diff --git a/rw_core/core/api/adapter_request_handler.go b/rw_core/core/api/adapter_request_handler.go
index 7175a2b..7c03618 100644
--- a/rw_core/core/api/adapter_request_handler.go
+++ b/rw_core/core/api/adapter_request_handler.go
@@ -115,10 +115,10 @@
 			}
 		}
 	}
-	logger.Debugw("GetDevice", log.Fields{"deviceID": pID.Id, "transactionID": transactionID.Val})
+	logger.Debugw("getDevice", log.Fields{"deviceID": pID.Id, "transactionID": transactionID.Val})
 
 	// Get the device via the device manager
-	device, err := rhp.deviceMgr.GetDevice(context.TODO(), pID.Id)
+	device, err := rhp.deviceMgr.GetDevice(context.TODO(), pID)
 	if err != nil {
 		logger.Debugw("get-device-failed", log.Fields{"deviceID": pID.Id, "error": err})
 	}
diff --git a/rw_core/core/api/grpc_nbi_handler.go b/rw_core/core/api/grpc_nbi_handler.go
index 3e06cf7..55117d2 100755
--- a/rw_core/core/api/grpc_nbi_handler.go
+++ b/rw_core/core/api/grpc_nbi_handler.go
@@ -18,795 +18,97 @@
 
 import (
 	"context"
-	"encoding/hex"
 	"encoding/json"
 	"errors"
 	"github.com/golang/protobuf/ptypes/empty"
-	da "github.com/opencord/voltha-go/common/core/northbound/grpc"
 	"github.com/opencord/voltha-go/rw_core/core/adapter"
 	"github.com/opencord/voltha-go/rw_core/core/device"
-	"github.com/opencord/voltha-lib-go/v3/pkg/log"
 	"github.com/opencord/voltha-lib-go/v3/pkg/version"
 	"github.com/opencord/voltha-protos/v3/go/common"
 	"github.com/opencord/voltha-protos/v3/go/omci"
-	"github.com/opencord/voltha-protos/v3/go/openflow_13"
 	"github.com/opencord/voltha-protos/v3/go/voltha"
-	"google.golang.org/grpc/codes"
-	"google.golang.org/grpc/status"
-	"io"
-	"sync"
 )
 
-// Image related constants
-const (
-	ImageDownload       = iota
-	CancelImageDownload = iota
-	ActivateImage       = iota
-	RevertImage         = iota
-)
-
-// NBIHandler represent attributes of API handler
+// NBIHandler combines the partial API implementations in various components into a complete voltha implementation
 type NBIHandler struct {
-	deviceMgr            *device.Manager
-	logicalDeviceMgr     *device.LogicalManager
-	adapterMgr           *adapter.Manager
-	packetInQueue        chan openflow_13.PacketIn
-	changeEventQueue     chan openflow_13.ChangeEvent
-	packetInQueueDone    chan bool
-	changeEventQueueDone chan bool
-	da.DefaultAPIHandler
+	*device.Manager
+	*device.LogicalManager
+	adapterManager // *adapter.Manager
 }
 
-// NewAPIHandler creates API handler instance
-func NewAPIHandler(deviceMgr *device.Manager, logicalDeviceMgr *device.LogicalManager, adapterMgr *adapter.Manager) *NBIHandler {
+// avoid having multiple embedded types with the same name (`<package>.Manager`s conflict)
+type adapterManager struct{ *adapter.Manager }
+
+// NewNBIHandler creates API handler instance
+func NewNBIHandler(deviceMgr *device.Manager, logicalDeviceMgr *device.LogicalManager, adapterMgr *adapter.Manager) *NBIHandler {
 	return &NBIHandler{
-		deviceMgr:            deviceMgr,
-		logicalDeviceMgr:     logicalDeviceMgr,
-		adapterMgr:           adapterMgr,
-		packetInQueue:        make(chan openflow_13.PacketIn, 100),
-		changeEventQueue:     make(chan openflow_13.ChangeEvent, 100),
-		packetInQueueDone:    make(chan bool, 1),
-		changeEventQueueDone: make(chan bool, 1),
+		Manager:        deviceMgr,
+		LogicalManager: logicalDeviceMgr,
+		adapterManager: adapterManager{adapterMgr},
 	}
 }
 
