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A new vision of harnessing the ocean of video data captured by cameras in an efficient, secure, and manageable way. Following the hardware trends in reality, we advocate to treat cameras as the first-class computing and storage platform, and expose their services to third parties. To this end, the cameras should move from hard-coded to software-defined, from dumb data source to autonomous data processor, from isolated to orchestrated, and from one-shot to human-in-the-loop.

The past decades witnessed the fast and wide deployment of Internet. The Internet has bred the ubiquitous computing environment that is spanning the cloud, edge, mobile devices, and IoT. Software running over such a ubiquitous computing environment environment is eating the world. A recently emerging trend of Internet-based software systems is “ resource adaptive ,” i.e., software systems should be robust and intelligent enough to the changes of heterogeneous resources, both physical and logical, provided by their running environment. To keep pace of such a trend, we argue that some considerations should be taken into account for the future operating system design and implementation. From the structural perspective, rather than the “monolithic OS” that manages the aggregated resources on the single machine, the OS should be dynamically composed over the distributed resources and flexibly adapt to the resource and environment changes. Meanwhile, the OS should leverage advanced machine/deep learning techniques to derive configurations and policies and automatically learn to tune itself and schedule resources. This article envisions our recent thinking of the new OS abstraction, namely, ServiceOS , for future resource-adaptive intelligent software systems. The idea of ServiceOS is inspired by the delivery model of “ Software-as-a-Service ” that is supported by the Service-Oriented Architecture (SOA). The key principle of ServiceOS is based on resource disaggregation, resource provisioning as a service, and learning-based resource scheduling and allocation. The major goal of this article is not providing an immediately deployable OS. Instead, we aim to summarize the challenges and potentially promising opportunities and try to provide some practical implications for researchers and practitioners.

Sentiment and emotion detection from textual communication records of developers have various application scenarios in software engineering (SE). However, commonly used off-the-shelf sentiment/emotion detection tools cannot obtain reliable results in SE tasks and misunderstanding of technical knowledge is demonstrated to be the main reason. Then researchers start to create labeled SE-related datasets manually and customize SE-specific methods. However, the scarce labeled data can cover only very limited lexicon and expressions. In this article, we employ emojis as an instrument to address this problem. Different from manual labels that are provided by annotators, emojis are self-reported labels provided by the authors themselves to intentionally convey affective states and thus are suitable indications of sentiment and emotion in texts. Since emojis have been widely adopted in online communication, a large amount of emoji-labeled texts can be easily accessed to help tackle the scarcity of the manually labeled data. Specifically, we leverage Tweets and GitHub posts containing emojis to learn representations of SE-related texts through emoji prediction. By predicting emojis containing in each text, texts that tend to surround the same emoji are represented with similar vectors, which transfers the sentiment knowledge contained in emoji usage to the representations of texts. Then we leverage the sentiment-aware representations as well as manually labeled data to learn the final sentiment/emotion classifier via transfer learning. Compared to existing approaches, our approach can achieve significant improvement on representative benchmark datasets, with an average increase of 0.036 and 0.049 in macro-F1 in sentiment and emotion detection, respectively. Further investigations reveal that the large-scale Tweets make a key contribution to the power of our approach. This finding informs future research not to unilaterally pursue the domain-specific resource but try to transform knowledge from the open domain through ubiquitous signals such as emojis. Finally, we present the open challenges of sentiment and emotion detection in SE through a qualitative analysis of texts misclassified by our approach.

In dynamic, open, and service-oriented computing environments, e.g., e-commerce and crowdsourcing, service consumers must choose one of the services or items to complete their tasks. Due to the scale and dynamic characteristics of these environments, service consumers may have little or no experience with the available services. To this end, reputation systems are proposed and have played a crucial role in the success of online service-oriented transactions. In this paper, we study the current reputation systems used in commercial environments. In these rating-based reputation systems, we found they are not only resilient to the changes (time lag) but also vulnerable to unfair ratings. To address the problems in parallel, we propose an adaptive reputation model (ARM). ARM can dynamically adjust its model parameters to adapt the latest changes in a service. To tackle time lag, the proposed model generalizes the fixed sliding window, used in current commercial platforms, into a dynamic sliding window mechanism. Thus, the model can completely mitigate the influence of obsolete ratings. To detect unfair ratings, our model implements a statistical strategy based on hypothesis testing after transforming the ratings in the linear window into residuals. Experiments not only validate the effectiveness of the proposed model but also show that it outperforms the existing reputation system by 45% on average based on five test cases. The results also show that the proposed model can asymptotically converge to the underlying reputation value as ratings begin to accumulate. Note to Practitioners —The reputation models adopted by current commercial platforms, such as Amazon, eBay, and Taobao, not only suffer heavily from unfair rating but also resilient to the changes in services. To address the problems simultaneously, we design and implement a hybrid model that continuously monitors received ratings and aggregates the reputation value in a self-adaptive way. Our model first fits received fair ratings using the Bayesian linear regression approach and captures the distribution of fair ratings; it then filters out unfair ratings leveraging hypothesis testing. Finally, to sensitively respond the dynamic service changes, the dynamic sliding window algorithm in our model shifts the rating collection window into a new one and discards outdated ratings, reputation value is aggregated in the new window to mitigate the influence of obsolete ratings. Extensive experiments are conducted on widely used scenarios to demonstrate the efficiency and the effectiveness of our proposed model.

We propose a cloud-native data analytics engine for processing data stored among geographically distributed cloud regions with reduced cost. A job is split into subtasks and placed across regions based on factors including prices of compute resources and data transmission. We present its architecture which leverages existing cloud infrastructures and discuss major challenges of its system design. Preliminary experiments show that the cost is reduced by 15.1% for a decision support query on a four-region public cloud setup.

