Facilitating sensor deployment, discovery and resource access using embedded web services

Smart embedded objects such as sensors and actuators will become an important part of the Internet of Things. With recent technologies, it has now become possible to deploy a sensor network and interconnect it with IPv6 Internet. However, several manual configuration steps are still needed to integrate a sensor network within an existing networking environment. In this paper we describe a novel self-organization solution to facilitate the deployment of sensor networks and enable the discovery, end-to-end connectivity and service usage of these newly deployed sensor nodes. The proposed approach makes use of embedded web service technology, i.e. the IETF Constrained Application Protocol (CoAP). Automatic hierarchical discovery of CoAP servers is one of the key features, resulting in a browsable hierarchy of CoAP servers, up to the level of the sensor resources, which can be accessed both over CoAP and HTTP and through the use of either DNS names or IPv6 addresses. To demonstrate the feasibility of our approach we have implemented the solution and deployed it on a test setup, which is publicly accessible to everyone.The research leading to these results has received funding from the European Union's Seventh Framework Programme (FP7/2007-2013) under grant agreement n°258885 (SPITFIRE project) and from the IBBT ICON project GreenWeCan

Integrated sensor and management system for urban waste water networks and prevention of critical situations

[EN] This work describes the design and implementation of improvements to the monitoring system of an urban waste water network, resulting in more efficient management of the system. To achieve this objective, the latest communications technology has been incorporated into heterogeneous networks and sensor systems. This technology includes mobile systems, which take measurements and transmit images in real time, an intelligent platform for processing and management of variables, and the implementation of wireless sensor networks (WSNs) designed with specific protocols and tools that allow the rapid deployment of the network and allow measurements to be taken in emergency situations. The sensors in this type of installation are extremely important for the management of the system as they allow us to collect information and make decisions with sufficient time to deal effectively with critical situations such as flooding or overloading of the waste water system, or environmental problems such as dumping of possible pollutants, as well as to make the best use of the water cycle. The solution presented here automates large portions of the processes, minimizing the possibility of human error, and increasing the frequency and accuracy of the measurements taken, ensuring a robust communication system covering all the elements involved to provide ubiquity of information, and finally gives an application layer to manage the system and receive alerts. © 2011 Elsevier Ltd.This work was supported by the MCyT (Spanish Ministry of Science and Technology) under the projects PET2007-0316 and TIN2010-21378-C02-02, which are partially funded by ERDF (European Regional Development Fund).Sempere Paya, VM.; Santonja Climent, S. (2012). Integrated sensor and management system for urban waste water networks and prevention of critical situations. Computers, Environment and Urban Systems. 36(1):65-80. https://doi.org/10.1016/j.compenvurbsys.2011.07.001S658036

Enabling the web of things: facilitating deployment, discovery and resource access to IoT objects using embedded web services

Today, the IETF Constrained Application Protocol (CoAP) is being standardised. CoAP takes the internet of things to the next level: it enables the implementation of RESTful web services on embedded devices, thus enabling the construction of an easily accessible web of things. However, before tiny objects can make themselves available through embedded web services, several manual configuration steps are still needed to integrate a sensor network within an existing networking environment. In this paper, we describe a novel self-organisation solution to facilitate the deployment of constrained networks and enable the discovery, end-to-end connectivity and service usage of these newly deployed sensor nodes. By using embedded web service technology, the need of other protocols on these resource constrained devices is avoided. It allows automatic hierarchical discovery of CoAP servers, resulting in a browsable hierarchy of CoAP servers, which can be accessed both over CoAP and hypertext transfer protocol.The research leading to these results has received funding from the European Union’s Seventh Framework Programme (FP7/2007-2013) under grant agreement no. 258885 (SPITFIRE project), from the iMinds ICON project O’CareCloudS, from a VLIR PhD grant to Isam Ishaq and through an FWO pos tdoc research grant for Eli De Poorter

Enabling the web of things: facilitating deployment, discovery and resource access to IoT objects using embedded web services

Today, the IETF Constrained Application Protocol (CoAP) is being standardised. CoAP takes the internet of things to the next level: it enables the implementation of RESTful web services on embedded devices, thus enabling the construction of an easily accessible web of things. However, before tiny objects can make themselves available through embedded web services, several manual configuration steps are still needed to integrate a sensor network within an existing networking environment. In this paper, we describe a novel self-organisation solution to facilitate the deployment of constrained networks and enable the discovery, end-to-end connectivity and service usage of these newly deployed sensor nodes. By using embedded web service technology, the need of other protocols on these resource constrained devices is avoided. It allows automatic hierarchical discovery of CoAP servers, resulting in a browsable hierarchy of CoAP servers, which can be accessed both over CoAP and hypertext transfer protocol

Discovery and Group Communication for Constrained Internet of Things Devices using the Constrained Application Protocol