-// waitForNilResponseOnSuccess is a helper function to wait for a response on channel monitorCh where an nil
-// response is expected in a successful scenario
-func waitForNilResponseOnSuccess(ctx context.Context, ch chan interface{}) (*empty.Empty, error) {
-	select {
-	case res := <-ch:
-		if res == nil {
-			return &empty.Empty{}, nil
-		} else if err, ok := res.(error); ok {
-			return &empty.Empty{}, err
-		} else {
-			logger.Warnw("unexpected-return-type", log.Fields{"result": res})
-			err = status.Errorf(codes.Internal, "%s", res)
-			return &empty.Empty{}, err
-		}
-	case <-ctx.Done():
-		logger.Debug("client-timeout")
-		return nil, ctx.Err()
-	}
-}
-
-// ListCoreInstances returns details on the running core containers
-func (handler *NBIHandler) ListCoreInstances(ctx context.Context, empty *empty.Empty) (*voltha.CoreInstances, error) {
-	logger.Debug("ListCoreInstances")
-	// TODO: unused stub
-	return &voltha.CoreInstances{}, status.Errorf(codes.NotFound, "no-core-instances")
-}
-
-// GetCoreInstance returns the details of a specific core container
-func (handler *NBIHandler) GetCoreInstance(ctx context.Context, id *voltha.ID) (*voltha.CoreInstance, error) {
-	logger.Debugw("GetCoreInstance", log.Fields{"id": id})
-	//TODO: unused stub
-	return &voltha.CoreInstance{}, status.Errorf(codes.NotFound, "core-instance-%s", id.Id)
-}
-
-// GetLogicalDevicePort returns logical device port details
-func (handler *NBIHandler) GetLogicalDevicePort(ctx context.Context, id *voltha.LogicalPortId) (*voltha.LogicalPort, error) {
-	logger.Debugw("GetLogicalDevicePort-request", log.Fields{"id": *id})
-
-	return handler.logicalDeviceMgr.GetLogicalPort(ctx, id)
-}
-
-// EnableLogicalDevicePort enables logical device port
-func (handler *NBIHandler) EnableLogicalDevicePort(ctx context.Context, id *voltha.LogicalPortId) (*empty.Empty, error) {
-	logger.Debugw("EnableLogicalDevicePort-request", log.Fields{"id": id, "test": common.TestModeKeys_api_test.String()})
-
-	ch := make(chan interface{})
-	defer close(ch)
-	go handler.logicalDeviceMgr.EnableLogicalPort(ctx, id, ch)
-	return waitForNilResponseOnSuccess(ctx, ch)
-}
-
-// DisableLogicalDevicePort disables logical device port
-func (handler *NBIHandler) DisableLogicalDevicePort(ctx context.Context, id *voltha.LogicalPortId) (*empty.Empty, error) {
-	logger.Debugw("DisableLogicalDevicePort-request", log.Fields{"id": id, "test": common.TestModeKeys_api_test.String()})
-
-	ch := make(chan interface{})
-	defer close(ch)
-	go handler.logicalDeviceMgr.DisableLogicalPort(ctx, id, ch)
-	return waitForNilResponseOnSuccess(ctx, ch)
-}
-
-// UpdateLogicalDeviceFlowTable updates logical device flow table
-func (handler *NBIHandler) UpdateLogicalDeviceFlowTable(ctx context.Context, flow *openflow_13.FlowTableUpdate) (*empty.Empty, error) {
-	logger.Debugw("UpdateLogicalDeviceFlowTable-request", log.Fields{"flow": flow, "test": common.TestModeKeys_api_test.String()})
-
-	ch := make(chan interface{})
-	defer close(ch)
-	go handler.logicalDeviceMgr.UpdateFlowTable(ctx, flow.Id, flow.FlowMod, ch)
-	return waitForNilResponseOnSuccess(ctx, ch)
-}
-
-// UpdateLogicalDeviceFlowGroupTable updates logical device flow group table
-func (handler *NBIHandler) UpdateLogicalDeviceFlowGroupTable(ctx context.Context, flow *openflow_13.FlowGroupTableUpdate) (*empty.Empty, error) {
-	logger.Debugw("UpdateLogicalDeviceFlowGroupTable-request", log.Fields{"flow": flow, "test": common.TestModeKeys_api_test.String()})
-	ch := make(chan interface{})
-	defer close(ch)
-	go handler.logicalDeviceMgr.UpdateGroupTable(ctx, flow.Id, flow.GroupMod, ch)
-	return waitForNilResponseOnSuccess(ctx, ch)
-}
-
-// GetDevice must be implemented in the read-only containers - should it also be implemented here?
-func (handler *NBIHandler) GetDevice(ctx context.Context, id *voltha.ID) (*voltha.Device, error) {
-	logger.Debugw("GetDevice-request", log.Fields{"id": id})
-	return handler.deviceMgr.GetDevice(ctx, id.Id)
-}
-
-// GetDevice must be implemented in the read-only containers - should it also be implemented here?
-
-// ListDevices retrieves the latest devices from the data model
-func (handler *NBIHandler) ListDevices(ctx context.Context, empty *empty.Empty) (*voltha.Devices, error) {
-	logger.Debug("ListDevices")
-	devices, err := handler.deviceMgr.ListDevices(ctx)
-	if err != nil {
-		logger.Errorw("Failed to list devices", log.Fields{"error": err})
-		return nil, err
-	}
-	return devices, nil
-}
-
-// ListDeviceIds returns the list of device ids managed by a voltha core
-func (handler *NBIHandler) ListDeviceIds(ctx context.Context, empty *empty.Empty) (*voltha.IDs, error) {
-	logger.Debug("ListDeviceIDs")
-	return handler.deviceMgr.ListDeviceIds()
-}
-
-//ReconcileDevices is a request to a voltha core to managed a list of devices  based on their IDs
-func (handler *NBIHandler) ReconcileDevices(ctx context.Context, ids *voltha.IDs) (*empty.Empty, error) {
-	logger.Debug("ReconcileDevices")
-
-	ch := make(chan interface{})
-	defer close(ch)
-	go handler.deviceMgr.ReconcileDevices(ctx, ids, ch)
-	return waitForNilResponseOnSuccess(ctx, ch)
-}
-
-// GetLogicalDevice provides a cloned most up to date logical device
-func (handler *NBIHandler) GetLogicalDevice(ctx context.Context, id *voltha.ID) (*voltha.LogicalDevice, error) {
-	logger.Debugw("GetLogicalDevice-request", log.Fields{"id": id})
-	return handler.logicalDeviceMgr.GetLogicalDevice(ctx, id.Id)
-}
-
-// ListLogicalDevices returns the list of all logical devices
-func (handler *NBIHandler) ListLogicalDevices(ctx context.Context, empty *empty.Empty) (*voltha.LogicalDevices, error) {
-	logger.Debug("ListLogicalDevices-request")
-	return handler.logicalDeviceMgr.ListLogicalDevices(ctx)
-}
-
-// ListAdapters returns the contents of all adapters known to the system
-func (handler *NBIHandler) ListAdapters(ctx context.Context, empty *empty.Empty) (*voltha.Adapters, error) {
-	logger.Debug("ListAdapters")
-	return handler.adapterMgr.ListAdapters(ctx)
-}
-
-// ListLogicalDeviceFlows returns the flows of logical device
-func (handler *NBIHandler) ListLogicalDeviceFlows(ctx context.Context, id *voltha.ID) (*openflow_13.Flows, error) {
-	logger.Debugw("ListLogicalDeviceFlows", log.Fields{"id": *id})
-	return handler.logicalDeviceMgr.ListLogicalDeviceFlows(ctx, id.Id)
-}
-
-// ListLogicalDeviceFlowGroups returns logical device flow groups
-func (handler *NBIHandler) ListLogicalDeviceFlowGroups(ctx context.Context, id *voltha.ID) (*openflow_13.FlowGroups, error) {
-	logger.Debugw("ListLogicalDeviceFlowGroups", log.Fields{"id": *id})
-	return handler.logicalDeviceMgr.ListLogicalDeviceFlowGroups(ctx, id.Id)
-}
-
-// ListLogicalDevicePorts returns ports of logical device
