How JD Finance Tackles HarmonyOS: A Dynamic Cross-Platform Adaptation Blueprint

1. Background

Huawei announced at the 2023‑09‑25 official launch that the new HarmonyOS will no longer be compatible with Android applications, meaning that all Android apps, including JD Finance, cannot run on the new system and must be redeveloped as dedicated HarmonyOS apps.

2. Native Adaptation Plan

The native adaptation approach would rewrite all business and infrastructure layers of the JD Finance app using HarmonyOS language, but it faces three major problems:

High initial development cost : 1:1 development of a HarmonyOS version requires a long development cycle and huge R&D investment.

High business iteration cost : Future updates must be performed simultaneously on iOS, Android, HarmonyOS and other platforms, increasing product communication, development, testing and UI acceptance costs.

Low release efficiency : After a business requirement is completed, the app must be submitted, reviewed and published on the Huawei AppGallery, resulting in a long release cycle and no ability for on-demand publishing.

3. Dynamic Adaptation Plan

“Dynamic” is a self-developed solution by JD Finance’s front-end team that enables a single codebase to run on iOS, Android and Web.

1. Plan Overview

The dynamic solution already supports one code running on iOS, Android and H5. By integrating this capability with HarmonyOS, the initial adaptation effort is reduced, allowing one-time development for four platforms and long-term reduction of business iteration costs, while also providing instant publishing capability.

2. Implementation

The implementation on HarmonyOS follows a process similar to Android but faces challenges such as the lack of a V8 virtual machine, complex core-layer communication, and the need to port the layout library.

Key steps include:

Virtual Machine Layer – V8

HarmonyOS does not provide a JSCore or V8 VM, so V8 must be ported (V8 For Harmony).

Virtual Machine Interface Layer

After porting V8, ArkTS is used to wrap and invoke V8 interfaces (ArkTs2V8).

Dynamic Engine Runtime

Running the RomaEngine JavaScript file generates a virtual DOM (V‑Dom) tree and performs diffing to trigger UI updates.

Communication Layer – JSI

RomaEngine’s V‑Dom creation triggers native rendering node creation. On iOS and Android this communication uses JSON, which has performance limits; on HarmonyOS we adopt the industry-standard JSI to establish JS ↔ C++ communication.

Native SDK Layer

JSI enables C++ to receive node-creation commands from JS. Since HarmonyOS native UI uses ArkTS, we use the NAPI interface to bridge C++ and ArkTS, achieving a JS → C++ → ArkTS communication chain (and the reverse).

Layout Layer

Yoga, a cross-platform layout engine, has been ported to HarmonyOS to compute final positions and sizes of UI elements, completing the rendering pipeline.

Interaction Handling

For example, a button click is propagated through ArkTS → C++ → JS to deliver the event to the business logic.

3. Key Technologies

V8 Virtual Machine Porting

Self‑compiled V8 cross‑compilation required mastering CMake, Clang, LLVM, Ninja, etc. The team has mastered V8 cross-compilation and porting techniques.

Huawei’s built-in V8 solution offers long-term benefits in package size, stability, compatibility and maintenance cost.

Communication Scheme Design

HarmonyOS provides NAPI for ArkTS ↔ C/C++ communication. The dynamic solution’s JSI establishes JS ↔ C++ communication, enabling three‑language interaction (JS, C++, ArkTS).

Page Rendering Scheme

RomaEngine produces a V‑Dom tree; through JSI, component creation commands are sent to build a ComponentTree that mirrors the V‑Dom. The ComponentTree is then mapped to a RenderTree using HarmonyOS custom components.

On subsequent updates, a new V‑Dom is diffed against the old one, and only changed nodes are sent via JSI to update the RenderTree.

Layout Scheme

Yoga has been compiled for HarmonyOS, ensuring consistent layout calculations across iOS, Android and HarmonyOS.

4. Future Plans

Self‑Draw Solution

With emerging OSes such as Xiaomi’s Pengpai OS and Vivo’s blueOS, the team plans to explore SKIA‑based self‑draw rendering to achieve a single rendering codebase across iOS, Android, HarmonyOS, Pengpai OS, blueOS and future systems.

Mini‑Program Conversion

The V‑Dom architecture can also generate code for WeChat, Douyin, Baidu and other mini‑programs, enabling low‑cost private‑domain deployment.

Ecosystem Expansion

Future devices will form an Internet‑of‑Things world; the dynamic solution will continue to explore techniques for running on more devices, such as seamless flow between smartphones and car systems.