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With the rapidly growing number of internet of things (IoT) devices connected to the internet, accessing the available internet services has become more significant to support the operation of these devices. However, according to the limited resources available on IoT devices, accessing these services can be exhaustive, which has encouraged the proposal of new light-weight protocols, e.g. the MQ Telemetry Transport (MQTT) and the Constrained Application Protocol (CoAP). Accordingly, a new system is proposed in this paper to proxy all internet services using their requirements and protocols to the IoT devices using these light-weight protocols. The proposed system has been able to significantly reduce the resources consumption on IoT devices, such as the energy, memory, time and network bandwidth. Accordingly, this system can significantly improve the efficiency of these devices, so that IoT devices can achieve more tasks using the same resources, or the same tasks using less resources.

Constrained Application Protocol (CoAP) is a communication protocol at application layer in the Internet of things (IoT). It employs NSTART parameter to maintain outstanding parallel connections toward individual destinations for data transfer. In the existing implementation of CoAP, the value for NSTART is defined statically. Where the higher values of this parameter up to a threshold give better throughput in moderate traffic, the lower values for the same control the congestion in overload situations. In overload situations, higher values of NSTART result in increased overhead and thereby perform poorly in terms of throughput. The static nature of the parameter and its relevant performance issues demand to manage NSTART dynamically in CoAP. In this work, we propose an algorithm to adjust the value of NSTART dynamically based on the congestion in the network. The proposed approach is an attempt to make the client free from managing NSTART dynamically. For the proof of concept, we implement and run simulations on Cooja mote at IoT/FIT-Lab testbed and Californium CoAP client. The results show 15% improvement in throughput, 15% reduction in average exchange duration, and 48% reduction in average number of retries (average taken of three scenarios) by proposed approach in comparison with the best case of CoCoA (NSTART = 4).

A great number of Internet of things (IoT) applications rely on real-time communication (RTC) mechanisms for transmission of media. Essentially, applications analyze and process media to make decisions that typically affect actuation and control of embedded devices. IoT networks, however, are subjected to constrains that limit the computational and resource complexity of all entities involved. This is particularly critical when considering the traditional RTC protocols like real-time protocol (RTP) that was not designed to perform well in the context of low-power lossy networks (LLNs). This paper focuses on alternatives to media transport in IoT networks. Specially, constrained application protocol (CoAP) and the message queuing telemetry transport sensor network protocol (MQTT-SN) are presented as valid technologies for media propagation in LLNs. The paper models and compares CoAP, RTP, and MQTT-SN to determine the most efficient scenario for audio, speech, and video transmission.

The Internet Engineering Task Force recommends the use of a group of well-defined protocols to support Internet of ThingsLow-Power Low-Rate Networks (LLNs). These mechanisms range from physical and media access layer technologies like IEEE 802.15.4 and Bluetooth Low Energy to session and application layer protocols like the Constrained Application Protocol (CoAP). Specifically, CoAP provides, by means of two different modes of operation, great flexibility to deal with the power requirements of wireless LLNs. One mode supports fire-and-forget packet transmission while the other, through retransmissions, guarantees delivery. The trade-off between these mechanisms is the exchange of high packet loss by high latency and increased power consumption. In this paper we introduce an algorithm that dynamically predicts these parameters, by means of supervised learning, based on network conditions that result from Maximum Likelihood Estimation. This prediction, in turns, can be used for on-the-fly CoAP mode selection that accomplishes quality goals.

One of the noticeable characteristics of the Internet-of-Things (IoT) devices is that they are resource-constrained, which makes them incompatible with the standard Internet protocols, e.g., HTTP. Nevertheless, IoT offers the Constrained Application Protocol (CoAP) as an alternative protocol for IoT devices where it is considered to be lightweight in regard to power consumption, network traffic, and so on. The main challenges associated with CoAP, however, still remain unsolved where most of the state-of-the-art approaches group servers manually and return the exact matches only. To address these issues, we propose a novel Semantically Enhanced CoAP Gateway (SECoG) for complex service mashups. SECoG enables users to create a simple or complex CoAP service mashup via a single HTTP request. Furthermore, a prototype implementation of SECoG was deployed on a real-world testbed to evaluate the proposed approach in terms of the reliability, execution time, network traffic, and accuracy.

