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/*
*
* Copyright (c) 2020 Project CHIP Authors
* All rights reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/**
* @file
* This file defines read handler for a CHIP Interaction Data model
*
*/
#pragma once
#include <access/AccessControl.h>
#include <app/AttributePathExpandIterator.h>
#include <app/AttributePathParams.h>
#include <app/AttributeValueEncoder.h>
#include <app/CASESessionManager.h>
#include <app/DataVersionFilter.h>
#include <app/EventManagement.h>
#include <app/EventPathParams.h>
#include <app/MessageDef/AttributePathIBs.h>
#include <app/MessageDef/DataVersionFilterIBs.h>
#include <app/MessageDef/EventFilterIBs.h>
#include <app/MessageDef/EventPathIBs.h>
#include <app/OperationalSessionSetup.h>
#include <app/SubscriptionResumptionSessionEstablisher.h>
#include <app/SubscriptionResumptionStorage.h>
#include <lib/core/CHIPCallback.h>
#include <lib/core/CHIPCore.h>
#include <lib/core/TLVDebug.h>
#include <lib/support/CodeUtils.h>
#include <lib/support/DLLUtil.h>
#include <lib/support/LinkedList.h>
#include <lib/support/logging/CHIPLogging.h>
#include <messaging/ExchangeHolder.h>
#include <messaging/ExchangeMgr.h>
#include <messaging/Flags.h>
#include <protocols/Protocols.h>
#include <system/SystemPacketBuffer.h>
// https://github.com/CHIP-Specifications/connectedhomeip-spec/blob/61a9d19e6af12fdfb0872bcff26d19de6c680a1a/src/Ch02_Architecture.adoc#1122-subscribe-interaction-limits
inline constexpr uint16_t kSubscriptionMaxIntervalPublisherLimit = 3600; // seconds (60 minutes)
namespace chip {
namespace app {
//
// Forward declare the Engine (which is in a different namespace) to be able to use
// it as a friend class below.
//
namespace reporting {
class Engine;
class TestReportingEngine;
class ReportScheduler;
class TestReportScheduler;
} // namespace reporting
class InteractionModelEngine;
class TestInteractionModelEngine;
/**
* @class ReadHandler
*
* @brief The read handler is responsible for processing a read request, asking the attribute/event store
* for the relevant data, and sending a reply.
*
*/
class ReadHandler : public Messaging::ExchangeDelegate
{
public:
using SubjectDescriptor = Access::SubjectDescriptor;
enum class InteractionType : uint8_t
{
Read,
Subscribe,
};
/*
* A callback used to interact with the application.
*/
class ApplicationCallback
{
public:
virtual ~ApplicationCallback() = default;
/*
* Called right after a SubscribeRequest has been parsed and processed. This notifies an interested application
* of a subscription that is about to be established. It also provides an avenue for altering the parameters of the
* subscription (specifically, the min/max negotiated intervals) or even outright rejecting the subscription for
* application-specific reasons.
*
* TODO: Need a new IM status code to convey application-rejected subscribes. Currently, a Failure IM status code is sent
* back to the subscriber, which isn't sufficient.
*
* To reject the subscription, a CHIP_ERROR code that is not equivalent to CHIP_NO_ERROR should be returned.
*
* More information about the set of paths associated with this subscription can be retrieved by calling the appropriate
* Get* methods below.
*
* aReadHandler: Reference to the ReadHandler associated with the subscription.
* aSecureSession: A reference to the underlying secure session associated with the subscription.
*
*/
virtual CHIP_ERROR OnSubscriptionRequested(ReadHandler & aReadHandler, Transport::SecureSession & aSecureSession)
{
return CHIP_NO_ERROR;
}
/*
* Called after a subscription has been fully established.
*/
virtual void OnSubscriptionEstablished(ReadHandler & aReadHandler){};
/*
* Called right before a subscription is about to get terminated. This is only called on subscriptions that were terminated
* after they had been fully established (and therefore had called OnSubscriptionEstablished).
* OnSubscriptionEstablishment().
*/
virtual void OnSubscriptionTerminated(ReadHandler & aReadHandler){};
};
/*
* A callback used to manage the lifetime of the ReadHandler object.