-func (handler *NBIHandler) ListLogicalDevicePorts(ctx context.Context, id *voltha.ID) (*voltha.LogicalPorts, error) {
-	logger.Debugw("ListLogicalDevicePorts", log.Fields{"logicaldeviceid": id})
-	return handler.logicalDeviceMgr.ListLogicalDevicePorts(ctx, id.Id)
-}
-
-// CreateDevice creates a new parent device in the data model
-func (handler *NBIHandler) CreateDevice(ctx context.Context, device *voltha.Device) (*voltha.Device, error) {
-	if device.MacAddress == "" && device.GetHostAndPort() == "" {
-		logger.Errorf("No Device Info Present")
-		return &voltha.Device{}, errors.New("no-device-info-present; MAC or HOSTIP&PORT")
-	}
-	logger.Debugw("create-device", log.Fields{"device": *device})
-
-	ch := make(chan interface{})
-	defer close(ch)
-	go handler.deviceMgr.CreateDevice(ctx, device, ch)
-	select {
-	case res := <-ch:
-		if res != nil {
-			if err, ok := res.(error); ok {
-				logger.Errorw("create-device-failed", log.Fields{"error": err})
-				return nil, err
-			}
-			if d, ok := res.(*voltha.Device); ok {
-				return d, nil
-			}
-		}
-		logger.Warnw("create-device-unexpected-return-type", log.Fields{"result": res})
-		err := status.Errorf(codes.Internal, "%s", res)
-		return &voltha.Device{}, err
-	case <-ctx.Done():
-		logger.Debug("createdevice-client-timeout")
-		return &voltha.Device{}, ctx.Err()
-	}
-}
-
-// EnableDevice activates a device by invoking the adopt_device API on the appropriate adapter
-func (handler *NBIHandler) EnableDevice(ctx context.Context, id *voltha.ID) (*empty.Empty, error) {
-	logger.Debugw("enabledevice", log.Fields{"id": id})
-
-	ch := make(chan interface{})
-	defer close(ch)
-	go handler.deviceMgr.EnableDevice(ctx, id, ch)
-	return waitForNilResponseOnSuccess(ctx, ch)
-}
-
-// DisableDevice disables a device along with any child device it may have
-func (handler *NBIHandler) DisableDevice(ctx context.Context, id *voltha.ID) (*empty.Empty, error) {
-	logger.Debugw("disabledevice-request", log.Fields{"id": id})
-
-	ch := make(chan interface{})
-	defer close(ch)
-	go handler.deviceMgr.DisableDevice(ctx, id, ch)
-	return waitForNilResponseOnSuccess(ctx, ch)
-}
-
-//RebootDevice invoked the reboot API to the corresponding adapter
-func (handler *NBIHandler) RebootDevice(ctx context.Context, id *voltha.ID) (*empty.Empty, error) {
-	logger.Debugw("rebootDevice-request", log.Fields{"id": id})
-
-	ch := make(chan interface{})
-	defer close(ch)
-	go handler.deviceMgr.RebootDevice(ctx, id, ch)
-	return waitForNilResponseOnSuccess(ctx, ch)
-}
-
-// DeleteDevice removes a device from the data model
-func (handler *NBIHandler) DeleteDevice(ctx context.Context, id *voltha.ID) (*empty.Empty, error) {
-	logger.Debugw("deletedevice-request", log.Fields{"id": id})
-
-	ch := make(chan interface{})
-	defer close(ch)
-	go handler.deviceMgr.DeleteDevice(ctx, id, ch)
-	return waitForNilResponseOnSuccess(ctx, ch)
-}
-
-// ListDevicePorts returns the ports details for a specific device entry
-func (handler *NBIHandler) ListDevicePorts(ctx context.Context, id *voltha.ID) (*voltha.Ports, error) {
-	logger.Debugw("listdeviceports-request", log.Fields{"id": id})
-	device, err := handler.deviceMgr.GetDevice(ctx, id.Id)
-	if err != nil {
-		return &voltha.Ports{}, err
-	}
-	ports := &voltha.Ports{}
-	ports.Items = append(ports.Items, device.Ports...)
-	return ports, nil
-}
-
-// ListDeviceFlows returns the flow details for a specific device entry
-func (handler *NBIHandler) ListDeviceFlows(ctx context.Context, id *voltha.ID) (*openflow_13.Flows, error) {
-	logger.Debugw("listdeviceflows-request", log.Fields{"id": id})
-
-	device, err := handler.deviceMgr.GetDevice(ctx, id.Id)
-	if err != nil {
-		return &openflow_13.Flows{}, err
-	}
-	flows := &openflow_13.Flows{}
-	flows.Items = append(flows.Items, device.Flows.Items...)
-	return flows, nil
-}
-
-// ListDeviceFlowGroups returns the flow group details for a specific device entry
-func (handler *NBIHandler) ListDeviceFlowGroups(ctx context.Context, id *voltha.ID) (*voltha.FlowGroups, error) {
-	logger.Debugw("ListDeviceFlowGroups", log.Fields{"deviceid": id})
-
-	if device, _ := handler.deviceMgr.GetDevice(ctx, id.Id); device != nil {
-		return device.GetFlowGroups(), nil
-	}
-	return &voltha.FlowGroups{}, status.Errorf(codes.NotFound, "device-%s", id.Id)
-}
-
-// ListDeviceGroups returns all the device groups known to the system
-func (handler *NBIHandler) ListDeviceGroups(ctx context.Context, empty *empty.Empty) (*voltha.DeviceGroups, error) {
-	logger.Debug("ListDeviceGroups")
-	return &voltha.DeviceGroups{}, errors.New("UnImplemented")
-}
-
-// GetDeviceGroup returns a specific device group entry
-func (handler *NBIHandler) GetDeviceGroup(ctx context.Context, id *voltha.ID) (*voltha.DeviceGroup, error) {
-	logger.Debug("GetDeviceGroup")
-	return &voltha.DeviceGroup{}, errors.New("UnImplemented")
-}
-
-// ListDeviceTypes returns all the device types known to the system
-func (handler *NBIHandler) ListDeviceTypes(ctx context.Context, _ *empty.Empty) (*voltha.DeviceTypes, error) {
-	logger.Debug("ListDeviceTypes")
-
-	return &voltha.DeviceTypes{Items: handler.adapterMgr.ListDeviceTypes()}, nil
-}
-
-// GetDeviceType returns the device type for a specific device entry
-func (handler *NBIHandler) GetDeviceType(ctx context.Context, id *voltha.ID) (*voltha.DeviceType, error) {
-	logger.Debugw("GetDeviceType", log.Fields{"typeid": id})
-
-	if deviceType := handler.adapterMgr.GetDeviceType(id.Id); deviceType != nil {
-		return deviceType, nil
-	}
-	return &voltha.DeviceType{}, status.Errorf(codes.NotFound, "device_type-%s", id.Id)
-}
-
-// GetVoltha returns the contents of all components (i.e. devices, logical_devices, ...)
-func (handler *NBIHandler) GetVoltha(ctx context.Context, empty *empty.Empty) (*voltha.Voltha, error) {
-
+// GetVoltha currently just returns version information
+func (handler *NBIHandler) GetVoltha(context.Context, *empty.Empty) (*voltha.Voltha, error) {
 	logger.Debug("GetVoltha")
 	/*
 	 * For now, encode all the version information into a JSON object and
 	 * pass that back as "version" so the client can get all the
 	 * information associated with the version. Long term the API should
-	 * better accomidate this, but for now this will work.
+	 * better accommodate this, but for now this will work.
 	 */
 	data, err := json.Marshal(&version.VersionInfo)
-	info := version.VersionInfo.Version
 	if err != nil {
 		logger.Warnf("Unable to encode version information as JSON: %s", err.Error())
-	} else {
-		info = string(data)
+		return &voltha.Voltha{Version: version.VersionInfo.Version}, nil
 	}
-
-	return &voltha.Voltha{
-		Version: info,
-	}, nil
+	return &voltha.Voltha{Version: string(data)}, nil
 }
 
