            "Processing operation: DiscoverVersions"
+        )
+        self.assertIsInstance(response, messages.ResponseMessage)
+        self.assertEqual(2 ** 20, max_size)
+        self.assertIsNotNone(response.response_header)
+
+        header = response.response_header
+
+        self.assertIsNotNone(header)
+        self.assertEqual(
+            contents.ProtocolVersion.create(1, 1),
+            header.protocol_version
+        )
+        self.assertIsInstance(header.time_stamp, contents.TimeStamp)
+        self.assertIsInstance(header.batch_count, contents.BatchCount)
+        self.assertEqual(1, header.batch_count.value)
+
+        batch = response.batch_items
+
+        self.assertNotEqual(list(), batch)
+
+        batch_item = batch[0]
+
+        self.assertIsInstance(batch_item.operation, contents.Operation)
+        self.assertEqual(
+            enums.Operation.DISCOVER_VERSIONS,
+            batch_item.operation.value
+        )
+        self.assertIsNone(batch_item.unique_batch_item_id)
+        self.assertEqual(
+            enums.ResultStatus.SUCCESS,
+            batch_item.result_status.value
+        )
+        self.assertIsNone(batch_item.result_reason)
+        self.assertIsNone(batch_item.result_message)
+        self.assertIsNone(batch_item.async_correlation_value)
+        self.assertIsInstance(
+            batch_item.response_payload,
+            discover_versions.DiscoverVersionsResponsePayload
+        )
+        self.assertIsNone(batch_item.message_extension)
+
+    def test_process_request_unsupported_version(self):
+        """
+        Test that an InvalidMessage exception is raised when processing a
+        request using an unsupported KMIP version.
+        """
+        e = engine.KmipEngine()
+        e._logger = mock.MagicMock()
+
+        protocol = contents.ProtocolVersion.create(0, 1)
+        header = messages.RequestHeader(
+            protocol_version=protocol
+        )
+        request = messages.RequestMessage(
+            request_header=header
+        )
+
+        args = (request, )
+        regex = "KMIP {0} is not supported by the server.".format(
+            protocol
+        )
+        self.assertRaisesRegexp(
+            exceptions.InvalidMessage,
+            regex,
+            e.process_request,
+            *args
+        )
+
+    def test_process_request_stale_timestamp(self):
+        """
+        Test that an InvalidMessage exception is raised when processing a
+        request with a stale timestamp.
+        """
+        e = engine.KmipEngine()
+        e._logger = mock.MagicMock()
+
+        protocol = contents.ProtocolVersion.create(1, 0)
+        header = messages.RequestHeader(
+            protocol_version=protocol,
+            time_stamp=contents.TimeStamp(0)
+        )
+        request = messages.RequestMessage(
+            request_header=header
+        )
+
+        args = (request, )
+        regex = "Stale request rejected by server."
+        self.assertRaisesRegexp(
+            exceptions.InvalidMessage,
+            regex,
+            e.process_request,
+            *args
+        )
+
+        e._logger.warning.assert_any_call(
+            MockRegexString(
+                "Received request with old timestamp. Possible replay attack."
+            )
+        )
+
+    def test_process_request_future_timestamp(self):
+        """
+        Test that an InvalidMessage exception is raised when processing a
+        request with a future timestamp.
+        """
+        e = engine.KmipEngine()
+        e._logger = mock.MagicMock()
+
+        protocol = contents.ProtocolVersion.create(1, 0)
+        header = messages.RequestHeader(
+            protocol_version=protocol,
+            time_stamp=contents.TimeStamp(10 ** 10)
+        )
+        request = messages.RequestMessage(
+            request_header=header
+        )
+
+        args = (request, )
+        regex = "Future request rejected by server."
+        self.assertRaisesRegexp(
+            exceptions.InvalidMessage,
+            regex,
+            e.process_request,
+            *args
+        )
+
+        e._logger.warning.assert_any_call(
+            MockRegexString(
+                "Received request with future timestamp."
+            )
+        )
+
+    def test_process_request_unsupported_async_indicator(self):
+        """
+        Test than an InvalidMessage error is generated while processing a
+        batch with an unsupported asynchronous indicator option.
+        """
+        e = engine.KmipEngine()
+        e._logger = mock.MagicMock()
+
+        protocol = contents.ProtocolVersion.create(1, 1)
+        header = messages.RequestHeader(
+            protocol_version=protocol,
+            asynchronous_indicator=contents.AsynchronousIndicator(True)
+        )
+        request = messages.RequestMessage(
+            request_header=header,
+        )
+
+        args = (request, )
+        regex = "Asynchronous operations are not supported."