Big data has become valuable property for enterprises and enabled various intelligent applications. Today, it is common to host data in big data platforms (e.g., Spark), where developers can submit scripts to process the original and intermediate data tables. Meanwhile, it is highly desirable to manage the data to comply with various privacy requirements. To enable flexible and automated privacy policy enforcement, we propose TaintStream, a fine-grained taint tracking framework for Spark-like big data platforms. TaintStream works by automatically injecting taint tracking logic into the data processing scripts, and the injected scripts are dynamically translated to maintain a taint tag for each cell during execution. The dynamic translation rules are carefully designed to guarantee non-interference in the original data operation. By defining different semantics of taint tags, TaintStream can enable various data management applications such as access control, data retention, and user data erasure. Our experiments on a self-crafted benchmarksuite show that TaintStream is able to achieve accurate cell-level taint tracking with a precision of 93.0% and less than 15% overhead. We also demonstrate the usefulness of TaintStream through several real-world use cases of privacy policy enforcement.

In enterprise organizations, the Bring-Your-Own-Device (BYOD) requirement has become prevalent as employees use their own mobile devices to process the workflow-oriented tasks. Consequently, it calls for approaches that can quickly develop and integrate mobile user interactions into existing business processes, and adapt to various contexts. However, designing, developing, and deploying adaptive and mobile-oriented user interfaces for existing process engines are non-trivial, and require significant systematic efforts. To address this issue, we present a novel middleware-based approach, called MUIT, to developing and deploying the Mobility, User Interactions and Tasks into WS-BPEL engines. MUIT provides a Domain-Specific Language (DSL) that provides some intuitive facilities to support the declarative development of adaptive, mobile-oriented, and Web-based user interfaces in WS-BPEL. The DSL can significantly reduce developers' manual efforts of developing user interactions by preventing arbitrarily mixed code, and its runtime supports satisfactory user experiences. Additionally, MUIT can be seamlessly integrated into WS-BPEL without intrusions of existing process instances. We implement a proof-of-concept prototype by integrating MUIT into the commodity WS-BPEL-based Apusic Platform, and evaluate the performance and usability of MUIT platform.

Mobile Web applications (a.k.a., Web apps) stand for an important trend for next-generation Internet-based software. Currently popular mobile Web apps need to be adapted to various and ever-changing contexts and personalized user requirements. Based on our over-decade research experiences and practice on the Internetware paradigm, this position article describes an Internetware-oriented approach to designing, developing, and deploying situational mobile Web apps, by synthesizing the resources and services of mobile and cloud. Guided by a novel Service-Model-View-Controller (SMVC) software model, a mobile Web app is organized into a well-defined structure that facilitates adaptation including online/offline data access, computation offloading, user interface optimization, hybrid composition, etc. We provide efficient runtime support spanning mobile and cloud to make mobile Web apps more flexibly adaptive. The proof-of-concept evaluation demonstrates that our approach can benefit end-users with optimized user experience of mobile Web apps.

As COVID-19 has been spreading across the world since early 2020, a growing number of malicious campaigns are capitalizing the topic of COVID-19. COVID-19 themed cryptocurrency scams are increasingly popular during the pandemic. However, these newly emerging scams are poorly understood by our community. In this paper, we present the first measurement study of COVID-19 themed cryptocurrency scams. We first create a comprehensive taxonomy of COVID-19 scams by manually analyzing the existing scams reported by users from online resources. Then, we propose a hybrid approach to perform the investigation by: 1) collecting reported scams in the wild; and 2) detecting undisclosed ones based on information collected from suspicious entities (e.g., domains, tweets, etc). We have collected 195 confirmed COVID-19 cryptocurrency scams in total, including 91 token scams, 19 giveaway scams, 9 blackmail scams, 14 crypto malware scams, 9 Ponzi scheme scams, and 53 donation scams. We then identified over 200 blockchain addresses associated with these scams, which lead to at least 330K US dollars in losses from 6,329 victims. For each type of scams, we further investigated the tricks and social engineering techniques they used. To facilitate future research, we have released all the well-labelled scams to the research community.

Sentiment classification typically relies on a large amount of labeled data. In practice, the availability of labels is highly imbalanced among different languages. To tackle this problem, cross-lingual sentiment classification approaches aim to transfer knowledge learned from one language that has abundant labeled examples (i.e., the source language, usually English) to another language with fewer labels (i.e., the target language). The source and the target languages are usually bridged through off-the-shelf machine translation tools. Through such a channel, cross-language sentiment patterns can be successfully learned from English and transferred into the target languages. This approach, however, often fails to capture sentiment knowledge specific to the target language. In this paper, we employ emojis, which are widely available in many languages, as a new channel to learn both the cross-language and the language-specific sentiment patterns. We propose a novel representation learning method that uses emoji prediction as an instrument to learn respective sentiment-aware representations for each language. The learned representations are then integrated to facilitate cross-lingual sentiment classification.

Elf is a runtime for an energy-constrained camera to continuously summarize video scenes as approximate object counts. Elf's novelty centers on planning the camera's count actions under energy constraint. (1) Elf explores the rich action space spanned by the number of sample image frames and the choice of per-frame object counters; it unifies errors from both sources into one single bounded error. (2) To decide count actions at run time, Elf employs a learning-based planner, jointly optimizing for past and future videos without delaying result materialization. Tested with more than 1,000 hours of videos and under realistic energy constraints, Elf continuously generates object counts within only 11% of the true counts on average. Alongside the counts, Elf presents narrow errors shown to be bounded and up to 3.4x smaller than competitive baselines. At a higher level, Elf makes a case for advancing the geographic frontier of video analytics.

