Understanding Android OS Forward Compatibility Support for Legacy Apps

The update of Android OS constantly brings users various new features and enhances system security. On the other hand, the system and API modifications with the update may introduce the app compatibility issue. The app's SDK version may not align with the Android OS version, making apps not work adequately. This condition will inevitably damage the Android ecosystem. Thus, while developing Android OS, Google considered and deployed compatibility support. The software engineering research community also noticed the Android compatibility issue and conducted some investigations. However, most previous studies focus on apps' performance and solutions on compatibility (apps running on multiple OS versions). Rare work considers the Android OS side's forward compatibility implementations (supporting legacy apps running on the latest OS).This work systematically studied how Android OS implements forward compatibility for the apps developed with outdated SDKs, primarily focusing on the targetSdkVersion-based fine-grained control. Specifically, we propose three research questions, covering: 1) the forward compatibility support approaches; 2) the stability of foforward compatibility support in third-party market apps. To address these questions, we conducted comprehensive measurements on Android's forward compatibility support, including its implementation, implications, and evolution. Our measurements were based on large-scale datasets covering the source code of Android 8.0~13 and 130,461 apps. Finally, we provide rich data support and analysis to answer these questions. This study offers new insights into Android's forward compatibility support, helping the research community understand the evolution of Android's API design.

Android 操作系统的持续更新为用户带来了多样化的新特性和系统安全性的提升。然而，伴随更新而来的系统及 API 的修改，可能引发应用程序的兼容性问题。应用程序的 SDK 版本可能与 Android 操作系统版本不匹配，导致应用程序无法充分运行。这种状况不可避免地会对 Android 生态系统造成损害。因此，在开发 Android 操作系统时，谷歌充分考虑并部署了兼容性支持措施。软件工程研究领域也关注到了 Android 的兼容性问题，并开展了一系列研究。然而，以往的大多数研究集中于应用程序的性能及兼容性解决方案（应用程序在多个操作系统版本上运行）。鲜有研究关注 Android 操作系统侧的前向兼容性实现（支持在最新操作系统上运行的遗留应用程序）。本研究系统地探讨了 Android 操作系统如何为使用过时 SDK 开发的应用程序实现前向兼容性，主要聚焦于基于 targetSdkVersion 的精细化管理。具体而言，我们提出了三个研究问题，涵盖：1）前向兼容性支持方法；2）第三方市场应用程序中前向兼容性支持稳定性。为解决这些问题，我们对 Android 的前向兼容性支持进行了全面的测量，包括其实施、影响和演变。我们的测量基于涵盖 Android 8.0 至 13 的源代码以及 130,461 个应用程序的大规模数据集。最后，我们提供了丰富的数据支持和分析来回答这些问题。本研究为 Android 的前向兼容性支持提供了新的洞见，有助于研究界理解 Android API 设计的演变。