-// processImageRequest is a helper method to execute an image download request
-func (handler *NBIHandler) processImageRequest(ctx context.Context, img *voltha.ImageDownload, requestType int) (*common.OperationResp, error) {
-	logger.Debugw("processImageDownload", log.Fields{"img": *img, "requestType": requestType})
+var errUnimplemented = errors.New("unimplemented")
 
-	failedresponse := &common.OperationResp{Code: voltha.OperationResp_OPERATION_FAILURE}
-
-	ch := make(chan interface{})
-	defer close(ch)
-	switch requestType {
-	case ImageDownload:
-		go handler.deviceMgr.DownloadImage(ctx, img, ch)
-	case CancelImageDownload:
-		go handler.deviceMgr.CancelImageDownload(ctx, img, ch)
-	case ActivateImage:
-		go handler.deviceMgr.ActivateImage(ctx, img, ch)
-	case RevertImage:
-		go handler.deviceMgr.RevertImage(ctx, img, ch)
-	default:
-		logger.Warn("invalid-request-type", log.Fields{"requestType": requestType})
-		return failedresponse, status.Errorf(codes.InvalidArgument, "%d", requestType)
-	}
-	select {
-	case res := <-ch:
-		if res != nil {
-			if err, ok := res.(error); ok {
-				return failedresponse, err
-			}
-			if opResp, ok := res.(*common.OperationResp); ok {
-				return opResp, nil
-			}
-		}
-		logger.Warnw("download-image-unexpected-return-type", log.Fields{"result": res})
-		return failedresponse, status.Errorf(codes.Internal, "%s", res)
-	case <-ctx.Done():
-		logger.Debug("downloadImage-client-timeout")
-		return &common.OperationResp{}, ctx.Err()
-	}
+func (handler *NBIHandler) ListCoreInstances(context.Context, *empty.Empty) (*voltha.CoreInstances, error) {
+	return nil, errUnimplemented
 }
-
-// DownloadImage execute an image download request
-func (handler *NBIHandler) DownloadImage(ctx context.Context, img *voltha.ImageDownload) (*common.OperationResp, error) {
-	logger.Debugw("DownloadImage-request", log.Fields{"img": *img})
-
-	return handler.processImageRequest(ctx, img, ImageDownload)
+func (handler *NBIHandler) GetCoreInstance(context.Context, *voltha.ID) (*voltha.CoreInstance, error) {
+	return nil, errUnimplemented
 }
-
-// CancelImageDownload cancels image download request
-func (handler *NBIHandler) CancelImageDownload(ctx context.Context, img *voltha.ImageDownload) (*common.OperationResp, error) {
-	logger.Debugw("cancelImageDownload-request", log.Fields{"img": *img})
-	return handler.processImageRequest(ctx, img, CancelImageDownload)
+func (handler *NBIHandler) ListDeviceGroups(context.Context, *empty.Empty) (*voltha.DeviceGroups, error) {
+	return nil, errUnimplemented
 }
-
-// ActivateImageUpdate activates image update request
-func (handler *NBIHandler) ActivateImageUpdate(ctx context.Context, img *voltha.ImageDownload) (*common.OperationResp, error) {
-	logger.Debugw("activateImageUpdate-request", log.Fields{"img": *img})
-	return handler.processImageRequest(ctx, img, ActivateImage)
+func (handler *NBIHandler) GetDeviceGroup(context.Context, *voltha.ID) (*voltha.DeviceGroup, error) {
+	return nil, errUnimplemented
 }
-
-// RevertImageUpdate reverts image update
-func (handler *NBIHandler) RevertImageUpdate(ctx context.Context, img *voltha.ImageDownload) (*common.OperationResp, error) {
-	logger.Debugw("revertImageUpdate-request", log.Fields{"img": *img})
-	return handler.processImageRequest(ctx, img, RevertImage)
+func (handler *NBIHandler) CreateEventFilter(context.Context, *voltha.EventFilter) (*voltha.EventFilter, error) {
+	return nil, errUnimplemented
 }
-
-// GetImageDownloadStatus returns status of image download
-func (handler *NBIHandler) GetImageDownloadStatus(ctx context.Context, img *voltha.ImageDownload) (*voltha.ImageDownload, error) {
-	logger.Debugw("getImageDownloadStatus-request", log.Fields{"img": *img})
-
-	failedresponse := &voltha.ImageDownload{DownloadState: voltha.ImageDownload_DOWNLOAD_UNKNOWN}
-
-	ch := make(chan interface{})
-	defer close(ch)
-	go handler.deviceMgr.GetImageDownloadStatus(ctx, img, ch)
-
-	select {
-	case res := <-ch:
-		if res != nil {
-			if err, ok := res.(error); ok {
-				return failedresponse, err
-			}
-			if downloadResp, ok := res.(*voltha.ImageDownload); ok {
-				return downloadResp, nil
-			}
-		}
-		logger.Warnw("download-image-status", log.Fields{"result": res})
-		return failedresponse, status.Errorf(codes.Internal, "%s", res)
-	case <-ctx.Done():
-		logger.Debug("downloadImage-client-timeout")
-		return failedresponse, ctx.Err()
-	}
+func (handler *NBIHandler) UpdateEventFilter(context.Context, *voltha.EventFilter) (*voltha.EventFilter, error) {
+	return nil, errUnimplemented
 }
-
-// GetImageDownload returns image download
-func (handler *NBIHandler) GetImageDownload(ctx context.Context, img *voltha.ImageDownload) (*voltha.ImageDownload, error) {
-	logger.Debugw("GetImageDownload-request", log.Fields{"img": *img})
-
-	download, err := handler.deviceMgr.GetImageDownload(ctx, img)
-	if err != nil {
-		return &voltha.ImageDownload{DownloadState: voltha.ImageDownload_DOWNLOAD_UNKNOWN}, err
-	}
-	return download, nil
+func (handler *NBIHandler) DeleteEventFilter(context.Context, *voltha.EventFilter) (*empty.Empty, error) {
+	return nil, errUnimplemented
 }
-
-// ListImageDownloads returns image downloads
-func (handler *NBIHandler) ListImageDownloads(ctx context.Context, id *voltha.ID) (*voltha.ImageDownloads, error) {
-	logger.Debugw("ListImageDownloads-request", log.Fields{"deviceId": id.Id})
-
-	downloads, err := handler.deviceMgr.ListImageDownloads(ctx, id.Id)
-	if err != nil {
-		failedResp := &voltha.ImageDownloads{
-			Items: []*voltha.ImageDownload{
-				{DownloadState: voltha.ImageDownload_DOWNLOAD_UNKNOWN},
-			},
-		}
-		return failedResp, err
-	}
-	return downloads, nil
+func (handler *NBIHandler) GetEventFilter(context.Context, *voltha.ID) (*voltha.EventFilters, error) {
+	return nil, errUnimplemented
 }
-
-// GetImages returns all images for a specific device entry
-func (handler *NBIHandler) GetImages(ctx context.Context, id *voltha.ID) (*voltha.Images, error) {
-	logger.Debugw("GetImages", log.Fields{"deviceid": id.Id})
-	device, err := handler.deviceMgr.GetDevice(ctx, id.Id)
-	if err != nil {
-		return &voltha.Images{}, err
-	}
-	return device.GetImages(), nil
+func (handler *NBIHandler) ListEventFilters(context.Context, *empty.Empty) (*voltha.EventFilters, error) {
+	return nil, errUnimplemented
 }
-
-// UpdateDevicePmConfigs updates the PM configs
-func (handler *NBIHandler) UpdateDevicePmConfigs(ctx context.Context, configs *voltha.PmConfigs) (*empty.Empty, error) {
-	logger.Debugw("UpdateDevicePmConfigs-request", log.Fields{"configs": *configs})