The Spatio-Temporal Traffic Prediction (STTP) problem is a classical problem with plenty of prior research efforts that benefit from traditional statistical learning and recent deep learning approaches. While STTP can refer to many real-world problems, most existing studies focus on quite specific applications, such as the prediction of taxi demand, ridesharing order, traffic speed, and so on. This hinders the STTP research as the approaches designed for different applications are hardly comparable, and thus how an application-driven approach can be generalized to other scenarios is unclear. To fill in this gap, this paper makes three efforts: (i) we propose an analytic framework, called STAnalytic, to qualitatively investigate STTP approaches regarding their design considerations on various spatial and temporal factors, aiming to make different application-driven approaches comparable; (ii) we design a spatio-temporal meta-model, called STMeta, which can flexibly integrate generalizable temporal and spatial knowledge identified by STAnalytic, (iii) we build an extensively large-scale STTP benchmark platform including ten datasets with five scenarios to quantitatively measure the generalizability of STTP approaches. In particular, we implement STMeta with different deep learning techniques, and STMeta demonstrates better generalizability than state-of-the-art approaches by achieving lower prediction error on average across all the datasets.

The prevalent smartphones have become the major entrance to accessing services on the Internet. On smartphones, users can have two options as the clients, i.e., native apps and Web apps. There have been several debates about native apps and Web apps. However, major service providers such as Google, Amazon , and Facebook provide both native apps and Web apps to end-users. Essentially, the performance differences between these two types of apps haven’t been addressed. Indeed, the performance differences make non-trivial impacts on apps development, deployment, and distribution. In this article, we conduct a measurement study on the performance of native apps and Web apps on Android smartphones. Specifically, we want to explore given the same functionalities, do Web apps always perform poorly compared to native apps. We select 328 services from some popular providers, covering various domains such as e-commerce, map, social networking, and entertainment. With HTTP-level trace analysis, we demystify the workflows on how native apps and Web apps deliver services on mobile devices, respectively. Then, we characterize the performance differences between native apps and Web apps with the metrics including the number of requests, response time, data drain, and energy consumption. We find that the performance of Web apps is better than native apps in more than 31 percent cases. Our derived knowledge can suggest some recommendations to improve the performance for mobile apps.

Web browsing is always a key requirement of Internet users. Current mobile Web apps can contain computation-intensive JavaScript logics and thus affect browsing performance. Learning from our over-decade research and development experiences of the Internetware paradigm, we present the novel and generic i - Jacob approach to improving the performance of mobile Web browsing with effective JavaScript-code offloading. Our approach proposes a programming abstraction to make mobile Web situational and adaptive to contexts, by specifying the computation-intensive and “ offloadable ” code, and develops a platform-independent lightweight runtime spanning the mobile devices and the cloud. We demonstrate the efficiency of i - Jacob with some typical computation-intensive tasks over various combinations of hardware, operating systems, browsers, and network connections. The improvements can reach up to 49× speed-up in response time and 90% saving in energy.

Numerous complains have been made by Android users who severely suffer from the sluggish response when interacting with their devices. However, very few studies have been conducted to understand the user-perceived latency or mitigate the UI-lagging problem. In this paper, we conduct the first systematic measurement study to quantify the user-perceived latency using typical interaction-intensive Android apps in running with and without background workloads. We reveal the insufficiency of Android system in ensuring the performance of foreground apps and therefore design a new system to address the insufficiency accordingly. We develop a lightweight tracker to accurately identify all delay-critical threads that contribute to the slow response of user interactions. We then build a resource manager that can efficiently schedule various system resources including CPU, I/O, and GPU, for optimizing the performance of these threads. We implement the proposed system on commercial smartphones and conduct comprehensive experiments to evaluate our implementation. Evaluation results show that our system is able to significantly reduce the user-perceived latency of foreground apps in running with aggressive background workloads, up to 10x, while incurring negligible system overhead of less than 3.1 percent CPU and 7 MB memory.

Imperfect Web resource loading prevents mobile Web browsing from providing satisfactory user experience. In this article, we design and implement the SWAROVsky system to address three main issues of current inefficient Web resource loading: (1) on-demand and thus slow loading of sub-resources of webpages ; (2) duplicated loading of resources with different URLs but the same content ; and (3) redundant loading of the same resource due to improper cache configurations . SWAROVsky employs a dual-proxy architecture that comprises a remote cloud-side proxy and a local proxy on mobile devices. The remote proxy proactively loads webpages from their original Web servers and maintains a resource loading graph for every single webpage. Based on the graph, the remote proxy is capable of deciding which resources are “really” needed for the webpage and their loading orders, and thus can synchronize these needed resources with the local proxy of a client efficiently and timely. The local proxy also runs an intelligent and light-weight algorithm to identify resources with different URLs but the same content, and thus can avoid duplicated downloading of the same content via network. Our system can be used with existing Web browsers and Web servers, and does not break the normal semantics of a webpage. Evaluations with 50 websites show that on average our system can reduce the page load time by 43.1 percent and the network data transmission by 57.6 percent, while imposing marginal system overhead.

Redundant transfer of resources is a critical issue for compromising the performance of mobile Web applications (a.k.a., apps) in terms of data traffic, load time, and even energy consumption. Evidence demonstrates that the current cache mechanisms are far from satisfactory. With lessons learned from how native apps manage their resources, in this article, we present the ReWAP approach to fundamentally reducing redundant transfers by restructuring the resource loading of mobile Web apps. ReWAP is based on an efficient resource-packaging mechanism where stable resources are encapsulated and maintained into a package, and such a package shall be loaded always from the local storage and updated by explicitly refreshing. By retrieving and analyzing the update of resources, ReWAP maintains resource packages that can accurately identify which resources can be loaded from the local storage for a considerably long period. ReWAP also provides a wrapper for mobile Web apps to enable loading and updating resource packages in the local storage as well as loading resources from resource packages. ReWAP can be easily and seamlessly deployed into existing mobile Web architectures with minimal modifications, and is transparent to end-users. We evaluate ReWAP based on continuous 15-day access traces of 50 mobile Web apps randomly chosen from Alexa top 500 ranking list. Compared to the original mobile Web apps with cache enabled, ReWAP can significantly reduce the data traffic, with the median saving up to 51 percent. In addition, ReWAP can incur only very minor runtime overhead of the client-side browsers and thus does not compromise user experiences.

