diff --git a/internal/pkg/core/openonu.go b/internal/pkg/core/openonu.go
new file mode 100755
index 0000000..a7ad35c
--- /dev/null
+++ b/internal/pkg/core/openonu.go
@@ -0,0 +1,1177 @@
+/*
+ * Copyright 2020-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 core provides the utility for onu devices, flows and statistics
+package core
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"sync"
+	"time"
+
+	vgrpc "github.com/opencord/voltha-lib-go/v7/pkg/grpc"
+	"github.com/opencord/voltha-protos/v5/go/adapter_services"
+
+	conf "github.com/opencord/voltha-lib-go/v7/pkg/config"
+	"github.com/opencord/voltha-protos/v5/go/common"
+	"google.golang.org/grpc"
+
+	"github.com/golang/protobuf/ptypes/empty"
+	"github.com/opencord/voltha-lib-go/v7/pkg/db/kvstore"
+	"github.com/opencord/voltha-lib-go/v7/pkg/events/eventif"
+	"github.com/opencord/voltha-lib-go/v7/pkg/log"
+	"github.com/opencord/voltha-protos/v5/go/extension"
+	ic "github.com/opencord/voltha-protos/v5/go/inter_container"
+	"github.com/opencord/voltha-protos/v5/go/voltha"
+
+	cmn "github.com/opencord/voltha-openonu-adapter-go/internal/pkg/common"
+	"github.com/opencord/voltha-openonu-adapter-go/internal/pkg/config"
+	"github.com/opencord/voltha-openonu-adapter-go/internal/pkg/swupg"
+	uniprt "github.com/opencord/voltha-openonu-adapter-go/internal/pkg/uniprt"
+)
+
+//OpenONUAC structure holds the ONU core information
+type OpenONUAC struct {
+	deviceHandlers              map[string]*deviceHandler
+	deviceHandlersCreateChan    map[string]chan bool //channels for deviceHandler create events
+	mutexDeviceHandlersMap      sync.RWMutex
+	coreClient                  *vgrpc.Client
+	parentAdapterClients        map[string]*vgrpc.Client
+	lockParentAdapterClients    sync.RWMutex
+	eventProxy                  eventif.EventProxy
+	kvClient                    kvstore.Client
+	cm                          *conf.ConfigManager
+	config                      *config.AdapterFlags
+	numOnus                     int
+	KVStoreAddress              string
+	KVStoreType                 string
+	KVStoreTimeout              time.Duration
+	mibTemplatesGenerated       map[string]bool
+	mutexMibTemplateGenerated   sync.RWMutex
+	exitChannel                 chan int
+	HeartbeatCheckInterval      time.Duration
+	HeartbeatFailReportInterval time.Duration
+	AcceptIncrementalEvto       bool
+	//GrpcTimeoutInterval         time.Duration
+	pSupportedFsms             *cmn.OmciDeviceFsms
+	maxTimeoutInterAdapterComm time.Duration
+	maxTimeoutReconciling      time.Duration
+	pDownloadManager           *swupg.AdapterDownloadManager
+	pFileManager               *swupg.FileDownloadManager //let coexist 'old and new' DownloadManager as long as 'old' does not get obsolete
+	MetricsEnabled             bool
+	mibAuditInterval           time.Duration
+	omciTimeout                int // in seconds
+	alarmAuditInterval         time.Duration
+	dlToOnuTimeout4M           time.Duration
+	rpcTimeout                 time.Duration
+}
+
+//NewOpenONUAC returns a new instance of OpenONU_AC
+func NewOpenONUAC(ctx context.Context, coreClient *vgrpc.Client, eventProxy eventif.EventProxy,
+	kvClient kvstore.Client, cfg *config.AdapterFlags, cm *conf.ConfigManager) *OpenONUAC {
+	var openOnuAc OpenONUAC
+	openOnuAc.exitChannel = make(chan int, 1)
+	openOnuAc.deviceHandlers = make(map[string]*deviceHandler)
+	openOnuAc.deviceHandlersCreateChan = make(map[string]chan bool)
+	openOnuAc.parentAdapterClients = make(map[string]*vgrpc.Client)
+	openOnuAc.mutexDeviceHandlersMap = sync.RWMutex{}
+	openOnuAc.config = cfg
+	openOnuAc.cm = cm
+	openOnuAc.coreClient = coreClient
+	openOnuAc.numOnus = cfg.OnuNumber
+	openOnuAc.eventProxy = eventProxy
+	openOnuAc.kvClient = kvClient
+	openOnuAc.KVStoreAddress = cfg.KVStoreAddress
+	openOnuAc.KVStoreType = cfg.KVStoreType
+	openOnuAc.KVStoreTimeout = cfg.KVStoreTimeout
+	openOnuAc.mibTemplatesGenerated = make(map[string]bool)
+	openOnuAc.mutexMibTemplateGenerated = sync.RWMutex{}
+	openOnuAc.HeartbeatCheckInterval = cfg.HeartbeatCheckInterval
+	openOnuAc.HeartbeatFailReportInterval = cfg.HeartbeatFailReportInterval
+	openOnuAc.AcceptIncrementalEvto = cfg.AccIncrEvto
+	openOnuAc.maxTimeoutInterAdapterComm = cfg.MaxTimeoutInterAdapterComm
+	openOnuAc.maxTimeoutReconciling = cfg.MaxTimeoutReconciling
+	//openOnuAc.GrpcTimeoutInterval = cfg.GrpcTimeoutInterval
+	openOnuAc.MetricsEnabled = cfg.MetricsEnabled
+	openOnuAc.mibAuditInterval = cfg.MibAuditInterval
+	// since consumers of OMCI timeout value everywhere in code is in "int seconds", do this useful conversion
+	openOnuAc.omciTimeout = int(cfg.OmciTimeout.Seconds())
+	openOnuAc.alarmAuditInterval = cfg.AlarmAuditInterval
+	openOnuAc.dlToOnuTimeout4M = cfg.DownloadToOnuTimeout4MB
+	openOnuAc.rpcTimeout = cfg.RPCTimeout
+
+	openOnuAc.pSupportedFsms = &cmn.OmciDeviceFsms{
+		"mib-synchronizer": {
+			//mibSyncFsm,        // Implements the MIB synchronization state machine
+			DatabaseClass: mibDbVolatileDictImpl, // Implements volatile ME MIB database
+			//true,                  // Advertise events on OpenOMCI event bus
+			AuditInterval: openOnuAc.mibAuditInterval, // Time to wait between MIB audits.  0 to disable audits.
