chromeos/dbus/bluetooth_gatt_characteristic_service_provider.h

   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_CHARACTERISTIC_SERVICE_PROVIDER_H_
   6 #define CHROMEOS_DBUS_BLUETOOTH_GATT_CHARACTERISTIC_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 // BluetoothGattCharacteristicServiceProvider is used to provide a D-Bus object
  20 // that represents a local GATT characteristic that the Bluetooth daemon can
  21 // communicate with.
  22 //
  23 // Instantiate with a chosen D-Bus object path, delegate, and other fields.
  24 // The Bluetooth daemon communicates with a GATT characteristic using the
  25 // standard DBus.Properties interface. While most properties of the GATT
  26 // characteristic 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 BluetoothGattCharacteristicServiceProvider {
  34  public:
  35   // Interface for reacting to GATT characteristic value requests.
  36   class Delegate {
  37    public:
  38     virtual ~Delegate() {}
  39
  40     // ValueCallback is used for methods that require a characteristic 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 characteristic. 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     // characteristic 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 GetCharacteristicValue(
  55         const ValueCallback& callback,
  56         const ErrorCallback& error_callback) = 0;
  57
  58     // This method will be called, when a remote device requests to write the
  59     // value of the exported GATT characteristic. Invoke |callback| to report
  60     // that the value was successfully written. Invoke |error_callback| to
  61     // report a failure to write the value. This can happen, for example, if the
  62     // characteristic has no write permission set. Either callback should be
  63     // invoked after a reasonable amount of time, since the request will time
  64     // out if left pending for too long.
  65     //
  66     // The delegate should use this method to perform any side-effects that may
  67     // occur based on the set value and potentially send a property changed
  68     // signal to notify the Bluetooth daemon that the value has changed.
  69     virtual void SetCharacteristicValue(
  70         const std::vector<uint8>& value,
  71         const base::Closure& callback,
  72         const ErrorCallback& error_callback) = 0;
  73   };
  74
  75   virtual ~BluetoothGattCharacteristicServiceProvider();
  76
  77   // Send a PropertyChanged signal to notify the Bluetooth daemon that the value
  78   // of the "Value" property has changed to |value|.
  79   virtual void SendValueChanged(const std::vector<uint8>& value) = 0;
  80
  81   // Creates the instance, where |bus| is the D-Bus bus connection to export
  82   // the object onto, |uuid| is the 128-bit GATT characteristic UUID,
  83   // |flags| is the list of GATT characteristic properties, |permissions| is the
  84   // list of attribute permissions, |service_path| is the object path of the
  85   // exported GATT service the characteristic belongs to, |object_path| is the
  86   // object path that the characteristic should have, and |delegate| is the
  87   // object that "Value" Get/Set requests will be passed to and responses
  88   // generated from.
  89   //
  90   // Object paths of GATT characteristics must be hierarchical to the path of
  91   // the GATT service they belong to. Hence, |object_path| must have
  92   // |service_path| as its prefix. Ownership of |delegate| is not taken, thus
  93   // the delegate should outlive this instance. A delegate should handle only
  94   // a single exported characteristic and own it.
  95   static BluetoothGattCharacteristicServiceProvider* Create(
  96       dbus::Bus* bus,
  97       const dbus::ObjectPath& object_path,
  98       Delegate* delegate,
  99       const std::string& uuid,
 100       const std::vector<std::string>& flags,
 101       const std::vector<std::string>& permissions,
 102       const dbus::ObjectPath& service_path);
 103
 104  protected:
 105   BluetoothGattCharacteristicServiceProvider();
 106
 107  private:
 108   DISALLOW_COPY_AND_ASSIGN(BluetoothGattCharacteristicServiceProvider);
 109 };
 110
 111 }  // namespace chromeos
 112
 113 #endif  // CHROMEOS_DBUS_BLUETOOTH_GATT_CHARACTERISTIC_SERVICE_PROVIDER_H_