Xuanzhe Liu

Discovering Homogeneous Web Service Community in the User-Centric Web Environment

The Web has undergone a tremendous change toward a highly user-centric environment. Millions of users can participate and collaborate for their own interests and benefits. Services computing paradigm together with the proliferation of Web services have created great potential opportunities for the users, also known as service consumers, to produce value-added services by means of service discovery and composition. In this paper, we propose an efficient approach to facilitating the service consumer on discovering Web services. First, we analyze the service discovery requirements from the service consumers perspective and outline a conceptual model of homogeneous Web service communities. The homogeneous service community contains two types of discovery: the search of similar operations and that of composible operations. Second, we describe a similarity measurement model for Web services by leveraging the metadata from WSDL, and design a graph-based algorithm to support both of the two discovery types. Finally, adopting the popular atom feeds, we design a prototype to facilitate the consumers to discover while subscribing Web services in an easy-of-use manner. With the experimental evaluation and prototype demonstration, our approach not only alleviates the consumers from time-consuming discovery tasks but also lowers their entry barrier in the user-centric Web environment.

Refactoring android Java code for on-demand computation offloading

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 todays 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%.

Integrating Resource Consumption and Allocation for Infrastructure Resources on-Demand

Infrastructure resources on-demand requires resource provision (e.g., CPU and memory) to be both sufficient and necessary, which is the most important issue and a challenge in Cloud Computing. Platform as a service (PaaS) encapsulates a layer of software that includes middleware, and even development environment, and provides them as a service for building and deploying cloud applications. In PaaS, the issue of on-demand infrastructure resource management becomes more challenging due to the thousands of cloud applications that share and compete for resources simultaneously. The fundamental solution is to integrate and coordinate the resource consumption and allocation management of a cloud application. The difficulties of such a solution in PaaS are essentially how to maximize the resource utilization of an application, and how to allocate resources to guarantee adequate resource provision for the system. In this paper, we propose an approach to managing infrastructure resources in PaaS by leveraging two adaptive control loops: the resource consumption optimization loop and the resource allocation loop. The optimization loop improves the resource utilization of a cloud application via management functions provided by the corresponding middleware layers of PaaS. The allocation loop provides or reclaims appropriate amounts of resources to/from the application system while guaranteeing its performance. The two loops are integrated to run consecutively and repeatedly to provide infrastructure resources on-demand by first trying to improve resource utilization, and then allocating more resources when necessary. We implement a framework, SmartRod, to investigate our approach. The experiment on SmartRod proves its effectiveness on infrastructure resource management.

Characterizing Smartphone Usage Patterns from Millions of Android Users

he prevalence of smart devices has promoted the popular- ity of mobile applications (a.k.a. apps) in recent years. A number of interesting and important questions remain unan- swered, such as why a user likes/dislikes an app, how an app becomes popular or eventually perishes, how a user selects apps to install and interacts with them, how frequently an app is used and how much traffic it generates, etc. This paper presents an empirical analysis of app usage behaviors collected from millions of users of Wandoujia, a leading An- droid app marketplace in China. The dataset covers two types of user behaviors of using over 0.2 million Android apps, including (1) app management activities (i.e., installa- tion, updating, and uninstallation) of over 0.8 million unique users and (2) app network traffic from over 2 million unique users. We explore multiple aspects of such behavior data and present interesting patterns of app usage. The results provide many useful implications to the developers, users, and disseminators of mobile apps.

Internetware: An Emerging Software Paradigm for Internet Computing

The Internet is undergoing a tremendous change towards the globalized computing environment. Due to the open, dynamic and uncontrollable natures of the Internet, software running in the Internet computing environment has some new features, which bring challenges to current software technologies in terms of software model, software operating platform, software engineering approaches and software quality. Researchers in China have proposed the term “Internetware” to present the emerging software paradigm. Sponsored by the National Basic Research 973 Program, several research practices have been done on the Internetware in the past decade. This paper summarizes the progress and status of the Internetware researches. A technical solution framework for the Internetware paradigm is proposed from four aspects: the Internetware software model defines what the Internetware is to be; the Internetware middleware determines how to run the Internetware applications; the engineering methodology determines how to develop the Internetware applications; the Internetware quality assurance determines how well the Internetware applications can perform. The paper also discusses the ongoing research issues and future trends of Internetware.