+			// map[string]func() error{
+			// 	"mib-upload":    onuDeviceEntry.MibUploadTask,
+			// 	"mib-template":  onuDeviceEntry.MibTemplateTask,
+			// 	"get-mds":       onuDeviceEntry.GetMdsTask,
+			// 	"mib-audit":     onuDeviceEntry.GetMdsTask,
+			// 	"mib-resync":    onuDeviceEntry.MibResyncTask,
+			// 	"mib-reconcile": onuDeviceEntry.MibReconcileTask,
+			// },
+		},
+	}
+
+	openOnuAc.pDownloadManager = swupg.NewAdapterDownloadManager(ctx)
+	openOnuAc.pFileManager = swupg.NewFileDownloadManager(ctx)
+	openOnuAc.pFileManager.SetDownloadTimeout(ctx, cfg.DownloadToAdapterTimeout)
+
+	return &openOnuAc
+}
+
+//Start starts (logs) the adapter
+func (oo *OpenONUAC) Start(ctx context.Context) error {
+	logger.Info(ctx, "starting-openonu-adapter")
+
+	return nil
+}
+
+/*
+//stop terminates the session
+func (oo *OpenONUAC) stop(ctx context.Context) error {
+	logger.Info(ctx,"stopping-device-manager")
+	oo.exitChannel <- 1
+	logger.Info(ctx,"device-manager-stopped")
+	return nil
+}
+*/
+
+func (oo *OpenONUAC) addDeviceHandlerToMap(ctx context.Context, agent *deviceHandler) {
+	oo.mutexDeviceHandlersMap.Lock()
+	defer oo.mutexDeviceHandlersMap.Unlock()
+	if _, exist := oo.deviceHandlers[agent.DeviceID]; !exist {
+		oo.deviceHandlers[agent.DeviceID] = agent
+		oo.deviceHandlers[agent.DeviceID].start(ctx)
+		if _, exist := oo.deviceHandlersCreateChan[agent.DeviceID]; exist {
+			logger.Debugw(ctx, "deviceHandler created - trigger processing of pending ONU_IND_REQUEST", log.Fields{"device-id": agent.DeviceID})
+			oo.deviceHandlersCreateChan[agent.DeviceID] <- true
+		}
+	}
+}
+
+func (oo *OpenONUAC) deleteDeviceHandlerToMap(agent *deviceHandler) {
+	oo.mutexDeviceHandlersMap.Lock()
+	defer oo.mutexDeviceHandlersMap.Unlock()
+	delete(oo.deviceHandlers, agent.DeviceID)
+	delete(oo.deviceHandlersCreateChan, agent.DeviceID)
+}
+
+//getDeviceHandler gets the ONU deviceHandler and may wait until it is created
+func (oo *OpenONUAC) getDeviceHandler(ctx context.Context, deviceID string, aWait bool) *deviceHandler {
+	oo.mutexDeviceHandlersMap.Lock()
+	agent, ok := oo.deviceHandlers[deviceID]
+	if aWait && !ok {
+		logger.Infow(ctx, "Race condition: deviceHandler not present - wait for creation or timeout",
+			log.Fields{"device-id": deviceID})
+		if _, exist := oo.deviceHandlersCreateChan[deviceID]; !exist {
+			oo.deviceHandlersCreateChan[deviceID] = make(chan bool, 1)
+		}
+		deviceCreateChan := oo.deviceHandlersCreateChan[deviceID]
+		//keep the read sema short to allow for subsequent write
+		oo.mutexDeviceHandlersMap.Unlock()
+		// based on concurrent processing the deviceHandler creation may not yet be finished at his point
+		// so it might be needed to wait here for that event with some timeout
+		select {
+		case <-time.After(1 * time.Second): //timer may be discussed ...
+			logger.Warnw(ctx, "No valid deviceHandler created after max WaitTime", log.Fields{"device-id": deviceID})
+			return nil
+		case <-deviceCreateChan:
+			logger.Debugw(ctx, "deviceHandler is ready now - continue", log.Fields{"device-id": deviceID})
+			oo.mutexDeviceHandlersMap.RLock()
+			defer oo.mutexDeviceHandlersMap.RUnlock()
+			return oo.deviceHandlers[deviceID]
+		}
+	}
+	oo.mutexDeviceHandlersMap.Unlock()
+	return agent
+}
+
+// GetHealthStatus is used as a service readiness validation as a grpc connection
+func (oo *OpenONUAC) GetHealthStatus(ctx context.Context, empty *empty.Empty) (*voltha.HealthStatus, error) {
+	return &voltha.HealthStatus{State: voltha.HealthStatus_HEALTHY}, nil
+}
+
+// AdoptDevice creates a new device handler if not present already and then adopts the device
+func (oo *OpenONUAC) AdoptDevice(ctx context.Context, device *voltha.Device) (*empty.Empty, error) {
+	if device == nil {
+		logger.Warn(ctx, "voltha-device-is-nil")
+		return nil, errors.New("nil-device")
+	}
+	logger.Infow(ctx, "adopt-device", log.Fields{"device-id": device.Id})
+	var handler *deviceHandler
+	if handler = oo.getDeviceHandler(ctx, device.Id, false); handler == nil {
+		handler := newDeviceHandler(ctx, oo.coreClient, oo.eventProxy, device, oo)
+		oo.addDeviceHandlerToMap(ctx, handler)
+
+		// Setup the grpc communication with the parent adapter
+		if err := oo.setupParentInterAdapterClient(ctx, device.ProxyAddress.AdapterEndpoint); err != nil {
+			// TODO: Cleanup on failure needed
+			return nil, err
+		}
+
+		go handler.adoptOrReconcileDevice(log.WithSpanFromContext(context.Background(), ctx), device)
+	}
+	return &empty.Empty{}, nil
+}
+
+//ReconcileDevice is called once when the adapter needs to re-create device - usually on core restart
+func (oo *OpenONUAC) ReconcileDevice(ctx context.Context, device *voltha.Device) (*empty.Empty, error) {
+	if device == nil {
+		logger.Warn(ctx, "reconcile-device-voltha-device-is-nil")
+		return nil, errors.New("nil-device")
+	}
+	logger.Infow(ctx, "reconcile-device", log.Fields{"device-id": device.Id})
+	var handler *deviceHandler
+	if handler = oo.getDeviceHandler(ctx, device.Id, false); handler == nil {
+		handler := newDeviceHandler(ctx, oo.coreClient, oo.eventProxy, device, oo)
+		oo.addDeviceHandlerToMap(ctx, handler)
+		handler.device = device
+		if err := handler.updateDeviceStateInCore(log.WithSpanFromContext(context.Background(), ctx), &ic.DeviceStateFilter{
+			DeviceId:   device.Id,
+			OperStatus: voltha.OperStatus_RECONCILING,
+			ConnStatus: device.ConnectStatus,
+		}); err != nil {
+			return nil, fmt.Errorf("not able to update device state to reconciling. Err : %s", err.Error())
+		}
+		// Setup the grpc communication with the parent adapter
+		if err := oo.setupParentInterAdapterClient(ctx, device.ProxyAddress.AdapterEndpoint); err != nil {
+			// TODO: Cleanup on failure needed
+			return nil, err
+		}
+
+		handler.StartReconciling(log.WithSpanFromContext(context.Background(), ctx), false)
+		go handler.adoptOrReconcileDevice(log.WithSpanFromContext(context.Background(), ctx), handler.device)
+		// reconcilement will be continued after onu-device entry is added
+	} else {
+		return nil, fmt.Errorf(fmt.Sprintf("device-already-reconciled-or-active-%s", device.Id))
+	}
+	return &empty.Empty{}, nil
+}
+
+//DisableDevice disables the given device
+func (oo *OpenONUAC) DisableDevice(ctx context.Context, device *voltha.Device) (*empty.Empty, error) {
+	logger.Infow(ctx, "disable-device", log.Fields{"device-id": device.Id})
+	if handler := oo.getDeviceHandler(ctx, device.Id, false); handler != nil {
+		go handler.disableDevice(log.WithSpanFromContext(context.Background(), ctx), device)
+		return &empty.Empty{}, nil
+	}
+	logger.Warnw(ctx, "no handler found for device-disable", log.Fields{"device-id": device.Id})
+	return nil, fmt.Errorf(fmt.Sprintf("handler-not-found-%s", device.Id))
+}
+
+//ReEnableDevice enables the onu device after disable
+func (oo *OpenONUAC) ReEnableDevice(ctx context.Context, device *voltha.Device) (*empty.Empty, error) {
+	logger.Infow(ctx, "reenable-device", log.Fields{"device-id": device.Id})
+	if handler := oo.getDeviceHandler(ctx, device.Id, false); handler != nil {
+		go handler.reEnableDevice(log.WithSpanFromContext(context.Background(), ctx), device)
+		return &empty.Empty{}, nil
+	}
+	logger.Warnw(ctx, "no handler found for device-reenable", log.Fields{"device-id": device.Id})
+	return nil, fmt.Errorf(fmt.Sprintf("handler-not-found-%s", device.Id))
+}
+
+//RebootDevice reboots the given device
+func (oo *OpenONUAC) RebootDevice(ctx context.Context, device *voltha.Device) (*empty.Empty, error) {
+	logger.Infow(ctx, "reboot-device", log.Fields{"device-id": device.Id})
+	if handler := oo.getDeviceHandler(ctx, device.Id, false); handler != nil {
+		go handler.rebootDevice(log.WithSpanFromContext(context.Background(), ctx), true, device) //reboot request with device checking
+		return &empty.Empty{}, nil
+	}
+	logger.Warnw(ctx, "no handler found for device-reboot", log.Fields{"device-id": device.Id})
+	return nil, fmt.Errorf("handler-not-found-for-device: %s", device.Id)
+}
+
+// DeleteDevice deletes the given device
+func (oo *OpenONUAC) DeleteDevice(ctx context.Context, device *voltha.Device) (*empty.Empty, error) {
+	nctx := log.WithSpanFromContext(context.Background(), ctx)
+
+	logger.Infow(ctx, "delete-device", log.Fields{"device-id": device.Id, "SerialNumber": device.SerialNumber, "ctx": ctx, "nctx": nctx})
+	if handler := oo.getDeviceHandler(ctx, device.Id, false); handler != nil {
+		var errorsList []error
+
+		handler.mutexDeletionInProgressFlag.Lock()
+		handler.deletionInProgress = true
+		handler.mutexDeletionInProgressFlag.Unlock()
+
