Diff: ble/GattClient.h

Revision:

1131:692ddf04fc42

Parent:

1116:9cb51490b3f7

Child:

1135:22aada733dbd

--- a/ble/GattClient.h	Tue Jan 12 19:47:52 2016 +0000
+++ b/ble/GattClient.h	Wed Apr 06 19:13:46 2016 +0100
@@ -1,475 +1,360 @@
-/* mbed Microcontroller Library
- * Copyright (c) 2006-2013 ARM Limited
- *
- * 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.
- */
-
-#ifndef __GATT_CLIENT_H__
-#define __GATT_CLIENT_H__
-
-#include "Gap.h"
-#include "GattAttribute.h"
-#include "ServiceDiscovery.h"
-#include "CharacteristicDescriptorDiscovery.h"
-
-#include "GattCallbackParamTypes.h"
-
-#include "CallChainOfFunctionPointersWithContext.h"
-
-class GattClient {
-public:
-    typedef FunctionPointerWithContext<const GattReadCallbackParams*> ReadCallback_t;
-    typedef CallChainOfFunctionPointersWithContext<const GattReadCallbackParams*> ReadCallbackChain_t;
-
-    enum WriteOp_t {
-        GATT_OP_WRITE_REQ = 0x01,  /**< Write request. */
-        GATT_OP_WRITE_CMD = 0x02,  /**< Write command. */
-    };
-
-    typedef FunctionPointerWithContext<const GattWriteCallbackParams*> WriteCallback_t;
-    typedef CallChainOfFunctionPointersWithContext<const GattWriteCallbackParams*> WriteCallbackChain_t;
-
-    typedef FunctionPointerWithContext<const GattHVXCallbackParams*> HVXCallback_t;
-    typedef CallChainOfFunctionPointersWithContext<const GattHVXCallbackParams*> HVXCallbackChain_t;
-
-    typedef FunctionPointerWithContext<const GattClient *> GattClientShutdownCallback_t;
-    typedef CallChainOfFunctionPointersWithContext<const GattClient *> GattClientShutdownCallbackChain_t;
-
-    /*
-     * The following functions are meant to be overridden in the platform-specific sub-class.
-     */
-public:
-    /**
-     * Launch service discovery. Once launched, application callbacks will be
-     * invoked for matching services or characteristics. isServiceDiscoveryActive()
-     * can be used to determine status, and a termination callback (if one was set up)
-     * will be invoked at the end. Service discovery can be terminated prematurely,
-     * if needed, using terminateServiceDiscovery().
-     *
-     * @param  connectionHandle
-     *           Handle for the connection with the peer.
-     * @param  sc
-     *           This is the application callback for a matching service. Taken as
-     *           NULL by default. Note: service discovery may still be active
-     *           when this callback is issued; calling asynchronous BLE-stack
-     *           APIs from within this application callback might cause the
-     *           stack to abort service discovery. If this becomes an issue, it
-     *           may be better to make a local copy of the discoveredService and
-     *           wait for service discovery to terminate before operating on the
-     *           service.
-     * @param  cc
-     *           This is the application callback for a matching characteristic.
-     *           Taken as NULL by default. Note: service discovery may still be
-     *           active when this callback is issued; calling asynchronous
-     *           BLE-stack APIs from within this application callback might cause
-     *           the stack to abort service discovery. If this becomes an issue,
-     *           it may be better to make a local copy of the discoveredCharacteristic
-     *           and wait for service discovery to terminate before operating on the
-     *           characteristic.
-     * @param  matchingServiceUUID
-     *           UUID-based filter for specifying a service in which the application is
-     *           interested. By default it is set as the wildcard UUID_UNKNOWN,
-     *           in which case it matches all services. If characteristic-UUID
-     *           filter (below) is set to the wildcard value, then a service
-     *           callback will be invoked for the matching service (or for every
-     *           service if the service filter is a wildcard).
-     * @param  matchingCharacteristicUUIDIn
-     *           UUID-based filter for specifying characteristic in which the application
-     *           is interested. By default it is set as the wildcard UUID_UKNOWN
-     *           to match against any characteristic. If both service-UUID
-     *           filter and characteristic-UUID filter are used with non-wildcard
-     *           values, then only a single characteristic callback is
-     *           invoked for the matching characteristic.
