## 2 Related Work  
Conventional solutions related to this paper can be classified into the following two approaches: Data Storage architecture in a wireless sensor network and Service Location protocols in an _ad hoc_ network, as shown in Table 1 [4,5,15,22,34,37,40]. In the early days of sensor networks, the data sensed by sensor nodes were collected by a base station and stored externally. Here, external storage means that the node providing the storage space is located separately from the sensor networks. For users on a wired network seeking to access and use the sensed data, there are no problems associated with the external storage. However, if users are mobile, it is difficult to access the external storage on the wired network. To address this problem, internal storage architectures are proposed. In internal storage, each sensor node saves the sensed data to its local storage. Users obtain the data by directly querying the sensor network. Internal storage architecture can reduce the data collection overhead; however, users have to query the entire network to find the data. Data-centric storage architecture provides fast data dissemination by storing the data on the basis of its name. Data-centric storage is an enhanced version of data-centric routing. A data-centric routing scheme presented firstly is directed diffusion. Directed diffusion uses flooding to advertise the interests from sinks to sources throughout the network [4, 13]. GHT is a type of data-centric storage architecture. GHT is based on the Distributed Hash Table (DHT) that is the results of research efforts on peer-to-peer (P2P) computing networks. GHT was proposed for data-centric storage with geographic information in a sensor network. GHT is a geographic hash table system that hashes keys into geographic points and stores the key-value set at the sensor node closest to the hashed point. GHT uses geographic perimeter routing to identify a packet home node. GHT provides fast access to the data in the sensor nodes but does not take account of availability and scalability. In GHT, only the home node responds to user queries. This causes a concentration of network load and reduces the energy of the home node [6, 22]. _Ad-hoc_ networks and DHT share key characteristics in terms of self organization, decentralization, redundancy requirements, and limited infrastructure. However, node mobility and the continually changing physical topology pose a special challenge to scalability and the design of a DHT for mobile ad-hoc network. Using DHT over wireless sensor networks has gained a lot of attention in the research arena recently. In wireless sensor network, the most important issue in routing is to gather the routed information coming from sensor nodes to the sink node regardless of the identity of the donating node. The problem in this context is to locate efficiently the sensor node, which holds the data item with the minimum number of intermediate nodes to save network energy. A ScatterPastry platform based on Pastry DHT as an overlay routing platform for distributed applications over wireless sensor network using Scatterweb nodes, a real-world wireless sensor platform was proposed in [27]. A topology-based distributed hash tables (T-DHT) as an infrastructure \begin{table}
\begin{tabular}{|p{113.8 pt}|p{113.8 pt}|p{113.8 pt}|} \hline  & **Data Storage Scheme** & **Service Location Protocol** \\ \hline
**Wired Networks** & External Storage & **Service Directory** \\ \hline  & Internal Storage & Flooding \\
**Wireless Networks** & Data Centric Storage & FMMS \\ \cline{2-3}  & GHT & GCLP \\ \hline \end{tabular}
\end{table} 
Table 1: Classification of Data Storage Schemes and Service Location Protocols. for data-centric storage, information processing, and routing in ad hoc and sensor networks was introduced in [28]. T-DHTs do not rely on location information and work even in the presence of voids in the network. Using a virtual coordinate system, we construct a distributed hash table which is strongly oriented to the underlying network topology.