+		if err := handler.deleteDevicePersistencyData(ctx); err != nil {
+			errorsList = append(errorsList, err)
+		}
+
+		// Stop PM, Alarm and Self Test event handler routines
+		if handler.GetCollectorIsRunning() {
+			handler.stopCollector <- true
+			logger.Debugw(ctx, "sent stop signal to metric collector routine", log.Fields{"device-id": device.Id})
+
+		}
+		if handler.GetAlarmManagerIsRunning(ctx) {
+			handler.stopAlarmManager <- true
+			logger.Debugw(ctx, "sent stop signal to alarm manager", log.Fields{"device-id": device.Id})
+		}
+		if handler.pSelfTestHdlr.GetSelfTestHandlerIsRunning() {
+			handler.pSelfTestHdlr.StopSelfTestModule <- true
+			logger.Debugw(ctx, "sent stop signal to self test handler module", log.Fields{"device-id": device.Id})
+		}
+
+		// Clear PM data on the KV store
+		if handler.pOnuMetricsMgr != nil {
+			if err := handler.pOnuMetricsMgr.ClearAllPmData(ctx); err != nil {
+				errorsList = append(errorsList, err)
+			}
+		}
+
+		//don't leave any garbage - even in error case
+		oo.deleteDeviceHandlerToMap(handler)
+		if len(errorsList) > 0 {
+			logger.Errorw(ctx, "one-or-more-error-during-device-delete", log.Fields{"device-id": device.Id})
+			return nil, fmt.Errorf("one-or-more-error-during-device-delete, errors:%v", errorsList)
+		}
+		return &empty.Empty{}, nil
+	}
+	logger.Warnw(ctx, "no handler found for device-deletion", log.Fields{"device-id": device.Id})
+	return nil, fmt.Errorf(fmt.Sprintf("handler-not-found-%s", device.Id))
+}
+
+//UpdateFlowsIncrementally updates (add/remove) the flows on a given device
+func (oo *OpenONUAC) UpdateFlowsIncrementally(ctx context.Context, incrFlows *ic.IncrementalFlows) (*empty.Empty, error) {
+	logger.Infow(ctx, "update-flows-incrementally", log.Fields{"device-id": incrFlows.Device.Id})
+
+	//flow config is relayed to handler even if the device might be in some 'inactive' state
+	// let the handler or related FSM's decide, what to do with the modified flow state info
+	// at least the flow-remove must be done in respect to internal data, while OMCI activity might not be needed here
+
+	// For now, there is no support for group changes (as in the actual Py-adapter code)
+	//   but processing is continued for flowUpdate possibly also set in the request
+	if incrFlows.Groups.ToAdd != nil && incrFlows.Groups.ToAdd.Items != nil {
+		logger.Warnw(ctx, "Update-flow-incr: group add not supported (ignored)", log.Fields{"device-id": incrFlows.Device.Id})
+	}
+	if incrFlows.Groups.ToRemove != nil && incrFlows.Groups.ToRemove.Items != nil {
+		logger.Warnw(ctx, "Update-flow-incr: group remove not supported (ignored)", log.Fields{"device-id": incrFlows.Device.Id})
+	}
+	if incrFlows.Groups.ToUpdate != nil && incrFlows.Groups.ToUpdate.Items != nil {
+		logger.Warnw(ctx, "Update-flow-incr: group update not supported (ignored)", log.Fields{"device-id": incrFlows.Device.Id})
+	}
+
+	if handler := oo.getDeviceHandler(ctx, incrFlows.Device.Id, false); handler != nil {
+		if err := handler.FlowUpdateIncremental(log.WithSpanFromContext(context.Background(), ctx), incrFlows.Flows, incrFlows.Groups, incrFlows.FlowMetadata); err != nil {
+			return nil, err
+		}
+		return &empty.Empty{}, nil
+	}
+	logger.Warnw(ctx, "no handler found for incremental flow update", log.Fields{"device-id": incrFlows.Device.Id})
+	return nil, fmt.Errorf(fmt.Sprintf("handler-not-found-%s", incrFlows.Device.Id))
+}
+
+//UpdatePmConfig returns PmConfigs nil or error
+func (oo *OpenONUAC) UpdatePmConfig(ctx context.Context, configs *ic.PmConfigsInfo) (*empty.Empty, error) {
+	logger.Infow(ctx, "update-pm-config", log.Fields{"device-id": configs.DeviceId})
+	if handler := oo.getDeviceHandler(ctx, configs.DeviceId, false); handler != nil {
+		if err := handler.updatePmConfig(log.WithSpanFromContext(context.Background(), ctx), configs.PmConfigs); err != nil {
+			return nil, err
+		}
+		return &empty.Empty{}, nil
+	}
+	logger.Warnw(ctx, "no handler found for update-pm-config", log.Fields{"device-id": configs.DeviceId})
+	return nil, fmt.Errorf(fmt.Sprintf("handler-not-found-%s", configs.DeviceId))
+}
+
+//DownloadImage requests downloading some image according to indications as given in request
+//The ImageDownload needs to be called `request`due to library reflection requirements
+func (oo *OpenONUAC) DownloadImage(ctx context.Context, imageInfo *ic.ImageDownloadMessage) (*voltha.ImageDownload, error) {
+	ctx = log.WithSpanFromContext(context.Background(), ctx)
+	if imageInfo != nil && imageInfo.Image != nil && imageInfo.Image.Name != "" {
+		if !oo.pDownloadManager.ImageExists(ctx, imageInfo.Image) {
+			logger.Debugw(ctx, "start image download", log.Fields{"image-description": imageInfo.Image})
+			// Download_image is not supposed to be blocking, anyway let's call the DownloadManager still synchronously to detect 'fast' problems
+			// the download itself is later done in background
+			if err := oo.pDownloadManager.StartDownload(ctx, imageInfo.Image); err != nil {
+				return nil, err
+			}
+			return imageInfo.Image, nil
+		}
+		// image already exists
+		logger.Debugw(ctx, "image already downloaded", log.Fields{"image-description": imageInfo.Image})
+		return imageInfo.Image, nil
+	}
+
+	return nil, errors.New("invalid image definition")
+}
+
+//ActivateImageUpdate requests downloading some Onu Software image to the INU via OMCI
+//  according to indications as given in request and on success activate the image on the ONU
+//The ImageDownload needs to be called `request`due to library reflection requirements
+func (oo *OpenONUAC) ActivateImageUpdate(ctx context.Context, imageInfo *ic.ImageDownloadMessage) (*voltha.ImageDownload, error) {
+	if imageInfo != nil && imageInfo.Image != nil && imageInfo.Image.Name != "" {
+		if oo.pDownloadManager.ImageLocallyDownloaded(ctx, imageInfo.Image) {
+			if handler := oo.getDeviceHandler(ctx, imageInfo.Device.Id, false); handler != nil {
+				logger.Debugw(ctx, "image download on omci requested", log.Fields{
+					"image-description": imageInfo.Image, "device-id": imageInfo.Device.Id})
+				if err := handler.doOnuSwUpgrade(ctx, imageInfo.Image, oo.pDownloadManager); err != nil {
+					return nil, err
+				}
+				return imageInfo.Image, nil
+			}
+			logger.Warnw(ctx, "no handler found for image activation", log.Fields{"device-id": imageInfo.Device.Id})
+			return nil, fmt.Errorf(fmt.Sprintf("handler-not-found - device-id: %s", imageInfo.Device.Id))
+		}
+		logger.Debugw(ctx, "image not yet downloaded on activate request", log.Fields{"image-description": imageInfo.Image})
+		return nil, fmt.Errorf(fmt.Sprintf("image-not-yet-downloaded - device-id: %s", imageInfo.Device.Id))
+	}
+	return nil, errors.New("invalid image definition")
+}
+
+//GetSingleValue handles the core request to retrieve uni status
+func (oo *OpenONUAC) GetSingleValue(ctx context.Context, request *extension.SingleGetValueRequest) (*extension.SingleGetValueResponse, error) {
+	logger.Infow(ctx, "Single_get_value_request", log.Fields{"request": request})
+
+	if handler := oo.getDeviceHandler(ctx, request.TargetId, false); handler != nil {
+		switch reqType := request.GetRequest().GetRequest().(type) {
+		case *extension.GetValueRequest_UniInfo:
+			return handler.GetUniPortStatus(ctx, reqType.UniInfo), nil
+		case *extension.GetValueRequest_OnuOpticalInfo:
+			CommChan := make(chan cmn.Message)
+			respChan := make(chan extension.SingleGetValueResponse)
+			// Initiate the self test request
+			if err := handler.pSelfTestHdlr.SelfTestRequestStart(ctx, *request, CommChan, respChan); err != nil {
+				return &extension.SingleGetValueResponse{
+					Response: &extension.GetValueResponse{
+						Status:    extension.GetValueResponse_ERROR,
+						ErrReason: extension.GetValueResponse_INTERNAL_ERROR,
+					},
+				}, err
+			}
+			// The timeout handling is already implemented in omci_self_test_handler module
+			resp := <-respChan
+			return &resp, nil
+		case *extension.GetValueRequest_OnuInfo:
+			return handler.getOnuOMCICounters(ctx, reqType.OnuInfo), nil
+		default:
+			return uniprt.PostUniStatusErrResponse(extension.GetValueResponse_UNSUPPORTED), nil
+
+		}
+	}
+	logger.Errorw(ctx, "Single_get_value_request failed ", log.Fields{"request": request})
+	return uniprt.PostUniStatusErrResponse(extension.GetValueResponse_INVALID_DEVICE_ID), nil
+}
+
+//if update >= 4.3.0
+// Note: already with the implementation of the 'old' download interface problems were detected when the argument name used here is not the same
+//   as defined in the adapter interface file. That sounds strange and the effects were strange as well.
