Quantification is the estimation of class proportions in a dataset. It is important in a wide range of fields, such as the proportion of positive reviews in sentiment analysis or the age and gender distribution of respondents in market research.

The national grid service (NGS) provides access to compute and data resources for UK academics. Currently users are required to have an X.509 certificate from the UK e-science certification authority (CA) or one of its international peers to access the NGS. The CA must satisfy the requirements for internationally agreed assurance levels and some users find the processes of obtaining and managing certificates difficult. Shibboleth, an implementation of federation identity based authentication, has been widely deployed in academic environments in the UK. The SARoNGS project, was proposed to integrate the Shibboleth and X.509 based infrastructures, to deliver a production level service for accessing the NGS in a user friendly way. This paper describes an architecture by which users are authenticated by the UK access management federation to acquire low assurance credentials to access Grid resources on the NGS. Users can login to NGS resources via NGS portal, using their local institution's authentication system.

This paper presents work undertaken to integrate the future UK national Shibboleth infrastructure with the UK's National Grid Service (NGS). Our work, ShibGrid, provides both transparent authentication for portal based Grid access and a credential transformation service for users of other Grid access methods. The ShibGrid support for portal-based transparent Grid authentication is provided as a set of standards-based drop-in modules which can be used with any project portal as well as the NGS project in which they are initially deployed. The ShibGrid architecture requires no changes to the UK national Shibboleth authentication infrastructure or the NGS security infrastructure and provides access for users both with and without UK e-Science certificates. In addition to presenting both the architecture of Shib- Grid and its implementation, we additionally place the ShibGrid project within the context of other efforts to integrate Shibboleth with Grids.

The high bandwidth and low latency of the modern internet has made possible the deployment of distributed computing platforms. The XenoServe platform provides a distributed computing platform open to all and presents three major new challenges for resource discovery: Firstly, network location is key for effectively provisioning services, to mitigate against high-latency, high-load or component failure. Secondly, many services require a presence on several servers, with inter-related requirements. Finally, as the platform is open with respect to users and servers, large numbers of queries and updates are expected.To address these requirements we introduce and evaluate XenoSearch, a new distributed service for selecting the machines to host components of multi-node distributed systems and which is uniquely able to express and efficiently answer complex queries with inter-related location constraints. We demonstrate that XenoSearch represents a trade-off between accuracy and query time which avoids exhaustive search and supports multiple resources. In addition the performance of the algorithm and the quality of its server selections is investigated and the performance of the distributed service shown to be invariant as the number of nodes or items indexed increases.

We describe the XenoSearch system for performing expressive resource discovery searches in a distributed environment. We represent server meta-data, such as their locations and facilities, as points in a multi-dimensional space and then express queries as predicates over these points. Each XenoSearch node holds a portion of this space and the key goal of XenoSearch is to direct queries to those nodes containing the meta-data of matching XenoServers. Communication between these XenoSearch nodes is based on the self-organizing Pastry peer-to-peer routing substrate. Our initial performance evaluation on a wide-area prototype shows that queries are only a factor of 3 to 5 times longer than basic Pastry routing, while supporting multi-dimensional searches of arbitrary shapes.