For more information on the improvements and additions please refer to the [class documentation](https://h2zero.github.io/esp-nimble-cpp/annotated.html) and [Improvements and updates](Improvements_and_updates.md)
(Mainly for Arduino) You may choose to include `NimBLELog.h` in your application if you want to use the `NIMBLE_LOGx` macros for debugging. These macros are used the same way as the `ESP_LOGx` macros.
For convenience definitions have been added to allow applications to use either name for all classes this means **no class names need to be changed in existing code** and makes migrating easier.
`BLEAddress` (`NimBLEAddress`) When constructing an address the constructor now takes an *(optional)*`uint8_t type` parameter to specify the address type. Default is (0) Public static address.
`BLEServerCallbacks` (`NimBLEServerCallbacks`) has new methods for handling security operations.
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`BLEServerCallbacks::onConnect` (`NimBLEServerCallbacks::onConnect`) only has a single callback declaration which takes an additional (required) parameter `NimBLEConnInfo & connInfo`, which has methods to get information about the connected peer.
`BLEServerCallbacks::onDisconnect` (`NimBLEServerCallbacks::onDisconnect`) only has a single callback declaration which takes 2 additional (required) parameters `NimBLEConnInfo & connInfo`, which provides information about the peer and `int reason`, which gives the reason code for disconnection.
```
void onDisconnect(NimBLEServer* pServer, NimBLEConnInfo& connInfo, int reason)`
`BLEServerCallbacks::onMtuChanged` is now (`NimBLEServerCallbacks::onMtuChange`) and takes the parameter `NimBLEConnInfo & connInfo` instead of `esp_ble_gatts_cb_param_t`, which has methods to get information about the connected peer.
`BLEService::createCharacteristic` (`NimBLEService::createCharacteristic`) is used the same way as originally except the properties parameter has changed.
`BLECharacteristicCallbacks` (`NimBLECharacteristicCallbacks`) has a new method `NimBLECharacteristicCallbacks::onSubscribe` which is called when a client subscribes to notifications/indications.
`BLECharacteristicCallbacks::onRead` (`NimBLECharacteristicCallbacks::onRead`) only has a single callback declaration, which takes an additional (required) parameter of `NimBLEConnInfo& connInfo`, which provides connection information about the peer.
`BLECharacteristicCallbacks::onWrite` (`NimBLECharacteristicCallbacks::onWrite`) only has a single callback declaration, which takes an additional (required) parameter of `NimBLEConnInfo& connInfo`, which provides connection information about the peer.
`BLECharacteristicCallbacks::onStatus` (`NimBLECharacteristicCallbacks::onStatus`) has had the status parameter removed as it was unnecessary since the status code from the BLE stack was also provided. The status code for success is 0 for notifications and BLE_HS_EDONE for indications, any other value is an error.
All other descriptors are now created just as characteristics are by using the `NimBLECharacteristic::createDescriptor` method (except 0x2904, see below).
Would create a descriptor with the UUID 0xABCD, publicly readable but only writable if paired/bonded (encrypted) and has a max value length of 25 bytes.
For the 0x2904, there is a specialized class that is created through `NimBLECharacteristic::create2904` which returns a pointer to a `NimBLE2904` instance which has specific
functions for handling the data expect in the Characteristic Presentation Format Descriptor specification.
The above descriptor callbacks take an additional (required) parameter `NimBLEConnInfo& connInfo`, which contains the connection information of the peer.
When a peer wants to read or write a characteristic or descriptor with any of these properties applied it will trigger the pairing process. By default the "just-works" pairing will be performed automatically.
Now takes 2 optional parameters, the first is the duration to advertise for (in milliseconds), the second `NimBLEAddress` to direct advertising to a specific device.
Multiple client instances can be created, up to the maximum number of connections set in the config file (default: 3). To delete a client instance you must use `NimBLEDevice::deleteClient`.
The type parameter has been removed and a new bool parameter has been added to indicate if the client should delete the attribute database previously retrieved (if applicable) for the peripheral, default value is true.
If set to false the client will use the attribute database it retrieved from the peripheral when previously connected. This allows for faster connections and power saving if the devices dropped connection and are reconnecting.
The parameter `bool asyncConnect` if true, will cause the client to send the connect command to the stack and return immediately without blocking. The return value will represent wether the command was sent successfully or not and the `NimBLEClientCallbacks::onConnect` or `NimBLEClientCallbacks::onConnectFail` will be called when the operation is complete.
The parameter `bool exchangeMTU` if true, will cause the client to perform the exchange MTU process upon connecting. If false the MTU exchange will need to be performed by the application by calling `NimBLEClient::exchangeMTU`. If the connection is only sending small payloads it may be advantageous to not exchange the MTU to gain performance in the connection process.
This method now takes an optional (bool) parameter to indicate if the services should be retrieved from the server (true) or the currently known database returned (false : default).
**Added:** `NimBLEClient::discoverAttributes` for the user to discover all the peripheral attributes to replace the the removed automatic functionality.
This method now takes an optional (bool) parameter to indicate if the characteristics should be retrieved from the server (true) or the currently known database returned, default = false.
This method now takes an optional (bool) parameter to indicate if the descriptors should be retrieved from the server (true) or the currently known database returned, default = false.
Unlike the original library pre-packaged in the esp32-arduino, this library has all the configuration options that are normally set in menuconfig available in the *src/nimconfig.h* file.