+//   The reason for that was never finally investigated.
+//   To be on the safe side argument names are left here always as defined in iAdapter.go .
+
+// DownloadOnuImage downloads (and optionally activates and commits) the indicated ONU image to the requested ONU(s)
+//   if the image is not yet present on the adapter it has to be automatically downloaded
+func (oo *OpenONUAC) DownloadOnuImage(ctx context.Context, request *voltha.DeviceImageDownloadRequest) (*voltha.DeviceImageResponse, error) {
+	if request != nil && len((*request).DeviceId) > 0 && (*request).Image.Version != "" {
+		loResponse := voltha.DeviceImageResponse{}
+		imageIdentifier := (*request).Image.Version
+		downloadedToAdapter := false
+		firstDevice := true
+		var vendorID string
+		for _, pCommonID := range (*request).DeviceId {
+			vendorIDMatch := true
+			loDeviceID := (*pCommonID).Id
+			loDeviceImageState := voltha.DeviceImageState{}
+			loDeviceImageState.DeviceId = loDeviceID
+			loImageState := voltha.ImageState{}
+			loDeviceImageState.ImageState = &loImageState
+			loDeviceImageState.ImageState.Version = (*request).Image.Version
+
+			handler := oo.getDeviceHandler(ctx, loDeviceID, false)
+			if handler == nil {
+				//cannot start ONU download for requested device
+				logger.Warnw(ctx, "no handler found for image activation", log.Fields{"device-id": loDeviceID})
+				loDeviceImageState.ImageState.DownloadState = voltha.ImageState_DOWNLOAD_FAILED
+				loDeviceImageState.ImageState.Reason = voltha.ImageState_UNKNOWN_ERROR
+				loDeviceImageState.ImageState.ImageState = voltha.ImageState_IMAGE_UNKNOWN
+				loResponse.DeviceImageStates = append(loResponse.DeviceImageStates, &loDeviceImageState)
+				continue
+			}
+
+			onuVolthaDevice, err := handler.getDeviceFromCore(ctx, loDeviceID)
+			if err != nil || onuVolthaDevice == nil {
+				logger.Warnw(ctx, "Failed to fetch Onu device for image download",
+					log.Fields{"device-id": loDeviceID, "err": err})
+				loDeviceImageState.ImageState.DownloadState = voltha.ImageState_DOWNLOAD_FAILED
+				loDeviceImageState.ImageState.Reason = voltha.ImageState_UNKNOWN_ERROR //proto restriction, better option: 'INVALID_DEVICE'
+				loDeviceImageState.ImageState.ImageState = voltha.ImageState_IMAGE_UNKNOWN
+			} else {
+				if firstDevice {
+					//start/verify download of the image to the adapter based on first found device only
+					//  use the OnuVendor identification from first given device
+					firstDevice = false
+					vendorID = onuVolthaDevice.VendorId
+					imageIdentifier = vendorID + imageIdentifier //head on vendor ID of the ONU
+					logger.Debugw(ctx, "download request for file", log.Fields{"image-id": imageIdentifier})
+
+					if !oo.pFileManager.ImageExists(ctx, imageIdentifier) {
+						logger.Debugw(ctx, "start image download", log.Fields{"image-description": request})
+						// Download_image is not supposed to be blocking, anyway let's call the DownloadManager still synchronously to detect 'fast' problems
+						// the download itself is later done in background
+						if err := oo.pFileManager.StartDownload(ctx, imageIdentifier, (*request).Image.Url); err == nil {
+							downloadedToAdapter = true
+						}
+						//else: treat any error here as 'INVALID_URL' (even though it might as well be some issue on local FS, eg. 'INSUFFICIENT_SPACE')
+						// otherwise a more sophisticated error evaluation is needed
+					} else {
+						// image already exists
+						downloadedToAdapter = true
+						logger.Debugw(ctx, "image already downloaded", log.Fields{"image-description": imageIdentifier})
+						// note: If the image (with vendorId+name) has already been downloaded before from some other
+						//   valid URL, the current URL is just ignored. If the operators want to ensure that the new URL
+						//   is really used, then they first have to use the 'abort' API to remove the existing image!