-     *
-     * @note     Using wildcard values for both service-UUID and characteristic-
-     *           UUID will result in complete service discovery: callbacks being
-     *           called for every service and characteristic.
-     *
-     * @note     Providing NULL for the characteristic callback will result in
-     *           characteristic discovery being skipped for each matching
-     *           service. This allows for an inexpensive method to discover only
-     *           services.
-     *
-     * @return
-     *           BLE_ERROR_NONE if service discovery is launched successfully; else an appropriate error.
-     */
-    virtual ble_error_t launchServiceDiscovery(Gap::Handle_t                               connectionHandle,
-                                               ServiceDiscovery::ServiceCallback_t         sc                           = NULL,
-                                               ServiceDiscovery::CharacteristicCallback_t  cc                           = NULL,
-                                               const UUID                                 &matchingServiceUUID          = UUID::ShortUUIDBytes_t(BLE_UUID_UNKNOWN),
-                                               const UUID                                 &matchingCharacteristicUUIDIn = UUID::ShortUUIDBytes_t(BLE_UUID_UNKNOWN)) {
-        /* Avoid compiler warnings about unused variables. */
-        (void)connectionHandle;
-        (void)sc;
-        (void)cc;
-        (void)matchingServiceUUID;
-        (void)matchingCharacteristicUUIDIn;
-
-        return BLE_ERROR_NOT_IMPLEMENTED; /* Requesting action from porters: override this API if this capability is supported. */
-    }
-
-    /**
-     * Launch service discovery for services. Once launched, service discovery will remain
-     * active with service-callbacks being issued back into the application for matching
-     * services. isServiceDiscoveryActive() can be used to
-     * determine status, and a termination callback (if set up) will be invoked
-     * at the end. Service discovery can be terminated prematurely, if needed,
-     * using terminateServiceDiscovery().
-     *
-     * @param  connectionHandle
-     *           Handle for the connection with the peer.
-     * @param  sc
-     *           This is the application callback for a matching service. Note: service discovery may still be active
-     *           when this callback is issued; calling asynchronous BLE-stack
-     *           APIs from within this application callback might cause the
-     *           stack to abort service discovery. If this becomes an issue, it
-     *           may be better to make a local copy of the discoveredService and
-     *           wait for service discovery to terminate before operating on the
-     *           service.
-     * @param  matchingServiceUUID
-     *           UUID-based filter for specifying a service in which the application is
-     *           interested. By default it is set as the wildcard UUID_UNKNOWN,
-     *           in which case it matches all services.
-     *
-     * @return
-     *           BLE_ERROR_NONE if service discovery is launched successfully; else an appropriate error.
-     */
-    virtual ble_error_t discoverServices(Gap::Handle_t                        connectionHandle,
-                                         ServiceDiscovery::ServiceCallback_t  callback,
-                                         const UUID                          &matchingServiceUUID = UUID::ShortUUIDBytes_t(BLE_UUID_UNKNOWN)) {
-        return launchServiceDiscovery(connectionHandle, callback, NULL, matchingServiceUUID); /* We take advantage of the property
-                                                                * that providing NULL for the characteristic callback will result in
-                                                                * characteristic discovery being skipped for each matching
-                                                                * service. This allows for an inexpensive method to discover only
-                                                                * services. Porters are free to override this. */
-    }
-
-    /**
-     * Launch service discovery for services. Once launched, service discovery will remain
-     * active with service-callbacks being issued back into the application for matching
-     * services. isServiceDiscoveryActive() can be used to
-     * determine status, and a termination callback (if set up) will be invoked
-     * at the end. Service discovery can be terminated prematurely, if needed,
-     * using terminateServiceDiscovery().
-     *
-     * @param  connectionHandle
-     *           Handle for the connection with the peer.
-     * @param  sc
-     *           This is the application callback for a matching service. Note: service discovery may still be active
-     *           when this callback is issued; calling asynchronous BLE-stack
-     *           APIs from within this application callback might cause the
-     *           stack to abort service discovery. If this becomes an issue, it
-     *           may be better to make a local copy of the discoveredService and
-     *           wait for service discovery to terminate before operating on the
-     *           service.
-     * @param  startHandle, endHandle
-     *           Handle range within which to limit the search.
