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No description available.

With the recent growth of the mobile market, companies want to target mobile devices while at the same time keeping product development costs low. One way to do this is to develop web applications, which are accessed from a mobile de- vice’s web browser, instead of native applications. The same web application can then be used on different platforms such as Android and iOS. However, devices such as smart phones and tablets often include cameras and sensors that a web ap- plication may want to access, but which are only accessible from native applica- tions. A framework was developed that enables web applications to communicate with native Android applications. Native applications are launched by clicking a link in the browser, and the result produced is made available to the web applica- tion through a HTTP POST request or a local web server running on the device. Key characteristics of the framework include ease of extension and the ability to enable secure (SSL) communication if desired. The ZXing Barcode Scanner ap- plication was integrated with the framework so that a scanned barcode can be dis- played in the browser. Performance measurements were conducted measuring the time taken from clicking a link to start a test application to the result being avail- able in the browser. The mean times measured were between 323 and 394 mil- liseconds. This indicates that the method used is sufficiently fast to not detract from the user experience. Future work could expand on the measurements or per- form a feature and performance comparison with PhoneGap.

Yes / The web environment has been developing remarkably, and much work has been done towards improving web based notification systems, where servers act smartly by notifying and feeding clients with subscribed data. In this paper we have reviewed some of the problems with current solutions to real-time updates of multi user web applications; we introduce a new concept “adaptive polling” based on one AJAX technique “Polling” to reduce the high volume of redundant server connections with reasonable latency, we demonstrated a prototype implementation of the new concept which is then evaluated against the existing one; the positive results clearly indicated more efficiency in terms of client-server bandwidth.

Portability of web applications between web servers of different organizations can be challenging and can complicate sharing and collaborative use of such tools. Given the distributed nature of the web, this lack of portability is usually not a concern because a user in one organization can link to and use a web application hosted by another organization. However, access control or differentiation may be needed by an organization in terms of area of interest, input data, analytical techniques, access control, presentation, branding, and language. This is true for many government organizations, and their associated web sites, and servers. In such cases, there are compelling political, branding, security, and privacy motivations that require each organization or agency to host and manage web applications on their own servers rather than using third party web sites over which they have little or no control. Also, web applications are classically developed by setting up a local software development and testing environment which can be challenging for new developers, be restricted by the software and hardware availability, cost significantly to obtain software development licenses and compatible hardware and is prone to code and data loss due to hardware damage or software corruptions. To simplify the discovery, deployment of web-based applications, I present the design, development, and testing of a system for discovering, installing, and configuring environmental analysis web applications on localized web servers. The system works with applications developed using Tethys Platform, which is an open-source software stack for creating geospatially enabled web-based applications. The developed Tethys App Store includes a Tethys application user interface that allows a server manager to retrieve applications from the central repository and install them on a local server with relatively simplicity, similar to the installation of a mobile application to a mobile device from a mobile application store. Next, I present the design concept of a cloud-based web application development platform, Tethys App Nursery, that attempts to overcome the above hurdles associated with localized development environments. A prototype of this system is developed and presented which is tightly integrated with Tethys platform and various cloud technologies provided by Amazon Web Services. The developed app nursery allows users to register for new Tethys portal instances in the cloud, develop new applications and test existing applications, without installing any local dependencies or development tools. Various cloud components used in this service's development as well as their associated costs are described. These systems were developed to support development of water and environmental analysis web apps for the international Group on Earth Observations (GEO) Global Water Sustainability (GEOGloWS) initiative of the National Aeronautics and Space Administration (NASA) and several partner organizations.

No description available.

No description available.

Service Oriented Architecture (SOA) is an increasingly important software architecture, designed to flexibly connect separate components in response to rapid changes in the business environment. SOA focuses on the exchange of information between independent software components and on the reusability of the components by separating communication interface from internal implementation. There are several features of SOA that make legacy system modernization to SOA appealing in today’s world. These are loose coupling, abstraction of underlying logic, agility, flexibility, reusability, autonomy, statelessness, discoverability and reduced cost. Migration of legacy systems to SOA is an important problem. While migration of legacy data processing systems has been widely studied, migration of legacy web applications has not. In this thesis we review existing strategies for migration of monolithic legacy web applications to web services, noting the unique challenges due to the highly dynamic nature of the systems, poorly structured code, and weakly typed languages in web applications, and the need for automation to assist in the process. We present a new semi-automated framework for the analysis and migration of monolithic web applications to web services using source analysis and transformation techniques, and outline a set of source transformation steps that can be used to migrate existing legacy web applications to web services form. We demonstrate our framework on the analysis and automated restructuring of two large existing web applications to extract and migrate integrated internal features to independent, reusable web services. / Thesis (Ph.D, Computing) -- Queen's University, 2013-03-28 14:23:24.797