+						//   (abort API can be used also after some successful download to just remove the image from adapter)
+					}
+				} else {
+					//for all following devices verify the matching vendorID
+					if onuVolthaDevice.VendorId != vendorID {
+						logger.Warnw(ctx, "onu vendor id does not match image vendor id, device ignored",
+							log.Fields{"onu-vendor-id": onuVolthaDevice.VendorId, "image-vendor-id": vendorID})
+						vendorIDMatch = false
+					}
+				}
+				if downloadedToAdapter && vendorIDMatch {
+					// start the ONU download activity for each possible device
+					// assumption here is, that the concerned device was already created (automatic start after device creation not supported)
+					if handler := oo.getDeviceHandler(ctx, loDeviceID, false); handler != nil {
+						logger.Debugw(ctx, "image download on omci requested", log.Fields{
+							"image-id": imageIdentifier, "device-id": loDeviceID})
+						//onu upgrade handling called in background without immediate error evaluation here
+						//  as the processing can be done for multiple ONU's and an error on one ONU should not stop processing for others
+						//  state/progress/success of the request has to be verified using the Get_onu_image_status() API
+						go handler.onuSwUpgradeAfterDownload(ctx, request, oo.pFileManager, imageIdentifier)
+						loDeviceImageState.ImageState.DownloadState = voltha.ImageState_DOWNLOAD_STARTED
+						loDeviceImageState.ImageState.Reason = voltha.ImageState_NO_ERROR
+						loDeviceImageState.ImageState.ImageState = voltha.ImageState_IMAGE_UNKNOWN
+					} else {
+						//cannot start ONU download for requested device
+						logger.Warnw(ctx, "no handler found for image activation", log.Fields{"device-id": loDeviceID})
+						loDeviceImageState.ImageState.DownloadState = voltha.ImageState_DOWNLOAD_FAILED
+						loDeviceImageState.ImageState.Reason = voltha.ImageState_UNKNOWN_ERROR //proto restriction, better option: 'INVALID_DEVICE'
+						loDeviceImageState.ImageState.ImageState = voltha.ImageState_IMAGE_UNKNOWN
+					}
+				} else {
+					loDeviceImageState.ImageState.DownloadState = voltha.ImageState_DOWNLOAD_FAILED
+					if !downloadedToAdapter {
+						loDeviceImageState.ImageState.Reason = voltha.ImageState_INVALID_URL
+					} else { //only logical option is !vendorIDMatch
+						loDeviceImageState.ImageState.Reason = voltha.ImageState_VENDOR_DEVICE_MISMATCH
+					}
+					loDeviceImageState.ImageState.ImageState = voltha.ImageState_IMAGE_UNKNOWN
+				}
+			}
+
+			// start the ONU download activity for each possible device
+			logger.Debugw(ctx, "image download on omci requested", log.Fields{
+				"image-id": imageIdentifier, "device-id": loDeviceID})
+			//onu upgrade handling called in background without immediate error evaluation here
+			//  as the processing can be done for multiple ONU's and an error on one ONU should not stop processing for others
+			//  state/progress/success of the request has to be verified using the Get_onu_image_status() API
+			go handler.onuSwUpgradeAfterDownload(ctx, request, oo.pFileManager, imageIdentifier)
+			loDeviceImageState.ImageState.DownloadState = voltha.ImageState_DOWNLOAD_STARTED
+			loDeviceImageState.ImageState.Reason = voltha.ImageState_NO_ERROR
+			loDeviceImageState.ImageState.ImageState = voltha.ImageState_IMAGE_UNKNOWN
+			loResponse.DeviceImageStates = append(loResponse.DeviceImageStates, &loDeviceImageState)
+		}
+		pImageResp := &loResponse
+		return pImageResp, nil
+	}
+	return nil, errors.New("invalid image download parameters")
+}
+
+// GetOnuImageStatus delivers the adapter-related information about the download/activation/commitment
+//   status for the requested image
+func (oo *OpenONUAC) GetOnuImageStatus(ctx context.Context, in *voltha.DeviceImageRequest) (*voltha.DeviceImageResponse, error) {
+	if in != nil && len((*in).DeviceId) > 0 && (*in).Version != "" {
+		loResponse := voltha.DeviceImageResponse{}
+		imageIdentifier := (*in).Version
+		var vendorIDSet bool
+		firstDevice := true
+		var vendorID string
+		for _, pCommonID := range (*in).DeviceId {
+			loDeviceID := (*pCommonID).Id
+			pDeviceImageState := &voltha.DeviceImageState{DeviceId: loDeviceID}
+			handler := oo.getDeviceHandler(ctx, loDeviceID, false)
+			if handler == nil {
+				//cannot get the handler
+				logger.Warnw(ctx, "no handler found for image status request ", log.Fields{"device-id": loDeviceID})
+				pDeviceImageState.DeviceId = loDeviceID
+				pDeviceImageState.ImageState.Version = (*in).Version
+				pDeviceImageState.ImageState.DownloadState = voltha.ImageState_DOWNLOAD_FAILED
+				pDeviceImageState.ImageState.Reason = voltha.ImageState_UNKNOWN_ERROR
+				pDeviceImageState.ImageState.ImageState = voltha.ImageState_IMAGE_UNKNOWN
+				loResponse.DeviceImageStates = append(loResponse.DeviceImageStates, pDeviceImageState)
+				continue
+			}
+			onuVolthaDevice, err := handler.getDeviceFromCore(ctx, loDeviceID)
+			if err != nil || onuVolthaDevice == nil {
+				logger.Warnw(ctx, "Failed to fetch Onu device to get image status",
+					log.Fields{"device-id": loDeviceID, "err": err})
+				pImageState := &voltha.ImageState{
+					Version:       (*in).Version,
+					DownloadState: voltha.ImageState_DOWNLOAD_UNKNOWN, //no statement about last activity possible
+					Reason:        voltha.ImageState_UNKNOWN_ERROR,    //something like "DEVICE_NOT_EXISTS" would be better (proto def)
+					ImageState:    voltha.ImageState_IMAGE_UNKNOWN,
+				}
+				pDeviceImageState.ImageState = pImageState
+			} else {
+				if firstDevice {
+					//start/verify download of the image to the adapter based on first found device only
+					//  use the OnuVendor identification from first given device
+					firstDevice = false
+					vendorID = onuVolthaDevice.VendorId
+					imageIdentifier = vendorID + imageIdentifier //head on vendor ID of the ONU
+					vendorIDSet = true
+					logger.Debugw(ctx, "status request for image", log.Fields{"image-id": imageIdentifier})
+				} else {
+					//for all following devices verify the matching vendorID
+					if onuVolthaDevice.VendorId != vendorID {
+						logger.Warnw(ctx, "onu vendor id does not match image vendor id, device ignored",
+							log.Fields{"onu-vendor-id": onuVolthaDevice.VendorId, "image-vendor-id": vendorID})
+					} else {
+						vendorIDSet = true
+					}
+				}
+				if !vendorIDSet {
+					pImageState := &voltha.ImageState{
+						Version:       (*in).Version,
+						DownloadState: voltha.ImageState_DOWNLOAD_UNKNOWN, //can't be sure that download for this device was really tried
+						Reason:        voltha.ImageState_VENDOR_DEVICE_MISMATCH,
+						ImageState:    voltha.ImageState_IMAGE_UNKNOWN,
+					}
+					pDeviceImageState.ImageState = pImageState
+				} else {
+					logger.Debugw(ctx, "image status request for", log.Fields{
+						"image-id": imageIdentifier, "device-id": loDeviceID})
+					//status request is called synchronously to collect the indications for all concerned devices
+					pDeviceImageState.ImageState = handler.requestOnuSwUpgradeState(ctx, imageIdentifier, (*in).Version)
+				}
+			}
+			loResponse.DeviceImageStates = append(loResponse.DeviceImageStates, pDeviceImageState)
+		}
+		pImageResp := &loResponse
+		return pImageResp, nil
+	}
+	return nil, errors.New("invalid image status request parameters")
+}
+
+// AbortOnuImageUpgrade stops the actual download/activation/commitment process (on next possibly step)
+func (oo *OpenONUAC) AbortOnuImageUpgrade(ctx context.Context, in *voltha.DeviceImageRequest) (*voltha.DeviceImageResponse, error) {
+	if in != nil && len((*in).DeviceId) > 0 && (*in).Version != "" {
+		loResponse := voltha.DeviceImageResponse{}
+		imageIdentifier := (*in).Version
+		firstDevice := true
+		var vendorID string
+		for _, pCommonID := range (*in).DeviceId {
+			loDeviceID := (*pCommonID).Id
+			pDeviceImageState := &voltha.DeviceImageState{}
+			loImageState := voltha.ImageState{}
+			pDeviceImageState.ImageState = &loImageState
+
+			handler := oo.getDeviceHandler(ctx, loDeviceID, false)
+			if handler == nil {
+				//cannot start ONU download for requested device
+				logger.Warnw(ctx, "no handler found for aborting upgrade ", log.Fields{"device-id": loDeviceID})
+				pDeviceImageState.DeviceId = loDeviceID
+				pDeviceImageState.ImageState.Version = (*in).Version
+				//nolint:misspell
+				pDeviceImageState.ImageState.DownloadState = voltha.ImageState_DOWNLOAD_CANCELLED
+				//nolint:misspell
+				pDeviceImageState.ImageState.Reason = voltha.ImageState_CANCELLED_ON_REQUEST
+				pDeviceImageState.ImageState.ImageState = voltha.ImageState_IMAGE_UNKNOWN
+				loResponse.DeviceImageStates = append(loResponse.DeviceImageStates, pDeviceImageState)
+				continue
+			}
+			onuVolthaDevice, err := handler.getDeviceFromCore(ctx, loDeviceID)
+			if err != nil || onuVolthaDevice == nil {
