This library implements an energy-aware wireless discovery service for Android, using Bluetooth Low Energy (BLE) technology, to discover other Android devices in the vicinity using the same service and compare service status, used by the DataHop Network platform. DataHop is a new platform aimed at exploring the potential of a user-operated, smartphone-centric content distribution model for user applications in contrast with the traditional client-server model, that is used by the majority of mobile data transfers today. In particular, we propose that some nodes, either fetching the content via Internet from the content provider (e.g., BBC, CNN), or via sharing user-generated content, could directly update and share content with other nodes in the vicinity in a D2D manner without requiring Internet connectivity. We leverage on sophisticated information-aware and application-centric connectivity techniques to distribute content between mobile devices in densely-populated urban environments or rural areas where Internet connectivity is poor.
Bluetooth Low Energy (BLE) beacons technology provides the features required for the necessary service discovery to provide a smart connectivity between users and transfer content without infrastructure participation. With this library, Android apps are able to discover other users in the vicinity and compare the status of the service before deciding whether to connect using Device-to-Device (D2D) communications (e.g., Wifi-DirecT) and establish a connection and proceed with a data transfer.
This library implements the native library for Android of the BLE service discovery specification to exchange service discovery information between peers before any connection. This library is compatible with Go and the IPFS-lite library, compatible with Android devices, created in https://github.com/datahop/ipfs-lite.
- User devices must automatically discover users in the vicinity without requiring user participation when required
- Devices must be able to exchange information about the status (e.g., list of files available to share) of the service after discovering the other device and before starting any connection.
- Connectivity should be transparent (and run as a background process) to the user and work when the device is in standby mode.
- Connectivity must take into account power consumption and must implement mechanisms to avoid battery depletion.
The library can be built manually using the following command:
$ ./gradlew blediscovery:assembleRelease
and copy the generated .aar library into the app/libs folder of your app.
Note: It requires Datahop Ipfs-lite aar in the libs folder to compile.
To add the library in your Android project first add the libs folder in your repositories list of the project build.gradle file,
allprojects {
repositories {
....
flatDir {
dirs 'libs'
}
}
}
and then add the library as a depencency of your project in the app build.gradle file.
dependencies {
....
implementation(name: 'blediscovery-release', ext: 'aar')
}
The library can be also automatically imported via gradle: TBC
The library is basically implementing two functionalities. The BLEAdvertising service is responsible of advertising service discovery data and exchange service status using BLE GATT server and GATT characteristics. Advertised data for each service is structured in "topics" and each topic is configured as a BLE characteristic in the GATT server. Characteristics are compared in the GATT Server when accepting connections to compare status for each "topic.
When detected different values of the "topics" means different service status and it can reply with network information.
The BLEServiceDiscovery service is responsible of scanning for BLE Beacons and starts a connection to the GATT server provided by the BLEAdvertising service
when found BLE Beacons with the same service id.
- From Android:
//Both instances must be created
BLEServiceDiscovery bleDiscoveryDriver = BLEServiceDiscovery.getInstance(getApplicationContext());
BLEAdvertising bleAdvertisingDriver = BLEAdvertising.getInstance(getApplicationContext());
//A notifier should be passed into the instance. These notifiers can be implemented in Go and must implement BleDiscoveryDriver and BleAdvertisingDriver interfaces defined in github.com/datahop/mobile
bleDiscoveryDriver.setNotifier(bdnotifier);
bleAdvertisingDriver.setNotifier(banotifier);
BLEServiceDiscovery and BLEAdvertising can be direclty handled from Go passing it to the Go app like the following
Datahop.init(getApplicationContext().getCacheDir() + "/" + root, this, bleDiscoveryDriver, bleAdvertisingDriver, hotspot,connection);
- From Go:
Generate the BleDiscoveryService, passing the BLEServiceDiscovery and BLEAdvertising native driver instance and starting the service afterwards.
service, err := NewBleDiscoveryService(hop.peer.Host, hop.discDriver, hop.advDriver, 1000, 20000, hop.wifiHS, hop.wifiCon, ipfslite.ServiceTag)
if err != nil {
log.Error("ble discovery setup failed : ", err.Error())
wg.Done()
return
}
if res, ok := service.(*bleDiscoveryService); ok {
hop.discService = res
}
hop.discService.RegisterNotifee(hop.notifier)
hop.discService.AddAdvertisingInfo("topic", "value")
hop.discService.Start()
https://github.com/datahop/datahop-android-demo
Please read and follow the steps in CONTRIBUTING.md
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.
This software is part of the NGI Pointer project "Incentivised Content Dissemination at the Network Edge" that has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 871528