EOSIO has become one of the most popular blockchain platforms since its mainnet launch in June 2018. In contrast to the traditional PoW-based systems (e.g., Bitcoin and Ethereum), which are limited by low throughput, EOSIO is the first high throughput Delegated Proof of Stake system that has been widely adopted by many decentralized applications. Although EOSIO has millions of accounts and billions of transactions, little is known about its ecosystem, especially related to security and fraud. In this paper, we perform a large-scale measurement study of the EOSIO blockchain and its associated DApps. We gather a large-scale dataset of EOSIO and characterize activities including money transfers, account creation and contract invocation. Using our insights, we then develop techniques to automatically detect bots and fraudulent activity. We discover thousands of bot accounts (over 30% of the accounts in the platform) and a number of real-world attacks (301 attack accounts). By the time of our study, 80 attack accounts we identified have been confirmed by DApp teams, causing 828,824 EOS tokens losses (roughly $2.6 million) in total.

Mobile app ecosystem has gained giant success in providing services on mobile devices to facilitate almost all aspects in our daily life. However, the whole-package installation and dramatically increasing package size are now preventing users from trying more apps. To address the issue, many lightweight frameworks have emerged, enabling to provide the experience of instant service consumption where apps are of small size and no installation is needed to consuming services provided by the apps. In this paper, we conduct the first empirical study on instant service consumption on mobile devices. We focus on one of the most popular frameworks, quick apps, which are proposed and supported by nine mainstream mobile phone manufacturers in China. Quick apps are implemented with Web-based technologies, and run as native apps without the need of installation. We find that quick apps have much smaller size and only provide a limited set of services compared to their corresponding native apps. Then, we characterize the performance differences between quick apps and native apps in terms of launching time, data drain, and network connections, when the two kinds of apps provide the same services. Our observations reveal that quick apps perform better than native apps thanks to its much smaller size and less functionalities in a single page. Finally, we propose a machine learning based approach to helping developers construct the quick app from an existing native app.

Automated-test-generation tools generate test cases to enable dynamic analysis of Android apps, such as functional testing. These tools build a GUI model to describe the app states during the app execution, and generate a script that performs actions on UI widgets to form a test case. However, when the test cases are re-executed, the apps under analysis often do not behave consistently. The major reasons for such limited reproducibility are due to (1) backend-service dependencies that cause non-determinism in app behaviors and (2) the severe fragmentation of Android platform (i.e., the alarming number of different Android OS versions in vendor-customized devices). To address these challenges, we design and implement Paladin, a novel system that generates reproducible test cases for Android apps. The key insight of Paladin is to provide a GUI model that leverages the structure of the GUI view tree to identify equivalent app states, since the structure can tolerate the changes on the UI contents for an app behavior performed in different test executions. Based on the model, Paladin can search the view tree to locate the desired UI widgets to trigger events and drive the app exploration to reach the desired app states, making the test cases reproducible. Evaluation results on real apps show that Paladin could reach a much higher reproduction ratio than the state-of-the-art tools when the generated test cases are re-executed across different device configurations. In addition, benefiting from the reproducible capability, Paladin is able to cover more app behaviors compared with the existing tools.

Recently, several JavaScript-based deep learning frameworks have emerged, making it possible to perform deep learning tasks directly in browsers. However, little is known on what and how well we can do with these frameworks for deep learning in browsers. To bridge the knowledge gap, in this paper, we conduct the first empirical study of deep learning in browsers. We survey 7 most popular JavaScript-based deep learning frameworks, investigating to what extent deep learning tasks have been supported in browsers so far. Then we measure the performance of different frameworks when running different deep learning tasks. Finally, we dig out the performance gap between deep learning in browsers and on native platforms by comparing the performance of TensorFlow.js and TensorFlow in Python. Our findings could help application developers, deep-learning framework vendors and browser vendors to improve the efficiency of deep learning in browsers.

The web browser is one of the most significant applications on mobile devices such as smartphones. However, the user experience of mobile web browsing is undesirable because of the slow resource loading. To improve the performance of web resource loading, client-side cache has been adopted as a key mechanism. However, the existing passive measurement studies cannot comprehensively characterize the “ client-side ” cache performance of mobile web browsing. For example, most of these studies mainly focus on client-side implementations but not server-side configurations, suffer from biased user behaviors, and fail to study “ miscached ” resources. To address these issues, in this article, we present a proactive approach to making a comprehensive measurement study on client-side cache performance. The key idea of our approach is to proactively crawl resources from hundreds of websites periodically with a fine-grained time interval. Thus, we are able to uncover the resource update history and cache configurations at the server side, and analyze the cache performance in various time granularities. Based on our collected data, we build a new cache analysis model and study the upper bound of how high percentage of resources could potentially be cached and how effectively the caching works in practice. We report detailed analysis results of different websites and various types of web resources, and identify the problems caused by unsatisfactory cache performance. In particular, we identify two major problems— Redundant Transfer and Miscached Resource , which lead to unsatisfactory cache performance. We investigate three main root causes: Same Content , Heuristic Expiration , and Conservative Expiration Time , and discuss what mobile web developers can do to mitigate those problems.