*/
class ManagementCallback
{
public:
virtual ~ManagementCallback() = default;
/*
* Method that signals to a registered callback that this object
* has completed doing useful work and is now safe for release/destruction.
*/
virtual void OnDone(ReadHandler & apReadHandlerObj) = 0;
/*
* Retrieve the ApplicationCallback (if a valid one exists) from our management entity. This avoids
* storing multiple references to the application provided callback and having to subsequently manage lifetime
* issues w.r.t the ReadHandler itself.
*/
virtual ApplicationCallback * GetAppCallback() = 0;
/*
* Retrieve the InteractionalModelEngine that holds this ReadHandler.
*/
virtual InteractionModelEngine * GetInteractionModelEngine() = 0;
};
// TODO (#27675) : Merge existing callback and observer into one class and have an observer pool in the Readhandler to notify
// every
/*
* Observer class for ReadHandler, meant to allow multiple objects to observe the ReadHandler. Currently only one observer is
* supported but all above callbacks should be merged into observer type and an observer pool should be added to allow multiple
* objects to observe ReadHandler
*/
class Observer
{
public:
virtual ~Observer() = default;
/// @brief Callback invoked to notify a subscription was successfully established for the ReadHandler
/// @param[in] apReadHandler ReadHandler that completed its subscription
virtual void OnSubscriptionEstablished(ReadHandler * apReadHandler) = 0;
/// @brief Callback invoked when a ReadHandler went from a non reportable state to a reportable state. Indicates to the
/// observer that a report should be emitted when the min interval allows it.
///
/// This will only be invoked for subscribe-type ReadHandler objects, and only after
/// OnSubscriptionEstablished has been called.
///
/// @param[in] apReadHandler ReadHandler that became dirty and in HandlerState::CanStartReporting state
virtual void OnBecameReportable(ReadHandler * apReadHandler) = 0;
/// @brief Callback invoked when the read handler needs to make sure to send a message to the subscriber within the next
/// maxInterval time period.
/// @param[in] apReadHandler ReadHandler that has generated a report
virtual void OnSubscriptionReportSent(ReadHandler * apReadHandler) = 0;
/// @brief Callback invoked when a ReadHandler is getting removed so it can be unregistered
/// @param[in] apReadHandler ReadHandler getting destroyed
virtual void OnReadHandlerDestroyed(ReadHandler * apReadHandler) = 0;
};
/*
* Destructor - as part of destruction, it will abort the exchange context
* if a valid one still exists.
*
* See Abort() for details on when that might occur.
*/
~ReadHandler() override;
/**
*
* Constructor.
*
* The callback passed in has to outlive this handler object.
*
*/
ReadHandler(ManagementCallback & apCallback, Messaging::ExchangeContext * apExchangeContext, InteractionType aInteractionType,
Observer * observer, DataModel::Provider * apDataModel);
#if CHIP_CONFIG_PERSIST_SUBSCRIPTIONS
/**
*
* Constructor in preparation for resuming a persisted subscription
*
* The callback passed in has to outlive this handler object.
*
*/
ReadHandler(ManagementCallback & apCallback, Observer * observer, DataModel::Provider * apDataModel);
#endif
const SingleLinkedListNode<AttributePathParams> * GetAttributePathList() const { return mpAttributePathList; }
const SingleLinkedListNode<EventPathParams> * GetEventPathList() const { return mpEventPathList; }
const SingleLinkedListNode<DataVersionFilter> * GetDataVersionFilterList() const { return mpDataVersionFilterList; }
void GetReportingIntervals(uint16_t & aMinInterval, uint16_t & aMaxInterval) const
{
aMinInterval = mMinIntervalFloorSeconds;
aMaxInterval = mMaxInterval;
}
CHIP_ERROR SetMinReportingIntervalForTests(uint16_t aMinInterval)
{
VerifyOrReturnError(IsIdle(), CHIP_ERROR_INCORRECT_STATE);
VerifyOrReturnError(aMinInterval <= mMaxInterval, CHIP_ERROR_INVALID_ARGUMENT);
// Ensures the new min interval is higher than the subscriber established one.
mMinIntervalFloorSeconds = std::max(mMinIntervalFloorSeconds, aMinInterval);
return CHIP_NO_ERROR;
}
/*
* Set the maximum reporting interval for the subscription. This SHALL only be called
* from the OnSubscriptionRequested callback above. The restriction is as below
* MinIntervalFloor ≤ MaxInterval ≤ MAX(SUBSCRIPTION_MAX_INTERVAL_PUBLISHER_LIMIT, MaxIntervalCeiling)
* Where SUBSCRIPTION_MAX_INTERVAL_PUBLISHER_LIMIT is set to 60m in the spec.
