# Transparent CoAP Services to IoT Endpoints through ICN Operator Networks +
## 4 Design and Implementation
### Response Processing
Afterwards, cNAP1 forwards all update notification received from the CoAP server to the client 1 and client 2. Similarly, if multiple cNAPs forwards observe requests to the same CoAP server through the same sNAP, sNAP maintains states for those cNAPs. When sNAP receives an update notification from the CoAP server, it forwards the response to all cNAPs using ICN multicast. As a result,

Figure 7: An overview of the group communication. ICN can benefit to CoAP observe by shifting both overhead and complexity from the CoAP endpoints to the ICN network. ### Limitations

The CoAP protocol runs on top of the UDP. There may be exceptional situations where the client and the server become out of sync due to the latency between the change of the resource state and update notification. In addition, CoAP messages with update notification may get lost. Furthermore, the CoAP server may stop sending update notifications, assuming that the client is no longer interested in the resource subscription. To overcome these exceptional situations, an efficient consistency model is required. ## 6 Related Work

During the last decade, many custom proprietary solutions have been developed and deployed in a multitude of the IoT applications. The interoperability of these solutions and integration of several enabling technologies for the evolution of IoT is a great challenge. It is necessary to have a globally unified IoT platform which enables smart devices or things to connect to the Internet, enabling new forms

Figure 8: Message Sequence Diagram of CoAP observer. of communication between humans and things, and between things. The unified IoT platform allows their information and services to be accessible to the standard communication protocols, and sharing information across the physical boundaries of the enterprise. In this context, several research groups in the Internet Engineering Task Force (IETF) are involved in the activity of developing IP-based IoT solutions, such as Low power Wireless Personal Area Networks (6 LoWPAN), Routing Over Low power and Lossy networks (ROLL), CoAP [8]. The IETF community related to the IoT technologies has chosen IPv6 to enable wireless communication due to the key features of IPv6, such as extensibility, universality and stability. The 6 LoWPAN working group has focused on supporting IPv6 to the MAC layer and the physical layer of IEEE 802.15.4. The RoLL working group focuses on the IPv6 routing protocol for lossy and low power networks (LLN). The CoRE working group has developed CoAP to extend the HTTP web services for the LLN. Recent efforts [15; 16] have been performed on proxy based CoAP observe in Wireless Sensor Network (WSNs). However, such IP-based IoT solutions could inherit some of the limitations of IP when dealing with intermittent connectivity and challenged networks [8]. Furthermore, unique identification of objects and the representation and storing of exchanged information in IoT is the most challenging issue. IoT is increasingly relying on data and information rather than on end-to-end communications, which could ultimately lead to the adoption of ICN architecture and principles. Unlike host-centric IP, every piece of information in ICN is identified by a unique, persistent, location-independent name, which is used by an application for accessing information. In addition, ICN provides security to content itself rather than to a communication channel and enables in-network caching. Such features of ICN provide a great promise to the IoT applications. In recent years, several ICN networking architectures have been proposed for Future Internet (e.g., CCN [17], DONA [18], PURSUIT/PSIRP [19], POINT [4], NetInf [20]) with aspiration to efficiently distribute and retrieve content. Various research efforts explore how these architectures can be used in the context of the IoT. At the same time, IPv6 over Low power Wireless Personal Area Networks (6 LoWPAN) [21] is a suggested standard to connect Wireless Sensor Networks (WSNs) to the conventional Internet.