A Policy-Driven Approach for Software-as-Services Customization

Software as services (SaS) is emerging as a new application software delivery approach, and has extensively leveraged Web services and other SOA concepts and technologies. Compared to the traditional ones, SaS has the following distinctive features: application delivery over Internet, usage based pricing mechanism, etc. Potentially, this approach can significantly reduce the total cost of ownership of application software. However, it does have a number of unique issues that include service customization, multi-tenancy, complex billing model, etc. If not handled properly, these issues can result in ad-hoc and manual service consumption practices, which could eliminate the benefits of the SaS approach. In this paper, we are going to specifically deal with the service customization issue. To that end, we proposed a novel SaS customization policy and a supporting framework that is realized through a design-time tooling and a runtime environment. We also provided a case study to verify the effectiveness of the proposed approach.

A Web-Based Mashup Environment for On-the-Fly Service Composition

The web-based service composition, e.g. mashup, is becoming a popular style to reuse web services. From the perspective of reuse, existing work has limitations on qualifying whether the service or the service composition satisfies user requirements and adapting the service or composition according to the qualification results. For addressing these limitations, this paper proposes an on-the-fly approach to web-based service composition. Firstly, we do not distinguish the design-time and run-time of services and their composition so that they can be qualified in a what you see is what you get manner when services are selected or assembled. Secondly, we propose a component model for separating the service business and user interface so that they can be changed dynamically and independently in the adaptation of service selection and composition. This approach is demonstrated by a browser-based mashup tool.

How Does Web Service API Evolution Affect Clients

Like traditional local APIs, web service APIs (web APIs for short) evolve, bringing new and improved functionality as well as incompatibilities. Client programs have to be modified according to these changes in order to use the new APIs. Unlike client programs of a local API, which could continue to use the old API, clients of a web API often do not have the option not to upgrade, since the old version of the API may not be provided as a service anymore. Therefore, migrating clients of web APIs is a more critical task. Research has been done in the evolution of local APIs and different approaches have been proposed to support the migration of client applications. However, in practice, we seldom observe that web API providers release automated tools or services to assist the migration of client applications. In this paper, we report an empirical study on web API evolution to address this issue. We analyzed the evolution of five popular web APIs, in total 256 hanged API elements, and carefully compared our results with existing empirical study on API evolution. Our findings are threefold: 1) We summarize the API changes into 16 change patterns, which provide grounded supports for future research, 2) We identify 6 completely new challenges in migrating web API clients, which do not exist in the migration of local API clients, 3) We also identify several unique characteristics in web API evolution.

Composing Data-Driven Service Mashups with Tag-Based Semantic Annotations

Spurred by Web 2.0 paradigm, there emerge large numbers of service mashups by composing readily accessible data and services. Mashups usually address solving situational problems and require quick and iterative development lifecyle. In this paper, we propose an approach to composing data driven mashups, based on tag-based semantics. The core principle is deriving semantic annotations from popular tags, and associating them with programmatic inputs and outputs data. Tag-based semantics promise a quick and simple comprehension of data capabilities. Mashup developers including end-users can intuitively search desired services with tags, and combine several services by means of data flows. Our approach takes a planning technique to retrieving the potentially relevant composition opportunities. With our graphical composition user interfaces, developers can iteratively modify, adjust and refine their mashups to be more satisfying.

A User-Oriented Approach to Automated Service Composition

In the past a few years, the Web has undergone a tremendous change towards a highly user-centric environment. Millions of users can participate and collaborate for their own interests and benefits. Service oriented computing and Web services have created great potential opportunities for the users to build their own applications. Then, it is a pressing issue that, the users can compose services without too complex tasks and efforts. In this paper, we introduce a user-oriented approach which aims to simplify service composition. We leverage the plentiful information residing in service tags, both from service descriptions (such as WSDL) and the annotations tagged by users. Employing some mining algorithms, a direct acyclic graph is built up to represent potential composition opportunities. With a simple and intuitive search, it allows users to explore the space of potentially composable services and achieve service composition in a heuristic manner. We have developed a composition advisor to provide recommendations guiding and assisting the users. It also lets the users discover and make use of services without having to understand too many details of individual candidate services. To enable the users to accomplish service composition in a more interactive access channel, we finally provide a user-friendly prototype based on Web browsers. It undoubtedly reduces the complexity and lowers the entry barrier for the users, and makes them better play their role in the service-oriented Web environment.