*/
CHIP_ERROR SetMaxReportingInterval(uint16_t aMaxInterval)
{
VerifyOrReturnError(IsIdle(), CHIP_ERROR_INCORRECT_STATE);
VerifyOrReturnError(mMinIntervalFloorSeconds <= aMaxInterval, CHIP_ERROR_INVALID_ARGUMENT);
VerifyOrReturnError(aMaxInterval <= std::max(GetPublisherSelectedIntervalLimit(), mMaxInterval),
CHIP_ERROR_INVALID_ARGUMENT);
mMaxInterval = aMaxInterval;
return CHIP_NO_ERROR;
}
#if CHIP_CONFIG_PERSIST_SUBSCRIPTIONS
/**
*
* @brief Initialize a ReadHandler for a resumed subsciption
*
* Used after the SubscriptionResumptionSessionEstablisher establishs the CASE session
*/
void OnSubscriptionResumed(const SessionHandle & sessionHandle, SubscriptionResumptionSessionEstablisher & sessionEstablisher);
#endif
private:
PriorityLevel GetCurrentPriority() const { return mCurrentPriority; }
EventNumber & GetEventMin() { return mEventMin; }
/**
* Returns SUBSCRIPTION_MAX_INTERVAL_PUBLISHER_LIMIT
* For an ICD publisher, this SHALL be set to the idle mode duration.
* Otherwise, this SHALL be set to 60 minutes.
*/
uint16_t GetPublisherSelectedIntervalLimit();
enum class ReadHandlerFlags : uint8_t
{
// The flag indicating we are in the middle of a series of chunked report messages, this flag will be cleared during
// sending last chunked message.
ChunkedReport = (1 << 0),
// Tracks whether we're in the initial phase of receiving priming
// reports, which is always true for reads and true for subscriptions
// prior to receiving a subscribe response.
PrimingReports = (1 << 1),
ActiveSubscription = (1 << 2),
FabricFiltered = (1 << 3),
// For subscriptions, we record the dirty set generation when we started to generate the last report.
// The mCurrentReportsBeginGeneration records the generation at the start of the current report. This only/
// has a meaningful value while IsReporting() is true.
//
// mPreviousReportsBeginGeneration will be set to mCurrentReportsBeginGeneration after we send the last
// chunk of the current report. Anything that was dirty with a generation earlier than
// mPreviousReportsBeginGeneration has had its value sent to the client.
// when receiving initial request, it needs mark current handler as dirty.
// when there is urgent event, it needs mark current handler as dirty.
ForceDirty = (1 << 4),
// Don't need the response for report data if true
SuppressResponse = (1 << 5),
};
/**
* Process a read/subscribe request. Parts of the processing may end up being asynchronous, but the ReadHandler
* guarantees that it will call Shutdown on itself when processing is done (including if OnReadInitialRequest
* returns an error).
*
* @retval #Others If fails to process read request
* @retval #CHIP_NO_ERROR On success.
*
*/
void OnInitialRequest(System::PacketBufferHandle && aPayload);
/**
* Send ReportData to initiator
*
* @param[in] aPayload A payload that has read request data
* @param[in] aMoreChunks A flags indicating there will be more chunks expected to be sent for this read request
*
* @retval #Others If fails to send report data
* @retval #CHIP_NO_ERROR On success.
*
* If an error is returned, the ReadHandler guarantees that it is not in
* a state where it's waiting for a response.
*/
CHIP_ERROR SendReportData(System::PacketBufferHandle && aPayload, bool aMoreChunks);
/*
* Get the appropriate size of a packet buffer to allocate for encoding a Report message.
* This size might depend on the underlying session used by the ReadHandler.
*
* The size returned here is the size not including the various prepended headers
* (what System::PacketBuffer calls the "available size").
