Computer Science
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ISSN 1508-2806
e-ISSN: 2300-7036
Issue Date
2012
Volume
Vol. 13
Number
No. 3
Description
Reviewed by: Katarzyna Węgrzyn-Wolska, Philip Moore, Włodzimierz Funika, Roland Wismüller, Juan Carlos Burguillo Rial, Rafał Tylman, Ewa Deelman, Maciej Malawski, Bartosz Baliś, Jacek Dajda, Dariusz Król, Bartosz Kryza, Ladislav Hluchy, Stefan Dlugolinsky, Piotr Malecki, Bogdan Pavkovic, Robert Schaefer, Curtis Menton, Ashwin Lall, Michał Ślaski, Robert Virding
Journal Volume
Computer Science
Vol. 13 (2012)
Projects
Pages
Articles
A study on the role of non-hyperlink text on web navigation
(Wydawnictwa AGH, 2012) Karanam, Saraschandra; Oostendorp, Herre van; Indurkhya, Bipin
Cognitive models of web navigation have been used for evaluating websites and predicting user navigation behavior. Currently they predict the correct hyperlink by using information from the hyperlink text alone and ignore all other textual information on a webpage. The validity of this assumption is examined by investigating the role of non-hyperlink text on user navigation behavior. In the first experiment, we created two versions of a website by removing the non-hyperlink text from it. We found that there was no significant effect of non-hyperlink text on the user navigation behavior. Participants were equally accurate, selected the same set of pages to visit and spent the same amount of time on that common set with or without non-hyperlink text. This result validates the assumptions of those models of user-navigation behavior that consider information from the hyperlink text only. However, in a follow-up experiment, we included high-relevance and low-relevance pictures on the website, and repeated the experiment with and without non-hyperlink text. We found that participants were more accurate in the presence of non-hyperlink text than without it. This result suggests that the presence of pictures might prime the users to pay attention to non-hyperlink text, which increases the task accuracy.
Identifying limits of scalability in distributed, heterogeneous, layer based monitoring concepts like SLAte
(Wydawnictwa AGH, 2012) Hilbrich, Marcus; Müller-Pfefferkorn, Ralph
In this paper we present the concept of a scalable job centric monitoring infrastructure. The overall performance of this distributed, layer based architecture called SLAte can be increased by installing additional servers to adapt to the demands of the monitored resources and users. Another important aspect is to offer a uniform global view on all data which are stored distributed to provide an easy access for users or visualisation tools. Additionally we discuss the impact of these uniform access layer on scalability.
Management methods in SLA-aware distributed storage systems
(Wydawnictwa AGH, 2012) Nikolow, Darin; Słota, Renata; Lakovic, Danilo; Winiarczyk, Paweł; Pogoda, Marek; Kitowski, Jacek
Traditional data storage systems provide access to user’s data on the “best effort” basis. While this paradigm is sufficient in many use cases it becomes an obstacle for applications with Quality of Service (QoS) constraints. Service Level Agreement (SLA) is a part of the contract agreed between the service provider and the client and contains a set of well defined QoS requirements regarding the provided service and the penalties applied in case of violations. In the paper we propose a set of SLA parameters and QoS metrics relevant to data storage processes and the management methods necessary for avoiding SLA violations. A key assumption in the proposed approach is that the underlying distributed storage system does not provide functionality for resource or bandwidth reservation for a given client request.
Automatic proxy generation and load-balancing-based dynamic choice of services
(Wydawnictwa AGH, 2012) Dąbrowski, Jarosław; Feduniak, Sebastian; Baliś, Bartosz; Bartyński, Tomasz; Funika, Włodzimierz
The paper addresses the issues of invoking services from within workflows which are becoming an increasingly popular paradigm of distributed programming. The main idea of our research is to develop a facility which enables load balancing between the available services and their instances. The system consists of three main modules: a proxy generator for a specific service according to its interface type, a proxy that redirects requests to a concrete instance of the service and load-balancer (LB) to choose the least loaded virtual machine (VM) which hosts a single service instance. The proxy generator was implemented as a bean (in compliance to EJB standard) which generates proxy according to the WSDL service interface description using XSLT engine and then deploys it on a GlassFish application server using GlassFish API, the proxy is a BPEL module and load-balancer is a stateful Web Service.
Enabling generic distributed computing infrastructure compatibility for workflow management systems
(Wydawnictwa AGH, 2012) Kozlovszky, Miklós; Karoczkai, Krisztián; Márton, István; Balaskó, Ákos; Marosi, Attila; Kacsuk, Péter
Solving workflow management system’s Distributed Computing Infrastructure (DCI) incompatibility and their workflow interoperability issues are very challenging and complex tasks. Workflow management systems (and therefore their workflows, workflow developers and also their end-users) are bounded tightly to some limited number of supported DCIs, and efforts required to allow additional DCI support. In this paper we are specifying a concept how to enable generic DCI compatibility for grid workflow management systems (such as ASKALON, MOTEUR, gUSE/WS-PGRADE, etc.) on job and indirectly on workflow level. To enable DCI compatibility among the different workflow management systems we have developed the DCI Bridge software solution. In this paper we wll describe its internal architecture, provide usage scenarios to show how the developed service resolve the DCI interoperability issues between various middleware types. The generic DCI Bridge service enables the execution of jobs onto the existing major DCI platforms (such as Service Grids (Globus Toolkit 2 and 4, gLite, ARC, UNICORE), Desktop Grids, Web services, or even cloud based DCIs).