-
-	ch := make(chan interface{})
-	defer close(ch)
-	go handler.deviceMgr.UpdatePmConfigs(ctx, configs, ch)
-	return waitForNilResponseOnSuccess(ctx, ch)
+func (handler *NBIHandler) SelfTest(context.Context, *voltha.ID) (*voltha.SelfTestResponse, error) {
+	return nil, errUnimplemented
 }
-
-// ListDevicePmConfigs returns pm configs of device
-func (handler *NBIHandler) ListDevicePmConfigs(ctx context.Context, id *voltha.ID) (*voltha.PmConfigs, error) {
-	logger.Debugw("ListDevicePmConfigs-request", log.Fields{"deviceId": *id})
-	return handler.deviceMgr.ListPmConfigs(ctx, id.Id)
+func (handler *NBIHandler) Subscribe(context.Context, *voltha.OfAgentSubscriber) (*voltha.OfAgentSubscriber, error) {
+	return nil, errUnimplemented
 }
-
-func (handler *NBIHandler) CreateEventFilter(ctx context.Context, filter *voltha.EventFilter) (*voltha.EventFilter, error) {
-	logger.Debugw("CreateEventFilter-request", log.Fields{"filter": *filter})
-	return nil, errors.New("UnImplemented")
+func (handler *NBIHandler) GetAlarmDeviceData(context.Context, *common.ID) (*omci.AlarmDeviceData, error) {
+	return nil, errUnimplemented
 }
-
-func (handler *NBIHandler) UpdateEventFilter(ctx context.Context, filter *voltha.EventFilter) (*voltha.EventFilter, error) {
-	logger.Debugw("UpdateEventFilter-request", log.Fields{"filter": *filter})
-	return nil, errors.New("UnImplemented")
+func (handler *NBIHandler) GetMibDeviceData(context.Context, *common.ID) (*omci.MibDeviceData, error) {
+	return nil, errUnimplemented
 }
-
-func (handler *NBIHandler) DeleteEventFilter(ctx context.Context, filterInfo *voltha.EventFilter) (*empty.Empty, error) {
-	logger.Debugw("DeleteEventFilter-request", log.Fields{"device-id": filterInfo.DeviceId, "filter-id": filterInfo.Id})
-	return nil, errors.New("UnImplemented")
-}
-
-// GetEventFilter returns all the filters present for a device
-func (handler *NBIHandler) GetEventFilter(ctx context.Context, id *voltha.ID) (*voltha.EventFilters, error) {
-	logger.Debugw("GetEventFilter-request", log.Fields{"device-id": id})
-	return nil, errors.New("UnImplemented")
-}
-
-// ListEventFilters returns all the filters known to the system
-func (handler *NBIHandler) ListEventFilters(ctx context.Context, empty *empty.Empty) (*voltha.EventFilters, error) {
-	logger.Debug("ListEventFilter-request")
-	return nil, errors.New("UnImplemented")
-}
-
-func (handler *NBIHandler) SelfTest(ctx context.Context, id *voltha.ID) (*voltha.SelfTestResponse, error) {
-	logger.Debugw("SelfTest-request", log.Fields{"id": id})
-	return &voltha.SelfTestResponse{}, errors.New("UnImplemented")
-}
-
-// StreamPacketsOut sends packets to adapter
-func (handler *NBIHandler) StreamPacketsOut(packets voltha.VolthaService_StreamPacketsOutServer) error {
-	logger.Debugw("StreamPacketsOut-request", log.Fields{"packets": packets})
-loop:
-	for {
-		select {
-		case <-packets.Context().Done():
-			logger.Infow("StreamPacketsOut-context-done", log.Fields{"packets": packets, "error": packets.Context().Err()})
-			break loop
-		default:
-		}
-
-		packet, err := packets.Recv()
-
-		if err == io.EOF {
-			logger.Debugw("Received-EOF", log.Fields{"packets": packets})
-			break loop
-		}
-
-		if err != nil {
-			logger.Errorw("Failed to receive packet out", log.Fields{"error": err})
-			continue
-		}
-
-		handler.logicalDeviceMgr.PacketOut(packets.Context(), packet)
-	}
-
-	logger.Debugw("StreamPacketsOut-request-done", log.Fields{"packets": packets})
-	return nil
-}
-
-func (handler *NBIHandler) SendPacketIn(deviceID string, transationID string, packet *openflow_13.OfpPacketIn) {
-	// TODO: Augment the OF PacketIn to include the transactionId
-	packetIn := openflow_13.PacketIn{Id: deviceID, PacketIn: packet}
-	logger.Debugw("SendPacketIn", log.Fields{"packetIn": packetIn})
-	handler.packetInQueue <- packetIn
-}
-
-type callTracker struct {
-	failedPacket interface{}
-}
-type streamTracker struct {
-	calls map[string]*callTracker
-	sync.Mutex
-}
-
-var streamingTracker = &streamTracker{calls: make(map[string]*callTracker)}
-
-func (handler *NBIHandler) getStreamingTracker(method string, done chan<- bool) *callTracker {
-	streamingTracker.Lock()
-	defer streamingTracker.Unlock()
-	if _, ok := streamingTracker.calls[method]; ok {
-		// bail out the other packet in thread
-		logger.Debugf("%s streaming call already running. Exiting it", method)
-		done <- true
-		logger.Debugf("Last %s exited. Continuing ...", method)
-	} else {
-		streamingTracker.calls[method] = &callTracker{failedPacket: nil}
-	}
-	return streamingTracker.calls[method]
-}
-
-func (handler *NBIHandler) flushFailedPackets(tracker *callTracker) error {
-	if tracker.failedPacket != nil {
-		switch tracker.failedPacket.(type) {
-		case openflow_13.PacketIn:
-			logger.Debug("Enqueueing last failed packetIn")
-			handler.packetInQueue <- tracker.failedPacket.(openflow_13.PacketIn)
-		case openflow_13.ChangeEvent:
-			logger.Debug("Enqueueing last failed changeEvent")
-			handler.changeEventQueue <- tracker.failedPacket.(openflow_13.ChangeEvent)
-		}
-	}
-	return nil
-}
-
-// ReceivePacketsIn receives packets from adapter
-func (handler *NBIHandler) ReceivePacketsIn(empty *empty.Empty, packetsIn voltha.VolthaService_ReceivePacketsInServer) error {
-	var streamingTracker = handler.getStreamingTracker("ReceivePacketsIn", handler.packetInQueueDone)
-	logger.Debugw("ReceivePacketsIn-request", log.Fields{"packetsIn": packetsIn})
-
-	err := handler.flushFailedPackets(streamingTracker)
-	if err != nil {
-		logger.Errorw("unable-to-flush-failed-packets", log.Fields{"error": err})
-	}
-
-loop:
-	for {
-		select {
-		case packet := <-handler.packetInQueue:
-			logger.Debugw("sending-packet-in", log.Fields{
-				"packet": hex.EncodeToString(packet.PacketIn.Data),
-			})
-			if err := packetsIn.Send(&packet); err != nil {
-				logger.Errorw("failed-to-send-packet", log.Fields{"error": err})
-				// save the last failed packet in
-				streamingTracker.failedPacket = packet
-			} else {
-				if streamingTracker.failedPacket != nil {
-					// reset last failed packet saved to avoid flush
-					streamingTracker.failedPacket = nil
-				}
-			}
-		case <-handler.packetInQueueDone:
-			logger.Debug("Another ReceivePacketsIn running. Bailing out ...")
-			break loop
-		}
-	}
-
-	//TODO: Find an elegant way to get out of the above loop when the Core is stopped
-	return nil
-}
-
-func (handler *NBIHandler) SendChangeEvent(deviceID string, portStatus *openflow_13.OfpPortStatus) {
-	// TODO: validate the type of portStatus parameter
