Nils Glombitza

Integrating wireless sensor networks into web service-based business processes

Wireless Sensor Networks (WSNs) are envisioned to become an integral part of the Future Internet where they extend the Internet to the physical world. Yet, while Service-Oriented Architectures (SOA) are prospering in Enterprise-IT, wireless sensor networks have -- despite contrary prognoses -- not found their way into enterprises. A major obstacle is certainly the different and resource-constraint nature of this class of devices. We argue that approaches for the seamless integration with existing, widely deployed SOA technologies such as XML, Web Services, and the Business Process Execution Language (BPEL) are key to the success of WSNs in enterprises. In this paper, we present our approach to integrate WSNs into SOA environments using these technologies in a resource-efficient but fully standard-compliant way. We evaluate our implementation and present a case study.

Using state machines for a model driven development of web service-based sensor network applications

In the Internet of Things, all kinds of devices will extend the Internet to the physical world. In that vision, even extremely resource constrained sensor nodes can be triggered by as well as trigger business processes and are not limited to sense-and-send anymore. Despite the large potential, due to the time consuming, inflexible, and error prone development of sensor network applications, sensor networks are rarely integrated into todays enterprise IT. In this paper, we present an approach using state machines for a Model Driven Development of Web Service-based sensor network applications. We show how Web Services can be realized on sensor nodes and present a domain-specific language called State Machine for Resource Constrained Devices (SM4RCD) to orchestrate these services.

Using BPEL to realize business processes for an internet of things

In the vision of an IoT, trillions of tiny devices extend the Internet to the physical world and enable novel applications that have not been possible before. Such applications emerge out of the interaction of these devices with each other and with more powerful server-class computers on the Internet. Programming such applications is challenging due to the massively distributed nature of these networks combined with the challenges of embedded programming. In addition, resource constraints, device heterogeneity, and the integration with the Internet further complicate this situation. In this paper, we present a programming-in-the-large approach for resource-constraint devices such as wireless sensor nodes. Our approach is to model such applications using the Business Process Execution Language (BPEL), which is successfully and widely used in the Internet to model complete applications and business processes. However, BPEL and its associated technologies are too resourcedemanding to be directly applied in resource-constraint environments. We therefore use the BPEL model as input to a code generation process that generates custom-tailored, lean code for different target platforms. The resulting code is fully standard-compliant and allows a seamless integration of IoT devices in enterprise IT environments. We present an exhaustive evaluation on real hardware showing the first-rate performance of the approach.

Using graphical process modeling for realizing SOA programming paradigms in sensor networks

Designing and modifying sensor network applications demand for IT expertise in the field of distributed systems. Programming paradigms used in application development for sensor networks like object orientation do not refer to the distributed nature of a sensor network application. This represses the usage of sensor network technology as part of industrial applications. In enterprises graphical tools like BPEL and BPMN are used to coordinate distributed processes and overcome the complexity of the interaction among different components. In this work we introduce the GWELS toolbox as graphical process modeling tool to realize the service oriented programming paradigm for sensor networks and ease the development and integration of sensor network applications. We exemplarily design and deploy a sensor network application with GWELS to demonstrate the applicability of our approach.

Self-Description and Protocol Conversion for a Web of Things

Many enterprise applications can benefit from the use of wireless sensors, for example for monitoring location and state of goods. While modern backend IT systems use elaborate Service Oriented Architectures based on Web Services, the resource constraints of sensor nodes require highly optimized embedded programming and proprietary networking protocols. This paper aims at bridging this gap by extending Web Service Oriented Architectures to wireless sensors in a standard compliant way while not exceeding the constrained resources of sensor nodes - thus contributing to the formation of a Web of Things. In particular, we enable self-description of embedded Web services through efficient compression of WSDL documents, we support discovery of embedded Web services by means of an efficient embedded discovery protocol, and we enable backend IT systems to invoke embedded Web services on sensor nodes and vice versa by providing an open framework for protocol conversion. We implement our proposal to obtain key performance figures.

LTP: An Efficient Web Service Transport Protocol for Resource Constrained Devices

Wireless Sensor Networks (WSNs) are envisioned to become an integral part of the Future Internet. Together with countless other embedded appliances, such resource-constraint devices will form an Internet of Things (IoT) where all kinds of devices extend the Internet to the physical world. In this vision, the seamless and flexible integration of IoT devices ranging from simple sensor nodes to large scale Enterprise IT servers are the basis for novel applications and business processes not possible before. A major challenge is to master the arising challenges of scale, low resources, and heterogeneity. In the Internet and especially in Enterprise IT, heterogeneity is addressed using Service-Oriented Architectures (SOA). However, todays technologies used to realize SOAs are to heavyweight to be used in resource-constraint networks (RCNs). In this paper, we introduce a novel, versatile, and light-weight Web Service transport protocol (called Lean Transport Protocol, LTP) that allows the transparent exchange of Web Service messages between all kinds of resource-constrained devices and server or PC class systems. We describe LTP in detail and show by real-world measurements that LTP has the potential to serve as standard Web Service transport protocol in the Internet of Things.

FRED - An Application for a Real-Life Large Scale Multihop Ad Hoc Network

Simulations were standard in the mobile ad hoc network (MANET) research community in the past New protocols and algorithms were validated via simulations by network simulators such as ns2 or GloMoSim. However, even with the increasing number of published simulation papers, contradictory results are decreasing the confidence in simulations today. First experimental results show that simulation models for ad hoc networks are far from being realistic and protocols developed in simulations failed in real word environments. As a result, the demand for experimental results and application deployments within the research community increases. In this paper, we introduce FRED as a suitable application to conduct protocol evaluations as well as user acceptance surveys. FRED (flexible radio enabled dialog) is an enhanced TED-System that allows asynchronous surveys or quizzes with a multi hop radio network, where individual participants conduct the survey independent of others. FRED is based on the pacemate sensor network platform that provides a comfortable lightweight housing, a simple radio interface and an intuitive GUI that allows long term evaluations of user acceptance and network protocols.

A service-oriented operating system and an application development infrastructure for wireless sensor networks

Due to the highly distributed nature and special basic conditions such as limited resources, implementing and maintaining a sensor network application is a tedious task. In this demonstration we present a service-oriented operating system for sensor nodes and a framework that allows a composition of services on the nodes. We show how sensor network applications can be composed and modified by using different services.

A Service-Oriented Operating System and an Application Development Infrastructure for Distributed Embedded Systems.

The paradigm of service-orientation promises a significant ease of use in creating and managing distributed software systems. A very important aspect here is that also application domain experts and stakeholders, who are not necessarily skilled in computer programming, get a chance to create, analyze, and adapt distributed applications. However, up to now, service-oriented architectures have been mainly discussed in the context of complex business applications. In this paper we will investigate how to transfer the benefits of a service-oriented architecture into the field of embedded systems, so that this technology gets accessible to a much wider range of users. As an example, we will demonstrate this scheme for sensor network applications. In order to address the problem of limited device resources we will introduce a minimal operating system for such devices. It organizes all pieces of code running on a sensor node in a service-oriented fashion and also features the relocation of code to a different node at runtime. We will demonstrate that it is possible to design a sensor network application from a set of already existing services in a highly modular way by employing already existing technologies and standards.