*/
size_t GetReportBufferMaxSize();
/**
* Returns whether this ReadHandler represents a subscription that was created by the other side of the provided exchange.
*/
bool IsFromSubscriber(Messaging::ExchangeContext & apExchangeContext) const;
bool IsIdle() const { return mState == HandlerState::Idle; }
/// @brief Returns whether the ReadHandler is in a state where it can send a report and there is data to report.
bool ShouldStartReporting() const
{
// Important: Anything that changes ShouldStartReporting() from false to true
// (which can only happen for subscriptions) must call
// mObserver->OnBecameReportable(this).
return CanStartReporting() && (ShouldReportUnscheduled() || IsDirty());
}
/// @brief CanStartReporting() is true if the ReadHandler is in a state where it could generate
/// a (possibly empty) report if someone asked it to.
bool CanStartReporting() const { return mState == HandlerState::CanStartReporting; }
/// @brief ShouldReportUnscheduled() is true if the ReadHandler should be asked to generate reports
/// without consulting the report scheduler.
bool ShouldReportUnscheduled() const
{
return CanStartReporting() && (IsType(ReadHandler::InteractionType::Read) || IsPriming());
}
bool IsAwaitingReportResponse() const { return mState == HandlerState::AwaitingReportResponse; }
// Resets the path iterator to the beginning of the whole report for generating a series of new reports.
void ResetPathIterator();
CHIP_ERROR ProcessDataVersionFilterList(DataVersionFilterIBs::Parser & aDataVersionFilterListParser);
// if current priority is in the middle, it has valid snapshoted last event number, it check cleaness via comparing
// with snapshotted last event number. if current priority is in the end, no valid
// sanpshotted last event, check with latest last event number, re-setup snapshoted checkpoint, and compare again.
bool CheckEventClean(EventManagement & aEventManager);
bool IsType(InteractionType type) const { return (mInteractionType == type); }
bool IsChunkedReport() const { return mFlags.Has(ReadHandlerFlags::ChunkedReport); }
// Is reporting indicates whether we are in the middle of a series chunks. As we will set mIsChunkedReport on the first chunk
// and clear that flag on the last chunk, we can use mIsChunkedReport to indicate this state.
bool IsReporting() const { return mFlags.Has(ReadHandlerFlags::ChunkedReport); }
bool IsPriming() const { return mFlags.Has(ReadHandlerFlags::PrimingReports); }
bool IsActiveSubscription() const { return mFlags.Has(ReadHandlerFlags::ActiveSubscription); }
bool IsFabricFiltered() const { return mFlags.Has(ReadHandlerFlags::FabricFiltered); }
CHIP_ERROR OnSubscribeRequest(Messaging::ExchangeContext * apExchangeContext, System::PacketBufferHandle && aPayload);
void GetSubscriptionId(SubscriptionId & aSubscriptionId) const { aSubscriptionId = mSubscriptionId; }
AttributePathExpandIterator * GetAttributePathExpandIterator() { return &mAttributePathExpandIterator; }
/// @brief Notifies the read handler that a set of attribute paths has been marked dirty. This will schedule a reporting engine
/// run if the change to the attribute path makes the ReadHandler reportable.
/// @param aAttributeChanged Path to the attribute that was changed.
void AttributePathIsDirty(const AttributePathParams & aAttributeChanged);
bool IsDirty() const
{
return (mDirtyGeneration > mPreviousReportsBeginGeneration) || mFlags.Has(ReadHandlerFlags::ForceDirty);
}
void ClearForceDirtyFlag() { ClearStateFlag(ReadHandlerFlags::ForceDirty); }
NodeId GetInitiatorNodeId() const
{
auto session = GetSession();
return session == nullptr ? kUndefinedNodeId : session->GetPeerNodeId();
}
FabricIndex GetAccessingFabricIndex() const
{
auto session = GetSession();
return session == nullptr ? kUndefinedFabricIndex : session->GetFabricIndex();
}
Transport::SecureSession * GetSession() const;
SubjectDescriptor GetSubjectDescriptor() const { return GetSession()->GetSubjectDescriptor(); }
auto GetTransactionStartGeneration() const { return mTransactionStartGeneration; }
/// @brief Forces the read handler into a dirty state, regardless of what's going on with attributes.
