Service Quality Assessment for Cloud-based Distributed Data Services

The issue of less-than-100% reliability and trust-worthiness of third-party controlled cloud components (e.g., IaaS and SaaS components from different vendors) may lead to laxity in the QoS guarantees offered by a service-support system S to various applications. An example of S is a replicated data service to handle customer queries with fault-tolerance and performance goals. QoS laxity (i.e., SLA violations) may be inadvertent: say, due to the inability of system designers to model the impact of sub-system behaviors onto a deliverable QoS. Sometimes, QoS laxity may even be intentional: say, to reap revenue-oriented benefits by cheating on resource allocations and/or excessive statistical-sharing of system resources (e.g., VM cycles, number of servers). Our goal is to assess how well the internal mechanisms of S are geared to offer a required level of service to the applications. We use computational models of S to determine the optimal feasible resource schedules and verify how close is the actual system behavior to a model-computed \u27gold-standard\u27. Our QoS assessment methods allow comparing different service vendors (possibly with different business policies) in terms of canonical properties: such as elasticity, linearity, isolation, and fairness (analogical to a comparative rating of restaurants). Case studies of cloud-based distributed applications are described to illustrate our QoS assessment methods. Specific systems studied in the thesis are: i) replicated data services where the servers may be hosted on multiple data-centers for fault-tolerance and performance reasons; and ii) content delivery networks to geographically distributed clients where the content data caches may reside on different data-centers. The methods studied in the thesis are useful in various contexts of QoS management and self-configurations in large-scale cloud-based distributed systems that are inherently complex due to size, diversity, and environment dynamicity

Dagstuhl News January - December 2007

"Dagstuhl News" is a publication edited especially for the members of the Foundation "Informatikzentrum Schloss Dagstuhl" to thank them for their support. The News give a summary of the scientific work being done in Dagstuhl. Each Dagstuhl Seminar is presented by a small abstract describing the contents and scientific highlights of the seminar as well as the perspectives or challenges of the research topic

Automating property-based testing of evolving web services

Web services are the most widely used service technology that drives the Service-Oriented Computing~(SOC) paradigm. As a result, effective testing of web services is getting increasingly important. In this paper, we present a framework and toolset for testing web services and for evolving test code in sync with the evolution of web services. Our approach to testing web services is based on the Erlang programming language and QuviQ QuickCheck, a property-based testing tool written in Erlang, and our support for test code evolution is added to Wrangler, the Erlang refactoring tool. The key components of our system include the automatic generation of initial test code, the inference of web service interface changes between versions, the provision of a number of domain specific refactorings and the automatic generation of refactoring scripts for evolving the test code. Our framework provides users with a powerful and expressive web service testing framework, while minimising users' effort in creating, maintaining and evolving the test model. The framework presented in this paper can be used by both web service providers and consumers, and can be used to test web services written in whatever language; the approach advocated here could also be adopted in other property-based testing frameworks and refactoring tools

An Attribution-Emotion Approach to Political Conflict

The current political system in the United States is marked by extreme levels of partisan hostility and polarization, which has not only resulted in a dysfunctional congress, but also increasing conflict between partisan groups in the general electorate. While political scientists have offered various explanations for this phenomenon, social-psychological theories provide opportunities for empirical investigation of psychological explanatory factors. This study applied Betancourt’s attribution-emotion model of conflict and violence to the ultimate attribution error in order to develop a contemporary and comprehensive understanding of the psychological factors relevant to partisan-based intergroup relations. Five hundred sixty-four participants from various demographic backgrounds were recruited using snowball convenience sampling. When participants read a hypothetical news article involving a congressperson from an opposing political party acting in an antisocial manner, the congressperson’s behavior was attributed as more intentional than when participants read an identical news article involving a congressperson from the same political party. Structural equation modeling also confirmed that attributions of intentionality and controllability influenced social judgments and voting intentions directly, and indirectly through anger. These findings are discussed in terms of implications for studying political polarization and bipartisan cooperation from a social-psychological perspective, as well as contributions to the body of knowledge regarding attribution theory in general, and the ultimate attribution error in specific

Developing a distributed electronic health-record store for India

The DIGHT project is addressing the problem of building a scalable and highly available information store for the Electronic Health Records (EHRs) of the over one billion citizens of India

Does Membership on the UN Security Council Influence IMF Decisions? Evidence from Panel Data

We investigate whether temporary members of the UN Security Council receive favorable treatment from the IMF, using panel data for 191 countries over the period 1951 to 2004. Our results indicate a robust positive relationship between temporary UN Security Council membership and participation in IMF programs, even after accounting for economic and political factors, as well as regional and country effects, and duration dependence. There is also evidence that UNSC membership reduces the number of conditions included in IMF programs. The size of the loan, however, is not affected by UNSC membership.IMF, UN Security Council, voting, aid

Dagstuhl News January - December 2011

"Dagstuhl News" is a publication edited especially for the members of the Foundation "Informatikzentrum Schloss Dagstuhl" to thank them for their support. The News give a summary of the scientific work being done in Dagstuhl. Each Dagstuhl Seminar is presented by a small abstract describing the contents and scientific highlights of the seminar as well as the perspectives or challenges of the research topic

Opinion Change or Differential Turnout: Changing Opinions on the Austin Police Department in a Budget Feedback Process

In 2020 the tragic murder of George Floyd at the hands of law enforcement ignited and intensified nationwide protests, demanding changes in police funding and allocation. This happened during a budgeting feedback exercise where residents of Austin, Texas were invited to share opinions on the budgets of various city service areas, including the Police Department, on an online platform designed by our team. Daily responses increased by a hundredfold and responses registered after the "exogenous shock" overwhelmingly advocated for reducing police funding. This opinion shift far exceeded what we observed in 14 other Participatory Budgeting elections on our Participatory Budgeting Platform, and can't be explained by shifts in the respondent demographics. Analysis of the results from an Austin budgetary feedback exercise in 2021 and a follow-up survey indicates that the opinion shift from 2020 persisted, with the opinion gap on police funding widening. We conclude that there was an actual change of opinion regarding police funding. This study not only sheds light on the enduring impact of the 2020 events and protests on public opinion, but also showcases the value of analysis of clustered opinions as a tool in the evaluation toolkit of survey organizers.Comment: This preprint is an extended version of a previously published conference paper: https://dl.acm.org/doi/10.1145/3551624.355529