+				logger.Warnw(ctx, "Failed to fetch Onu device to abort its download",
+					log.Fields{"device-id": loDeviceID, "err": err})
+				continue //try the work with next deviceId
+			}
+
+			if firstDevice {
+				//start/verify download of the image to the adapter based on first found device only
+				//  use the OnuVendor identification from first given device
+				firstDevice = false
+				vendorID = onuVolthaDevice.VendorId
+				imageIdentifier = vendorID + imageIdentifier //head on vendor ID of the ONU
+				logger.Debugw(ctx, "abort request for file", log.Fields{"image-id": imageIdentifier})
+			} else {
+				//for all following devices verify the matching vendorID
+				if onuVolthaDevice.VendorId != vendorID {
+					logger.Warnw(ctx, "onu vendor id does not match image vendor id, device ignored",
+						log.Fields{"onu-vendor-id": onuVolthaDevice.VendorId, "image-vendor-id": vendorID})
+					continue //try the work with next deviceId
+				}
+			}
+
+			// cancel the ONU upgrade activity for each possible device
+			logger.Debugw(ctx, "image upgrade abort requested", log.Fields{
+				"image-id": imageIdentifier, "device-id": loDeviceID})
+			//upgrade cancel is called synchronously to collect the imageResponse indications for all concerned devices
+			handler.cancelOnuSwUpgrade(ctx, imageIdentifier, (*in).Version, pDeviceImageState)
+			loResponse.DeviceImageStates = append(loResponse.DeviceImageStates, pDeviceImageState)
+		}
+		if !firstDevice {
+			//if at least one valid device was found cancel also a possibly running download to adapter and remove the image
+			//  this is to be done after the upgradeOnu cancel activities in order to not subduct the file for still running processes
+			oo.pFileManager.CancelDownload(ctx, imageIdentifier)
+		}
+		pImageResp := &loResponse
+		return pImageResp, nil
+	}
+	return nil, errors.New("invalid image upgrade abort parameters")
+}
+
+// GetOnuImages retrieves the ONU SW image status information via OMCI
+func (oo *OpenONUAC) GetOnuImages(ctx context.Context, id *common.ID) (*voltha.OnuImages, error) {
+	logger.Infow(ctx, "Get_onu_images", log.Fields{"device-id": id.Id})
+	if handler := oo.getDeviceHandler(ctx, id.Id, false); handler != nil {
+		images, err := handler.getOnuImages(ctx)
+		if err == nil {
+			return images, nil
+		}
+		return nil, fmt.Errorf(fmt.Sprintf("%s-%s", err, id.Id))
+	}
+	logger.Warnw(ctx, "no handler found for Get_onu_images", log.Fields{"device-id": id.Id})
+	return nil, fmt.Errorf(fmt.Sprintf("handler-not-found-%s", id.Id))
+}
+
+// ActivateOnuImage initiates the activation of the image for the requested ONU(s)
+//  precondition: image downloaded and not yet activated or image refers to current inactive image
+func (oo *OpenONUAC) ActivateOnuImage(ctx context.Context, in *voltha.DeviceImageRequest) (*voltha.DeviceImageResponse, error) {
+	if in != nil && len((*in).DeviceId) > 0 && (*in).Version != "" {
+		loResponse := voltha.DeviceImageResponse{}
+		imageIdentifier := (*in).Version
+		//let the deviceHandler find the adequate way of requesting the image activation
+		for _, pCommonID := range (*in).DeviceId {
+			loDeviceID := (*pCommonID).Id
+			loDeviceImageState := voltha.DeviceImageState{}
+			loDeviceImageState.DeviceId = loDeviceID
+			loImageState := voltha.ImageState{}
+			loDeviceImageState.ImageState = &loImageState
+			loDeviceImageState.ImageState.Version = imageIdentifier
+			//compared to download procedure the vendorID (from device) is secondary here
+			//   and only needed in case the upgrade process is based on some ongoing download process (and can be retrieved in deviceHandler if needed)
+			// start image activation activity for each possible device
+			// assumption here is, that the concerned device was already created (automatic start after device creation not supported)
+			if handler := oo.getDeviceHandler(ctx, loDeviceID, false); handler != nil {
+				logger.Debugw(ctx, "onu image activation requested", log.Fields{
+					"image-id": imageIdentifier, "device-id": loDeviceID})
+				//onu activation handling called in background without immediate error evaluation here
+				//  as the processing can be done for multiple ONU's and an error on one ONU should not stop processing for others
+				//  state/progress/success of the request has to be verified using the Get_onu_image_status() API
+				if pImageStates, err := handler.onuSwActivateRequest(ctx, imageIdentifier, (*in).CommitOnSuccess); err != nil {
+					loDeviceImageState.ImageState.DownloadState = voltha.ImageState_DOWNLOAD_UNKNOWN
+					loDeviceImageState.ImageState.Reason = voltha.ImageState_UNKNOWN_ERROR
+					loDeviceImageState.ImageState.ImageState = voltha.ImageState_IMAGE_ACTIVATION_ABORTED
+				} else {
+					loDeviceImageState.ImageState.DownloadState = pImageStates.DownloadState
+					loDeviceImageState.ImageState.Reason = pImageStates.Reason
+					loDeviceImageState.ImageState.ImageState = pImageStates.ImageState
+				}
+			} else {
+				//cannot start SW activation for requested device
+				logger.Warnw(ctx, "no handler found for image activation", log.Fields{"device-id": loDeviceID})
+				loDeviceImageState.ImageState.DownloadState = voltha.ImageState_DOWNLOAD_UNKNOWN
+				loDeviceImageState.ImageState.Reason = voltha.ImageState_UNKNOWN_ERROR
+				loDeviceImageState.ImageState.ImageState = voltha.ImageState_IMAGE_ACTIVATION_ABORTED
+			}
+			loResponse.DeviceImageStates = append(loResponse.DeviceImageStates, &loDeviceImageState)
+		}
+		pImageResp := &loResponse
+		return pImageResp, nil
+	}
+	return nil, errors.New("invalid image activation parameters")
+}
+
+// CommitOnuImage enforces the commitment of the image for the requested ONU(s)
+//  precondition: image activated and not yet committed
+func (oo *OpenONUAC) CommitOnuImage(ctx context.Context, in *voltha.DeviceImageRequest) (*voltha.DeviceImageResponse, error) {
+	if in != nil && len((*in).DeviceId) > 0 && (*in).Version != "" {
+		loResponse := voltha.DeviceImageResponse{}
+		imageIdentifier := (*in).Version
+		//let the deviceHandler find the adequate way of requesting the image activation
+		for _, pCommonID := range (*in).DeviceId {
+			loDeviceID := (*pCommonID).Id
+			loDeviceImageState := voltha.DeviceImageState{}
+			loDeviceImageState.DeviceId = loDeviceID
+			loImageState := voltha.ImageState{}
+			loDeviceImageState.ImageState = &loImageState
+			loDeviceImageState.ImageState.Version = imageIdentifier
+			//compared to download procedure the vendorID (from device) is secondary here
+			//   and only needed in case the upgrade process is based on some ongoing download process (and can be retrieved in deviceHandler if needed)
+			// start image activation activity for each possible device
+			// assumption here is, that the concerned device was already created (automatic start after device creation not supported)
+			if handler := oo.getDeviceHandler(ctx, loDeviceID, false); handler != nil {
+				logger.Debugw(ctx, "onu image commitment requested", log.Fields{
+					"image-id": imageIdentifier, "device-id": loDeviceID})
+				//onu commitment handling called in background without immediate error evaluation here
+				//  as the processing can be done for multiple ONU's and an error on one ONU should not stop processing for others
+				//  state/progress/success of the request has to be verified using the Get_onu_image_status() API
+				if pImageStates, err := handler.onuSwCommitRequest(ctx, imageIdentifier); err != nil {
+					loDeviceImageState.ImageState.DownloadState = voltha.ImageState_DOWNLOAD_FAILED
+					loDeviceImageState.ImageState.Reason = voltha.ImageState_UNKNOWN_ERROR //can be multiple reasons here
+					loDeviceImageState.ImageState.ImageState = voltha.ImageState_IMAGE_COMMIT_ABORTED
+				} else {
+					loDeviceImageState.ImageState.DownloadState = pImageStates.DownloadState
+					loDeviceImageState.ImageState.Reason = pImageStates.Reason
+					loDeviceImageState.ImageState.ImageState = pImageStates.ImageState
+				}
+			} else {
+				//cannot start SW commitment for requested device
+				logger.Warnw(ctx, "no handler found for image commitment", log.Fields{"device-id": loDeviceID})
+				loDeviceImageState.ImageState.DownloadState = voltha.ImageState_DOWNLOAD_UNKNOWN
+				loDeviceImageState.ImageState.Reason = voltha.ImageState_UNKNOWN_ERROR
+				loDeviceImageState.ImageState.ImageState = voltha.ImageState_IMAGE_COMMIT_ABORTED
+			}
+			loResponse.DeviceImageStates = append(loResponse.DeviceImageStates, &loDeviceImageState)
+		}
+		pImageResp := &loResponse
+		return pImageResp, nil
+	}
+	return nil, errors.New("invalid image commitment parameters")
+}
+
+// Adapter interface required methods ################ end #########
+// #################################################################
+
+/*
+ *
+ * ONU inter adapter service
+ *
+ */
+
+// OnuIndication is part of the ONU Inter-adapter service API.