Internet of Things (IoT) refers to uniquely identifiable entities. Its vision is the world of connected objects. Due to its connected nature the data produced by IoT is being used for different purposes. Since IoT generates huge amount of data, we need some scalable storage to store and compute the data sensed from the sensors. To overcome this issue, we need the integration of cloud and IoT, so that the data might be stored and computed in a scalable environment. Harmonization of IoT in Cloud might be a novel solution in this regard. IoT devices will interact with each other using Constrained Application Protocol (CoAP). In this paper, we have implemented harmonizing IoT in Cloud. We have used CoAP to get things connected to each other through the Internet. For the implementation we have used two sensors, fire detector and the sensor attached with the door which is responsible for opening it. Thus our implementation will be storing and retrieving the sensed data from the cloud. We have also compared our implementation with different parameters. The comparison shows that our implementation significantly improves the performance compared to the existing system.

Many IoT deployments rely on an access network that is characterized by densely distributed power constrained devices. Power restrictions, in turns, lead to transmission rate limitations and increased bit errors responsible of network packet loss. Among the many technologies available to deal with these issues, the Constrained Application Protocol (CoAP) introduces an efficient session layer mechanism that provides, as the Hypertext Transport Protocol (HTTP), Representational State Transfer (REST) functionality. However, as opposed to HTTP that relies mostly on the transmission of TCP segments, CoAP has been standardized to support both UDP and TCP transport layers. In IoT scenarios, the CoAP transport protocol selection combined with network conditions can greatly affect overall application Quality of Service (QoS). Under HTTP, the Quick UDP Internet Connection (QUIC) protocol has been introduced as a hybrid alternative to TCP. In this paper, we analyze, model and compare the use of QUIC transport against that of both UDP and TCP in the context of CoAP traffic.

Sensing devices are expected to interconnect over large geographical areas and federations of wireless sensor networks are expected in a near future. In such environments a critical issue is how to discover the resources available at devices in a scalable manner. For this purpose, a Constrained Application Protocol (CoAP) Usage for REsource LOcation And Discovery (RELOAD), a generic self-organizing Peer-to-Peer (P2P) overlay network service, has been defined to be used as a lookup service, to store available device resources and as a cache for sensor data. Each P2P resource, at the RELOAD/CoAP overlay, includes references to device resources, hosted at one or more constrained nodes, but no provision is made for the insertion of bindings/references to P2P resources already available at the P2P overlay network. Such feature would increase the efficiency and consistency of storage, avoiding duplicate references, a very relevant issue for future IoT applications relying on the federation of wireless sensor networks. In this article an extension to the service provided by CoAP Usage is proposed so that resource bindings can be managed. Two binding models, and a heuristic algorithm for their implementation, are proposed. Results show that such models lead to a better resource organization, reducing the number of sensor resource entries and/or fetches to the P2P overlay. FCT (Foundation for Science and Technology) from Portugal within CEOT (Center for Electronic, Optoelectronic and Telecommunications) [UID/MULTI/00631/2013] info:eu-repo/semantics/publishedVersion

The Semantic Web of Things (SWoT) integrates knowledge representation and reasoning techniques originally devised for the Semantic Web into Internet of Things architectures, in order to provide more advanced service/resource management and discovery. This paper proposes a novel SWoT framework, enabling collaborative discovery of sensors and actuators in pervasive contexts. It is based on a backward-compatible extension of the Constrained Application Protocol (CoAP), supporting advanced semantic matchmaking via non-standard inference services. The proposed mobile agent is able to discover devices and share smartphone embedded sensors in a peer-to-peer fashion. Efficient data stream mining is also integrated to analyze raw data gathered from the environment and detect high-level events, annotating them with machine-understandable metadata. Finally, a case study about cooperative environmental risk monitoring and prevention in Hybrid Sensor and Vehicular Networks is presented. Experimental performance results on a real testbed assess the approach.

Over the last few years, the Internet of Things (IoT) has grown in protocols, implementations and use cases. In terms of communication protocols, the Constrained Application Protocol (CoAP) prevails among the rest, such as MQ Telemetry Transport (MQTT) or Advanced Message Queuing Protocol (AMQP). This protocol is lightweight and capable of running in resource constrained devices and networks and can be securized using Datagram Transport Layer Security (DTLS). Having a secure channel of communication is important in IoT environments, since IoT devices affect the physical world and exchange personal private data. There exist many implementations of CoAP, each of these with its own particular features and requirements. Therefore, it is important to choose the CoAP implementation that suits better to the specific requirements of each application. This paper presents a feature and empirical comparison of several open source CoAP implementations and also analyzes the security libraries they use. First of all, it surveys current CoAP implementations, and compares them in terms of built-in core, extensions, target platform, programming language and interoperability. Then, a theoretical analysis of the security libraries is provided. Finally, it analyzes CoAP libraries’ performance in terms of latency, memory and CPU consumption in a real testbed deployed in an industrial scenario, in order to help in adopting a decision criterion for similar deployments.

