476 lines
16 KiB
Markdown
476 lines
16 KiB
Markdown
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# Nearby Service
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#### Connecting phones in a P2P network
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[](https://xenikii.one)
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[](https://github.com/ksenia312/nearby_service/blob/main/LICENSE)
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Nearby Service Flutter Plugin is used to create connections in a P2P network.
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The plugin supports sending text messages and files. With it,
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you can easily create any kind of information sharing application **without Internet connection**.
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## Table of Contents
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- [About](#about)
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- [Android](#android-)
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- [IOS](#ios-)
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- [Setup](#setup)
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- [Android](#android--1)
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- [IOS](#ios--1)
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- [Usage](#usage)
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- [Data sharing](#data-sharing)
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- [Text messages](#text-messages)
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- [Resource messages](#resource-messages)
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- [Additional features](#additional-features)
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- [Demo](#demo)
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## About
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> A peer-to-peer (P2P) network is a decentralized network architecture in which each participant, called a peer, can act
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> as both a client and a server. This means that peer-to-peer networks can exchange resources such as files, data or
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> services directly with each other without needing a central authority or server.
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### Android <a id="android_about"></a>
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For Android, **Wi-fi Direct** is used as a P2P network.
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It is implemented through the `android.net.wifi.p2p` module.
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It **requires** permissions for `ACCESS_FINE_LOCATION` and `NEARBY_WIFI_DEVICES` (for Android 13+).
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It is also important that you need **Wi-fi enabled** on your device to use it.
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To check permissions and Wi-fi status, the
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`nearby_service` plugin includes a set of methods:
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- `checkWifiService()` (Android only): returns true if Wi-fi is enabled
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- `requestPermissions()` (Android only): requests permissions for location and nearby devices and returns true if
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granted
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- `openServicesSettings()`: opens Wi-fi settings for Android and general settings for iOS
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> Testing the plugin **is not possible** on Android emulators, as they usually do not contain the Wi-fi Direct function
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> in general! Use physical devices for that.
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### IOS <a id="ios_about"></a>
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For IOS, the P2P connection is implemented through the `Multipeer Connectivity` framework.
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This framework **automatically selects** the best network technology depending on the situation—using **Wi-Fi**
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if both devices are on the same network, or using **peer-to-peer Wi-Fi** or **Bluetooth** otherwise.
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The module will work even with Wi-fi turned off (via Bluetooth), but you can still use `openServicesSettings()` from
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the `nearby_service` plugin to open the settings and prompt the user to turn Wi-fi on.
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## Setup
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### Android <a id="android_setup"></a>
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All necessary Android permissions are already in the **AndroidManifest.xml** of the plugin,
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so you don't need to add anything **to work with p2p network**.
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### IOS <a id="ios_setup"></a>
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For IOS, you need to add the following values to **Info.plist**:
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```
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<key>NSBonjourServices</key>
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<array>
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<string>_mp-connection._tcp</string>
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</array>
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<key>UIRequiresPersistentWiFi</key>
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<true/>
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<key>NSLocalNetworkUsageDescription</key>
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<string>[Your description here]</string>
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```
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- `NSBonjourServices`
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For the `nearby_service` plugin, you should add the value `<string>_mp-connection._tcp</string>`. This key is
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required for **Multipeer Connectivity**. It defines the Bonjour services
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that your application will look for. Bonjour is Apple's implementation of zero-configuration networking, which allows
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devices on a LAN to discover each other and establish connections without requiring manual configuration.
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- `UIRequiresPersistentWiFi`
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This key is not strictly required for **Multipeer Connectivity** to work. This key is used
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to indicate that your application requires a persistent Wi-Fi connection even when the screen is off. This can be
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useful for maintaining a network connection for continuous data transfer.
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- `NSLocalNetworkUsageDescription`
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This key is needed to inform users why your application will use the local network. You must provide a string value
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that explains why your application needs LAN access.
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> Note that if you want to use the plugin **to send files**, you also need to follow the instructions about permissions
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> of the filesystem management package you are using.
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## Usage
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> The full example demonstrating the functionality can be viewed at
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> the [link](https://github.com/ksenia312/nearby_service/tree/main/example_full).
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> **Important note:** for functionality that is only available for one of the platforms, you should use the
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> corresponding
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> API element from `NearbyService`.
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>
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> For Android:
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>
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> ```dart
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> final _nearbyService = NearbyService.getInstance();
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> _nearbyService.android..
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> ```
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> For IOS:
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>
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> ```dart
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> final _nearbyService = NearbyService.getInstance();
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> _nearbyService.ios..
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> ```
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1. Import the package:
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```dart
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import 'package:nearby_service/nearby_service.dart';
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```
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2. Create an instance of NearbyService:
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```dart
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// getInstance() returns an instance for the current platform.
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final _nearbyService = NearbyService.getInstance();
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```
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3. Initialize the plugin:
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```dart
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// You can change the device name on a P2P network only for iOS.
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// Optionally pass the [iosDeviceName].