The ubiquitous Internet is rapidly spreading to new domains. This expansion of the Internet is comparable in scale to the spread of the Internet in the ’90s. The resulting Internet is now commonly referred to as the Internet of Things (IoT) and is expected to connect about 50 billion devices by the year 2020. This means that in just five years from the time of writing this PhD the number of interconnected devices will exceed the number of humans by sevenfold. It is further expected that the majority of these IoT devices will be resource constrained embedded devices such as sensors and actuators. Sensors collect information about the physical world and inject this information into the virtual world. Next processing and reasoning can occur and decisions can be taken to enact upon the physical world by injecting feedback to actuators. The integration of embedded devices into the Internet introduces new challenges, since many of the existing Internet technologies and protocols were not designed for this class of constrained devices. These devices are typically optimized for low cost and power consumption and thus have very limited power, memory, and processing resources and have long sleep periods. The networks formed by these embedded devices are also constrained and have different characteristics than those typical in todays Internet. These constrained networks have high packet loss, low throughput, frequent topology changes and small useful payload sizes. They are referred to as LLN. Therefore, it is in most cases unfeasible to run standard Internet protocols on this class of constrained devices and/or LLNs. New or adapted protocols that take into consideration the capabilities of the constrained devices and the characteristics of LLNs, are required. In the past few years, there were many efforts to enable the extension of the Internet technologies to constrained devices. Initially, most of these efforts were focusing on the networking layer. However, the expansion of the Internet in the 90s was not due to introducing new or better networking protocols. It was a result of introducing the World Wide Web (WWW), which made it easy to integrate services and applications. One of the essential technologies underpinning the WWW was the Hypertext Transfer Protocol (HTTP). Today, HTTP has become a key protocol in the realization of scalable web services building around the Representational State Transfer (REST) paradigm. The REST architectural style enables the realization of scalable and well-performing services using uniform and simple interfaces. The availability of an embedded counterpart of HTTP and the REST architecture could boost the uptake of the IoT. Therefore, more recently, work started to allow the integration of constrained devices in the Internet at the service level. The Internet Engineering Task Force (IETF) Constrained RESTful Environments (CoRE) working group has realized the REST architecture in a suitable form for the most constrained nodes and networks. To that end the Constrained Application Protocol (CoAP) was introduced, a specialized RESTful web transfer protocol for use with constrained networks and nodes. CoAP realizes a subset of the REST mechanisms offered by HTTP, but is optimized for Machine-to-Machine (M2M) applications. This PhD research builds upon CoAP to enable a better integration of constrained devices in the IoT and examines proposed CoAP solutions theoretically and experimentally proposing alternatives when appropriate. The first part of this PhD proposes a mechanism that facilitates the deployment of sensor networks and enables the discovery, end-to-end connectivity and service usage of newly deployed sensor nodes. The proposed approach makes use of CoAP and combines it with Domain Name System (DNS) in order to enable the use of userfriendly Fully Qualified Domain Names (FQDNs) for addressing sensor nodes. It includes the automatic discovery of sensors and sensor gateways and the translation of HTTP to CoAP, thus making the sensor resources globally discoverable and accessible from any Internet-connected client using either IPv6 addresses or DNS names both via HTTP or CoAP. As such, the proposed approach provides a feasible and flexible solution to achieve hierarchical self-organization with a minimum of pre-configuration. By doing so we minimize costly human interventions and eliminate the need for introducing new protocols dedicated for the discovery and organization of resources. This reduces both cost and the implementation footprint on the constrained devices. The second, larger, part of this PhD focuses on using CoAP to realize communication with groups of resources. In many IoT application domains, sensors or actuators need to be addressed as groups rather than individually, since individual resources might not be sufficient or useful. A simple example is that all lights in a room should go on or off as a result of the user toggling the light switch. As not all IoT applications may need group communication, the CoRE working group did not include it in the base CoAP specification. This way the base protocol is kept as efficient and as simple as possible so it would run on even the most constrained devices. Group communication and other features that might not be needed by all devices are standardized in a set of optional separate extensions. We first examined the proposed CoAP extension for group communication, which utilizes Internet Protocol version 6 (IPv6) multicasts. We highlight its strengths and weaknesses and propose our own complementary solution that uses unicast to realize group communication. Our solution offers capabilities beyond simple group communication. For example, we provide a validation mechanism that performs several checks on the group members, to make sure that combining them together is possible. We also allow the client to request that results of the individual members are processed before they are sent to the client. For example, the client can request to obtain only the maximum value of all individual members. Another important optional extension to CoAP allows clients to continuously observe resources by registering their interest in receiving notifications from CoAP servers once there are changes to the values of the observed resources. By using this publish/subscribe mechanism the client does not need to continuously poll the resource to find out whether it has changed its value. This typically leads to more efficient communication patterns that preserve valuable device and LLN resources. Unfortunately CoAP observe does not work together with the CoAP group communication extension, since the observe extension assumes unicast communication while the group communication extension only support multicast communication. In this PhD we propose to extend our own group communication solution to offer group observation capabilities. By combining group observation with group processing features, it becomes possible to notify the client only about certain changes to the observed group (e.g., the maximum value of all group members has changed). Acknowledging that the use of multicast as well as unicast has strengths and weaknesses we propose to extend our unicast based solution with certain multicast features. By doing so we try to combine the strengths of both approaches to obtain a better overall group communication that is flexible and that can be tailored according to the use case needs. Together, the proposed mechanisms represent a powerful and comprehensive solution to the challenging problem of group communication with constrained devices. We have evaluated the solutions proposed in this PhD extensively and in a variety of forms. Where possible, we have derived theoretical models and have conducted numerous simulations to validate them. We have also experimentally evaluated those solutions and compared them with other proposed solutions using a small demo box and later on two large scale wireless sensor testbeds and under different test conditions. The first testbed is located in a large, shielded room, which allows testing under controlled environments. The second testbed is located inside an operational office building and thus allows testing under normal operation conditions. Those tests revealed performance issues and some other problems. We have provided some solutions and suggestions for tackling those problems. Apart from the main contributions, two other relevant outcomes of this PhD are described in the appendices. In the first appendix we review the most important IETF standardization efforts related to the IoT and show that with the introduction of CoAP a complete set of standard protocols has become available to cover the complete networking stack and thus making the step from the IoT into the Web of Things (WoT). Using only standard protocols makes it possible to integrate devices from various vendors into one bigWoT accessible to humans and machines alike. In the second appendix, we provide an alternative solution for grouping constrained devices by using virtualization techniques. Our approach focuses on the objects, both resource-constrained and non-constrained, that need to cooperate by integrating them into a secured virtual network, named an Internet of Things Virtual Network or IoT-VN. Inside this IoT-VN full end-to-end communication can take place through the use of protocols that take the limitations of the most resource-constrained devices into account. We describe how this concept maps to several generic use cases and, as such, can constitute a valid alternative approach for supporting selected applications