This paper presents the Dynamic Adaptive Streaming over CoAP (DASCo), a solution for adaptive media streaming in the Internet of Things (IoT) environment. DASCo combines DASH (Dynamic Adaptive Streaming over HTTP), the widespread open standard for HTTP-compliant streaming, with Constrained Application Protocol (CoAP), the vendor-independent web transfer protocol designed for resource-constrained devices. The proposed solution uses DASH formats and mechanisms to make media segments available for consumers, and exploits CoAP to deliver media segments to consumers’ applications. Consequently, the DASCo player offers native interoperability with IoT devices that are accessed via CoAP, thus it allows easy access to data collected by different sensors in order to enrich the multimedia services. In the paper we present an overview of constraints of default CoAP implementation with respect to media streaming, and propose guidelines for development of adaptive streaming service over CoAP. Moreover, we discuss the features of CoAP that can be investigated when designing an efficient adaptive algorithm for DASCo. Presented experimental results show poor performance of DASCo when default values of CoAP transmission parameters have been used. However, adjusting the parameters according to the network conditions considerably improves DASCo efficiency. Furthermore, in bad network conditions the enhanced DASCo is characterized by a more stable download rate compared to DASH. This feature is important in the context of dynamic media adaptation, since it allows an adaptation algorithm to better fit media bit rate with download conditions.

Wireless network devices are used for the Internet of Things in a variety of applications, and although the IoT has many benefits, there are some security issues in this area. Hacking tools that are widely used in wireless communication enable the attacker to export the information stored in the device memory. Devices within the IoT should not allow this information to be accessed without an authentication. In this paper, we propose an efficient device authentication protocol without certification authority for the Internet of Things. Compared to the existing Constrained Application Protocol, the proposed protocol increases efficiency by minimizing the number of message exchanges. Since our protocol is based on a keyed hash algorithm, the Certificate of Authority is not required. Experimental results show that the proposed authentication protocol improves the security level and reduces the resource consumption of devices.

Web of Things (WoT) makes it possible to connect tremendous embedded devices to web in Representational State Transfer (REST) style. Some lightweight RESTful protocols have been proposed for the WoT to replace the HTTP protocol running on embedded devices. However, they keep the principal characteristic of the REST style. In particular, they support one-to-one requests in the client–server mode by four standard RESTful methods (GET, PUT, POST, and DELETE). This characteristic is however inconsistent with the practical networks of embedded devices, which typically perform a group operation. In order to meet the requirement of group communication in the WoT, we propose a resource-oriented protocol called SeaHttp to extend the REST style by introducing two new methods, namely BRANCH and COMBINE respectively. SeaHttp supports parallel processing of group requests by means of splitting and merging them. In addition SeaHttp adds spatiotemporal attributes to the standard URI for naming a dynamic request group of physical resource. Experimental results show that SeaHttp can reduce average energy consumption of group communication in the WoT by 18.5%, compared with the Constrained Application Protocol (CoAP).

With the advent of IPv6, the world is getting ready to incorporate smart objects to the current Internet to realize the idea of Internet of Things. The biggest challenge faced is the resource constraint of the smart objects to directly utilize the existing standard protocols and applications. A number of initiatives are currently witnessed to resolve this situation. One of such initiatives is the introduction of Constrained Application Protocol. This protocol is developed to fit in the resource-constrained smart object with the ability to easily translate to the prominent representational state transfer implementation, hypertext transfer protocol (and vice versa). The protocol has several optional extensions, one of them being, resource observation. With resource observation, a client may ask a server to be notified every state change of the resource. However, in many applications, all state changes are not significant enough for the clients. Therefore, the client will have to decide whether to use a value sent by a server or not. This results in wastage of the already constrained resources (bandwidth, processing power,…). In this paper, we introduced an alternative to the normal resource observation function, named Conditional Observation, where clients tell the servers the criteria for notification. We evaluated the power consumption and number of packets transmitted between clients and servers by using different network sizes and number of servers. In all cases, we found out that the existing observe option results in excessive number of packets (most of them unimportant for the client) and higher power consumption. We also made an extensive theoretical evaluation of the two approaches which give consistent result with the results we got from experimentation.