In-app advertising has served as the major revenue source for millions of app developers in the mobile Internet ecosystem. Ad networks play an important role in app monetization by providing third-party libraries for developers to choose and embed into their apps. Various ad mediations help developers manage all of the ad libraries used in apps to show the best available ad among received ads from different ad network servers. However, developers lack guidelines on how to choose from hundreds of ad networks or ad mediations and various ad features to maximize their revenues without hurting the user experience of their apps. Our work aims to provide app developers guidelines on the selection of ad networks, ad mediations and ad placement by observing current common practices. To this end, we investigate 838 unique APIs from 207 ad networks which are extracted from 277,616 Android apps, develop a methodology of ad type classification based on UI interaction and behavior, and perform a large scale measurement study of in-app ads with static analysis techniques at the API granularity. We found that developers have more choices about ad networks than several years before. Most developers are conservative about ad placement and about 77% of the apps contain at most one ad library. Besides, the likeliness of an app containing ads depends on the app category to which it belongs. Furthermore, we propose a terminology and classify mobile ads into five ad types: Embedded, Popup, Notification, Offerwall, and Floating. Also, our research shows that it is a better solution for developers to integrate ad libraries with ad mediation feature in their apps because it may avoid bad ratings and improve user experience. And in our findings, more than 95% of Embedded, Popup, Notification and Offer ads locate in the zero activity (main activity), the first activity and the second activity of Android apps. More interestingly, developers tend to put high aggressive ads on activities which need deeper user interaction. Our research is the first to reveal the preference of both developers and users for ad networks, ad mediation feature and ad types.

中文翻译：

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MAdLens：在 API 粒度上调查 Android 应用内广告实践

应用内广告已成为移动互联网生态系统中数百万应用开发者的主要收入来源。广告网络通过提供第三方库供开发人员选择并嵌入到他们的应用程序中，在应用程序货币化中发挥着重要作用。各种广告中介可帮助开发人员管理应用中使用的所有广告库，以便在从不同广告网络服务器接收到的广告中展示最佳可用广告。但是，开发人员缺乏关于如何从数百个广告网络或广告中介以及各种广告功能中进行选择以在不损害其应用程序的用户体验的情况下最大化收入的指南。我们的工作旨在通过观察当前的常见做法，为应用程序开发人员提供有关选择广告网络、广告中介和广告展示位置的指南。为此，我们调查了从 277,616 个 Android 应用程序中提取的 207 个广告网络中的 838 个独特 API，开发了一种基于 UI 交互和行为的广告类型分类方法，并在 API 处使用静态分析技术对应用内广告进行了大规模测量研究粒度。我们发现，与几年前相比，开发人员在广告网络方面有更多的选择。大多数开发者对广告投放持保守态度，大约 77% 的应用最多包含一个广告库。此外，包含广告的应用程序的可能性取决于它所属的应用程序类别。此外，我们提出了一个术语并将移动广告分为五种广告类型：嵌入式、弹出式、通知、优惠墙和浮动。还，我们的研究表明，对于开发人员来说，将广告库与广告中介功能集成到他们的应用程序中是一个更好的解决方案，因为它可以避免不良评级并改善用户体验。在我们的调查结果中，超过 95% 的嵌入式、弹出式、通知和优惠广告位于 Android 应用程序的零活动（主要活动）、第一活动和第二活动中。更有趣的是，开发人员倾向于在需要更深入用户交互的活动上投放高攻击性广告。我们的研究首次揭示了开发者和用户对广告网络、广告中介功能和广告类型的偏好。Android 应用程序的第一个活动和第二个活动。更有趣的是，开发人员倾向于在需要更深入用户交互的活动上投放高攻击性广告。我们的研究首次揭示了开发者和用户对广告网络、广告中介功能和广告类型的偏好。Android 应用程序的第一个活动和第二个活动。更有趣的是，开发人员倾向于在需要更深入用户交互的活动上投放高攻击性广告。我们的研究首次揭示了开发者和用户对广告网络、广告中介功能和广告类型的偏好。