-     *
-     * @return
-     *           BLE_ERROR_NONE if service discovery is launched successfully; else an appropriate error.
-     */
-    virtual ble_error_t discoverServices(Gap::Handle_t                        connectionHandle,
-                                         ServiceDiscovery::ServiceCallback_t  callback,
-                                         GattAttribute::Handle_t              startHandle,
-                                         GattAttribute::Handle_t              endHandle) {
-        /* Avoid compiler warnings about unused variables. */
-        (void)connectionHandle;
-        (void)callback;
-        (void)startHandle;
-        (void)endHandle;
-
-        return BLE_ERROR_NOT_IMPLEMENTED; /* Requesting action from porters: override this API if this capability is supported. */
-    }
-
-    /**
-     * Is service-discovery currently active?
-     */
-    virtual bool isServiceDiscoveryActive(void) const {
-        return false; /* Requesting action from porters: override this API if this capability is supported. */
-    }
-
-    /**
-     * Terminate an ongoing service discovery. This should result in an
-     * invocation of TerminationCallback if service-discovery is active.
-     */
-    virtual void terminateServiceDiscovery(void) {
-        /* Requesting action from porters: override this API if this capability is supported. */
-    }
-
-    /* Initiate a GATT Client read procedure by attribute-handle. */
-    virtual ble_error_t read(Gap::Handle_t connHandle, GattAttribute::Handle_t attributeHandle, uint16_t offset) const {
-        /* Avoid compiler warnings about unused variables. */
-        (void)connHandle;
-        (void)attributeHandle;
-        (void)offset;
-
-        return BLE_ERROR_NOT_IMPLEMENTED; /* Requesting action from porters: override this API if this capability is supported. */
-    }
-
-    /**
-     * Initiate a GATT Client write procedure.
-     *
-     * @param[in] cmd
-     *              Command can be either a write-request (which generates a
-     *              matching response from the peripheral), or a write-command
-     *              (which doesn't require the connected peer to respond).
-     * @param[in] connHandle
-     *              Connection handle.
-     * @param[in] attributeHandle
-     *              Handle for the target attribtue on the remote GATT server.
-     * @param[in] length
-     *              Length of the new value.
-     * @param[in] value
-     *              New value being written.
-     */
-    virtual ble_error_t write(GattClient::WriteOp_t    cmd,
-                              Gap::Handle_t            connHandle,
-                              GattAttribute::Handle_t  attributeHandle,
-                              size_t                   length,
-                              const uint8_t           *value) const {
-        /* Avoid compiler warnings about unused variables. */
-        (void)cmd;
-        (void)connHandle;
-        (void)attributeHandle;
-        (void)length;
-        (void)value;
-
-        return BLE_ERROR_NOT_IMPLEMENTED; /* Requesting action from porters: override this API if this capability is supported. */
-    }
-
-    /* Event callback handlers. */
-public:
-    /**
-     * Set up a callback for read response events.
-     * It is possible to remove registered callbacks using
-     * onDataRead().detach(callbackToRemove)
-     */
-    void onDataRead(ReadCallback_t callback) {
-        onDataReadCallbackChain.add(callback);
-    }
-
-    /**
-     * @brief provide access to the callchain of read callbacks
-     * It is possible to register callbacks using onDataRead().add(callback);
-     * It is possible to unregister callbacks using onDataRead().detach(callback)
-     * @return The read callbacks chain
-     */
-    ReadCallbackChain_t& onDataRead() {
-        return onDataReadCallbackChain;
-    }
-
-    /**
-     * Set up a callback for write response events.
-     * It is possible to remove registered callbacks using
-     * onDataWritten().detach(callbackToRemove).
-     * @Note: Write commands (issued using writeWoResponse) don't generate a response.
-     */
-    void onDataWritten(WriteCallback_t callback) {
-        onDataWriteCallbackChain.add(callback);
-    }
-
-    /**
-     * @brief provide access to the callchain of data written callbacks
-     * It is possible to register callbacks using onDataWritten().add(callback);
-     * It is possible to unregister callbacks using onDataWritten().detach(callback)
-     * @return The data written callbacks chain
-     */
-    WriteCallbackChain_t& onDataWritten() {
-        return onDataWriteCallbackChain;
-    }
-
-    /**
-     * Set up a callback for write response events.
-     * @Note: Write commands (issued using writeWoResponse) don't generate a response.