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await _nearbyService.initialize(
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data: NearbyInitializeData(iosDeviceName: iosDeviceName),
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);
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```
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**Extra step for Android:** ask for permissions and make sure Wi-fi is enabled:
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```dart
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final granted = await _nearbyService.android?.requestPermissions();
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if (granted ?? false) {
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// go to the checking Wi-fi step
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}
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```
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```dart
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final isWifiEnabled = await _nearbyService.android?.checkWifiService();
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if (isWifiEnabled ?? false) {
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// go to the starting discovery step
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}
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```
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**Extra step for IOS:** ask the user to choose whether they are a Browser or Advertiser:
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> In IOS Multipeer Connectivity, there are 2 roles for the discovery process and connection between devices: **browser**
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> and **advertiser**.
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>
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> **Browser**: This component discovers nearby devices that report their availability. It is
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> responsible for finding peers that advertise themselves and inviting them to join the shared session.
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>
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> **Advertiser**: This component advertises the availability of the device to nearby peers. It is used to let know
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> the browser that the device is available for inviting and connecting.
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The code for selecting a role:
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```dart
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_nearbyService.ios?.setIsBrowser(value: isBrowser);
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// go to the starting discovery step
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```
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4. Start to discover the P2P network.
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```dart
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final result = await _nearbyService.discover();
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if (result) {
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// go to the listening peers step
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}
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```
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5. Start listening to peers:
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```dart
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_nearbyService.getPeersStream().listen((event) => peers = event);
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```
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6. Each of the peers is a `NearbyDevice` and you can connect to it:
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> Remember that when used on the Android platform, you can only pass `NearbyAndroidDevice` to the `connect()` method.
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> Similarly for iOS, `NearbyIOSDevice`. Devices automatically come from the discovery state in the correct type, so you
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> just need to use the received data.
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```dart
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final result = await _nearbyService.connect(device);
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if (result) {
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// go the the listening the device step
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}
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```
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7. Once you are connected via P2P network, you can start listening to the connected device. If `null` comes from the
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stream, it means the devices lost connection.
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```dart
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_connectedDeviceSubscription = _nearbyService.getConnectedDeviceStream(device).listen(
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(event) async {
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final wasConnected = connectedDevice?.status.isConnected ?? false;
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final nowConnected = event?.status.isConnected ?? false;
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if (wasConnected && !nowConnected) {
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// return to the discovery state
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}
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connectedDevice = event;
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},
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);
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```
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8. Once you have connected over a P2P network, you still need to create a **communication channel** to transfer data.
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For Android, this is a **socket** embedded in `NearbyService`, for iOS it's a setup to listen to messages and
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resources from the desired device. There is a method `startCommunicationChannel()` for this purpose. You should pass
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to it listeners for messages and resources received from the connected device. There can only be one communication
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channel, if you create a new one, the previous one will be **cancelled**.
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```dart
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final messagesListener = NearbyServiceMessagesListener(
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onData: (message) {
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// handle the message from NearbyServiceMessagesListener
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},
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);
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final filesListener = NearbyServiceFilesListener(
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onData: (pack) async {
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// handle the files pack from NearbyServiceFilesListener
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},
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);
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await _nearbyService.startCommunicationChannel(
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NearbyCommunicationChannelData(
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connectedDevice.info.id,
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messagesListener: messagesListener,
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filesListener: filesListener,
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),
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);
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```
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9. I think you've already guessed that since there are listeners of messages from another device, we can send them
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ourselves too :) There is a method `send()` for that:
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```dart
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_nearbyService.send(
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OutgoingNearbyMessage(
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content: NearbyMessageTextRequest.create(value: message),
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receiver: connectedDevice.info,
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),
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);
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```
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## Data sharing
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This is a very important topic for the `nearby_service` plugin because it provides unique functionality for sharing
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typed data.
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First, it's essential to say that when you send a message, you are required to pass the `OutgoingNearbyMessage` model.
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This contains the `receiver` - the recipient to whom the message is addressed. The receiver is someone with whom you
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already have an established communication channel. Also `OutgoingNearbyMessage` contains a `content` field, it can be
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one of 4 types:
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- `NearbyMessageTextRequest`
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- `NearbyMessageTextResponse`
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- `NearbyMessageFilesRequest`
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- `NearbyMessageFilesResponse`
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We will talk more about them later.
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Second, there is another type of message, `ReceivedNearbyMessage`. This is what comes to you from
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the `NearbyServiceMessagesListener`. It contains a `sender` field so that you can identify who the message came from and
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use that information.
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### Text messages
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Description of the operating logic:
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1. One of the devices sends a message using the `send()` method:
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```dart
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// DEVICE A
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_nearbyService.send(
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OutgoingNearbyMessage(
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content: NearbyMessageTextRequest.create(value: message),
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receiver: connectedDevice.info,
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),
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);
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```
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2. Another device receives the `ReceivedNearbyMessage` with content cast as `NearbyMessageTextRequest` from the
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`NearbyServiceMessagesListener`.