+func (oo *OpenONUAC) OnuIndication(ctx context.Context, onuInd *ic.OnuIndicationMessage) (*empty.Empty, error) {
+	logger.Debugw(ctx, "onu-indication", log.Fields{"onu-indication": onuInd})
+
+	if onuInd == nil || onuInd.OnuIndication == nil {
+		return nil, fmt.Errorf("invalid-onu-indication-%v", onuInd)
+	}
+
+	onuIndication := onuInd.OnuIndication
+	onuOperstate := onuIndication.GetOperState()
+	waitForDhInstPresent := false
+	if onuOperstate == "up" {
+		//Race condition (relevant in BBSIM-environment only): Due to unsynchronized processing of olt-adapter and rw_core,
+		//ONU_IND_REQUEST msg by olt-adapter could arrive a little bit earlier than rw_core was able to announce the corresponding
+		//ONU by RPC of Adopt_device(). Therefore it could be necessary to wait with processing of ONU_IND_REQUEST until call of
+		//Adopt_device() arrived and DeviceHandler instance was created
+		waitForDhInstPresent = true
+	}
+	if handler := oo.getDeviceHandler(ctx, onuInd.DeviceId, waitForDhInstPresent); handler != nil {
+		logger.Infow(ctx, "onu-ind-request", log.Fields{"device-id": onuInd.DeviceId,
+			"OnuId":      onuIndication.GetOnuId(),
+			"AdminState": onuIndication.GetAdminState(), "OperState": onuOperstate,
+			"SNR": onuIndication.GetSerialNumber()})
+
+		if onuOperstate == "up" {
+			if err := handler.createInterface(ctx, onuIndication); err != nil {
+				return nil, err
+			}
+			return &empty.Empty{}, nil
+		} else if (onuOperstate == "down") || (onuOperstate == "unreachable") {
+			return nil, handler.updateInterface(ctx, onuIndication)
+		} else {
+			logger.Errorw(ctx, "unknown-onu-ind-request operState", log.Fields{"OnuId": onuIndication.GetOnuId()})
+			return nil, fmt.Errorf("invalidOperState: %s, %s", onuOperstate, onuInd.DeviceId)
+		}
+	}
+	logger.Warnw(ctx, "no handler found for received onu-ind-request", log.Fields{
+		"msgToDeviceId": onuInd.DeviceId})
+	return nil, fmt.Errorf(fmt.Sprintf("handler-not-found-%s", onuInd.DeviceId))
+}
+
+// OmciIndication is part of the ONU Inter-adapter service API.
+func (oo *OpenONUAC) OmciIndication(ctx context.Context, msg *ic.OmciMessage) (*empty.Empty, error) {
+	logger.Debugw(ctx, "omci-response", log.Fields{"parent-device-id": msg.ParentDeviceId, "child-device-id": msg.ChildDeviceId})
+
+	if handler := oo.getDeviceHandler(ctx, msg.ChildDeviceId, false); handler != nil {
+		if err := handler.handleOMCIIndication(log.WithSpanFromContext(context.Background(), ctx), msg); err != nil {
+			return nil, err
+		}
+		return &empty.Empty{}, nil
+	}
+	return nil, fmt.Errorf(fmt.Sprintf("handler-not-found-%s", msg.ChildDeviceId))
+}
+
+// DownloadTechProfile is part of the ONU Inter-adapter service API.
+func (oo *OpenONUAC) DownloadTechProfile(ctx context.Context, tProfile *ic.TechProfileDownloadMessage) (*empty.Empty, error) {
+	logger.Debugw(ctx, "download-tech-profile", log.Fields{"uni-id": tProfile.UniId})
+
+	if handler := oo.getDeviceHandler(ctx, tProfile.DeviceId, false); handler != nil {
+		if err := handler.handleTechProfileDownloadRequest(log.WithSpanFromContext(context.Background(), ctx), tProfile); err != nil {
+			return nil, err
+		}
+		return &empty.Empty{}, nil
+	}
+	return nil, fmt.Errorf(fmt.Sprintf("handler-not-found-%s", tProfile.DeviceId))
+}
+
+// DeleteGemPort is part of the ONU Inter-adapter service API.
+func (oo *OpenONUAC) DeleteGemPort(ctx context.Context, gPort *ic.DeleteGemPortMessage) (*empty.Empty, error) {
+	logger.Debugw(ctx, "delete-gem-port", log.Fields{"device-id": gPort.DeviceId, "uni-id": gPort.UniId})
+
+	if handler := oo.getDeviceHandler(ctx, gPort.DeviceId, false); handler != nil {
+		if err := handler.handleDeleteGemPortRequest(log.WithSpanFromContext(context.Background(), ctx), gPort); err != nil {
+			return nil, err
+		}
+		return &empty.Empty{}, nil
+	}
+	return nil, fmt.Errorf(fmt.Sprintf("handler-not-found-%s", gPort.DeviceId))
+}
+
+// DeleteTCont is part of the ONU Inter-adapter service API.
+func (oo *OpenONUAC) DeleteTCont(ctx context.Context, tConf *ic.DeleteTcontMessage) (*empty.Empty, error) {
+	logger.Debugw(ctx, "delete-tcont", log.Fields{"tconf": tConf})
+
+	if handler := oo.getDeviceHandler(ctx, tConf.DeviceId, false); handler != nil {
+		if err := handler.handleDeleteTcontRequest(log.WithSpanFromContext(context.Background(), ctx), tConf); err != nil {
+			return nil, err
+		}
+		return &empty.Empty{}, nil
+	}
+	return nil, fmt.Errorf(fmt.Sprintf("handler-not-found-%s", tConf.DeviceId))
+}
+
+/*
+ * Parent GRPC clients
+ */
+
+func (oo *OpenONUAC) setupParentInterAdapterClient(ctx context.Context, endpoint string) error {
+	logger.Infow(ctx, "setting-parent-adapter-connection", log.Fields{"parent-endpoint": endpoint})
+	oo.lockParentAdapterClients.Lock()
+	defer oo.lockParentAdapterClients.Unlock()
+	if _, ok := oo.parentAdapterClients[endpoint]; ok {
+		return nil
+	}
+
+	childClient, err := vgrpc.NewClient(endpoint,
+		oo.oltAdapterRestarted,
+		vgrpc.ActivityCheck(true))
+
+	if err != nil {
+		return err
+	}
+
+	oo.parentAdapterClients[endpoint] = childClient
+
+	go oo.parentAdapterClients[endpoint].Start(log.WithSpanFromContext(context.TODO(), ctx), setAndTestAdapterServiceHandler)
+
+	// Wait until we have a connection to the child adapter.