-	//if _, ok := portStatus.(*openflow_13.OfpPortStatus); ok {
-	//}
-	event := openflow_13.ChangeEvent{Id: deviceID, Event: &openflow_13.ChangeEvent_PortStatus{PortStatus: portStatus}}
-	logger.Debugw("SendChangeEvent", log.Fields{"event": event})
-	handler.changeEventQueue <- event
-}
-
-// ReceiveChangeEvents receives change in events
-func (handler *NBIHandler) ReceiveChangeEvents(empty *empty.Empty, changeEvents voltha.VolthaService_ReceiveChangeEventsServer) error {
-	var streamingTracker = handler.getStreamingTracker("ReceiveChangeEvents", handler.changeEventQueueDone)
-	logger.Debugw("ReceiveChangeEvents-request", log.Fields{"changeEvents": changeEvents})
-
-	err := handler.flushFailedPackets(streamingTracker)
-	if err != nil {
-		logger.Errorw("unable-to-flush-failed-packets", log.Fields{"error": err})
-	}
-
-loop:
-	for {
-		select {
-		// Dequeue a change event
-		case event := <-handler.changeEventQueue:
-			logger.Debugw("sending-change-event", log.Fields{"event": event})
-			if err := changeEvents.Send(&event); err != nil {
-				logger.Errorw("failed-to-send-change-event", log.Fields{"error": err})
-				// save last failed changeevent
-				streamingTracker.failedPacket = event
-			} else {
-				if streamingTracker.failedPacket != nil {
-					// reset last failed event saved on success to avoid flushing
-					streamingTracker.failedPacket = nil
-				}
-			}
-		case <-handler.changeEventQueueDone:
-			logger.Debug("Another ReceiveChangeEvents already running. Bailing out ...")
-			break loop
-		}
-	}
-
-	return nil
-}
-
-func (handler *NBIHandler) GetChangeEventsQueueForTest() <-chan openflow_13.ChangeEvent {
-	return handler.changeEventQueue
-}
-
-// Subscribe subscribing request of ofagent
-func (handler *NBIHandler) Subscribe(
-	ctx context.Context,
-	ofAgent *voltha.OfAgentSubscriber,
-) (*voltha.OfAgentSubscriber, error) {
-	logger.Debugw("Subscribe-request", log.Fields{"ofAgent": ofAgent})
-	return &voltha.OfAgentSubscriber{OfagentId: ofAgent.OfagentId, VolthaId: ofAgent.VolthaId}, nil
-}
-
-// GetAlarmDeviceData @TODO useless stub, what should this actually do?
-func (handler *NBIHandler) GetAlarmDeviceData(ctx context.Context, in *common.ID) (*omci.AlarmDeviceData, error) {
-	logger.Debug("GetAlarmDeviceData-stub")
-	return &omci.AlarmDeviceData{}, errors.New("UnImplemented")
-}
-
-// ListLogicalDeviceMeters returns logical device meters
-func (handler *NBIHandler) ListLogicalDeviceMeters(ctx context.Context, id *voltha.ID) (*openflow_13.Meters, error) {
-
-	logger.Debugw("ListLogicalDeviceMeters", log.Fields{"id": *id})
-	return handler.logicalDeviceMgr.ListLogicalDeviceMeters(ctx, id.Id)
-}
-
-// GetMeterStatsOfLogicalDevice @TODO useless stub, what should this actually do?
-func (handler *NBIHandler) GetMeterStatsOfLogicalDevice(ctx context.Context, in *common.ID) (*openflow_13.MeterStatsReply, error) {
-	logger.Debug("GetMeterStatsOfLogicalDevice")
-	return &openflow_13.MeterStatsReply{}, errors.New("UnImplemented")
-}
-
-// GetMibDeviceData @TODO useless stub, what should this actually do?
-func (handler *NBIHandler) GetMibDeviceData(ctx context.Context, in *common.ID) (*omci.MibDeviceData, error) {
-	logger.Debug("GetMibDeviceData")
-	return &omci.MibDeviceData{}, errors.New("UnImplemented")
-}
-
-// SimulateAlarm sends simulate alarm request
-func (handler *NBIHandler) SimulateAlarm(
-	ctx context.Context,
-	in *voltha.SimulateAlarmRequest,
-) (*common.OperationResp, error) {
-	logger.Debugw("SimulateAlarm-request", log.Fields{"id": in.Id})
-	successResp := &common.OperationResp{Code: common.OperationResp_OPERATION_SUCCESS}
-	ch := make(chan interface{})
-	defer close(ch)
-	go handler.deviceMgr.SimulateAlarm(ctx, in, ch)
-	return successResp, nil
-}
-
-// UpdateLogicalDeviceMeterTable - This function sends meter mod request to logical device manager and waits for response
-func (handler *NBIHandler) UpdateLogicalDeviceMeterTable(ctx context.Context, meter *openflow_13.MeterModUpdate) (*empty.Empty, error) {
-	logger.Debugw("UpdateLogicalDeviceMeterTable-request",
-		log.Fields{"meter": meter, "test": common.TestModeKeys_api_test.String()})
-	ch := make(chan interface{})
-	defer close(ch)
-	go handler.logicalDeviceMgr.UpdateMeterTable(ctx, meter.Id, meter.MeterMod, ch)
-	return waitForNilResponseOnSuccess(ctx, ch)
-}
-
-// GetMembership returns membership
 func (handler *NBIHandler) GetMembership(context.Context, *empty.Empty) (*voltha.Membership, error) {
-	return &voltha.Membership{}, errors.New("UnImplemented")
+	return nil, errUnimplemented
 }
-
-// UpdateMembership updates membership
 func (handler *NBIHandler) UpdateMembership(context.Context, *voltha.Membership) (*empty.Empty, error) {
-	return &empty.Empty{}, errors.New("UnImplemented")
-}
-
-func (handler *NBIHandler) EnablePort(ctx context.Context, port *voltha.Port) (*empty.Empty, error) {
-	logger.Debugw("EnablePort-request", log.Fields{"device-id": port.DeviceId, "port-no": port.PortNo})
-	ch := make(chan interface{})
-	defer close(ch)
-	go handler.deviceMgr.EnablePort(ctx, port, ch)
-	return waitForNilResponseOnSuccess(ctx, ch)
-}
-
-func (handler *NBIHandler) DisablePort(ctx context.Context, port *voltha.Port) (*empty.Empty, error) {
-
-	logger.Debugw("DisablePort-request", log.Fields{"device-id": port.DeviceId, "port-no": port.PortNo})
-	ch := make(chan interface{})
-	defer close(ch)
-	go handler.deviceMgr.DisablePort(ctx, port, ch)
-	return waitForNilResponseOnSuccess(ctx, ch)
-}
-
-func (handler *NBIHandler) StartOmciTestAction(ctx context.Context, omcitestrequest *voltha.OmciTestRequest) (*voltha.TestResponse, error) {
-	logger.Debugw("Omci_test_Request", log.Fields{"id": omcitestrequest.Id, "uuid": omcitestrequest.Uuid})
-	return handler.deviceMgr.StartOmciTest(ctx, omcitestrequest)
-}
-
-func (handler *NBIHandler) GetExtValue(ctx context.Context, valueparam *voltha.ValueSpecifier) (*voltha.ReturnValues, error) {
-	log.Debugw("GetExtValue-request", log.Fields{"onu-id": valueparam.Id})
-	return handler.deviceMgr.GetExtValue(ctx, valueparam)
+	return nil, errUnimplemented
 }
diff --git a/rw_core/core/api/grpc_nbi_handler_test.go b/rw_core/core/api/grpc_nbi_handler_test.go
index 0579f94..e8b651d 100755
--- a/rw_core/core/api/grpc_nbi_handler_test.go
+++ b/rw_core/core/api/grpc_nbi_handler_test.go
@@ -1,18 +1,19 @@
 /*
-* Copyright 2019-present Open Networking Foundation
-*
-* 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.
+ * Copyright 2019-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
  */
+
 package api
 