After its birth since early 1990s, the Web has been the major factor that drives the success of the Internet. In the past decade, the access to the Web has undergone a tremendous evolution from PC to mobile devices, i.e., via smartphones, tablet computers, and wearable devices. It is a key challenge to make the future mobile Web more "user friendly", i.e., smooth interactions, fast page load time, reasonable data traffic volume, efficient energy drain, etc. Due to the device diversity and dynamic network connections, a better client-side resource management is quite critical. This paper presents a new perspective of measuring the resource management in a proactive fashion, and identifies various insights that have not been covered by existing efforts. Then we present our visionary holistic approach to optimizing the mobile Web, including the new deployment model and runtime support along with the preliminary principled design.

Many apps benefit from knowing their power consumption and adapting their behaviors on the fly. To offer apps power knowledge at run time, an OS often meters system power and divides it among apps. Since the impacts of concurrent apps on system power are entangled, this approach not only makes it difficult to reason about power but also results in power side channels, a serious vulnerability. To this end, we introduce a new OS principal called power sandbox, which enables one app to observe the fine-grained power consumption of itself running in its vertical slice of the hardware/software stack. The observed power is insulated from the impacts of other apps. Our contribution is a set of lightweight kernel extensions that simultaneously i) enforce the power sandbox boundaries and ii) confine entailed performance loss to the sandboxed apps. Our experiences on two embedded platforms show that power sandboxes simplify reasoning about power, maintain fairness among apps, and minimize power side channels, thus facilitating construction of power-aware apps.

Service computing promotes a large number of web-delivered services, including web services, APIs and data feeds. Composing data, functionalities and even UI from these web-delivered services into a single web application, usually called service mashup , becomes a popular web development paradigm. The web-delivered services can be modeled as mashup components , while the development of mashup actually yields a set of inter-connected mashup components. The growing popularity of mashup components enriches functionality and user experiences, while the possible connections among components are complex and difficult to mashup developers, who might be non-professional programmers or even end-users, as actions over one component may have potential impacts on another. This paper proposes a novel approach for recommending developers in terms of navigation and completion of mashup components with a large-scale components repository. From data-driven perspective, we model the relationships between mashup components by a generic layered-graph model. Developers are allowed to select some initial components as starting point, while a graph-based algorithm recommends how to navigate to potentially relevant mashup components and complete the relevant mashup application. We experimentally demonstrate the efficiency and effectiveness of our approach for rapid mashup construction.

The convergence of Services Computing and Web 2.0 gains a large space of opportunities to compose “situational” web applications from web-delivered services. However, the large number of services and the complexity of composition constraints make manual composition difficult to application developers, who might be non-professional programmers or even end-users. This paper presents a systematic data-driven approach to assisting situational application development. We first propose a technique to extract useful information from multiple sources to abstract service capabilities with a set tags. This supports intuitive expression of user’s desired composition goals by simple queries, without having to know underlying technical details. A planning technique then exploits composition solutions which can constitute the desired goals, even with some potential new interesting composition opportunities. A browser-based tool facilitates visual and iterative refinement of composition solutions, to finally come up with the satisfying outputs. A series of experiments demonstrate the efficiency and effectiveness of our approach.

Unlike the Web where each web page has a global URL to reach, a specific "content page" inside a mobile app cannot be opened unless the user explores the app with several operations from the landing page. Recently, deep links have been advocated by major companies to enable targeting and opening a specific page of an app externally with an accessible uniform resource identifier (URI). In this paper, we present an empirical study of deep links over 20,000 Android apps, and find that deep links do not get wide adoption among current Android apps, and non-trivial manual efforts are required for app developers to support deep links. To address such an issue, we propose the Aladdin approach and supporting tool to release deep links to access arbitrary locations of existing apps. We evaluate Aladdin with popular apps and demonstrate its effectiveness and performance.

Background activities on smartphones are essential to today's "always-on" mobile device experience. Yet, there lacks a clear understanding of the cooperative behaviors among background activities as well as a quantification of the consequences. In this paper, we present the first in-depth study of app collusion, in which one app surreptitiously launches others in the background without user's awareness. To enable the study, we develop AppHolmes, a static analysis tool for detecting app collusion by examining the app binaries. By analyzing 10,000 apps from top third-party app markets, we found that i) covert, cooperative behaviors in background app launch are surprisingly pervasive, ii) most collusion is caused by shared services, libraries, or common interest among apps, and iii) collusion has serious impact on performance, efficiency, and security. Overall, our work presents a strong implication on future mobile system design.

As a typical situational application, Web mashup reflects and accommodates some key features of Internetware paradigm. Mashup provides a development fashion that integrates data, computation and UI elements from multiple resources into a single Web application, and promises the quick rollout of creating potential new functionalities opportunistically. This paper focuses on the problem of recommending useful suggestions for developing data-driven mashups by synthesis of multiple patterns. We present a rapid and intuitive system called iMashupAdvisor, for aiding mashup development based on a novel automated suggestion mechanism. The key observation guiding the development of iMashupAdvisor is that mashups developed by different users might share some common patterns, for instance, selecting similar mashup components for similar goals, and gluing them in a similar manner. Such patterns could reside in multiple sources, e.g., the data dependency between mashup components, the interaction between users and mashup components, or the collective intelligence from existing applications created and maintained by programmers, etc. iMashupAdvisor leverages the synthesis of these patterns to recommend useful suggestions for a partial mashup, such as the missing components, connections between them, or potentially relevant options, to assist mashup completion. This paper presents the data model and ranking metrics of the synthesis process, and introduces efficient algorithms for the retrieval of recommendations. We also experimentally demonstrate the efficiency of our approach for benefiting the proposed rapid mashup development.