+        self.assertRaisesRegexp(
+            exceptions.InvalidMessage,
+            regex,
+            e.process_request,
+            *args
+        )
+
+    def test_process_request_unsupported_batch_option(self):
+        """
+        Test that an InvalidMessage error is generated while processing a
+        batch with an unsupported batch error continuation option.
+        """
+        e = engine.KmipEngine()
+        e._logger = mock.MagicMock()
+
+        protocol = contents.ProtocolVersion.create(1, 1)
+        header = messages.RequestHeader(
+            protocol_version=protocol,
+            authentication=contents.Authentication(),
+            batch_error_cont_option=contents.BatchErrorContinuationOption(
+                enums.BatchErrorContinuationOption.UNDO
+            )
+        )
+        request = messages.RequestMessage(
+            request_header=header,
+        )
+
+        args = (request, )
+        regex = "Undo option for batch handling is not supported."
+        self.assertRaisesRegexp(
+            exceptions.InvalidMessage,
+            regex,
+            e.process_request,
+            *args
+        )
+
+    def test_build_error_response(self):
+        """
+        Test that a bare bones response containing a single error result can
+        be constructed correctly.
+        """
+        e = engine.KmipEngine()
+        e._logger = mock.MagicMock()
+
+        response = e.build_error_response(
+            contents.ProtocolVersion.create(1, 1),
+            enums.ResultReason.GENERAL_FAILURE,
+            "A general test failure occurred."
+        )
+
+        self.assertIsInstance(response, messages.ResponseMessage)
+
+        header = response.response_header
+
+        self.assertEqual(
+            contents.ProtocolVersion.create(1, 1),
+            header.protocol_version
+        )
+        self.assertIsNotNone(header.time_stamp)
+        self.assertIsNotNone(header.batch_count)
+        self.assertEqual(1, header.batch_count.value)
+
+        batch = response.batch_items
+
+        self.assertEqual(1, len(batch))
+
+        batch_item = batch[0]
+
+        self.assertIsNone(batch_item.operation)
+        self.assertIsNone(batch_item.unique_batch_item_id)
+        self.assertEqual(
+            enums.ResultStatus.OPERATION_FAILED,
+            batch_item.result_status.value
+        )
+        self.assertEqual(
+            enums.ResultReason.GENERAL_FAILURE,
+            batch_item.result_reason.value
+        )
+        self.assertEqual(
+            "A general test failure occurred.",
+            batch_item.result_message.value
+        )
+        self.assertIsNone(batch_item.async_correlation_value)
+        self.assertIsNone(batch_item.response_payload)
+        self.assertIsNone(batch_item.message_extension)
+
+    def test_process_batch(self):
+        """
+        Test that a batch is processed correctly.
+        """
+        e = engine.KmipEngine()
+        e._logger = mock.MagicMock()
+
+        payload = discover_versions.DiscoverVersionsRequestPayload()
+        batch = list([
+            messages.RequestBatchItem(
+                operation=contents.Operation(
+                    enums.Operation.DISCOVER_VERSIONS
+                ),
+                request_payload=payload
+            )
+        ])
+
+        results = e._process_batch(
+            batch,
+            enums.BatchErrorContinuationOption.STOP,
+            True
+        )
+
+        self.assertIsNotNone(results)
+        self.assertEqual(1, len(results))
+
+    def test_process_multibatch(self):
+        """
+        Test that a batch containing multiple operations is processed
+        correctly.
+        """
+        e = engine.KmipEngine()
+        e._logger = mock.MagicMock()
+
+        payload = discover_versions.DiscoverVersionsRequestPayload()
+        batch = list([
+            messages.RequestBatchItem(
+                operation=contents.Operation(
+                    enums.Operation.DISCOVER_VERSIONS
+                ),
+                unique_batch_item_id=contents.UniqueBatchItemID(1),
+                request_payload=payload
+            ),
+            messages.RequestBatchItem(
+                operation=contents.Operation(
+                    enums.Operation.DISCOVER_VERSIONS
+                ),
+                unique_batch_item_id=contents.UniqueBatchItemID(2),
+                request_payload=payload
+            )
+        ])
+
+        results = e._process_batch(
+            batch,
+            enums.BatchErrorContinuationOption.STOP,
+            True
+        )
+
+        self.assertIsNotNone(results)
+        self.assertEqual(2, len(results))
+
+    def test_process_batch_missing_batch_id(self):
+        """
+        Test that an InvalidMessage error is generated while processing a
+        batch with missing batch IDs.
+        """
+        e = engine.KmipEngine()
+        e._logger = mock.MagicMock()
+
+        batch = list([
+            messages.RequestBatchItem(),
+            messages.RequestBatchItem()
+        ])
+
+        args = (batch, None, None)
+        self.assertRaisesRegexp(
+            exceptions.InvalidMessage,
+            "Batch item ID is undefined.",
+            e._process_batch,
+            *args
+        )
+
+    def test_process_batch_expected_error(self):
+        """
+        Test than an expected KMIP error is handled appropriately while
+        processing a batch of operations.