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```dart
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// DEVICE B
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final messagesListener = NearbyServiceMessagesListener(
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onData: (message) {
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// message is ReceivedNearbyMessage with content cast as NearbyMessageTextRequest here
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},
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);
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```
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3. If you want the sender to make sure the message has been received, you can send them `NearbyMessageTextResponse`. You
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need to add the `id` from the received `NearbyMessageTextRequest` to it:
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```dart
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// DEVICE B
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_nearbyService.send(
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OutgoingNearbyMessage(
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receiver: connectedDevice.info,
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content: NearbyMessageTextResponse(id: requestId),
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),
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);
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```
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4. If everything is fine, the sender will receive your `NearbyMessageTextResponse` from
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their `NearbyServiceMessagesListener`:
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```dart
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// DEVICE A
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final messagesListener = NearbyServiceMessagesListener(
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onData: (message) {
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// message is ReceivedNearbyMessage with content cast as NearbyMessageTextResponse here
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},
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);
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```
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> Throughout the process, you can use the `id`s of the messages to identify them.
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### Resource messages
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Description of the operating logic:
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1. One of the devices sends a message with `NearbyMessageFilesRequest` using the `send()` method:
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```dart
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// DEVICE A
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_nearbyService.send(
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OutgoingNearbyMessage(
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// files here is List<NearbyFileInfo>, it can be easily created from the file path: NearbyFileInfo(path: file.path)
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content: NearbyMessageFilesRequest.create(files: files),
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receiver: connectedDevice.info,
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),
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);
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```
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2. Another device receives the `ReceivedNearbyMessage` with content cast as `NearbyMessageFilesRequest` from the
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`NearbyServiceMessagesListener`.
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> The file request comes from the `NearbyServiceMessagesListener` because it doesn't contain the transferred files, only
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> the request to send them! For files, confirmation by the other party before starting the data transfer is required!
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```dart
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// DEVICE B
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final messagesListener = NearbyServiceMessagesListener(
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onData: (message) {
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// message is ReceivedNearbyMessage with content cast as NearbyMessageFilesRequest here
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},
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);
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```
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3. In order to receive the files, the other party must confirm that it wants to do so and send a message
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with `NearbyMessageFilesResponse` content. The `NearbyMessageFilesResponse` contains the `isAccepted` field,
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which will determine whether the file sending will start or not.
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> If you don't want to use confirmation logic to send files, just send the automatic positive responses
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> to `NearbyMessageFilesRequest` in `NearbyServiceMessagesListener`.
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```dart
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// DEVICE B
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_nearbyService.send(
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OutgoingNearbyMessage(
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receiver: connectedDevice!.info,
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content: NearbyMessageFilesResponse(
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id: request.id,
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isAccepted: isAccepted,
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),
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),
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);
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```
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4. The sender will receive `NearbyMessageFilesResponse` in their `NearbyServiceMessagesListener` and can notify the
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user.
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```dart
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// DEVICE A
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final messagesListener = NearbyServiceMessagesListener(
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onData: (message) {
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// message is ReceivedNearbyMessage with content cast as NearbyMessageFilesResponse here
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},
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);
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```
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At this time under the hood, the sending of files will begin and the recipient will receive `ReceivedNearbyFilesPack` in
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the `NearbyServiceFilesListener` when sending is complete. `ReceivedNearbyFilesPack` holds the paths of the received
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files already stored on the device's temporary directory. You can overwrite them to the desired location, delete them,
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or do anything else you like.
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```dart
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// DEVICE B
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final filesListener = NearbyServiceFilesListener(
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onData: (pack) async {
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// pack is ReceivedNearbyFilesPack here
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},
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);
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```
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## Additional features
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- Each `NearbyDevice` contains `NearbyDeviceInfo` that presents different meanings depending on the platform. For
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Android `id` is the MAC address of the device, and for iOS it is the unique identifier of its MCPeerID. In general, id
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identifies the device
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in its platform.
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- Use the getter `communicationChannelState` of `NearbyService` to know the state of the communication channel. It may
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be:
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```dart
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enum CommunicationChannelState {
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notConnected,
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loading,
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connected;
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bool get isNotConnected => this == CommunicationChannelState.notConnected;
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bool get isLoading => this == CommunicationChannelState.loading;
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bool get isConnected => this == CommunicationChannelState.connected;
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}
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```
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The getter is `ValueListenable` so you can listen to its state.
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- There are methods `getPlatformVersion()` and `getPlatformModel()` of `NearbyService` to determine the version and
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model of the device respectively. You can use them to specify a
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name for the IOS.
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- Use `getCurrentDeviceInfo()` of `NearbyService` to get information about the current device on the P2P network. Note
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that the ID obtained from `getCurrentDeviceInfo()` for Android will always be **02:00:00:00:00:00** for privacy
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issues.
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- For Android, it is possible to listen to the current state of the connection using
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method `getConnectionInfoStream` of `NearbyAndroidService`.
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- When you are creating a service with `getInstance()`, you can define the logging level in the plugin using
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field `logLevel`.
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Possible logging levels:
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```dart
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enum NearbyServiceLogLevel {
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debug,
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info,
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error,
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disabled,
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}
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```
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## Demo
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### Android
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### IOS
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