Special Section: Content management and delivery through P2P-based content networks
Multiagent and Grid Systems
Content Networks (CNs) are distributed networks/systems tailored to the management, distribution, discovery and delivery of content to Internet users. They can be considered as an extension and improvement of Content Distribution Networks that emerged previously as an innovative technology that can improve the efficiency of static, time-dependent and rich media content delivery atop large-scale IP-based networks. This special section is dedicated to "Content Management and Delivery through
... ased Content Networks" and contains an invited paper and three papers selected from those presented at the second edition of the UPGRADE-CN workshop, which took place at the ACM/IEEE International Symposium on High Performance Distributed Computing (HPDC 2007), in Monterey Bay, CA, USA, in June 2007. The intent of the UPGRADE-CN workshop is to provide a forum to discuss recent enhancements of Content Networks. Design and implementation of robust and efficient CNs in large-scale computing environments demand for emerging paradigms and software technologies that can improve the performance and extend the functionalities of CNs. For example, multi-agent systems, peer-to-peer (P2P) and Grid computing paradigms and technologies have demonstrated their suitability in supporting the development of contentoriented high-performance systems over large-scale, dynamic and heterogeneous environments. In particular, the best three papers presented at UPGRADE-CN'07 focus on the use of decentralized techniques and protocols, based on the P2P paradigm, and on their efficient adoption for the management and delivery of content in distributed systems. Moreover, the invited paper written by two very active researchers in this field Schiely and Felber focuses on the same topics and, particularly, on P2P-based multimedia content delivery. These four articles were fully peer-reviewed according to the practice of this journal. They offer a very interesting and broad range of views on the actual use of peer-to-peer technologies for content distribution infrastructures. Though this research area is very recent, the selected papers already present an evaluation of real systems or prototypes, discuss architectural aspects of content-oriented systems based on decentralized algorithms, and provide simulation or analytical performance analysis. In the following the main content of these papers is briefly described.