/// This can lead to scheduling of a reporting run immediately, if the min interval has been reached,
/// or after the min interval is reached if it has not yet been reached.
void ForceDirtyState();
const AttributeEncodeState & GetAttributeEncodeState() const { return mAttributeEncoderState; }
void SetAttributeEncodeState(const AttributeEncodeState & aState) { mAttributeEncoderState = aState; }
uint32_t GetLastWrittenEventsBytes() const { return mLastWrittenEventsBytes; }
// Returns the number of interested paths, including wildcard and concrete paths.
size_t GetAttributePathCount() const { return mpAttributePathList == nullptr ? 0 : mpAttributePathList->Count(); };
size_t GetEventPathCount() const { return mpEventPathList == nullptr ? 0 : mpEventPathList->Count(); };
size_t GetDataVersionFilterCount() const { return mpDataVersionFilterList == nullptr ? 0 : mpDataVersionFilterList->Count(); };
CHIP_ERROR SendStatusReport(Protocols::InteractionModel::Status aStatus);
friend class TestReadInteraction;
friend class chip::app::reporting::TestReportingEngine;
friend class chip::app::reporting::TestReportScheduler;
//
// The engine needs to be able to Abort/Close a ReadHandler instance upon completion of work for a given read/subscribe
// interaction. We do not want to make these methods public just to give an adjacent class in the IM access, since public
// should really be taking application usage considerations as well. Hence, make it a friend.
//
friend class chip::app::reporting::Engine;
friend class chip::app::InteractionModelEngine;
friend class TestInteractionModelEngine;
// The report scheduler needs to be able to access StateFlag private functions ShouldStartReporting(), CanStartReporting(),
// ForceDirtyState() and IsDirty() to know when to schedule a run so it is declared as a friend class.
friend class chip::app::reporting::ReportScheduler;
enum class HandlerState : uint8_t
{
Idle, ///< The handler has been initialized and is ready
CanStartReporting, ///< The handler has is now capable of generating reports and may generate one immediately
///< or later when other criteria are satisfied (e.g hold-off for min reporting interval).
AwaitingReportResponse, ///< The handler has sent the report to the client and is awaiting a status response.
AwaitingDestruction, ///< The object has completed its work and is awaiting destruction by the application.
};
enum class CloseOptions
{
kDropPersistedSubscription,
kKeepPersistedSubscription
};
/**
* Called internally to signal the completion of all work on this objecta and signal to a registered callback that it's
* safe to release this object.
*
* @param options This specifies whether to drop or keep the subscription
*
*/
void Close(CloseOptions options = CloseOptions::kDropPersistedSubscription);
CHIP_ERROR SendSubscribeResponse();
CHIP_ERROR ProcessSubscribeRequest(System::PacketBufferHandle && aPayload);
CHIP_ERROR ProcessReadRequest(System::PacketBufferHandle && aPayload);
CHIP_ERROR ProcessAttributePaths(AttributePathIBs::Parser & aAttributePathListParser);
CHIP_ERROR ProcessEventPaths(EventPathIBs::Parser & aEventPathsParser);
CHIP_ERROR ProcessEventFilters(EventFilterIBs::Parser & aEventFiltersParser);
CHIP_ERROR OnStatusResponse(Messaging::ExchangeContext * apExchangeContext, System::PacketBufferHandle && aPayload,
bool & aSendStatusResponse);
CHIP_ERROR OnMessageReceived(Messaging::ExchangeContext * apExchangeContext, const PayloadHeader & aPayloadHeader,
System::PacketBufferHandle && aPayload) override;
void OnResponseTimeout(Messaging::ExchangeContext * apExchangeContext) override;
void MoveToState(const HandlerState aTargetState);
const char * GetStateStr() const;
void PersistSubscription();
/// @brief Modifies a state flag in the read handler. If the read handler went from a
/// non-reportable state to a reportable state, schedules a reporting engine run.
/// @param aFlag Flag to set
/// @param aValue Flag new value
void SetStateFlag(ReadHandlerFlags aFlag, bool aValue = true);
/// @brief This function call SetStateFlag with the flag value set to false, thus possibly emitting a report
/// generation.
