Wojtek Sylwestrzak

A distributed WWW cache

Abstract The deployment of large caches and of caches at high levels in the hierarchy demonstrates the need for more efficient and scalable solutions in the area of caching software design. This article describes a design of a distributed web cache. The design is based on a functional decomposition — components of the cluster are not monolithic caches. The distributed cache utilizes filtering algorithms for the placement of objects in main memory caches. A two-level routing scheme enables load sharing among the components by the means of routing arrays. The distributed cache does not have a single point of failure.

A filtering algorithm for Web caches

Abstract Most proxies use an aggressive caching policy: they cache all objects that can be cached. This policy has the advantage that given sufficient disk space it maximizes the hit rate. However, maximizing hit rate does not necessarily maximize proxy cache performance. Cache administrators often report that disks are the main bottleneck of busy cache servers. Overloaded disks increase service time, which results in overall lower performance of the proxy. The high disk load is caused mainly by writing all cacheable objects to disk. As an alternative caching policy, we propose the use of filtering algorithms. These algorithms filter out from the request stream objects that are likely to be accessed in the future. Only these objects are cached, others are forwarded to clients without making a local copy. We present a filtering algorithm that bases on sharing of origin servers among clients. We show that our approach gives a significantly lower disk load while maintaining high hit rates.

Infrastructural Approach to Modern Digital Library and Repository Management Systems

Traditional DLM Systems were usually implemented in the form of an either monolithic or distributed applications. The paper presents a modern approach, where a modular environment provides an infrastructure of components to build DMLS applications upon. A case study of an open Synat Software Platform is presented, together with its sample applications, and the key benefits of the approach are discussed.

YADDA2: assemble your own digital library application from LEGO bricks

YADDA2 is an open software platform which facilitates creation of digital library applications. It consists of versatile building blocks providing, among others: storage, relational and full-text indexing, process management, and asynchronous communication. Its loosely-coupled service-oriented architecture enables deployment of highly-scalable, distributed systems.

ThePrimate® - HPW and NNs Ecosystem based on DDC⁺ classification oriented to singularities

ThePrimate® is an HPW [High Power Web] platform which allows dynamic classification of digital resources from european databases - including those coming from Europeana - the easy retrieval of data, reuse of items and methods based on enhanced tools, a deeper layer of attached information. The platform is strictly connected to Filamento®, an original IoT [Internet of Things] framework, determining a lattice of precisely identifiable talking objects in the real environment, related as digital items in a Network of networks (NNs). The structure of graph is founded on the keys of “affinity” and “proximity”, it is modifiable according to singular needs and reusable to many different issues. The circulation of resources among the users is reinforced by an original economic paradigm based on a virtual currency, determining self- sustaining.