-     *
-     * @note: This API is now *deprecated* and will be dropped in the future.
-     * Please use onDataWritten() instead.
-     */
-    void onDataWrite(WriteCallback_t callback) {
-        onDataWritten(callback);
-    }
-
-    /**
-     * Set up a callback for when serviceDiscovery terminates.
-     */
-    virtual void onServiceDiscoveryTermination(ServiceDiscovery::TerminationCallback_t callback) {
-        (void)callback; /* Avoid compiler warnings about ununsed variables. */
-
-        /* Requesting action from porters: override this API if this capability is supported. */
-    }
-
-    /**
-     * @brief launch discovery of descriptors for a given characteristic
-     * @details This function will discover all descriptors available for a
-     * specific characteristic.
-     *
-     * @param characteristic[in] The characteristic targeted by this discovery
-     * procedure
-     * @param discoveryCallback[in] User function called each time a descriptor
-     * is found during the procedure.
-     * @param terminationCallback[in] User provided function which will be called
-     * once the discovery procedure is terminating. This will get called when all
-     * the descriptors have been discovered or if an error occur during the discovery
-     * procedure.
-     *
-     * @return
-     *   BLE_ERROR_NONE if characteristic descriptor discovery is launched
-     *   successfully; else an appropriate error.
-     */
-    virtual ble_error_t discoverCharacteristicDescriptors(
-        const DiscoveredCharacteristic& characteristic,
-        const CharacteristicDescriptorDiscovery::DiscoveryCallback_t& discoveryCallback,
-        const CharacteristicDescriptorDiscovery::TerminationCallback_t& terminationCallback) {
-        (void) characteristic;
-        (void) discoveryCallback;
-        (void) terminationCallback;
-        /* Requesting action from porter(s): override this API if this capability is supported. */
-        return BLE_ERROR_NOT_IMPLEMENTED;
-    }
-
-    /**
-     * @brief Indicate if the discovery of characteristic descriptors is active for a given characteristic
-     * or not.
-     * @param characteristic[in] The characteristic concerned by the descriptors discovery.
-     * @return true if a descriptors discovery is active for the characteristic in input; otherwise false.
-     */
-    virtual bool isCharacteristicDescriptorDiscoveryActive(const DiscoveredCharacteristic& characteristic) const
-     {
-        (void) characteristic;
-        return false; /* Requesting action from porter(s): override this API if this capability is supported. */
-    }
-
-    /**
-     * @brief Terminate an ongoing characteristic descriptor discovery.
-     * @detail This should result in an invocation of the TerminationCallback if
-     * the characteristic descriptor discovery is active.
-     * @param characteristic[in] The characteristic on which the running descriptors
-     * discovery should be stopped.
-     */
-    virtual void terminateCharacteristicDescriptorDiscovery(const DiscoveredCharacteristic& characteristic) {
-        /* Requesting action from porter(s): override this API if this capability is supported. */
-        (void) characteristic;
-    }
-
-    /**
-     * Set up a callback for when the GATT client receives an update event
-     * corresponding to a change in the value of a characteristic on the remote
-     * GATT server.
-     * It is possible to remove registered callbacks using onHVX().detach(callbackToRemove).
-     */
-    void onHVX(HVXCallback_t callback) {
-        onHVXCallbackChain.add(callback);
-    }
-
-    /**
-     * Setup a callback to be invoked to notify the user application that the
-     * GattClient instance is about to shutdown (possibly as a result of a call
-     * to BLE::shutdown()).
-     *
-     * @Note: It is possible to chain together multiple onShutdown callbacks
-     * (potentially from different modules of an application) to be notified
-     * before the GattClient is shutdown.
-     *
-     * @Note: It is also possible to set up a callback into a member function of
-     * some object.
