“…Despite the fact that availability and rapidity of access are guaranteed with systems using centralized directories (Chen et al, 2006), (Hwang et al, 2007), these systems suffer from problems like SPOF and bottleneck as the number of registration and discovery queries increases. To address the scalability issues related to centralized architectures, solutions have been proposed dealing mainly with decentralization of directory nodes (Kang et al, 2007), (Xu et al, 2008), (Gao and Steenkiste, 2004), (Kim et al, 2005), (Liu et al, 2002). Kim et al proposed a fully distributed architecture by electing for every service requestor or provider, K volunteer nodes (directory nodes) to which publication and discovery queries are sent (Kim et al, 2005).…”