Thesis (Ph. D.)--College of Computing, Georgia Institute of Technology, 2004. Directed by Ling Liu. / Vita. Includes bibliographical references (leaves 147-155).

Thesis (M.S. in Computer Science)--Naval Postgraduate School, December 2003. / Thesis advisor(s): Don Brutzman, Curt Blair, Barb Helfer. Includes bibliographical references (p. 95-99). Also available online.

The water balance equation is one of the most fundamental concepts in hydrology. How much precipitation a river basin receives, and where that water goes, defines what flora, fauna, and industry the basin can support. Models for solving this equation originally relied only on precipitation, air temperature, and day length, but have adapted as new data becomes available. Recent advances in technology, especially remote sensing and web services, make it cheaper and easier than ever to obtain hydrological data, including many variables that were previously impossible to measure. This thesis will examine the water balance of the San Marcos River Basin and demonstrate how remote sensing and web services can improve our understanding of the basin's hydrology. It was found that 72% of precipitation in the San Marcos Basin is lost to evapotranspiration. This percentage varies from year to year as a function of precipitation, but the annual volume of evapotranspiration stays almost constant. It was only during the second consecutive year of drought that there was an appreciable change in evapotranspiration. This suggests that annual evapotranspiration can be thought of as a property inherent to a watershed's hydrology, and so long as there is enough stored water in the soil, that demand will be met. The water left over after ET takes its share can either flow out of the basin through a river channel or stay within the basin as storage. After examining methods for partitioning the available water between outflow and storage, it was found that lumped water balance models cannot be used in the San Marcos River Basin because of its complex interactions with the Edwards Aquifer. In order to better model soil moisture dynamics and groundwater infiltration, a distributed model will have to be developed that accounts for flow in and out of the aquifer. / text

published_or_final_version / abstract / toc / Computer Science and Information Systems / Master / Master of Philosophy

Mobile devices are the dominant interface for interacting with online services as well as an efficient platform for cloud data consumption. Cloud computing allows the delivery of applications/functionalities as services over the internet and provides the software/hardware infrastructure to host these services in a scalable manner. In mobile cloud computing, the apps running on the mobile device use cloud hosted services to overcome resource constraints of the host device. This approach allows mobile devices to outsource the resource-consuming tasks. Furthermore, as the number of devices owned by a single user increases, there is the growing demand for cross-platform application deployment to ensure a consistent user experience. However, the mobile devices communicate through unstable wireless networks, to access the data and services hosted in the cloud. The major challenges that mobile clients face when accessing services hosted in the cloud, are network latency and synchronization of data. To address the above mentioned challenges, this research proposed an architecture which introduced a policy-based middleware that supports user to access cloud hosted digital assets and services via an application across multiple mobile devices in a seamless manner. The major contribution of this thesis is identifying different information, used to configure the behavior of the middleware towards reliable and consistent communication among mobile clients and the cloud hosted services. Finally, the advantages of the using policy-based middleware architecture are illustrated by experiments conducted on a proof-of-concept prototype.

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In the era of mobile cloud computing, the consumption of virtualized software and Web-based services from super-back-end infrastructure using smartphones and tablets is gaining much research attention from both the industry and academia. Nowadays, these mobile devices generate and access multimedia data hosted in social media and other sources in order to enhance the users’ multimedia experience. However, multimedia data is unstructured which can lead to challenges with data synchronization between these mobile devices and the cloud computing back-end. The issue with data synchronization is further fueled by the fact that mobile devices can experience intermittent connectivity losses due to unstable wireless bandwidths. While previous works proposed Simple Object Access Protocol (SOAP) -based middleware for the Web services’ synchronization, this approach is not efficient in a mobile environment because the SOAP protocol is verbose. Thus, the Representational State Transfer (REST) standard has been proposed recently to model the Web services since it is lightweight. This thesis proposes a novel approach for implementing a REST-based mobile Web Service for multimedia file sharing that utilizes a channel-based publish/subscribe communication scheme to synchronize smartphone or tablet-hosted NoSQL databases with a cloud-hosted NoSQL database. This thesis evaluates the synchronicity and the scalability of a prototype system that was implemented according to this approach. Also, this thesis assesses the overhead of the middleware component of the system.

A functional ASP.NET application relies on the successful interoperation of many different elements and technologies. Each solution component provides security capabilities designed to meet its own requirements. However, it is not enough to look at security purely from the perspective of individual components. To provide security for the overall solution you must also consider how the components interact. This paper describes the common characteristics of .NET Web applications from a security perspective. It contains a detail analysis of the key elements of authentication, authorization, and secure communication models, mechanisms (including NTLM, Kerberos and Certificates technologies). It also describes a set of specifications and scenarios that show how these elements might be used together to improve a better Web-Services security.

The web of the future will require automated tagging of equivalent or similar services in support of service discovery and the selection of appropriate alternatives in case of failure. Code similarity detection tools, or clone detectors, provide a mature and scalable method of identifying these kinds of similarities and can be used to assist in this problem. However, they require a set of units to be compared; something to which the most popular description language, WSDL (Web Service Description Language), does not lend itself. First, each WSDL description can contain more than one operation description, which does not provide the granularity we need to compare services on the operation level. Secondly, these operation descriptions are mixed together throughout the file, often sharing some common elements. This thesis describes a technique for extracting the elements of each operation description and consolidating them into a self-contained unit using TXL, a source transformation language. These units, referred to as Web Service Cells or WSCells (pronounced “wizzles”), can then be used by similarity detectors to search for similarities. We describe a modified architecture to the NICAD clone detector to support the creation of WSCells, and the implementation of a special WSDL extractor we used to emulate this modification in its absence. / Thesis (Master, Computing) -- Queen's University, 2011-10-04 09:33:36.932

Web services is a relatively recent initiative that aims to promote program-toprogram interaction across the Internet, but while web services is based on a set of XML standards, new standards continue to emerge and existing standards to evolve. Also, web services relies on Remote Procedure Call (RPC) for communication and is thus influenced by the semantics of RPC. In this research, we investigated the juxtaposition of RPC with Generative Communications (GC). GC is a communication paradigm where messages exist independently of the sender and receiver and are stored in a network accessible buffer called a &quotspace": this leads to interactions which are inherently decoupled (in time and space). Also, messages are addressed to recipients by their content, rather than by network addresses, opening up the possibility for one-to-many interactions. These aspects are a marked departure from the RPC paradigm and introduce two main implications: 1) GC messages can be intercepted when in-transit between participants thus introducing the opportunity for mediation and 2) GC can be used as the basis for the aggregation of simple services into more complex ensembles. In this research, we explored these possibilities by creating proof-of-concept prototypes in three areas. 1) Mediation - GC based mediation was used to intercede between clients and services to allow a client using one protocol to interact with a service using a different protocol. For example, a GC based client interacting with a SOAP service (leading to backward compatibility). 2) Location services - a location service is a GC based service that performs a similar function to a UDDI registry but can be treated as just another service rather than part of an architecture. 3) Aggregation - a workflow design was used as the basis of an aggregated service using GC as the means by which the aggregation elements interact. We concluded that GC provides a natural platform for mediation, location services and aggregation and that these aspects could be combined to produce a holistic service environment.