Pablo Ezequiel Guerrero

From calls to events: architecting future BPM systems

Contemporary BPM systems fit very well with traditional architectures that are based on a pull invocation principle, such as SOA. The proliferation of sensors and streams of events has led to event driven architectures that decouple event producers and consumers. EDAs are push-based and support different control structures. Future BPM systems must therefore deal both with pull and push-based architectures. In this talk we will analyze the interplay of the different architectures, their components and the desirable and achievable correctness notions and non-functional properties.

On the selection of testbeds for the evaluation of sensor network protocols and applications

Wireless sensor network protocols and applications typically need to be evaluated and tested not only using simulators but also on testbeds. While simulations allow studying the performance of protocols and applications in a controlled environment, they usually do not provide a sufficient level of realism. On the contrary, testbeds allow exposing protocols and applications to the real vagaries of wireless communication as well as to other “non-idealities” that typically occur in real wireless sensor network scenarios. Experimental results gathered in one or more testbeds are thus typically reported in most recent research papers on wireless sensor networks. Usually, the higher the number of different testbeds has been used, the more significant the obtained results are considered to be. However, it is often unclear whether the used testbeds actually expose protocols and applications to significantly different experimental conditions. Experiments involving a high number of testbeds are very time-consuming and cumbersome to run, but cannot guarantee that a protocol or application has been evaluated or tested in significantly different scenarios. In this paper, we argue that a systematic methodology that allows describing how significant the differences between testbeds actually are is needed. As a first step towards the definition of this methodology, we define several quantitative properties that can be used to describe and compare testbeds in a coherent manner. We show how a representative subset of these properties can be computed in real testbeds and present the results obtained by running this computation on two different testbeds. Furthermore, we describe how we plan to use our methodology to allow researchers to automatically select - out of a set of testbeds - those that are most adequate to run a specific experiment.

Pushing Business Data Processing Towards the Periphery

The usage of RFID and sensing technologies in supply chain management applications requires the automatic conversion of large amounts of raw data into manageable business process information. This has led to many performance and scalability issues in existing RFID infrastructures. We present an approach to alleviate these shortcomings based on a flexible system architecture that partially migrates business data processing towards the periphery.

Towards a FIPA compliant multiagent based middleware architecture for sensor networks

In this paper we suggest a multiagent based middleware architecture that is particularly suitable for supporting wireless sensor network deployments in industrial environments like mines and chemical processing plants. Our intention is to make the proposed middleware architecture to be as closely aligned to the Foundation for Intelligent Physical Agents standards as possible. The existing agent based solutions for wireless sensor networks lack some important features that these standards mandate and thus reduce their interoperability with other existing or upcoming agent based systems. These standards that we choose for our middleware have the potential of providing a more reliable event reporting mechanism than the one supported by existing agent based middleware.

Workflow support for wireless sensor and actor networks: a position paper

As initial challenges of wireless sensor and actor networks (WSANs) are overcome, their application possibilities evolve. For these applications to move mainstream, efficient programming methods are required which can be used by domain experts. So far, the question of how can WSANs be efficiently programmed remains unanswered. In this paper we examine proposed middleware approaches, and show that they have focused on data extraction rather than in-network actuation. We thus propose the usage of workflows as a means to define the logic that orchestrates the network activity, and introduce a language to express WSAN interactions. At this time, a concrete system is not given, but the paper discusses the relevant aspects towards one, and poses many questions for future research.

A Metropolitan-Scale Testbed for Heterogeneous Wireless Sensor Networks to Support CO2 Reduction

There exist two major contributions of network technology to reduce CO2 levels: reducing the energy consumption of the network itself, and supporting areas of application to reduce CO2 levels. The impact of the latter is potentially higher. Therefore, we present TUDμNet, a testbed for a metropolitan-scale heterogeneous sensor network with hundreds of nodes that help monitor and control CO2 levels in urban areas. Our testbed has four major application domains where it is being applied: TU Darmstadt’s award winning solar house, where temperature and CO2 levels are monitored; an 80 year old building in which a WSN is deployed to measure ambient parameters that contribute to future energy-saving remodeling; mobile sensors mounted on the streetcars of the public tramway system to measure location-specific CO2 levels that are collected in a publicly accessible database to obtain CO2 profiles; and a hybrid sensor network in TUD’s botanical garden to measure humidity, CO2 levels and soil properties to improve the management of urban parks. In this paper we present the concepts behind the design of our testbed, its design challenges and our solutions, and potential applications of such metropolitan-scale sensor networks.

Towards declarative query scoping in sensor networks

In the last decade, several large-scale wireless sensor networks have been deployed to monitor a variety of environments. The declarative nature of the database approach for accessing sensor data has gained great popularity because of both its simplicity and its energy-efficient implementation. At the same time another declarative abstraction made its way into mainstream sensor network deployments: user-defined groups of nodes. By restricting the set of nodes that participate in a task to such a group, the overall network lifetime can be prolonged. It is straightforward to see that integrating these two approaches, that is, restricting a querys scope to a group of sensor nodes, is beneficial. In this work we explore the integration of two such database and scoping technologies: TikiDB, a modern reincarnation of a sensor network query processor, and Scopes, a network-wide grouping mechanism.

A site properties assessment framework for wireless sensor networks

Comparing experimental results obtained on different wireless sensor network deployments is typically very cumbersome and in most cases unfeasible. This is due to the lack of a methodology to describe the properties of network deployments and the experimental conditions under which experiments have been run. Our work focuses on the design and development of a site properties assessment framework, called SiteWork, that aims at providing the means to quickly, automatically and accurately quantify their properties. This poster abstract describes the preliminary design and evaluation of the basic site properties assessment mechanisms provided by SiteWork.

Whac-A-Bee: a sensor network game

This paper illustrates both challenges and benefits found in expanding a traditional game concept to a situated environment with a distributed set of wireless sensing modules. Our pervasive game equivalent of the Whac-A-Mole game, Whac-A-Bee, retains the find-and-seek aspects of the original game while extending the location, the number of players, and the time-span in which it can be played. We discuss the obstacles met during this work, and specifically address challenges in making the game robust and flexible enough for large and long-term deployments in unknown territory.

Performance Evaluation of Embedded ECA Rule Engines: A Case Study

Embedded systems operating on high data workloads are becoming pervasive. ECA rule engines provide a flexible environment to support the management, reconfiguration and execution of business rules. However, modeling the performance of a rule engine is challenging because of its reactive nature. In this work we present the performance analysis of an ECA rule engine in the context of a supply chain scenario. We compare the performance predictions against the measured results obtained from our performance tool set, and show that despite its simplicity the performance prediction model is reasonably accurate.