Want to build your own smart home system? Using HarmonyOS makes it incredibly enjoyable! In this article, we will discuss how to design the core architecture of a home smart control system based on HarmonyOS, covering everything from device discovery to state synchronization, interface design to data flow!
Unique Advantages of HarmonyOS Smart Home
Traditional smart home systems… always feel a bit fragmented. Devices from different brands are incompatible, each operating independently, forcing users to download a bunch of apps. Annoying, right? Yes! However, the HarmonyOS system, based on the “distributed soft bus” design concept, completely breaks this limitation.
How to understand the distributed soft bus? Imagine that every smart device in your home is a worker; previously, they spoke different languages and needed translation (various apps) to communicate. Now, the soft bus is like installing the same language chip in everyone, allowing devices to “talk” directly! It’s incredibly convenient.
The distributed capability of HarmonyOS is its biggest highlight, enabling collaboration between devices to be as smooth as interactions between components within a single system. This capability is simply a perfect fit for smart home scenarios—lighting, temperature control, curtains, security—all can be unified and managed with a single click.
Architecture Design: From Zero to One
Let’s discuss the key points—the HarmonyOS smart home control architecture is divided into three layers:
- Device Discovery and Connection Layer
- Device Management and Control Layer
- User Interaction Interface Layer
What are the benefits of this layered design? Decoupling! Each layer has its own responsibilities, operating independently, so changes in one layer do not affect the others—this is a lifesaver for later maintenance! I once worked on a project without layering, and changing a small feature required modifying a large amount of code… it was painful!
Device Discovery and Connection Layer
This layer is primarily implemented based on Harmony’s DeviceManager API. The core code looks something like this:
1import deviceManager from '@ohos.distributedHardware.deviceManager';
2
3// Create device management instance
4let dmInstance = null;
5deviceManager.createDeviceManager('com.example.smarthome', (err, dm) => {
6 if (err) {
7 console.error('Failed to create device manager:', err);
8 return;
9 }
10 dmInstance = dm;
11 // Register device discovery callback
12 dmInstance.on('deviceFound', (data) => {
13 console.info('New device found:', JSON.stringify(data));
14 // Handle new device discovery logic here
15 });
16
17 // Start device discovery
18 dmInstance.startDeviceDiscovery({
19 filterOptions: {
20 capability: {
21 audio: false,
22 display: false,
23 input: true, // For input devices
24 storage: false
25 }
26 }
27 });
28});
Can you spot any issues in the code above?—There is no exception handling! This is a big no-no in actual development. I encountered a situation where, once the network was unstable, device discovery failed, and the entire application froze…
Be sure to implement error handling and retry mechanisms, especially for operations like device discovery that depend on network conditions. Additionally, handle search timeouts properly to avoid keeping users waiting indefinitely.
Device Management and Control Layer
This layer is the “brain” of the entire system, responsible for maintaining device states and sending control commands. We use ArkTS’s state management to implement it:
1// DeviceModel.ets
2import { DeviceState } from '../common/DeviceState';
3
4@Observed class DeviceModel {
5 id: string;
6 name: string;
7 type: string;
8 state: DeviceState;
9
10 // Method to control the device
11 async controlDevice(command: string, params: object): Promise<boolean> {
12 try {
13 // Call distributed capability to send control command
14 // Implementation omitted...
15
16 // Update device state
17 this.state = /* new state */;
18 return true;
19 } catch (error) {
20 console.error(`Failed to control device: ${this.id}`, error);
21 return false;
22 }
23 }
24}
25
26// Controller managing all devices
27export class DeviceController {
28 @State devices: Array<DeviceModel> = [];
29
30 // Methods for adding, deleting, querying devices, etc...
31}
Here, we used the @Observed and @State decorators—the state management mechanism of Harmony is quite nice! When the device state changes, the UI updates automatically without needing manual refresh. This is much simpler than traditional event listening methods…
However, be cautious of memory leaks! I once had an issue where I didn’t properly unregister observers, leading to a significant increase in memory usage after the application ran for a long time.Always release resources promptly after using distributed capabilities, which is very important.
User Interaction Interface Layer
The declarative UI of ArkUI is truly a great thing! Let’s see how to design the smart home control panel:
1@Entry
2@Component
3struct SmartHomePanel {
4 @State deviceController: DeviceController = new DeviceController();
5
6 build() {
7 Column() {
8 // Room selector
9 Tabs() {
10 TabContent() {
11 this.buildLivingRoom();
12 }.tabBar("Living Room")
13
14 TabContent() {
15 this.buildBedroom();
16 }.tabBar("Bedroom")
17
18 // Other rooms...
19 }
20
21 // Quick scenes
22 Row() {
23 Button("Homecoming Mode")
24 .onClick(() => this.activateScene("homecoming"))
25 Button("Leaving Mode")
26 .onClick(() => this.activateScene("leaving"))
27 Button("Sleep Mode")
28 .onClick(() => this.activateScene("sleeping"))
29 }
30 .width('100%')
31 .justifyContent(FlexAlign.SpaceAround)
32 .padding(10)
33 }
34 }
35
36 // Build device control UI for each room
37 buildLivingRoom() {
38 // Implementation omitted...
39 }
40
41 // Activate scene mode
42 activateScene(sceneName: string) {
43 // Implementation omitted...
44 }
45}
UI design should follow the “what you see is what you get” principle—users should understand it at a glance and be able to use it immediately. Avoid overly fancy but difficult-to-use interfaces… I once saw a smart home panel designed by a developer with beautifully crafted icons, but they were so mixed together that it was impossible to tell which controlled which device, leading to a terrible user experience!
Practical Experience and Pitfall Guide
After working on several Harmony smart home projects, I have summarized these experiences:
-
Device discovery is crucial—sometimes devices are online but cannot be found. The solution is to implement a “force refresh” feature, allowing users to manually trigger a new search when devices are not discovered.
-
Control delay issues—more complex smart home systems may experience noticeable delays. The solution is to implement local state caching, updating the UI first and then waiting for the actual device response to enhance user experience.
-
Permission management is easily overlooked—especially when you need to control sensitive devices (like door locks). Harmony’s permission management is quite strict, so you need to declare it in module.json5 in advance.
-
Power optimization—smart home control centers usually need to run in the background. Using the WorkScheduler API instead of traditional polling can significantly reduce power consumption… I had a project where I overlooked this, and users reported that their phones were overheating!
Advanced Features: Super Terminal
If you want to go further, you can utilize Harmony’s “Super Terminal” feature to achieve cross-device control. For example, controlling a smart TV to display camera footage from your phone, or using a tablet to take over home control from a smartwatch… This seamless collaboration experience is hard to achieve with other systems.
Implementing the Super Terminal feature requires using the ability migration capability, which is quite complex—if you’re interested, feel free to leave a comment, and I can write a detailed article next time.
Practical Exercise Suggestions
Find a few common smart devices (like smart bulbs, sockets, etc.) to start practicing. Begin with the simplest control flow, implementing basic on/off functionality, and then gradually add more complex scene interactions. During debugging, you can use the DevEco Studio simulator, which supports simulating various smart devices.
What to do if you encounter problems during development?—The HarmonyOS Developer Alliance is a great place to go, where many experienced developers are willing to help answer questions.
Have you tried developing smart home applications on Harmony? What special challenges have you encountered in device discovery and control? Feel free to share your experiences in the comments!