 import (
@@ -125,7 +126,7 @@
 	endpointMgr := kafka.NewEndpointManager(backend)
 	proxy := model.NewProxy(backend, "/")
 	nb.adapterMgr = adapter.NewAdapterManager(proxy, nb.coreInstanceID, nb.kClient)
-	nb.deviceMgr, nb.logicalDeviceMgr = device.NewDeviceManagers(proxy, nb.adapterMgr, nb.kmp, endpointMgr, cfg.CorePairTopic, nb.coreInstanceID, cfg.DefaultCoreTimeout)
+	nb.deviceMgr, nb.logicalDeviceMgr = device.NewManagers(proxy, nb.adapterMgr, nb.kmp, endpointMgr, cfg.CorePairTopic, nb.coreInstanceID, cfg.DefaultCoreTimeout)
 	if err = nb.adapterMgr.Start(ctx); err != nil {
 		logger.Fatalf("Cannot start adapterMgr: %s", err)
 	}
@@ -396,7 +397,7 @@
 	// Try to create the same device
 	_, err = nbi.CreateDevice(getContext(), &voltha.Device{Type: nb.oltAdapterName, MacAddress: "aa:bb:cc:cc:ee:ee"})
 	assert.NotNil(t, err)
-	assert.Equal(t, "Device is already pre-provisioned", err.Error())
+	assert.Equal(t, "device is already pre-provisioned", err.Error())
 