+        """
+        e = engine.KmipEngine()
+        e._logger = mock.MagicMock()
+        e._protocol_version = contents.ProtocolVersion.create(1, 0)
+
+        batch = list([
+            messages.RequestBatchItem(
+                operation=contents.Operation(
+                    enums.Operation.DISCOVER_VERSIONS
+                )
+            )
+        ])
+
+        results = e._process_batch(
+            batch,
+            enums.BatchErrorContinuationOption.STOP,
+            True
+        )
+
+        self.assertIsNotNone(results)
+        self.assertEqual(1, len(results))
+
+        result = results[0]
+
+        self.assertIsInstance(result, messages.ResponseBatchItem)
+        self.assertIsNotNone(result.operation)
+        self.assertEqual(
+            enums.Operation.DISCOVER_VERSIONS,
+            result.operation.value
+        )
+        self.assertIsNone(result.unique_batch_item_id)
+        self.assertIsNotNone(result.result_status)
+        self.assertEqual(
+            enums.ResultStatus.OPERATION_FAILED,
+            result.result_status.value
+        )
+        self.assertIsNotNone(result.result_reason)
+        self.assertEqual(
+            enums.ResultReason.OPERATION_NOT_SUPPORTED,
+            result.result_reason.value
+        )
+        self.assertIsNotNone(result.result_message)
+        error_message = "DiscoverVersions is not supported by KMIP {0}".format(
+            e._protocol_version
+        )
+        self.assertEqual(error_message, result.result_message.value)
+        self.assertIsNone(result.async_correlation_value)
+        self.assertIsNone(result.response_payload)
+        self.assertIsNone(result.message_extension)
+
+    def test_process_batch_unexpected_error(self):
+        """
+        Test that an unexpected, non-KMIP error is handled appropriately
+        while processing a batch of operations.
+        """
+        e = engine.KmipEngine()
+        e._logger = mock.MagicMock()
+
+        test_exception = Exception("A general test failure occurred.")
+        e._process_operation = mock.MagicMock(side_effect=test_exception)
+
+        batch = list([
+            messages.RequestBatchItem(
+                operation=contents.Operation(
+                    enums.Operation.DISCOVER_VERSIONS
+                )
+            )
+        ])
+
+        results = e._process_batch(
+            batch,
+            enums.BatchErrorContinuationOption.STOP,
+            True
+        )
+
+        self.assertIsNotNone(results)
+        self.assertEqual(1, len(results))
+
+        result = results[0]
+
+        e._logger.warning.assert_called_with(
+            "Error occurred while processing operation."
+        )
+        e._logger.exception.assert_called_with(test_exception)
+        self.assertIsInstance(result, messages.ResponseBatchItem)
+        self.assertIsNotNone(result.operation)
+        self.assertEqual(
+            enums.Operation.DISCOVER_VERSIONS,
+            result.operation.value
+        )
+        self.assertIsNone(result.unique_batch_item_id)
+        self.assertIsNotNone(result.result_status)
+        self.assertEqual(
+            enums.ResultStatus.OPERATION_FAILED,
+            result.result_status.value
+        )
+        self.assertIsNotNone(result.result_reason)
+        self.assertEqual(
+            enums.ResultReason.GENERAL_FAILURE,
+            result.result_reason.value
+        )
+        self.assertIsNotNone(result.result_message)
+        self.assertEqual(
+            "Operation failed. See the server logs for more information.",
+            result.result_message.value
+        )
+        self.assertIsNone(result.async_correlation_value)
+        self.assertIsNone(result.response_payload)
+        self.assertIsNone(result.message_extension)
+
+    def test_supported_operation(self):
+        """
+        Test that the right subroutine is called when invoking operations
+        supported by the server.
+        """
+        e = engine.KmipEngine()
+        e._logger = mock.MagicMock()
+
+        e._process_query = mock.MagicMock()
+        e._process_discover_versions = mock.MagicMock()
+
+        e._process_operation(enums.Operation.QUERY, None)
+        e._process_operation(enums.Operation.DISCOVER_VERSIONS, None)
+
+        e._process_query.assert_called_with(None)
+        e._process_discover_versions.assert_called_with(None)
+
+    def test_unsupported_operation(self):
+        """
+        Test that an OperationNotSupported error is generated when invoking
+        an operation not supported by the server.