-     *
-     * @Note It is possible to unregister a callback using onShutdown().detach(callback)
-     */
-    void onShutdown(const GattClientShutdownCallback_t& callback) {
-        shutdownCallChain.add(callback);
-    }
-    template <typename T>
-    void onShutdown(T *objPtr, void (T::*memberPtr)(void)) {
-        shutdownCallChain.add(objPtr, memberPtr);
-    }
-
-    /**
-     * @brief provide access to the callchain of shutdown event callbacks
-     * It is possible to register callbacks using onShutdown().add(callback);
-     * It is possible to unregister callbacks using onShutdown().detach(callback)
-     * @return The shutdown event callbacks chain
-     */
-    GattClientShutdownCallbackChain_t& onShutdown() {
-        return shutdownCallChain;
-    }
-
-    /**
-     * @brief provide access to the callchain of HVX callbacks
-     * It is possible to register callbacks using onHVX().add(callback);
-     * It is possible to unregister callbacks using onHVX().detach(callback)
-     * @return The HVX callbacks chain
-     */
-    HVXCallbackChain_t& onHVX() {
-        return onHVXCallbackChain;
-    }
-
-public:
-    /**
-     * Notify all registered onShutdown callbacks that the GattClient is
-     * about to be shutdown and clear all GattClient state of the
-     * associated object.
-     *
-     * This function is meant to be overridden in the platform-specific
-     * sub-class. Nevertheless, the sub-class is only expected to reset its
-     * state and not the data held in GattClient members. This shall be achieved
-     * by a call to GattClient::reset() from the sub-class' reset()
-     * implementation.
-     *
-     * @return BLE_ERROR_NONE on success.
-     */
-    virtual ble_error_t reset(void) {
-        /* Notify that the instance is about to shutdown */
-        shutdownCallChain.call(this);
-        shutdownCallChain.clear();
-
-        onDataReadCallbackChain.clear();
-        onDataWriteCallbackChain.clear();
-        onHVXCallbackChain.clear();
-
-        return BLE_ERROR_NONE;
-    }
-
-protected:
-    GattClient() {
-        /* Empty */
-    }
-
-    /* Entry points for the underlying stack to report events back to the user. */
-public:
-    void processReadResponse(const GattReadCallbackParams *params) {
-        onDataReadCallbackChain(params);
-    }
-
-    void processWriteResponse(const GattWriteCallbackParams *params) {
-        onDataWriteCallbackChain(params);
-    }
-
-    void processHVXEvent(const GattHVXCallbackParams *params) {
-        if (onHVXCallbackChain) {
-            onHVXCallbackChain(params);
-        }
-    }
-
-protected:
-    ReadCallbackChain_t               onDataReadCallbackChain;
-    WriteCallbackChain_t              onDataWriteCallbackChain;
-    HVXCallbackChain_t                onHVXCallbackChain;
-    GattClientShutdownCallbackChain_t shutdownCallChain;
-
-private:
-    /* Disallow copy and assignment. */
-    GattClient(const GattClient &);
-    GattClient& operator=(const GattClient &);
-};
-
+/* mbed Microcontroller Library
+ * Copyright (c) 2006-2013 ARM Limited
+ *
+ * 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.
+ */
+
+#ifndef __GATT_CLIENT_H__
+#define __GATT_CLIENT_H__
+
+#include "Gap.h"
+#include "GattAttribute.h"
+#include "ServiceDiscovery.h"
+
+#include "GattCallbackParamTypes.h"
+
+#include "CallChainOfFunctionPointersWithContext.h"
+
+class GattClient {
+public:
+    typedef FunctionPointerWithContext<const GattReadCallbackParams*> ReadCallback_t;
+    typedef CallChainOfFunctionPointersWithContext<const GattReadCallbackParams*> ReadCallbackChain_t;
+
+    enum WriteOp_t {
+        GATT_OP_WRITE_REQ = 0x01,  /**< Write request. */
+        GATT_OP_WRITE_CMD = 0x02,  /**< Write command. */
+    };
+
+    typedef FunctionPointerWithContext<const GattWriteCallbackParams*> WriteCallback_t;
+    typedef CallChainOfFunctionPointersWithContext<const GattWriteCallbackParams*> WriteCallbackChain_t;
+
+    typedef FunctionPointerWithContext<const GattHVXCallbackParams*> HVXCallback_t;
+    typedef CallChainOfFunctionPointersWithContext<const GattHVXCallbackParams*> HVXCallbackChain_t;
+
+    /*
+     * The following functions are meant to be overridden in the platform-specific sub-class.
+     */
+public:
+    /**
+     * Launch service discovery. Once launched, application callbacks will be
+     * invoked for matching services or characteristics. isServiceDiscoveryActive()
+     * can be used to determine status, and a termination callback (if one was set up)
+     * will be invoked at the end. Service discovery can be terminated prematurely,
+     * if needed, using terminateServiceDiscovery().