The Web has undergone a tremendous change from a primarily publication platform towards a participatory and “programmable” platform, where a large number of heterogeneous Web-delivered services (including SOAP and RESTful Web services, RSS and Atom feeds) are emerging. It results in the creation of Web mashup applications with rich user experiences. However, the integration of Web-delivered services is still a challenging issue. It not only requires the developers’ tedious efforts in understanding and coordinating heterogeneous service types, but also results in the time-consuming development of user interfaces. In this paper, we propose the iMashup composition framework to facilitate mashup development and deployment. We provide a unified mashup component model for the common representation of heterogeneous Web-delivered service interfaces. The component model specifies necessary properties and behaviors at both business and user interface level. We associate the component model with semantically meaningful tags, so that mashup developers can fast understand the service capabilities. The mashup developers can search and put the proper mashup components into the Web browser based composition environment, and connect them by data flows based on the tag-based semantics. Such an integration manner might prevent some low-level programming efforts and improve the composition efficiency. A series of experimental study are conducted to evaluate our framework.

More and more Web applications are now running on mobile devices such as smart phones and tablet computers. Compared with PC using wired internet, mobile devices using mobile internet bring some new and critical challenges to mobile Web applications, such as diverse and usually limited computing power, flexible access to multiple data sources, different screen sizes and resolutions, emergent interactions among native applications and web applications, and so on. This paper presents a mobile Web application platform by means of the synergy of cloud and client. First of all, we derive a new component model from the Model-View-Controller web architecture style and the Service Oriented Architecture for specifying a mobile Web application. Based on the component model, we design a set of mechanisms for adapting mobile web applications to different computing powers, storages and screens: compute-intensive functions can be dynamically offloaded from the mobile device to the cloud for the poor computing power; application data can be flexibly stored in the mobile device or the cloud with offline support; dynamic web pages can be refactored to the mobile screen size. The platform also provides a framework to encapsulate the standard Web applications, web services and native mobile applications into the components, which can then be assembled on-the-fly via an event bus running in the mobile device. We have implemented a web browser-based platform prototype with these capabilities, supporting JavaScript and HTML5. A set of experiments on the well-known web benchmarks and popular web applications demonstrate the effectiveness and applicability of this platform.

When reengineering a monolithic application to be a distributed one, programmers always have to decide how many distributed parts the application should be partitioned, and write many codes related to where a partwill be placed on network nodes and how these parts communicate with each other through the network. These codes usually have nothing to do with the business functions of the application, and they are laborious to write. In addition, as the distribution architecture of the application is finalized beforehand, it may not adapt well to the ever-changing execution environment. In this paper, we propose DPartner, an automatic partitioning system, to help programmers create a distributed Java application without explicitly writing the distribution-related codes. Unlike the other partitioning systems, DPartner does not partition an application directly into the coarse-grained client and server. Instead, it first partitions the application into several modules where each module performs a relatively independent business function of the application. Then it makes these modules be distributable through automatic bytecode rewriting. These modules can distribute in different nodes and cooperate to work just as the original monolithic application. Such a module-based partitioning approach enables a relatively easy reshaping of the distribution architecture of an application, which facilitates the application adapt to the environmental changes without manual recoding or repartitioning with regard to distribution. This paper gives the detailed design of DPartner, and evaluates it using real-world applications. The evaluation results demonstrate the effectiveness and efficiency of DPartner.

Mobile devices with 3G/4G networking often waste energy in the so-called ``tail time during which the radio is kept on even though no communication is occurring. Prior work has proposed policies to reduce this energy waste by batching network requests. However, this work is challenging to apply in practice due to a lack of mechanisms. In response, we have developed DelayDroid, a framework that allows a developer to add the needed policy to existing, unmodified Android applications (apps) with no human effort as well as no SDK/OS changes. This allows such prior work (as well as our own policies) to be readily deployed and evaluated. The DelayDroid compile-time uses static analysis and bytecode refactoring to identify method calls that send network requests and modify such calls to detour them to the DelayDroid run-time. The run-time then applies a policy to batch them, avoiding the tail time energy waste. DelayDroid also includes a cross-app communication mechanism that supports policies that optimize across multiple apps running together, and we propose a policy that does so. We evaluated the correctness and universality of the DelayDroid mechanisms on 14 popular Android apps chosen from the Google App Store. To evaluate our proposed policy, we studied three DelayDroid-enabled apps (weather forecasting, email client, and news client) running together, finding that the DelayDroid mechanisms combined with our policy can reduce 3G/4G tail time energy waste by 36\\%.

HTTP/2 is the next-generation Web protocol based on Google's SPDY protocol, and attempts to solve the shortcomings and inflexibilities of HTTP/1.x. As smartphones become the main access channel for Web services, we are curious if HTTP/2 can really help the performance of Web browsing. In this paper, we conduct a measurement study on the performance of HTTP/2 and HTTPS to reveal the mystery of HTTP/2. We clone the Alexa top 200 websites into our own server, and revisit them through HTTP/2-enabled proxy, and HTTPS-enabled proxy, respectively. We compare HTTP/2 and HTTPS as a transport protocol to transfer Web objects to identify the factors that may affect HTTP/2, including Round-Trip Time (RTT), bandwidth, loss rate, number of objects on a page, and objects sizes. We find that HTTP/2 hurts with high packet loss, but helps many small objects. The computation and dependencies of fetching Web objects reduce the performance improvement of HTTP/2, and sometimes can even hurt the performance of page loading. At last, we test the server push feature of HTTP/2 to leverage the performance.

With the dramatic growth of mobile application (app) markets, users can find various apps with any functionalities they desire in these markets. However, the huge amounts of apps make it quite a challenge for users to discover good apps efficiently. Previous studies recommend apps by considering all apps equal without capturing the specific interests of each individual user. To address this problem, we propose a model called Weight-based Matrix Factorization (WMF), which can capture user-specific interests and give a more accurate prediction on these apps. WMF views each user as a document and each app as a word, and calculates the weight of each app for target users. The weights are calculated by employing term frequency inverse document frequency (TF-IDF) algorithm, which are then introduced into matrix factorization to predict app ratings. Comprehensive experiments are conducted on a real-world datasets with 5057 users and 4496 apps. The experimental results show that WMF achieves a convincing performance and surpasses other existing prediction models.