An infrastructure for service oriented sensor networks

Emerging wireless technologies enable ubiquitous access to networked services. Integration of wireless technologies into sensor and actuator nodes provides the means for remote access and control. However, ad hoc deployment of nodes complicates the process of finding, selecting and sing these in a meaningful way. The use of a service discovery framework enables nodes to present themselves and the resources they hold. In this paper, we review the applicability of a number of well-known service discovery protocols in the context of networked nodes. Multicast DNS and Service Discovery (mDNS-SD) stands out with its auto-configuration, distributed architecture,sharing of resources, and wide area access. For wireless battery operated and resource constrained nodes, we seek to integrate SD and power management techniques. This leads us to a standards based infrastructure for service oriented sensor networks where; 1) nodes collaborate in an ad hoc fashion by using SD techniques to discover (and announce) resources locally and over the public Internet, 2) nodes preserve power through aggressive utilization of low power (sleep) modes, while yet being reachable for clients according to defined schemas, and 3) clients may access and configure nodes, and (if possible) access sleeping nodes by implicit wake-up procedures. To demonstrate the proposed infrastructure a complete experimental setup has been devised featuring; Bluetooth enabled nodes, lightweight implementations of mDNS-SD and communication stacks, Internet access through cellular/wired gateways, together with a public DNS server. Our experiments verify that mDNS-SD can be effectively deployed on small wireless sensor and actuator nodes and provides the basis of a service oriented infrastructure for low power sensor networks.Validerad; 2006; 20061206 (jench)</p

An infrastructure for service oriented sensor networks

Emerging wireless technologies enable ubiquitous access to networked services. Integration of wireless technologies into sensor and actuator nodes provides the means for remote access and control. However, ad hoc deployment of nodes complicates the process of finding, selecting and sing these in a meaningful way. The use of a service discovery framework enables nodes to present themselves and the resources they hold. In this paper, we review the applicability of a number of well-known service discovery protocols in the context of networked nodes. Multicast DNS and Service Discovery (mDNS-SD) stands out with its auto-configuration, distributed architecture,sharing of resources, and wide area access. For wireless battery operated and resource constrained nodes, we seek to integrate SD and power management techniques. This leads us to a standards based infrastructure for service oriented sensor networks where; 1) nodes collaborate in an ad hoc fashion by using SD techniques to discover (and announce) resources locally and over the public Internet, 2) nodes preserve power through aggressive utilization of low power (sleep) modes, while yet being reachable for clients according to defined schemas, and 3) clients may access and configure nodes, and (if possible) access sleeping nodes by implicit wake-up procedures. To demonstrate the proposed infrastructure a complete experimental setup has been devised featuring; Bluetooth enabled nodes, lightweight implementations of mDNS-SD and communication stacks, Internet access through cellular/wired gateways, together with a public DNS server. Our experiments verify that mDNS-SD can be effectively deployed on small wireless sensor and actuator nodes and provides the basis of a service oriented infrastructure for low power sensor networks.Validerad; 2006; 20061206 (jench)</p