Systematic Asynchrony Bug Exploration for Android Apps

The Real-Time Specification for Java (RTSJ) is silent on multiprocessor issues. It attempts not to preclude multiprocessor implementations but provides no direct support. Many areas of the RTSJ leave an implementation considerable freedom on how it provides the defined functionality. One such area is the asynchronous event handling (AEH) model. Events are fired and associated handlers are scheduled for execution in response; handlers have defined scheduling parameters and deadlines. The primary goal of the AEH model is to support a lightweight real-time concurrency model. Hence handlers, in general, do not have dedicated threads. Rather, the implementation is responsible for ensuring that all handlers meet their deadlines. Typically real-time threads are assigned to execute handlers by the implementation. This paper discusses the issues associated with implementing the AEH model on multiprocessor systems. The emphasis here is on achieving a lightweight model. A model is lightweight if it is able to meet the deadlines of all handlers with as few as possible real-time threads. In the RTSJ this is made more complicated because asynchronous event handlers are allowed to suspend themselves (for example, by waiting on a monitor condition). Such handlers are called blocking handlers. Most of an implementation's freedom comes from being able to optimize the support for those handlers that do not block. The paper first examines all possible releasing sequences of non-blocking handlers on multiprocessor systems. Based on this, it proposes an efficient and scalable AEH mapping model for multiprocessor systems, which limits the number of real-time threads even in the worst case while retaining the schedulability of the system. The proposed model is then examined to prove its safety and liveness requirements using a model checking tool, UPPAAL. The verification and simulation results of the model indicate that the safety and liveness requirements are satisfied. Most importantly, this paper derives the proposed model's greatest lower and least upper bounds of real-time threads required to execute a given number of non-blocking handlers. The greatest lower bound is equal to the number of processors, and the least upper bound is equal to the number of processors times that of the priority levels in the system. In the model, the number of real-time threads required to execute a given number of non-blocking handlers is restricted to between these two bounds depending on the releasing sequence of handlers. Even in the worst case, the model requires the least upper bound of real-time threads which is, in most cases, considerably less than the actual number of handlers in the system. This, in turn, enables the proposed model to be efficient and scalable by reducing time and space overheads, compared with a traditional 1:1 AEH mapping model where each handler is mapped to a single thread.

chapter 8 - Developing GUIs

Developing modern collaborative applications burdens the programmer with local event handling (e.g. user interaction), remote event handling (e.g. updates from the server) and shared state (e.g. in order to allow operations while being disconnected). ...

In recent years, with the growing popularity of smartphones, the number of Android malware shows explosive growth. As malicious apps may steal users' sensitive data and money from mobile and bank accounts, it's important to detect potential malicious behavior in real time. To achieve this goal, we propose a dynamic behavior inspection and analysis framework for malicious behavior detection in Android apps. A customized Android system is built to record apps' API (Application Programming Interface) calls, permission uses, and some other runtime features such as user operations. We also develop an automated testing platform to test massive samples so as to collect dynamic app behavior records. Then we exploit these records to extract apps' runtime features of both user interaction and app dynamic behavior for benign and malicious behavior classification. The experimental results show that the app behavior classification can reach an accuracy of 99.0%, identifying 71.8% instances of malware samples by running each app for only 18 minutes.

During recent years, huge efforts have been made to establish digital libraries, in a variety of media, offered from a variety of sources, and intended for a variety of professional and private user communities. As digital data collections proliferate, problems of resource selection and data fusion become major issues. Traditional search engines, even the best ones, are unable to provide access to the hidden web of information that is only available via digital library search interfaces. Originating from the SIGIR 2003 Workshop on Distributed Information Retrieval, held in Toronto, Canada in August 2003, this book presents extended and revised workshop papers as well as several invited papers on the topic to round off coverage of the core issues. The papers are devoted to recent research on the design and implementation of methods and tools for resource discovery, resource description, resource selection, data fusion, and user interaction.

The aim of this study is to investigate the public opinion (i.e., the learners themselves) of apps incorporating emerging technologies Augmented Reality (AR) and Virtual Reality (VR) and find out how satisfied mobile platform users are with these technologies for educational purposes. We performed sentiment analysis of more than one million reviews from 800 different Android apps collected by systematic scrapping of the Google Play Store. Identified apps were separated into five categories: AR, AR+Educational, VR, VR+Educational, and Educational. We identify reviews from each app as positive, negative, or neutral, and apply aspect labels depending on the content of the review. We adopted Bidirectional Encoder Representations from Transformers (BERT) and classify the labels into seven categories: technical issues, usability, content, user interaction, feature request, learning qualities, and advert-related. The results indicate that the positive sentiments are 54.6% for AR, 49.6% for AR+Educational, 47.7% for VR, 71.4% for VR+Educational, and 75.2% for Educational. The results suggest that education apps that do not incorporate AR or VR are receiving higher user satisfaction than apps that incorporate these emerging technologies. Analyzing and understanding user reviews will help instructional designers, software developers, and hardware designers to resolve the key inhibitors .of these apps.

Artificial Intelligence Techniques in Real-time Control Systems

Forms allow applications to collect data from the user. In this chapter, I explain how React works with form elements, using state properties to set their value and event handlers to respond to user interactions. I show you how to work with different element types and show you how to validate the data that the user provides in a form so that the application receives data it can use. Table 15-1 puts forms and validation in context.

