Andrei Vancea

CoopSC: A Cooperative Database Caching Architecture

Semantic caching is a technique used for optimizing the evaluation of database queries by caching results of old queries and using them when answering new queries. CoopSC is a cooperative database caching architecture, which extends the classic semantic caching approach by allowing clients to share their local caches in a cooperative matter. Cache entries of all clients are indexed in a distributed data structure constructed on top of a Peer-to-Peer (P2P) overlay network. This distributed index is used for determining those cache entries that can be used for answering a specific query. Thus, this approach decreases the response time of database queries and the amount of data sent by database server, because the server only answers those parts of queries that are not available in the cooperative cache.

Answering Queries Using Cooperative Semantic Caching

Semantic caching is a technique used for optimizing the evaluation of database queries by caching results of previous answered queries at the client side and using the cached results when trying to answer new queries. Before sending a query to the database server, the client first checks, if there are any cached query results that semantically contain the new query or parts of the query. If such cached results are found, they can be used when answering the new query. Otherwise, the query will be answered by the database management server. This paper proposes to extend the general semantic caching mechanism by enabling clients to share their local semantic caches in a cooperative matter. If a particular query cannot be answered using the local cache, the system will verify, if there are other clients, located across the Internet, that are able to answer the query using the data stored in their caches. Such an approach will increase the throughput of database servers, because servers will only receive queries that cannot be answered using the cooperative cache concept.

A proposal for structured diagnosis reporting in echocardiography, using a DICOM compliant environment

Structured diagnosis of echocardiography is useful both for report generation and for indexing and retrieval of echocardiographic images, for the purpose of database generation. This paper presents a proposal for structured diagnosis reporting in echocardiography, dealing with both numerical and nonnumerical findings. For each cardiac disease, an exhaustive description of the morphological, functional and homodynamic changes related to the various cardiac structures was attempted. A database of concepts, contexts and templates for echocardiographic diagnosis reporting was implemented. This database will be used for DICOM structured reporting generation and the implementation of structured reports databases.

Generic proxies: supporting data integration inside the database

Existing approaches to data integration generally propose building a layer on top of database systems to perform the necessary data transformations and manage data consistency. We show how support for the integration of heterogeneous data sources can instead be built into a database system through the introduction of a generic proxy concept.

Optimization of flow record handling by applying a decentralized cooperative semantic caching approach

Analyzing IP traffic is an important task on which many network management applications are based. Ciscos Net-Flow system is one of the most widely used approaches for accomplishing a measurement and collection of flow records, needed to analyze traffic. Working with NetFlow means to involve very large amounts of data, while the collection, storing, and enabling of analyzers demands the access to this data in the fastest possible manner. Thus, this paper addresses this challenging task and presents a newly developed cooperative caching approach (CoopSC) that can be used to improve access time and data transfers between the centralized flow-based storage solution and those analyzers in operation. Such an improvement can positively influence the performance of flow-based solutions. Therefore, this approach NMCoopSC (Network Management CoopSC) has been validated, and experiments show that NMCoopSC improves the performance of NetFlow-based range queries.

The Design of a Single Funding Point Charging Architecture

Most federations across the world apply Single Sign-On (SSO) Authentication and Authorization Infrastructure (AAI) platforms. Thus, access to services offered by organizations, which belong to such a federation, can be granted to their users independent of their current location. The increasing demand to charge users for those service usages lead organizations to establish various charging mechanisms. However, until today the majority of organizations is using service-dependent solutions to perform charging. This policy absorbs the utility of an SSO system, since users still have to monitor and control each credit account separately. Therefore, the approach proposed defines an extension to SSO platforms, which is consolidated, non dispersed and service-independent. A Single Funding Point Charging Architecture (SFP-CA) allows users to settle payments using funds from the same credit account, for any type of service they use inside their federation.

Attacks on internet names

The Domain Name System (DNS) determines the major component in todays Internet, as it maps memorable names, such as www.uzh.ch into routable Internet Protocol addresses, such as 136.105.200.244. Since the early days of trusted hosts in the Internet have passed, the potential of severe attacks on DNS has reached a level of higher risk, e.g. DNS Spoofing or Cache Poisoning, such that work on DNS Security Extensions (DNSSEC) did commence. However, the deployment of DNSSEC has not reached that large attention needed to safeguard fully future Internet communications for all services.