+     *
+     * @param  connectionHandle
+     *           Handle for the connection with the peer.
+     * @param  sc
+     *           This is the application callback for a matching service. Taken as
+     *           NULL by default. Note: service discovery may still be active
+     *           when this callback is issued; calling asynchronous BLE-stack
+     *           APIs from within this application callback might cause the
+     *           stack to abort service discovery. If this becomes an issue, it
+     *           may be better to make a local copy of the discoveredService and
+     *           wait for service discovery to terminate before operating on the
+     *           service.
+     * @param  cc
+     *           This is the application callback for a matching characteristic.
+     *           Taken as NULL by default. Note: service discovery may still be
+     *           active when this callback is issued; calling asynchronous
+     *           BLE-stack APIs from within this application callback might cause
+     *           the stack to abort service discovery. If this becomes an issue,
+     *           it may be better to make a local copy of the discoveredCharacteristic
+     *           and wait for service discovery to terminate before operating on the
+     *           characteristic.
+     * @param  matchingServiceUUID
+     *           UUID-based filter for specifying a service in which the application is
+     *           interested. By default it is set as the wildcard UUID_UNKNOWN,
+     *           in which case it matches all services. If characteristic-UUID
+     *           filter (below) is set to the wildcard value, then a service
+     *           callback will be invoked for the matching service (or for every
+     *           service if the service filter is a wildcard).
+     * @param  matchingCharacteristicUUIDIn
+     *           UUID-based filter for specifying characteristic in which the application
+     *           is interested. By default it is set as the wildcard UUID_UKNOWN
+     *           to match against any characteristic. If both service-UUID
+     *           filter and characteristic-UUID filter are used with non-wildcard
+     *           values, then only a single characteristic callback is
+     *           invoked for the matching characteristic.
+     *
+     * @note     Using wildcard values for both service-UUID and characteristic-
+     *           UUID will result in complete service discovery: callbacks being
+     *           called for every service and characteristic.
+     *
+     * @note     Providing NULL for the characteristic callback will result in
+     *           characteristic discovery being skipped for each matching
+     *           service. This allows for an inexpensive method to discover only
+     *           services.
+     *
+     * @return
+     *           BLE_ERROR_NONE if service discovery is launched successfully; else an appropriate error.
+     */
+    virtual ble_error_t launchServiceDiscovery(Gap::Handle_t                               connectionHandle,
+                                               ServiceDiscovery::ServiceCallback_t         sc                           = NULL,
+                                               ServiceDiscovery::CharacteristicCallback_t  cc                           = NULL,
+                                               const UUID                                 &matchingServiceUUID          = UUID::ShortUUIDBytes_t(BLE_UUID_UNKNOWN),
+                                               const UUID                                 &matchingCharacteristicUUIDIn = UUID::ShortUUIDBytes_t(BLE_UUID_UNKNOWN)) {
+        /* Avoid compiler warnings about unused variables. */
+        (void)connectionHandle;
+        (void)sc;
+        (void)cc;
+        (void)matchingServiceUUID;
+        (void)matchingCharacteristicUUIDIn;
+
+        return BLE_ERROR_NOT_IMPLEMENTED; /* Requesting action from porters: override this API if this capability is supported. */
+    }
+
+    /**
+     * Launch service discovery for services. Once launched, service discovery will remain
+     * active with service-callbacks being issued back into the application for matching
+     * services. isServiceDiscoveryActive() can be used to
+     * determine status, and a termination callback (if set up) will be invoked
+     * at the end. Service discovery can be terminated prematurely, if needed,
+     * using terminateServiceDiscovery().
+     *
+     * @param  connectionHandle
+     *           Handle for the connection with the peer.
+     * @param  sc
+     *           This is the application callback for a matching service. Note: service discovery may still be active
+     *           when this callback is issued; calling asynchronous BLE-stack
+     *           APIs from within this application callback might cause the
+     *           stack to abort service discovery. If this becomes an issue, it
+     *           may be better to make a local copy of the discoveredService and
+     *           wait for service discovery to terminate before operating on the
+     *           service.
