“…Much research has been conducted on resource indexing. Mohamed Y Elmahi et al [9] showed a survey in which resource discovery techniques were classified into different categories: (i) protocol-based, in which protocols are used to find the appropriate device, such as CoAP [10,11], SSDP [12], TRENDY [13], and DNSNA [14], which mainly rely on the domain name system DNS; (ii) architecture-based, where different architectures were discussed, such as centralized [15], distributed [16], and hybrid [17]; (iii) semantic approaches, where devices are represented and grouped depending on their knowledge, such as in [18,19]; (iv) location-based, which focuses on the device discovery in a local area, such as in [20] (smart homes for example), or a remote area for larger environments, such as in [21]; and (v) clustering-based, which builds communities or groups by connecting and linking resources, such as in [22,23].…”