Software libraries implement APIs that deliver reusable functionalities. To
correctly use these functionalities, software applications must satisfy certain
correctness policies, for instance policies about the order some API methods
can be invoked and about the values that can be used for the parameters. If
these policies are violated, applications may produce misbehaviors and failures
at runtime. Although this problem is general, applications that incorrectly use
API methods are more frequent in certain contexts. For instance, Android
provides a rich and rapidly evolving set of APIs that might be used incorrectly
by app developers who often implement and publish faulty apps in the
marketplaces. To mitigate this problem, we introduce the novel notion of
proactive library, which augments classic libraries with the capability of
proactively detecting and healing misuses at run- time. Proactive libraries
blend libraries with multiple proactive modules that collect data, check the
correctness policies of the libraries, and heal executions as soon as the
violation of a correctness policy is detected. The proactive modules can be
activated or deactivated at runtime by the users and can be implemented without
requiring any change to the original library and any knowledge about the
applications that may use the library. We evaluated proactive libraries in the
context of the Android ecosystem. Results show that proactive libraries can
automati- cally overcome several problems related to bad resource usage at the
cost of a small overhead.Comment: O. Riganelli, D. Micucci and L. Mariani, "Policy Enforcement with
Proactive Libraries" 2017 IEEE/ACM 12th International Symposium on Software
Engineering for Adaptive and Self-Managing Systems (SEAMS), Buenos Aires,
Argentina, 2017, pp. 182-19