+     * @param  matchingServiceUUID
+     *           UUID-based filter for specifying a service in which the application is
+     *           interested. By default it is set as the wildcard UUID_UNKNOWN,
+     *           in which case it matches all services.
+     *
+     * @return
+     *           BLE_ERROR_NONE if service discovery is launched successfully; else an appropriate error.
+     */
+    virtual ble_error_t discoverServices(Gap::Handle_t                        connectionHandle,
+                                         ServiceDiscovery::ServiceCallback_t  callback,
+                                         const UUID                          &matchingServiceUUID = UUID::ShortUUIDBytes_t(BLE_UUID_UNKNOWN)) {
+        return launchServiceDiscovery(connectionHandle, callback, NULL, matchingServiceUUID); /* We take advantage of the property
+                                                                * that providing NULL for the characteristic callback will result in
+                                                                * characteristic discovery being skipped for each matching
+                                                                * service. This allows for an inexpensive method to discover only
+                                                                * services. Porters are free to override this. */
+    }
+
+    /**
+     * Launch service discovery for services. Once launched, service discovery will remain
+     * active with service-callbacks being issued back into the application for matching
+     * services. isServiceDiscoveryActive() can be used to
+     * determine status, and a termination callback (if set up) will be invoked
+     * at the end. Service discovery can be terminated prematurely, if needed,
+     * using terminateServiceDiscovery().
+     *
+     * @param  connectionHandle
+     *           Handle for the connection with the peer.
+     * @param  sc
+     *           This is the application callback for a matching service. Note: service discovery may still be active
+     *           when this callback is issued; calling asynchronous BLE-stack
+     *           APIs from within this application callback might cause the
+     *           stack to abort service discovery. If this becomes an issue, it
+     *           may be better to make a local copy of the discoveredService and
+     *           wait for service discovery to terminate before operating on the
+     *           service.
+     * @param  startHandle, endHandle
+     *           Handle range within which to limit the search.
+     *
+     * @return
+     *           BLE_ERROR_NONE if service discovery is launched successfully; else an appropriate error.
+     */
+    virtual ble_error_t discoverServices(Gap::Handle_t                        connectionHandle,
+                                         ServiceDiscovery::ServiceCallback_t  callback,
+                                         GattAttribute::Handle_t              startHandle,
+                                         GattAttribute::Handle_t              endHandle) {
+        /* Avoid compiler warnings about unused variables. */
+        (void)connectionHandle;
+        (void)callback;
+        (void)startHandle;
+        (void)endHandle;
+
+        return BLE_ERROR_NOT_IMPLEMENTED; /* Requesting action from porters: override this API if this capability is supported. */
+    }
+
+    /**
+     * Is service-discovery currently active?
+     */
+    virtual bool isServiceDiscoveryActive(void) const {
+        return false; /* Requesting action from porters: override this API if this capability is supported. */
+    }
+
+    /**
+     * Terminate an ongoing service discovery. This should result in an
+     * invocation of TerminationCallback if service-discovery is active.
+     */
+    virtual void terminateServiceDiscovery(void) {
+        /* Requesting action from porters: override this API if this capability is supported. */
+    }
+
+    /* Initiate a GATT Client read procedure by attribute-handle. */
+    virtual ble_error_t read(Gap::Handle_t connHandle, GattAttribute::Handle_t attributeHandle, uint16_t offset) const {
+        /* Avoid compiler warnings about unused variables. */
+        (void)connHandle;
+        (void)attributeHandle;
+        (void)offset;
+
+        return BLE_ERROR_NOT_IMPLEMENTED; /* Requesting action from porters: override this API if this capability is supported. */
+    }
+
+    /**
+     * Initiate a GATT Client write procedure.
+     *
+     * @param[in] cmd
+     *              Command can be either a write-request (which generates a 
+     *              matching response from the peripheral), or a write-command 
+     *              (which doesn't require the connected peer to respond).
+     * @param[in] connHandle
+     *              Connection handle.
+     * @param[in] attributeHandle
+     *              Handle for the target attribtue on the remote GATT server.
+     * @param[in] length
+     *              Length of the new value.
+     * @param[in] value
+     *              New value being written.