It is not a secret that communications between client sides and server sides in web applications can leak user confidential data through side-channel attacks. The lower lever traffic features, such as packet sizes, packet lengths, timings, etc., are public to attackers. Attackers can infer a user's web activities including web browsing histories and user sensitive information by analysing web traffic generated during communications, even when the traffic is encrypted. There has been an increasing public concern about the disclosure of user privacy through side-channel attacks in web applications. A large amount of work has been proposed to analyse and evaluate this kind of security threat in the real world. This dissertation addresses side-channel vulnerabilities from different perspectives. First, a new approach based on verification and quantitative information flow is proposed to perform a fully automated analysis of side-channel leakages in web applications. Core to this aim is the generation of test cases without developers' manual work. Techniques are implemented into a tool, called SideAuto, which targets at the Apache Struts web applications. Then the focus is turned to real-world web applications. A black-box methodology of automatically analysing side-channel vulnerabilities in real-world web applications is proposed. This research demonstrates that communications which are not explicitly involving user sensitive information can leak user secrets, even more seriously than a traffic explicitly transmitting user information. Moreover, this thesis also examines side-channel leakages of user identities from Google accounts. The research demonstrates that user identities can be revealed, even when communicating with external websites included in Alexa Top 150 websites, which have no relation to Google accounts.

Application record and replay is the ability to record application execution and replay it at a later time. Record-replay has many use cases including diagnosing and debugging applications by capturing and reproducing hard to find bugs, providing transparent application fault tolerance by maintaining a live replica of a running program, and offline instrumentation that would be too costly to run in a production environment. Different record-replay systems may offer different levels of replay faithfulness, the strongest level being deterministic replay which guarantees an identical reenactment of the original execution. Such a guarantee requires capturing all sources of nondeterminism during the recording phase. In the general case, such record-replay systems can dramatically hinder application performance, rendering them unpractical in certain application domains. Furthermore, various use cases are incompatible with strictly replaying the original execution. For example, in a primary-secondary database scenario, the secondary database would be unable to serve additional traffic while being replicated. No record-replay system fit all use cases. This dissertation shows how to make deterministic record-replay fast and efficient, how broadening replay semantics can enable powerful new use cases, and how choosing the right level of abstraction for record-replay can support distributed and heterogeneous database replication with little effort. We explore four record-replay systems with different semantics enabling different use cases. We first present Scribe, an OS-level deterministic record-replay mechanism that support multi-process applications on multi-core systems. One of the main challenge is to record the interaction of threads running on different CPU cores in an efficient manner. Scribe introduces two new lightweight OS mechanisms, rendezvous point and sync points, to efficiently record nondeterministic interactions such as related system calls, signals, and shared memory accesses. Scribe allows the capture and replication of hard to find bugs to facilitate debugging and serves as a solid foundation for our two following systems. We then present RacePro, a process race detection system to improve software correctness. Process races occur when multiple processes access shared operating system resources, such as files, without proper synchronization. Detecting process races is difficult due to the elusive nature of these bugs, and the heterogeneity of frameworks involved in such bugs. RacePro is the first tool to detect such process races. RacePro records application executions in deployed systems, allowing offline race detection by analyzing the previously recorded log. RacePro then replays the application execution and forces the manifestation of detected races to check their effect on the application. Upon failure, RacePro reports potentially harmful races to developers. Third, we present Dora, a mutable record-replay system which allows a recorded execution of an application to be replayed with a modified version of the application. Mutable record-replay provides a number of benefits for reproducing, diagnosing, and fixing software bugs. Given a recording and a modified application, finding a mutable replay is challenging, and undecidable in the general case. Despite the difficulty of the problem, we show a very simple but effective algorithm to search for suitable replays. Lastly, we present Synapse, a heterogeneous database replication system designed for Web applications. Web applications are increasingly built using a service-oriented architecture that integrates services powered by a variety of databases. Often, the same data, needed by multiple services, must be replicated across different databases and kept in sync. Unfortunately, these databases use vendor specific data replication engines which are not compatible with each other. To solve this challenge, Synapse operates at the application level to access a unified data representation through object relational mappers. Additionally, Synapse leverages application semantics to replicate data with good consistency semantics using mechanisms similar to Scribe.