Abstract—This paper aims to present a model to achieve complex searching (e.g. Wild card searching, blind searching, full text searching, metadata searching, etc.) over Structured P2P Overlay under dynamic environment. Lack of complex searching over Structured Overlay network and poor resilience due to peer dynamics makes it unsuitable for implementing the P2P systems and thus makes it very unpopular. In implementing the complex searching technique in structured overlay, the query must be processed by each node (peer) locally. This requires query to be efficiently broadcasted to all the nodes. However, broadcasting based algorithms tend to perform badly under highly dynamic environment and also create huge amount of maintenance traffic. This paper proposes a model which combines broadcasting based algorithm with efficient maintenance algorithm, which will reduce the maintenance traffic and increase the search efficiency. Index Terms—Structured overlay, distributed hash table (dht), churn, P2P and broadcast. I. INTRODUCTION P2P system is a distributed network architecture, where interconnected nodes able to self-organize into network topologies with the purpose of resource sharing (e.g. processing power, storage capacity, network link capacity, printers). P2P system support wide area routing, efficient search of data, massive scalability, fault tolerance and redundant storage. P2P system does not depend on the central server for storage, lookup and to meditate between end systems. In P2P nodes behave as client as well as server. On the other hand high-end desktop computing is emerging and P2P system exploits the effective utilization of resources by increasing the utilization of resources at the edge of the internet. So the popularity of P2P system is increasing rapidly. However, the current P2P system is still partially centralized due to the deficiency of the Structured and Unstructured Overlay network. Structured Overlay implements decentralized system with lots of benefits, except its inability to perform complex searching and poor performance in dynamic environment. This paper proposes a conceptual model to achieve complex searching over Structured Overlay under dynamic environment. II. MOTIVATION P2P is emerging as most powerful distributed system, which provide high degree of decentralization, Manuscript received January 10, 2012; revised February 26, 2012. Saiful Khan and Abdullah Gani are with the University of Malaya, Kuala Lumpur, Malaysia (e-mail: saifulkhan@siswa.um.edu.my, abdullah@um.edu.my). self-organization, low cost deployment, organic growth, resilience to faults and attacks and abundance of diverse resources [1]. P2P system has been successfully deployed in sharing and distributing files, streaming media, telephony, application layer multicasting, volunteer computing, etc. Current P2P architecture is based on centralized and hybrid architecture, which is more or less dependent on central server, also the problem lies due to the huge amount of traffic induced that renders the solution un-scalable[2]. The problem of implementing a scalable P2P overlay with no central server has became a challenging problem, and the efforts to solve this problem emerged as Structured Overlay, also called as Distributed Hash Tables (DHTs). Structured P2P Overlay offers fully decentralized system. It provides efficient look-up operations via DHT with complexity of OሺlogNሻ, where N is total number of nodes [3]. Structured Overlay use Consistent Hashing [4] to distribute resources among the nodes across the Overlay Network and achieve efficient load balancing. Structured Overlay only supports exact keyword based simple search, it is not possible to perform complex queries over Structured Overlay [2, 5]. The ease of manageability of P2P system under Dynamic environment is a open question [1]. Structured Overlay network has highly transient nodes which are not well supported by DHT [2] so the searching over Structured Overlay within dynamic environment (Churn) is not efficient [2]. These problems make Structured Overlay very unpopular. III. STATEMENT OF PROBLEM A. Evolution of P2P System Over the years many popular P2P application has been developed based on several architecture. The evolution of P2P architecture according to the degree of centralization can be divided in to three categories (a) Centralized (b) Hybrid and (c) Decentralized [3]. Centralized and Hybrid system do not offer scalability and resilience due to the dependency on server. Therefore, to address the problems of centralized and hybrid systems, decentralized systems have been introduced. The main challenge in decentralized system is searching or lookup of resources. Advanced searching mechanism allows users to effectively locate desired data in a resource efficient manner. Searching in decentralized system is classified in two broad categories- Unstructured Overlay and Structured Overlay [3]. Unstructured Overlay does not impose any well defined network structure and build a random graph, so this kind of system work without any prior knowledge of the topology Model of Complex Searching Over Structured P2P Overlay under Dynamic Environment Saiful Khan and Abdullah Gani International Journal of Information and Electronics Engineering, Vol. 2, No. 2, March 2012 146