+        """
+        e = engine.KmipEngine()
+        e._logger = mock.MagicMock()
+
+        args = (enums.Operation.POLL, None)
+        regex = "{0} operation is not supported by the server.".format(
+            args[0].name.title()
+        )
+        self.assertRaisesRegexp(
+            exceptions.OperationNotSupported,
+            regex,
+            e._process_operation,
+            *args
+        )
+
+    def test_query(self):
+        """
+        Test that a Query request can be processed correctly, for different
+        versions of KMIP.
+        """
+        e = engine.KmipEngine()
+
+        # Test for KMIP 1.0.
+        e._logger = mock.MagicMock()
+        e._protocol_version = contents.ProtocolVersion.create(1, 0)
+
+        payload = query.QueryRequestPayload([
+            misc.QueryFunction(enums.QueryFunction.QUERY_OPERATIONS),
+            misc.QueryFunction(enums.QueryFunction.QUERY_OBJECTS),
+            misc.QueryFunction(
+                enums.QueryFunction.QUERY_SERVER_INFORMATION
+            ),
+            misc.QueryFunction(
+                enums.QueryFunction.QUERY_APPLICATION_NAMESPACES
+            ),
+            misc.QueryFunction(enums.QueryFunction.QUERY_EXTENSION_LIST),
+            misc.QueryFunction(enums.QueryFunction.QUERY_EXTENSION_MAP)
+        ])
+
+        result = e._process_query(payload)
+
+        e._logger.info.assert_called_once_with("Processing operation: Query")
+        self.assertIsInstance(result, query.QueryResponsePayload)
+        self.assertIsNotNone(result.operations)
+        self.assertEqual(1, len(result.operations))
+        self.assertEqual(enums.Operation.QUERY, result.operations[0].value)
+        self.assertEqual(list(), result.object_types)
+        self.assertIsNotNone(result.vendor_identification)
+        self.assertEqual(
+            "PyKMIP {0} Software Server".format(kmip.__version__),
+            result.vendor_identification.value
+        )
+        self.assertIsNone(result.server_information)
+        self.assertEqual(list(), result.application_namespaces)
+        self.assertEqual(list(), result.extension_information)
+
+        # Test for KMIP 1.1.
+        e._logger = mock.MagicMock()
+        e._protocol_version = contents.ProtocolVersion.create(1, 1)
+
+        result = e._process_query(payload)
+
+        e._logger.info.assert_called_once_with("Processing operation: Query")
+        self.assertIsNotNone(result.operations)
+        self.assertEqual(2, len(result.operations))
+        self.assertEqual(enums.Operation.QUERY, result.operations[0].value)
+        self.assertEqual(
+            enums.Operation.DISCOVER_VERSIONS,
+            result.operations[1].value
+        )
+
+    def test_discover_versions(self):
+        """
+        Test that a DiscoverVersions request can be processed correctly for
+        different inputs.
+        """
+        e = engine.KmipEngine()
+
+        # Test default request.
+        e._logger = mock.MagicMock()
+        payload = discover_versions.DiscoverVersionsRequestPayload()
+
+        result = e._process_discover_versions(payload)
+
+        e._logger.info.assert_called_once_with(
+            "Processing operation: DiscoverVersions"
+        )
+        self.assertIsInstance(
+            result,
+            discover_versions.DiscoverVersionsResponsePayload
+        )
+        self.assertIsNotNone(result.protocol_versions)
+        self.assertEqual(3, len(result.protocol_versions))
+        self.assertEqual(
+            contents.ProtocolVersion.create(1, 2),
+            result.protocol_versions[0]
+        )
+        self.assertEqual(
+            contents.ProtocolVersion.create(1, 1),
+            result.protocol_versions[1]
+        )
+        self.assertEqual(
+            contents.ProtocolVersion.create(1, 0),
+            result.protocol_versions[2]
+        )
+
+        # Test detailed request.
+        e._logger = mock.MagicMock()
+        payload = discover_versions.DiscoverVersionsRequestPayload([
+            contents.ProtocolVersion.create(1, 0)
+        ])
+
+        result = e._process_discover_versions(payload)
+
+        e._logger.info.assert_called_once_with(
+            "Processing operation: DiscoverVersions"
+        )
+        self.assertIsNotNone(result.protocol_versions)
+        self.assertEqual(1, len(result.protocol_versions))
+        self.assertEqual(
+            contents.ProtocolVersion.create(1, 0),
+            result.protocol_versions[0]
+        )
+
+        # Test disjoint request.
+        e._logger = mock.MagicMock()
+        payload = discover_versions.DiscoverVersionsRequestPayload([
+            contents.ProtocolVersion.create(0, 1)
+        ])
+
+        result = e._process_discover_versions(payload)
+
+        e._logger.info.assert_called_once_with(
+            "Processing operation: DiscoverVersions"
+        )
+        self.assertEqual([], result.protocol_versions)