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HarmonyOS Next distributed development: cross-device collaboration and data flow

In the HarmonyOS Next ecosystem, distributed development is one of the core features. It breaks the device boundaries and realizes seamless collaboration and data flow between multiple devices.Through distributed capabilities, developers can build integrated applications across multiple terminals such as mobile phones, tablets, smart wearables, smart screens, etc., bringing users a new experience of "device as a service, service with people flowing".This article will deeply analyze the key technologies and practical scenarios of HarmonyOS Next distributed development.

1. Distributed task scheduling: collaborative execution across devices

HarmonyOS Next realizes flexible migration and collaborative execution of application tasks between different devices through the distributed task scheduling mechanism.Developers can dynamically assign tasks based on device capabilities (such as computing power, screen size, input method, etc.) to optimize user experience.

1. Task migration: Switch devices on demand

Taking video editing scenarios as an example, after users start editing videos on their mobile phones, they can seamlessly migrate tasks to tablets or laptops to continue processing, using a larger screen and stronger computing power to improve efficiency.

// Get the device list (supports distributed devices)
List<DeviceInfo> devices = DeviceManager.getDeviceList(DeviceState.ONLINE);

// Migrate tasks to target devices (such as tablets)
if (devices.contains(targetDevice)) {
    DistributedTaskScheduler.startRemoteMission(targetDevice.getId(), missionData);
// Local suspended tasks
    localMission.pause();
}
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2. Multi-device collaboration: task split execution

For complex tasks (such as image rendering and big data computing), they can be split into multiple subtasks and assigned to different devices for parallel processing.For example, 3D modeling applications assign model rendering tasks to high-performance PCs, while interactions remain on the tablet.

// Split the task into a subtask (rendering task is assigned to PC devices)
List<SubTask> subTasks = mission.split();
for (SubTask subTask : subTasks) {
    if (subTask.getType() == TaskType.RENDER) {
        Device pcDevice = devices.stream().filter(d -> d.getType() == DeviceType.PC).findFirst().get();
        DistributedTaskScheduler.submitRemoteTask(pcDevice.getId(), subTask);
    } else {
// Handle other tasks locally
        localExecutor.execute(subTask);
    }
}
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2. Distributed data management: real-time synchronization across devices

HarmonyOS Next provides Distributed Data Service (DDS), which supports real-time synchronization, sharing and subscription of application data between multiple devices, ensuring the consistency of user data on different devices.

1. Data synchronization: real-time update of multiple devices

Taking the note-taking application as an example, notes created by users on their mobile phones can be synchronized to tablets and office computers in real time, supporting offline editing and online conflict resolution.

// Create distributed data objects
DataObject noteData = DataManager.createDataObject("note_data", DataSyncMode.REAL_TIME);

// Listen to data changes (triggered when cross-device update)
noteData.addDataChangeListener(new DataChangeListener() {
    @Override
    public void onDataChanged(String deviceId, DataObject data) {
// Update local UI
        updateNoteList(data.getContent());
    }
});

// Locally modify data and synchronize
noteData.setContent(newNoteContent);
DataManager.syncData(noteData);
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2. Data Sharing: Secure Sharing across Applications

Through distributed data permission control, different applications can share data safely.For example, the map application and the taxi-hailing application share user location information to realize the "one-click taxi-hailing" function.

// Apply for data sharing permissions
boolean hasPermission = PermissionManager.checkPermission("location_share", targetDevice);
if (hasPermission) {
// Share location data for taxi apps
    DistributedDataShare.shareData("location_data", currentLocation, targetAppId);
}
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3. Distributed device virtualization: hardware capability sharing

HarmonyOS Next's device virtualization technology virtualizes the hardware resources of multiple devices (such as cameras, microphones, sensors, etc.) into a "resource pool". Applications can call cross-device hardware capabilities on demand to create innovative interactive scenarios.

