44,004 research outputs found
Middleware-based Database Replication: The Gaps between Theory and Practice
The need for high availability and performance in data management systems has
been fueling a long running interest in database replication from both academia
and industry. However, academic groups often attack replication problems in
isolation, overlooking the need for completeness in their solutions, while
commercial teams take a holistic approach that often misses opportunities for
fundamental innovation. This has created over time a gap between academic
research and industrial practice.
This paper aims to characterize the gap along three axes: performance,
availability, and administration. We build on our own experience developing and
deploying replication systems in commercial and academic settings, as well as
on a large body of prior related work. We sift through representative examples
from the last decade of open-source, academic, and commercial database
replication systems and combine this material with case studies from real
systems deployed at Fortune 500 customers. We propose two agendas, one for
academic research and one for industrial R&D, which we believe can bridge the
gap within 5-10 years. This way, we hope to both motivate and help researchers
in making the theory and practice of middleware-based database replication more
relevant to each other.Comment: 14 pages. Appears in Proc. ACM SIGMOD International Conference on
Management of Data, Vancouver, Canada, June 200
Comparison of German and Czech public procurement system and economic impacts
Purpose: The paper determines the similarities and divergences in the public procurement system in Germany and the Czech Republic. The authors assessed the contribution of the public procurement system in each country’s GDP, identified similarities in the procurement process and how they affect the overall outcome. Divergences in the two countries procurement process and how they affect the outcome were also identified. Design/Methodology/Approach: The research was designed by using secondary research method as it has a wide scope that would be a challenge to achieve using primary research method. Secondary research methods were utilized to generate data which is analyzed by quantitative techniques. Findings: The most notable similarities include the use of e-procurement and the different types of public procurement contracts to enhance transparency and efficiency. Apart from that, there are some divergences where Germany seems to be a little bit more efficient compared to the Czech procurement system. Some of the divergences include higher corruption levels in the Czech Republic system than in Germany and also higher efficiency in terms of processing tender in German system than in the Czech Republic. Practical Implications: The study compares the public procurement systems in Germany and the Czech Republic and underlines potentials and disadvantages of both systems. Originality/Value: The research delivers a legal-economic comparison of German and Czech public procurement systems, including influence and effects made by European Law.peer-reviewe
A scalable reliable instant messenger using the SD Erlang libraries
Erlang has world leading reliability capabilities, but while it scales
extremely well within a single node, distributed Erlang has some
scalability issues. The Scalable Distributed (SD) Erlang libraries
have been designed to address the scalability limitations while
preserving the reliability model, and shown to deliver significant
performance benefits above 40 hosts using some relatively simple
benchmarks.
This paper compares the reliability and scalability of SD Erlang
and distributed Erlang using an Instant Messaging (IM) server
benchmark that is a far more typical Erlang application; a relatively
large and sophisticated benchmark; has throughput as the key
performance metric; and uses non-trivial reliability mechanisms.
We provide a careful reliability evaluation using chaos monkey.
The key performance results consider scenarios with and without
failures on up to 17 server hosts (272 cores). We show that SD
Erlang adds no performance overhead when all nodes are grouped in
a single s_group. However, either adding redundant router nodes in
distributed Erlang applications, or dividing a set of nodes into small
s_groups in SD Erlang applications, have small negative impact.
Both the distributed Erlang and SD Erlang IM tolerate failures and,
up to the failure rates measured, the failures have no impact on
throughput. The IM implementations show that SD Erlang preserves
the distributed Erlang reliability properties and mechanisms
Security oriented e-infrastructures supporting neurological research and clinical trials
The neurological and wider clinical domains stand to gain greatly from the vision of the grid in providing seamless yet secure access to distributed, heterogeneous computational resources and data sets. Whilst a wealth of clinical data exists within local, regional and national healthcare boundaries, access to and usage of these data sets demands that fine grained security is supported and subsequently enforced. This paper explores the security challenges of the e-health domain, focusing in particular on authorization. The context of these explorations is the MRC funded VOTES (Virtual Organisations for Trials and Epidemiological Studies) and the JISC funded GLASS (Glasgow early adoption of Shibboleth project) which are developing Grid infrastructures for clinical trials with case studies in the brain trauma domain
A Taxonomy of Data Grids for Distributed Data Sharing, Management and Processing
Data Grids have been adopted as the platform for scientific communities that
need to share, access, transport, process and manage large data collections
distributed worldwide. They combine high-end computing technologies with
high-performance networking and wide-area storage management techniques. In
this paper, we discuss the key concepts behind Data Grids and compare them with
other data sharing and distribution paradigms such as content delivery
networks, peer-to-peer networks and distributed databases. We then provide
comprehensive taxonomies that cover various aspects of architecture, data
transportation, data replication and resource allocation and scheduling.
Finally, we map the proposed taxonomy to various Data Grid systems not only to
validate the taxonomy but also to identify areas for future exploration.
Through this taxonomy, we aim to categorise existing systems to better
understand their goals and their methodology. This would help evaluate their
applicability for solving similar problems. This taxonomy also provides a "gap
analysis" of this area through which researchers can potentially identify new
issues for investigation. Finally, we hope that the proposed taxonomy and
mapping also helps to provide an easy way for new practitioners to understand
this complex area of research.Comment: 46 pages, 16 figures, Technical Repor
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