+	// Unlimited retries or until context expires
+	subCtx := log.WithSpanFromContext(context.TODO(), ctx)
+	backoff := vgrpc.NewBackoff(oo.config.MinBackoffRetryDelay, oo.config.MaxBackoffRetryDelay, 0)
+	for {
+		client, err := oo.parentAdapterClients[endpoint].GetOltInterAdapterServiceClient()
+		if err == nil && client != nil {
+			logger.Infow(subCtx, "connected-to-parent-adapter", log.Fields{"parent-endpoint": endpoint})
+			break
+		}
+		logger.Warnw(subCtx, "connection-to-parent-adapter-not-ready", log.Fields{"error": err, "parent-endpoint": endpoint})
+		// Backoff
+		if err = backoff.Backoff(subCtx); err != nil {
+			logger.Errorw(subCtx, "received-error-on-backoff", log.Fields{"error": err, "parent-endpoint": endpoint})
+			break
+		}
+	}
+	return nil
+}
+
+func (oo *OpenONUAC) getParentAdapterServiceClient(endpoint string) (adapter_services.OltInterAdapterServiceClient, error) {
+	// First check from cache
+	oo.lockParentAdapterClients.RLock()
+	if pgClient, ok := oo.parentAdapterClients[endpoint]; ok {
+		oo.lockParentAdapterClients.RUnlock()
+		return pgClient.GetOltInterAdapterServiceClient()
+	}
+	oo.lockParentAdapterClients.RUnlock()
+
+	// Set the parent connection - can occur on restarts
+	ctx, cancel := context.WithTimeout(context.Background(), oo.config.RPCTimeout)
+	err := oo.setupParentInterAdapterClient(ctx, endpoint)
+	cancel()
+	if err != nil {
+		return nil, err
+	}
+
+	// Get the parent client now
+	oo.lockParentAdapterClients.RLock()
+	defer oo.lockParentAdapterClients.RUnlock()
+	if pgClient, ok := oo.parentAdapterClients[endpoint]; ok {
+		return pgClient.GetOltInterAdapterServiceClient()
+	}
+
+	return nil, fmt.Errorf("no-client-for-endpoint-%s", endpoint)
+}
+
+// TODO:  Any action the adapter needs to do following an olt adapter restart?
+func (oo *OpenONUAC) oltAdapterRestarted(ctx context.Context, endPoint string) error {
+	logger.Errorw(ctx, "olt-adapter-restarted", log.Fields{"endpoint": endPoint})
+	return nil
+}
+
+// setAndTestAdapterServiceHandler is used to test whether the remote gRPC service is up
+func setAndTestAdapterServiceHandler(ctx context.Context, conn *grpc.ClientConn) interface{} {
+	svc := adapter_services.NewOltInterAdapterServiceClient(conn)
+	if h, err := svc.GetHealthStatus(ctx, &empty.Empty{}); err != nil || h.State != voltha.HealthStatus_HEALTHY {
+		return nil
+	}
+	return svc
+}
+
+/*
+ *
+ * Unimplemented APIs
+ *
+ */
+
+//GetOfpDeviceInfo returns OFP information for the given device.  Method not implemented as per [VOL-3202].
+// OF port info is now to be delivered within UniPort create cmp changes in onu_uni_port.go::CreateVolthaPort()
+//
+func (oo *OpenONUAC) GetOfpDeviceInfo(ctx context.Context, device *voltha.Device) (*ic.SwitchCapability, error) {
+	return nil, errors.New("unImplemented")
+}
+
+//SimulateAlarm is unimplemented
+func (oo *OpenONUAC) SimulateAlarm(context.Context, *ic.SimulateAlarmMessage) (*common.OperationResp, error) {
+	return nil, errors.New("unImplemented")
+}
+
+//SetExtValue is unimplemented
+func (oo *OpenONUAC) SetExtValue(context.Context, *ic.SetExtValueMessage) (*empty.Empty, error) {
+	return nil, errors.New("unImplemented")
+}
+
+//SetSingleValue is unimplemented
+func (oo *OpenONUAC) SetSingleValue(context.Context, *extension.SingleSetValueRequest) (*extension.SingleSetValueResponse, error) {
+	return nil, errors.New("unImplemented")
+}
+
+//StartOmciTest not implemented
+func (oo *OpenONUAC) StartOmciTest(ctx context.Context, test *ic.OMCITest) (*voltha.TestResponse, error) {
+	return nil, errors.New("unImplemented")
+}
+
+//SuppressEvent unimplemented
+func (oo *OpenONUAC) SuppressEvent(ctx context.Context, filter *voltha.EventFilter) (*empty.Empty, error) {
+	return nil, errors.New("unImplemented")
+}
+
+//UnSuppressEvent  unimplemented
+func (oo *OpenONUAC) UnSuppressEvent(ctx context.Context, filter *voltha.EventFilter) (*empty.Empty, error) {
+	return nil, errors.New("unImplemented")
+}
+
+//GetImageDownloadStatus is unimplemented
+func (oo *OpenONUAC) GetImageDownloadStatus(ctx context.Context, imageInfo *ic.ImageDownloadMessage) (*voltha.ImageDownload, error) {
+	return nil, errors.New("unImplemented")
+}
+
+//CancelImageDownload is unimplemented
+func (oo *OpenONUAC) CancelImageDownload(ctx context.Context, imageInfo *ic.ImageDownloadMessage) (*voltha.ImageDownload, error) {
+	return nil, errors.New("unImplemented")
+}
+
+//RevertImageUpdate is unimplemented
+func (oo *OpenONUAC) RevertImageUpdate(ctx context.Context, imageInfo *ic.ImageDownloadMessage) (*voltha.ImageDownload, error) {
+	return nil, errors.New("unImplemented")
+}
+
+// UpdateFlowsBulk is unimplemented
+func (oo *OpenONUAC) UpdateFlowsBulk(ctx context.Context, flows *ic.BulkFlows) (*empty.Empty, error) {
+	return nil, errors.New("unImplemented")
+}
+
+//SelfTestDevice unimplented
+func (oo *OpenONUAC) SelfTestDevice(ctx context.Context, device *voltha.Device) (*empty.Empty, error) {
+	return nil, errors.New("unImplemented")
+}
+
+//SendPacketOut sends packet out to the device
+func (oo *OpenONUAC) SendPacketOut(ctx context.Context, packet *ic.PacketOut) (*empty.Empty, error) {
+	return nil, errors.New("unImplemented")
+}
+
+// EnablePort to Enable PON/NNI interface - seems not to be used/required according to python code
+func (oo *OpenONUAC) EnablePort(ctx context.Context, port *voltha.Port) (*empty.Empty, error) {
+	return nil, errors.New("unImplemented")
+}
+
+// DisablePort to Disable pon/nni interface  - seems not to be used/required according to python code
+func (oo *OpenONUAC) DisablePort(ctx context.Context, port *voltha.Port) (*empty.Empty, error) {
+	return nil, errors.New("unImplemented")
+}
+
+// GetExtValue - unimplemented
+func (oo *OpenONUAC) GetExtValue(ctx context.Context, extInfo *ic.GetExtValueMessage) (*voltha.ReturnValues, error) {
+	return nil, errors.New("unImplemented")
+}
+
+// ChildDeviceLost - unimplemented
+func (oo *OpenONUAC) ChildDeviceLost(ctx context.Context, childDevice *voltha.Device) (*empty.Empty, error) {
+	return nil, errors.New("unImplemented")
+}
+
+// GetSupportedFsms - TODO: add comment
+func (oo *OpenONUAC) GetSupportedFsms() *cmn.OmciDeviceFsms {
+	return oo.pSupportedFsms
+}
+
+// LockMutexMibTemplateGenerated - TODO: add comment
+func (oo *OpenONUAC) LockMutexMibTemplateGenerated() {
+	oo.mutexMibTemplateGenerated.Lock()
+}
+
+// UnlockMutexMibTemplateGenerated - TODO: add comment
+func (oo *OpenONUAC) UnlockMutexMibTemplateGenerated() {
+	oo.mutexMibTemplateGenerated.Unlock()
+}
+
+// GetMibTemplatesGenerated - TODO: add comment
+func (oo *OpenONUAC) GetMibTemplatesGenerated(mibTemplatePath string) (value bool, exist bool) {
+	value, exist = oo.mibTemplatesGenerated[mibTemplatePath]
+	return value, exist
+}
+
+// SetMibTemplatesGenerated - TODO: add comment
+func (oo *OpenONUAC) SetMibTemplatesGenerated(mibTemplatePath string, value bool) {
+	oo.mibTemplatesGenerated[mibTemplatePath] = value
+}
+
+// RLockMutexDeviceHandlersMap - TODO: add comment
+func (oo *OpenONUAC) RLockMutexDeviceHandlersMap() {
+	oo.mutexDeviceHandlersMap.RLock()
+}
+
+// RUnlockMutexDeviceHandlersMap - TODO: add comment
+func (oo *OpenONUAC) RUnlockMutexDeviceHandlersMap() {
+	oo.mutexDeviceHandlersMap.RUnlock()
+}
+
+// GetDeviceHandler - TODO: add comment
+func (oo *OpenONUAC) GetDeviceHandler(deviceID string) (value cmn.IdeviceHandler, exist bool) {
+	value, exist = oo.deviceHandlers[deviceID]
+	return value, exist
+}