The growing popularity of Web 2.0 applications is increasing user expectations for high-quality website design, presentation, and functionality. It is into this climate that Microsoft is releasing Silverlight 5, thelatest iteration of its cross-browser web presentation technology. Beginning Silverlight 5 in C#brings you to the cutting edge of Web 2.0 application design and includes plenty of practical guidance to get you started straight away. Silverlight design tools have important differences comparedwith those used to create Ajax and JavaScript functionality. Robert Lair takes you on a tour of all the tools, including: Microsoft Expression Design, which plays an important role in creating Silverlight assets Microsoft Expression Blend, which is used to build user interaction for Silverlight elements Microsoft Visual Studio, which manages the interaction between designers and developers, providing the coding environment for nuts and bolts wiring Once youve mastered the basics, you'll move on to gain a more in-depth knowledge of some of the features introduced with Silverlight 5, including H.264 protected content, right-click event handling, a new printing API, and support for the Managed Extensibility Framework. What youll learn Discover the tools needed for Silverlight 5 development, the roles each plays, and how they interact to produce a seamless result Understand the fundamental concepts and techniques that lie at the heart of every successful Silverlight application and how to apply them to your own projects Explore the new features and coding practices which Silverlight gives you, setting it apart from other web development tools Who this book is for This book is for anyone with an interest in web development. A basic familiarity with web development and simple C# coding is useful, but by no means a requirement. This book will teach you everything that you need to know.

Secure pairing of Internet-of-Things (IoT) devices is a challenging problem because many of them lack the typical user interfaces to provide credentials in the authentication process different from conventional computing platforms. The identical problem is observed in a modern automotive environment. Users bring various smart devices besides smartphones to the cabin and want to connect to their vehicles. Moreover, as car/ride-sharing economy is expected to be continuously grown, such an in-vehicle device authentication will soon become a roadblock, without a proper mechanism, before enabling emerging services. In this study, we develop a novel authentication mechanism, which uses the shared context of two pairing ends. In a moving vehicle, for example, a vehicle and an IoT device located in cabin share the motion. The proposed mechanism compares the motion data from accelerometer sensors in both paring ends to determine their spatial co- existence. We implement a proof- of-concept Android app to prove its feasibility and evaluate in practical user scenarios. By minimizing the user interaction in device authentication, the proposed mechanism will improve safety and usability as well as security.

BACKGROUND Internet-based intervention platforms may improve access to mental health care for women with perinatal depression (PND). Though the majority of platforms in the market lack an evidence base, a small number of them are supported by research evidence. OBJECTIVE This study aims to assess the current status of internet-based PND intervention platforms supported by published evidence, understand the reasons behind the disappearance of any of these previously accessible platforms, examine adjustments made by those active platforms between research trials and market implementation, and evaluate their current quality. METHODS A cohort of internet-based PND intervention platforms was first identified by systematic searches in multiple academic databases from database inception until March 26, 2021. We searched on the World Wide Web and the iOS and Android app stores to assess which of these were available in the marketplace between April and May 2021. The basic characteristics of all platforms were collected. For inaccessible platforms, inquiries were made via email to the authors of publications to determine the reasons for their unavailability. We compared the intervention-related information of accessible platforms in the marketplace with that reported in original publications and conducted quality assessments using the App Evaluation Model of the American Psychiatric Association. Fisher exact tests were used to compare the functional characteristics in publications of available and unavailable platforms and to investigate potential associations between functional adjustments or quality indices and platform survival time. RESULTS Out of 35 platforms supported by research evidence, only 19 (54%) were still accessible in the marketplace. The main reason for platforms disappearing was the termination of research projects. No statistically significant differences were found in functional characteristics between available and unavailable platforms. A total of 18 (95%) platforms adapted their core functions from what was reported in related publications. The adjustments included changes to intervention methods (11/19, 58%), target population (10/19, 53%), human resources for intervention support (9/19, 47%), mood assessment and monitoring (8/19, 42%), communication modality (4/19, 21%), and platform type (2/19, 11%). Quality issues across platforms included low frequency of update, lack of crisis management mechanism, poor user interactivity, and weak evidence base or absence of citation of supporting evidence. Platforms that survived longer than 10 years had a higher tendency to use external resources from third parties compared to those that survived less than 10 years (<i>P</i>=.04). No significant differences were found for functional adjustments or other quality indices. CONCLUSIONS Internet-based platforms supported by evidence were not effectively translated into real-world practice. It is unclear if adjustments to accessible platforms made during actual operation may undermine the proven validity of the original research. Future research to explore the reasons behind the success of the implementation of evidence-based platforms in the marketplace is warranted.

The primary goal for asynchronous event handling (AEH) in the Real-Time Specification for Java (RTSJ) is to have a lightweight concurrency mechanism. However the RTSJ neither provides a well-defined guideline on how to implement AEH nor requires the documentation of the AEH model used in the implementation. Also the AEH API in the RTSJ are criticized as lacking in configurability as they do not provide any means for programmers to have fine control over the AEH facilities, such as the mapping between real-time threads and handlers. For these reasons, it needs the refactoring of its application programming interface (API) to give programmers more configurability. This paper, therefore, proposes a set of AEH related classes and interfaces to enable flexible configurability over AEH components. We have implemented the refactored configurable AEH API using the new specifications on an existing RTSJ implementation and this paper shows that it allows more configurability for programmers than the current AEH API in the RTSJ does. Consequently programmers are able to specifically tailor the AEH subsystem to fit their applicationspsila particular needs.

Object Composition Petri Nets, Priority Petri Nets, Dynamic OCPN, and Enhanced P-Nets have extended the original Petri Net to achieve the modeling of media synchronization and asynchronous user interactions during multimedia playback. The dynamic Petri Net (DPN) has been conceptualized to tackle existing problems in these two areas of modeling distributed multimedia systems. DPN features dynamic modeling elements which allows iteration and hence is able to reduce graph sizes of synchronous playback models while allowing greater details to be shown. DPN also introduces asynchronous event handling techniques that are powerful and effective. DPN was used in the design and modeling of a multimedia orchestration tool which is a typical representation of an application that works in a distributed multimedia system.