Computation offloading is a promising way to improve the performance as well as reducing the battery power consumption of a smartphone application by executing some parts of the application on a remote server. Supporting such capability is not easy for smartphone application developers due to (1) correctness: some code, e.g., that for GPS, gravity, and other sensors, can run only on the smartphone so that developers have to identify which parts of the application cannot be offloaded; (2) effectiveness: the reduced execution time must be greater than the network delay caused by computation offloading so that developers need to calculate which parts are worth offloading; (3) adaptability: smartphone applications often face changes of user requirements and runtime environments so that developers need to implement the adaptation on offloading. More importantly, considering the large number of today's smartphone applications, solutions applicable for legacy applications will be much more valuable. In this paper, we present a tool, named DPartner, that automatically refactors Android applications to be the ones with computation offloading capability. For a given Android application, DPartner first analyzes its bytecode for discovering the parts worth offloading, then rewrites the bytecode to implement a special program structure supporting on-demand offloading, and finally generates two artifacts to be deployed onto an Android phone and the server, respectively. We evaluated DPartner on three real-world Android applications, demonstrating the reduction of execution time by 46%-97% and battery power consumption by 27%-83%.

Facilitated by the SOA and new Web technologies, Service-Oriented Rich Clients (SORCs) compose various Web-delivered services in Web browser to create new applications. The SORCs support client-side data storage and manipulation and provide more features than traditional thin clients. However, the SORCs might suffer from data access issues, mainly due to both client-side incompatible data sources and server-side improper or even undesirable cache strategies. Addressing the data access issues, this paper proposes a data access framework for SORCs. The main contributions of this paper are as follows. First, the framework makes the SORCs accommodate heterogeneous local storage solutions and diverse Web browsers properly. The framework abstracts the underlying details of different local storages and selects the most proper data sources for current SORC in use. Secondly, the framework provides a cache mechanism, which supports client-side customized cache strategies. An adaptive technique for the strategies is also proposed to adjust cache strategies based on users' historical actions to achieve better performance.

As a popular infrastructure for distributed systems running on the Internet, middle-ware has to support much more diverse and complex interactions for coping with the drastically increasing demand on information technology and the extremely open and dynamic nature of the Internet. These supporting mechanisms facilitate the development, deployment, and integration of distributed systems, as well as increase the occasions for distributed systems to interact in an undesired way. The undesired interactions may cause serious problems, such as quality violation, function loss, and even system crash. In this paper, the problem is studied from the perspective of the feature interaction problem (FIP) in telecom, and an online approach to the detection and solution on runtime systems is proposed. Based on a classification of middleware enabled interactions, the existence of FIP in middleware based systems is illustrated by four real cases and a conceptual comparison between middleware based systems and telecom systems. After that, runtime software architecture is employed to facilitate the online detection and solution of FIP. The approach is demonstrated on J2EE (Java 2 Platform Enterprise Edition) and applied to detect and resolve all of the four real cases.

Mobile devices with 3G/4G networking often waste energy in the so-called "tail time" during which the radio is kept on even though no communication is occurring. Prior work has proposed policies to reduce this energy waste by batching network requests. However, this work is challenging to apply in practice due to a lack of mechanisms. In response, we have developed DelayDroid, a framework that allows a developer to add the needed policy to existing, unmodified Android applications (apps) with no human effort. This allows such prior work (as well as our own policies) to be readily deployed and evaluated. The DelayDroid compile-time uses static analysis and bytecode refactoring to identify method calls that send network requests and modify such calls to detour them to the DelayDroid run-time. The run-time then applies a policy to batch them, avoiding the tail time energy waste. DelayDroid also includes a cross-app communication mechanism that supports policies that optimize across multiple apps running together, and we propose a policy that does so. We evaluated the correctness and universality of the DelayDroid mechanisms on 14 popular Android apps chosen from the Google App Store. To evaluate our proposed policy, we studied three DelayDroid-enabled apps (weather forecasting, email client, and news client) running together, finding that the DelayDroid mechanisms combined with our policy can reduce 3G/4G tail time energy waste by 36%.

Modern mobile devices like smartphones and tablet computers are equipped with browsers like Apple Safari, Mozilla Fire Fox and Google Chrome. People begin to pay more time on mobile devices than on desktop PCs. Though most popular websites have been optimized for mobile browsing, some web applications, particularly those legacy web-based processes, e.g., Office Automation applications, still keep the same PC-version. Users are possibly influenced by poor browsing experiences and low work efficiency due to limited screen estate and touch-centric interaction pattern. To enable collaborative process on multiple devices, a browser-level and process-oriented capture-and-replay might be an option. However, the changes of web contents and structures, diverse user interaction patterns and performance make cross-device capture-and-replay challenging. This paper presents Carpet, a non-intrusive, low-overhead and intuitive cross-device capture-and-replay system. Unlike previous capture-and-replay efforts that mainly focus on reporting bugs, Carpet is designed for automating web-based processes across multiple devices. Carpet is built atop standard browser kernels without modifying original browsers. Carpet can capture all user interactions and data on a web application, and replay consistently on various devices. We demonstrate Carpet on some typical web applications, including web game, online office, e-commerce, etc. Our initial experiences suggest that Carpet is surprisingly effective in automating the web-based process.

