Striking a balance between the costs for Web content providers and the quality of service for Web customers. More efficient content delivery over the Web has become an important element of improving Web performance. Content Delivery Networks (CDNs) have been proposed to maximize bandwidth, improve accessibility, and maintain correctness through content replication [11]. With CDNs, content is distributed to cache servers located close to users, resulting in fast, reliable applications and Web services for the users. More specifically, CDNs maintain multiple Points of Presence (PoP) with clusters of (the so-called surrogate) servers that store copies of identical content, such that users ’ requests are satisfied by the most appropriate site (see the figure here). Typically, a CDN topology involves: • A set of surrogate servers (distributed around the world) that cache the origin servers ’ content; • Routers and network elements that deliver

Content Distribution Networks (CDNs) are increasingly being used to disseminate data in today's Internet aiming at reducing the load on the origin server and the traffic on the Internet, and ultimately improving response time to users. In this direction, crucial data management issues should be addressed. A very important issue is the optimal placement of the outsourced content to CDN’s servers. All the approaches developed so far assume the existence of adequate popularity statistics. Such information though, is not always available, or it is extremely volatile, turning such methods problematic. This paper develops a network-adaptive, non-parameterized technique to place the outsourced content to CDN’s servers, which requires no a-priori knowledge of request statistics. We place the outsourced objects to these servers with respect to the network latency that each object produces. Through a detailed simulation environment, using both real and synthetic data, we show that the proposed technique can yield up to 25% reduction in user-perceived latency, compared with other heuristic schemes which have knowledge of the content popularity. 1.

Users tend to use the Internet for “resource-hungry” applications (which involve content such as video, audio on-demand and distributed data) and at the same time, more and more applications (such as e-commerce, elearning etc.) are relying on the Web. In this framework, Content Distribution Networks (CDNs) are increasingly being used to disseminate data in today's Internet, providing a delicate balance between costs for Web content providers and quality of services for Web customers. The growing interest in CDNs is motivated by a common problem across disciplines: how does one reduce the load on the origin server and the traffic on the Internet, and ultimately improve response time to users? In this direction, crucial data management issues should be addressed. A very important issue is the optimal placement of the outsourced content to CDN’s servers. Taking into account that this problem is NP complete, an heuristic method should be developed. All the approaches developed so far either take as criterion the network’s latency or the workload. This paper develops a novel technique to place the outsourced content to CDN’s servers, integrating both the latency and the load. Through a detailed simulation environment, using both real and synthetic data, we show that the proposed method can improve significantly the response time of requests while keeping the CDNs ’ servers ’ load at a very low level. 1.

Abstract. Web caching and replication tune capacity with performance and they have become essential components of the Web. In practice, caching and replication techniques have been applied in proxy servers and Content Distribution Networks (CDNs) respectively. In this paper, we investigate the benefits of integrating caching policies on a CDN ’ s infrastructure. Using a simulation testbed, our results indicate that there is much room for performance improvement in terms of perceived latency, hit ratio and byte hit ratio. Moreover, we show that the combination of caching with replication fortifies CDNs against flash crowd events. 1

In recent years, the World Wide Web, or simply the Web

Caching Web objects has become a common practice towards improving content delivery and users ’ servicing. A Web caching framework is characterized by its cache replacement policy, which identifies the objects (i.e. the elements on a Web page, which include text, graphics, and scripts) to be replaced in a cache upon a request arrival. In this paper, we present a cache replacement algorithm (so-called FRES-CAR), which identifies the objects that should be evicted by considering together three important criteria: object’s frequency, recency and size. Experimentation under synthetic workloads has shown that FRES-CAR achieves higher hit rates when compared with the most popular and existing algorithms. 1.

this article, we describe SliCache's design and present performance results that show significant improvements over other policies in terms of average stretch --- the ratio of an object's access latency to its service time

Abstract not found