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      1 // Copyright 2014 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #ifndef CHROMEOS_DBUS_BLUETOOTH_GATT_DESCRIPTOR_SERVICE_PROVIDER_H_
      6 #define CHROMEOS_DBUS_BLUETOOTH_GATT_DESCRIPTOR_SERVICE_PROVIDER_H_
      7 
      8 #include <string>
      9 #include <vector>
     10 
     11 #include "base/basictypes.h"
     12 #include "base/callback.h"
     13 #include "chromeos/chromeos_export.h"
     14 #include "dbus/bus.h"
     15 #include "dbus/object_path.h"
     16 
     17 namespace chromeos {
     18 
     19 // BluetoothGattDescriptorServiceProvider is used to provide a D-Bus object that
     20 // represents a local GATT characteristic descriptor that the Bluetooth daemon
     21 // can communicate with.
     22 //
     23 // Instantiate with a chosen D-Bus object path, delegate, and other fields.
     24 // The Bluetooth daemon communicates with a GATT descriptor using the
     25 // standard DBus.Properties interface. While most properties of the GATT
     26 // descriptor interface are read-only and don't change throughout the
     27 // life-time of the object, the "Value" property is both writeable and its
     28 // value can change. Both Get and Set operations performed on the "Value"
     29 // property are delegated to the Delegate object, an instance of which is
     30 // mandatory during initialization. In addition, a "SendValueChanged" method is
     31 // provided, which emits a DBus.Properties.PropertyChanged signal for the
     32 // "Value" property.
     33 class CHROMEOS_EXPORT BluetoothGattDescriptorServiceProvider {
     34  public:
     35   // Interface for reacting to GATT characteristic descriptor value requests.
     36   class Delegate {
     37    public:
     38     virtual ~Delegate() {}
     39 
     40     // ValueCallback is used for methods that require a descriptor value
     41     // to be returned.
     42     typedef base::Callback<void(const std::vector<uint8>&)> ValueCallback;
     43 
     44     // ErrorCallback is used by methods to report failure.
     45     typedef base::Closure ErrorCallback;
     46 
     47     // This method will be called when a remote device requests to read the
     48     // value of the exported GATT descriptor. Invoke |callback| with a value
     49     // to return that value to the requester. Invoke |error_callback| to report
     50     // a failure to read the value. This can happen, for example, if the
     51     // descriptor has no read permission set. Either callback should be
     52     // invoked after a reasonable amount of time, since the request will time
     53     // out if left pending for too long.
     54     virtual void GetDescriptorValue(const ValueCallback& callback,
     55                                     const ErrorCallback& error_callback) = 0;
     56 
     57     // This method will be called, when a remote device requests to write the
     58     // value of the exported GATT descriptor. Invoke |callback| to report
     59     // that the value was successfully written. Invoke |error_callback| to
     60     // report a failure to write the value. This can happen, for example, if the
     61     // descriptor has no write permission set. Either callback should be
     62     // invoked after a reasonable amount of time, since the request will time
     63     // out if left pending for too long.
     64     //
     65     // The delegate should use this method to perform any side-effects that may
     66     // occur based on the set value and potentially send a property changed
     67     // signal to notify the Bluetooth daemon that the value has changed.
     68     virtual void SetDescriptorValue(const std::vector<uint8>& value,
     69                                     const base::Closure& callback,
     70                                     const ErrorCallback& error_callback) = 0;
     71   };
     72 
     73   virtual ~BluetoothGattDescriptorServiceProvider();
     74 
     75   // Send a PropertyChanged signal to notify the Bluetooth daemon that the value
     76   // of the "Value" property has changed to |value|.
     77   virtual void SendValueChanged(const std::vector<uint8>& value) = 0;
     78 
     79   // Creates the instance, where |bus| is the D-Bus bus connection to export
     80   // the object onto, |uuid| is the 128-bit GATT descriptor UUID, |permissions|
     81   // is the list of attribute permissions, |characteristic_path| is the object
     82   // path of the exported GATT characteristic the descriptor belongs to,
     83   // |object_path| is the object path that the descriptor should have, and
     84   // |delegate| is the object that value Get/Set requests will be passed to and
     85   // responses generated from.
     86   //
     87   // Object paths of GATT descriptors must be hierarchical to the path of the
     88   // GATT characteristic they belong to. Hence, |object_path| must have
     89   // |characteristic_path| as its prefix. Ownership of |delegate| is not taken,
     90   // thus the delegate should outlive this instance. A delegate should handle
     91   // only a single exported descriptor and own it.
     92   static BluetoothGattDescriptorServiceProvider* Create(
     93       dbus::Bus* bus,
     94       const dbus::ObjectPath& object_path,
     95       Delegate* delegate,
     96       const std::string& uuid,
     97       const std::vector<std::string>& permissions,
     98       const dbus::ObjectPath& characteristic_path);
     99 
    100  protected:
    101   BluetoothGattDescriptorServiceProvider();
    102 
    103  private:
    104   DISALLOW_COPY_AND_ASSIGN(BluetoothGattDescriptorServiceProvider);
    105 };
    106 
    107 }  // namespace chromeos
    108 
    109 #endif  // CHROMEOS_DBUS_BLUETOOTH_GATT_DESCRIPTOR_SERVICE_PROVIDER_H_
    110