 	// Try to create a device with invalid data
 	_, err = nbi.CreateDevice(getContext(), &voltha.Device{Type: nb.oltAdapterName})
@@ -431,7 +432,7 @@
 	// Try to enable the oltDevice and check the error message
 	_, err = nbi.EnableDevice(getContext(), &voltha.ID{Id: oltDeviceNoAdapter.Id})
 	assert.NotNil(t, err)
-	assert.Equal(t, "Adapter-not-registered-for-device-type noAdapterRegistered", err.Error())
+	assert.Equal(t, "adapter-not-registered-for-device-type noAdapterRegistered", err.Error())
 
 	//Remove the device
 	_, err = nbi.DeleteDevice(getContext(), &voltha.ID{Id: oltDeviceNoAdapter.Id})
@@ -833,7 +834,7 @@
 
 	// Update the OLT Connection Status to REACHABLE and operation status to ACTIVE
 	// Normally, in a real adapter this happens after connection regain via a heartbeat mechanism with real hardware
-	err = nbi.deviceMgr.UpdateDeviceStatus(getContext(), oltDevice.Id, voltha.OperStatus_ACTIVE, voltha.ConnectStatus_REACHABLE)
+	err = nbi.UpdateDeviceStatus(getContext(), oltDevice.Id, voltha.OperStatus_ACTIVE, voltha.ConnectStatus_REACHABLE)
 	assert.Nil(t, err)
 
 	// Verify the device connection and operation states
@@ -884,7 +885,7 @@
 	request = &voltha.OmciTestRequest{Id: deviceNoAdapter.Id, Uuid: "456"}
 	_, err = nbi.StartOmciTestAction(getContext(), request)
 	assert.NotNil(t, err)
-	assert.Equal(t, "Adapter-not-registered-for-device-type noAdapterRegisteredOmciTest", err.Error())
+	assert.Equal(t, "adapter-not-registered-for-device-type noAdapterRegisteredOmciTest", err.Error())
 
 	//Remove the device
 	_, err = nbi.DeleteDevice(getContext(), &voltha.ID{Id: deviceNoAdapter.Id})
@@ -1064,7 +1065,6 @@
 
 func (nb *NBTest) monitorLogicalDevice(t *testing.T, nbi *NBIHandler, numNNIPorts int, numUNIPorts int, wg *sync.WaitGroup) {
 	defer wg.Done()
-	nb.logicalDeviceMgr.SetEventCallbacks(nbi)
 
 	// Clear any existing flows on the adapters
 	nb.oltAdapter.ClearFlows()
@@ -1124,7 +1124,7 @@
 	processedNniLogicalPorts := 0
 	processedUniLogicalPorts := 0
 
-	for event := range nbi.changeEventQueue {
+	for event := range nbi.GetChangeEventsQueueForTest() {
 		startingVlan++
 		if portStatus, ok := (event.Event).(*ofp.ChangeEvent_PortStatus); ok {
 			ps := portStatus.PortStatus
@@ -1185,7 +1185,7 @@
 	nb.startCore(false)
 
 	// Set the grpc API interface - no grpc server is running in unit test
-	nbi := NewAPIHandler(nb.deviceMgr, nb.logicalDeviceMgr, nb.adapterMgr)
+	nbi := NewNBIHandler(nb.deviceMgr, nb.logicalDeviceMgr, nb.adapterMgr)
 
 	// 1. Basic test with no data in Core
 	nb.testCoreWithoutData(t, nbi)