The popularity of smartphones and tablet computers in recent years makes mobile apps burst. Mobile apps have become the main consumers of the Internet-based services. Compared to traditional applications in the desktop computing era, mobile devices with their apps bring new opportunities and challenges to service computing community, in various aspects like service publication, discovery, interaction, composition, et al. In this paper, we propose a novel data-driven, content-based mobile apps composition approach, called Mash Droid, by leveraging a novel In-App Search mechanism, i.e., Discovering relevant services for the data and content in apps. Rather than existing techniques that usually integrate fixed Web services, our approach relies on the dynamic service discovery and flexible data exchange between several apps. The unique feature of our approach is enabling the data communication channel between apps by the content index services provided by a leading Android appstore, Wandoujia, which now has over 1,000,000 apps and 200 million users. We employ the In-App Search mechanism to define a Restful-style app model and resource-oriented app description model. Based on the models, we design a framework for dynamically discovering relevant apps that could be composed with current app's contexts. We implement a prototype to demonstrate our approach.

The burst of Web-based Restful services brings us a number of facilities in our life and work. We are used to take smartphones to access these Web services, like location-based services, weather search, mapping, social networking, et al. On smartphones, we have two options of service consumers, a.k.a, Native apps and Web apps. Despite the platform-independence, Web apps are claimed to provide the same features and comparable user experiences with native apps. However, one fact is that more and more people prefer native apps rather than Web apps. In this paper, we make an empirical study on characterizing the performance disparity of native apps and Web apps. Given the same functionalities provided by the same service providers, we explore the Restful Web services that are used by native apps and Web apps. With HTTP-level trace analysis, we demystify the workflows on how native apps and Web apps use Web services and summarize different service usage patterns from architectural style perspective. Then we characterize the performance differences between native apps and Web apps on realizing Restful Web services including GET, DELETE, PUT a POST, in terms of number of network connections, response time, and data drain, given the same functional features. Our observations reveal that Web apps do not always perform worse than native apps using Restful Web services under the same context. We further propose some implications to improve both native apps and Web apps on smartphones.

The Web browser is a killer app on mobile devices such as smartphones. However, the user experience of mobile Web browsing is undesirable because of the slow resource loading. To improve the performance of Web resource loading, caching has been adopted as a key mechanism. However, the existing passive measurement studies cannot comprehensively characterize the performance of mobile Web caching. For example, most of these studies mainly focus on client-side implementations but not server-side configurations, suffer from biased user behaviors, and fail to study "miscached" resources. To address these issues, in this paper, we present a proactive approach for a comprehensive measurement study on mobile Web cache performance. The key idea of our approach is to proactively crawl resources from hundreds of websites periodically with a fine-grained time interval. Thus, we are able to uncover the resource update history and cache configurations at the server side, and analyze the cache performance in various time granularities. Based on our collected data, we build a new cache analysis model and study the upper bound of how high percentage of resources could potentially be cached and how effective the caching works in practice. We report detailed analysis results of different websites and various types of Web resources, and identify the problems caused by unsatisfactory cache performance. In particular, we identify two major problems -- Redundant Transfer and Miscached Resource, which lead to unsatisfactory cache performance. We investigate three main root causes: Same Content, Heuristic Expiration, and Conservative Expiration Time, and discuss what mobile Web developers can do to mitigate those problems.

Business processes built from web services need a more adaptable composition solution. In this paper, an approach based on agents is proposed to control the executions of business processes via agent behavior rules, which can be generated automatically and modified dynamically to enable the adaptations of business process. In the approach, the adaptations of the business process are specified in independent adaptation units and agents can load and interpret user-defined adaptation units at runtime. Thus, the executions of business processes can be adapted dynamically. This paper also describes a running support of lightweight agents on a reflective middleware, on which agents can be generated automatically to compose web service to support adaptable business processes according to the specifications of business processes and the adaptation units.

As a popular approach to dependable service oriented architecture (SOA), a service pool collects a set of services that provide the same functionality by different service providers for achieving desired reliability. However, if the tradeoff between reliability and other important qualities, e.g., performance, has to be considered, the construction and management of a service pool become much more complex. In this paper, an automated approach to this problem is presented. Based on the investigation of service pools in the typical triangle SOA model, two challenges critical to the effectiveness and efficiency of service pools are identified, including which services should be held by a pool and what order these services are invoked in. A set of algorithms are designed to address the two challenges and then a service pool can be automatically constructed and managed for given reliability and performance requirements in polynomial time. The approach is demonstrated on a J2EE based service platform and the comparison results between different pooling algorithms are evaluated.

Web application is a key app on mobile devices. However, the performance of mobile Web applications is known to be poor. Resource loading is a key factor influencing Web applications performance. Cache is an effective mechanism to accelerate resource loading by enabling to access resources directly from local storage. In this paper, we make a quantitative study to characterize how mobile Web applications leverage cache to improve its performance. The results show that mobile Web cache is not so efficient. On one hand, redundant transfers are always there to waste data traffic and energy consumption no matter the client support is perfect or not. On the other hand, changed resources are not replaced from cache in time, leading to incorrect functions.

Web applications have played an important role in mobile computing since they are developed by standard web technology, easy to achieve portability and always up to date. As a widely adopted development fashion, mashup integrates data, computation and UI elements from multiple web-delivered services into a single web application, which is a promising way to develop applications for mobile devices. However, developing mobile web applications by mashup has faced two challenges: on one hand, the growing popularity of web-delivered services, especially those equipped with mobile features like LBS, increases the difficulty of finding proper services and connections between services to create situational applications, on the other hand, mobile computing yields for agile development and fast iteration to meet users everchanging requirements, imposing more burden on developers. This paper presents a graph-based approach to helping mobile developers create mobile web applications. Based on this graph model, algorithms by synthesizing different recommendation patterns are designed to assist mashup completion, such as finding the missing components, connections between them, or potentially relevant options.