+     */
+    virtual ble_error_t write(GattClient::WriteOp_t    cmd,
+                              Gap::Handle_t            connHandle,
+                              GattAttribute::Handle_t  attributeHandle,
+                              size_t                   length,
+                              const uint8_t           *value) const {
+        /* Avoid compiler warnings about unused variables. */
+        (void)cmd;
+        (void)connHandle;
+        (void)attributeHandle;
+        (void)length;
+        (void)value;
+
+        return BLE_ERROR_NOT_IMPLEMENTED; /* Requesting action from porters: override this API if this capability is supported. */
+    }
+
+    /* Event callback handlers. */
+public:
+    /**
+     * Set up a callback for read response events. 
+     * It is possible to remove registered callbacks using 
+     * onDataRead().detach(callbackToRemove)
+     */
+    void onDataRead(ReadCallback_t callback) {
+        onDataReadCallbackChain.add(callback);
+    }
+
+    /**
+     * @brief provide access to the callchain of read callbacks
+     * It is possible to register callbacks using onDataRead().add(callback);
+     * It is possible to unregister callbacks using onDataRead().detach(callback) 
+     * @return The read callbacks chain
+     */
+    ReadCallbackChain_t& onDataRead() {
+        return onDataReadCallbackChain;
+    }
+
+    /**
+     * Set up a callback for write response events.
+     * It is possible to remove registered callbacks using 
+     * onDataWritten().detach(callbackToRemove).
+     * @Note: Write commands (issued using writeWoResponse) don't generate a response.
+     */
+    void onDataWritten(WriteCallback_t callback) {
+        onDataWriteCallbackChain.add(callback);
+    }
+
+    /**
+     * @brief provide access to the callchain of data written callbacks
+     * It is possible to register callbacks using onDataWritten().add(callback);
+     * It is possible to unregister callbacks using onDataWritten().detach(callback) 
+     * @return The data written callbacks chain
+     */
+    WriteCallbackChain_t& onDataWritten() { 
+        return onDataWriteCallbackChain;
+    }
+
+    /**
+     * Set up a callback for write response events.
+     * @Note: Write commands (issued using writeWoResponse) don't generate a response.
+     *
+     * @note: This API is now *deprecated* and will be dropped in the future.
+     * Please use onDataWritten() instead.
+     */
+    void onDataWrite(WriteCallback_t callback) {
+        onDataWritten(callback);
+    }
+
+    /**
+     * Set up a callback for when serviceDiscovery terminates.
+     */
+    virtual void onServiceDiscoveryTermination(ServiceDiscovery::TerminationCallback_t callback) {
+        (void)callback; /* Avoid compiler warnings about ununsed variables. */
+
+        /* Requesting action from porters: override this API if this capability is supported. */
+    }
+
+    /**
+     * Set up a callback for when the GATT client receives an update event
+     * corresponding to a change in the value of a characteristic on the remote
+     * GATT server.
+     * It is possible to remove registered callbacks using onHVX().detach(callbackToRemove).
+     */
+    void onHVX(HVXCallback_t callback) {
+        onHVXCallbackChain.add(callback);
+    }
+
+
+    /**
+     * @brief provide access to the callchain of HVX callbacks
+     * It is possible to register callbacks using onHVX().add(callback);
+     * It is possible to unregister callbacks using onHVX().detach(callback) 
+     * @return The HVX callbacks chain
+     */
+    HVXCallbackChain_t& onHVX() { 
+        return onHVXCallbackChain;
+    }
+
+protected:
+    GattClient() {
+        /* Empty */
+    }
+
+    /* Entry points for the underlying stack to report events back to the user. */
+public:
+    void processReadResponse(const GattReadCallbackParams *params) {
+        onDataReadCallbackChain(params);
+    }
+
+    void processWriteResponse(const GattWriteCallbackParams *params) {
+        onDataWriteCallbackChain(params);
+    }
+
+    void processHVXEvent(const GattHVXCallbackParams *params) {
+        if (onHVXCallbackChain) {
+            onHVXCallbackChain(params);
+        }
+    }
+
+protected:
+    ReadCallbackChain_t  onDataReadCallbackChain;
+    WriteCallbackChain_t onDataWriteCallbackChain;
+    HVXCallbackChain_t   onHVXCallbackChain;
+
+private:
+    /* Disallow copy and assignment. */
+    GattClient(const GattClient &);
+    GattClient& operator=(const GattClient &);
+};
+
 #endif // ifndef __GATT_CLIENT_H__
\ No newline at end of file