1. Cross-device camera call: multi-camera shooting

In video conferencing scenarios, the application can simultaneously call the main camera of the mobile phone, the front camera of the tablet and the smart glasses camera to realize multi-camera picture acquisition and synthesis.

// Get a list of device cameras (including mobile phones, tablets, glasses)
List<CameraDevice> cameras = DeviceHardwareManager.getDevicesByType(DeviceHardwareType.CAMERA);

// Turn on the remote device camera (such as a flat-panel camera)
CameraDevice remoteCamera = cameras.stream().filter(c -> c.getDeviceId().equals("tablet_device_id")).findFirst().get();
remoteCamera.open();
remoteCamera.startPreview();
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2. Sensor Fusion: Cross-device Environment Sensing

Smart home applications can integrate data from mobile phone gyroscopes, smart watch heart rate sensors and home gateway environment sensors to achieve more accurate scene recognition (such as automatically turning on security mode when the user leaves home).

// Subscribe to cross-device sensor data
SensorManager.subscribeSensor(DeviceId.ALL, SensorType.ALL, new SensorDataCallback() {
    @Override
    public void onSensorData(DeviceInfo device, SensorData data) {
// Converge multi-device data
        if (device.getType() == DeviceType.WATCH && data instanceof HeartRateData) {
// Process watch heart rate data
        } else if (device.getType() == DeviceType.PHONE && data instanceof GyroscopeData) {
// Process mobile phone gyroscope data
        }
    }
});
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4. Distributed security mechanism: Ensure data and equipment security

HarmonyOS Next ensures the security and reliability of data transmission, device authentication and permission control in distributed scenarios through a multi-layer security protection system.

1. Device Authentication: Two-way Authentication

When the device is interconnected, illegal device access is prevented through **two-way authentication based on public key infrastructure (PKI).

// Initiate a device authentication request
boolean isAuthenticated = DeviceSecurity.authenticate(targetDevice, LocalDevice.getPublicKey());
if (isAuthenticated) {
// Establish a secure communication channel
    SecureChannel channel = new SecureChannel(targetDevice);
    channel.startEncryptedCommunication();
}
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2. Data encryption: End-to-end encrypted transmission

Distributed data uses the **AES-256 encryption algorithm during transmission, and sensitive data is protected by the **Trustful Execution Environment (TEE) during storage.

// Encrypt data
byte[] encryptedData = SecurityUtils.encrypt(data.getBytes(), encryptionKey);

// Transmission through secure channel
channel.sendData(encryptedData);

// The receiver decrypts the data
byte[] decryptedData = SecurityUtils.decrypt(encryptedData, decryptionKey);
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5. Typical scenario practice: Smart office and home interconnection

1. Smart office: Cross-device document collaboration

  • Scenario: Multiple people jointly edit a document on different devices, view the modification records in real time, and support local and cloud synchronization.
  • Technology implementation: Distribute editing tasks through distributed task scheduling, use DDS to realize real-time synchronization of document content, and combine device virtualization to call tablet stylus for annotation.

2. Home Internet: Intelligent linkage for the whole house

  • Scenario: When the user returns home, the mobile phone detects a change in geographical location and automatically links smart door locks, lighting, air conditioning and audio-visual equipment to create a personalized home environment.
  • Technology implementation: Obtain user location and environmental data through cross-device sensor fusion, use distributed task scheduling to trigger device linkage logic, and ensure the security of home equipment communication through security mechanisms.

Summarize

HarmonyOS Next's distributed development capabilities redefine the boundaries of multi-device collaboration. Through the four core technologies of task scheduling, data management, device virtualization and security mechanisms, developers can build smarter and smoother cross-device applications.In the future, with the continued enrichment of ecological equipment, distributed development will become a key technical base for creating a smart experience in all scenarios.Mastering distributed development means that developers can provide users with the ultimate experience of "unsensitivity switching of devices and seamless service flow" and seize the initiative in the era of Internet of Things.

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