/// @param aFlag Flag to clear
void ClearStateFlag(ReadHandlerFlags aFlag);
AttributePathExpandIterator mAttributePathExpandIterator;
// The current generation of the reporting engine dirty set the last time we were notified that a path we're interested in was
// marked dirty.
//
// This allows us to detemine whether any paths we care about might have
// been marked dirty after we had already sent reports for them, which would
// mean we should report those paths again, by comparing this generation to the
// current generation when we started sending the last set reports that we completed.
//
// This allows us to reset the iterator to the beginning of the current
// cluster instead of the beginning of the whole report in AttributePathIsDirty, without
// permanently missing dirty any paths.
uint64_t mDirtyGeneration = 0;
// For subscriptions, we record the timestamp when we started to generate the last report.
// The mCurrentReportsBeginGeneration records the timestamp for the current report, which won;t be used for checking if this
// ReadHandler is dirty.
// mPreviousReportsBeginGeneration will be set to mCurrentReportsBeginGeneration after we sent the last chunk of the current
// report.
uint64_t mPreviousReportsBeginGeneration = 0;
uint64_t mCurrentReportsBeginGeneration = 0;
/*
* (mDirtyGeneration = b > a, this is a dirty read handler)
* +- Start Report -> mCurrentReportsBeginGeneration = c
* | +- AttributePathIsDirty (Attribute Y) -> mDirtyGeneration = d
* | | +- Last Chunk -> mPreviousReportsBeginGeneration = mCurrentReportsBeginGeneration = c
* | | | +- (mDirtyGeneration = d) > (mPreviousReportsBeginGeneration = c), this is a dirty read handler
* | | | | Attribute X has a dirty generation less than c, Attribute Y has a dirty generation larger than c
* | | | | So Y will be included in the report but X will not be inclued in this report.
* -a--b--c------d-----e---f---> Generation
* | |
* | +- AttributePathIsDirty (Attribute X) (mDirtyGeneration = b)
* +- mPreviousReportsBeginGeneration
* For read handler, if mDirtyGeneration > mPreviousReportsBeginGeneration, then we regard it as a dirty read handler, and it
* should generate report on timeout reached.
*/
// When we don't have enough resources for a new subscription, the oldest subscription might be evicted by interaction model
// engine, the "oldest" subscription is the subscription with the smallest generation.
uint64_t mTransactionStartGeneration = 0;
SubscriptionId mSubscriptionId = 0;
uint16_t mMinIntervalFloorSeconds = 0;
uint16_t mMaxInterval = 0;
EventNumber mEventMin = 0;
// The last schedule event number snapshoted in the beginning when preparing to fill new events to reports
EventNumber mLastScheduledEventNumber = 0;
// TODO: We should shutdown the transaction when the session expires.
SessionHolder mSessionHandle;
Messaging::ExchangeHolder mExchangeCtx;
#if CHIP_CONFIG_UNSAFE_SUBSCRIPTION_EXCHANGE_MANAGER_USE
// TODO: this should be replaced by a pointer to the InteractionModelEngine that created the ReadHandler
// once InteractionModelEngine is no longer a singleton (see issue 23625)
Messaging::ExchangeManager * mExchangeMgr = nullptr;
#endif // CHIP_CONFIG_UNSAFE_SUBSCRIPTION_EXCHANGE_MANAGER_USE
SingleLinkedListNode<AttributePathParams> * mpAttributePathList = nullptr;
SingleLinkedListNode<EventPathParams> * mpEventPathList = nullptr;
SingleLinkedListNode<DataVersionFilter> * mpDataVersionFilterList = nullptr;
ManagementCallback & mManagementCallback;
uint32_t mLastWrittenEventsBytes = 0;
// The detailed encoding state for a single attribute, used by list chunking feature.
// The size of AttributeEncoderState is 2 bytes for now.
AttributeEncodeState mAttributeEncoderState;
// Current Handler state
HandlerState mState = HandlerState::Idle;
PriorityLevel mCurrentPriority = PriorityLevel::Invalid;
BitFlags<ReadHandlerFlags> mFlags;
InteractionType mInteractionType = InteractionType::Read;
// TODO (#27675): Merge all observers into one and that one will dispatch the callbacks to the right place.
Observer * mObserver = nullptr;
};
} // namespace app
} // namespace chip