Nelson Souto Rosa

Mires: a publish/subscribe middleware for sensor networks

A wireless sensor network (WSN) consists of a large number of small devices with computational power, wireless communication and sensing capability. These networks have been developed for a wide range of applications, such as habitat monitoring, object tracking, precision agriculture, building monitoring and military systems. Meanwhile, middleware systems have also been proposed in to facilitate both the development of these applications and provide common application services. The development of middleware for sensor networks, however, places new challenges on middleware developers due to the low availability of resources and processing capacity of the sensor nodes. In this context, this paper presents the design and implementation of a middleware for WSN named Mires. Mires incorporates characteristics of message-oriented middleware by allowing applications communicate in a publish/subscribe way. In order to illustrate the proposed middleware, we have also developed an environment-monitoring application and a data aggregation service.

A message-oriented middleware for sensor networks

The miniaturization of hardware components has lead to the development of Wireless Sensor Networks (WSN) and networked-applications over them. Meanwhile, middleware systems have also been proposed in order to both facilitating the development of these applications and providing common application services. The development of middleware for sensor networks, however, places new challenges to middleware developers due to the low availability of resources and processing capacity of the sensor nodes. In this context, this paper presents a middleware for WSN named Mires. Mires incorporates characteristics of message-oriented middleware by allowing applications communicate in a publish/subscribe way. In order to illustrate the proposed middleware, we implement an aggregation middleware service for an environment-monitoring application.

Process/sup NFL/: a language for describing non-functional properties

Nonfunctional requirements (NFRs) are rarely taken in account in software development. There are reasons that help us to understand why these requirements are not explicitly dealt with: their complexity NFRs are usually stated only informally, their high abstraction level, and the rare support of languages, methodologies and tools. In this scenario, we concentrate on defining a language, namely Process/sup NFL/, that expresses NFRs during software development. This language has been designed to consider specific characteristics of NFRs like their correlations and conflicts. In order to illustrate our language, we describe NFRs of software radios and the NFRs performance and security, which are usually present in software requirements specifications.

A framework for building non-functional software architectures

requirements ( NFRs ) are rarely taken in ac- count in most software development processes. There exist reasons that can help us to understand why these require- ments are not explicitly dealt with: their complexity,their usually informal statement,their high abstraction level,as well as the rare support of languages,methodologies and tools for them. In this paper,we introduce a framework for explicitly dealing with NFRs in the software development process. This framework addresses the description,integra- tion with functional requirements,refinement and mapping of NFRs into actual implementation elements.

Reliability of Wireless Sensor Networks

Wireless Sensor Networks (WSNs) consist of hundreds or thousands of sensor nodes with limited processing, storage, and battery capabilities. There are several strategies to reduce the power consumption of WSN nodes (by increasing the network lifetime) and increase the reliability of the network (by improving the WSN Quality of Service). However, there is an inherent conflict between power consumption and reliability: an increase in reliability usually leads to an increase in power consumption. For example, routing algorithms can send the same packet though different paths (multipath strategy), which it is important for reliability, but they significantly increase the WSN power consumption. In this context, this paper proposes a model for evaluating the reliability of WSNs considering the battery level as a key factor. Moreover, this model is based on routing algorithms used by WSNs. In order to evaluate the proposed models, three scenarios were considered to show the impact of the power consumption on the reliability of WSNs.

Evaluating the Power Consumption of Wireless Sensor Network Applications Using Models

Power consumption is the main concern in developing Wireless Sensor Network (WSN) applications. Consequently, several strategies have been proposed for investigating the power consumption of this kind of application. These strategies can help to predict the WSN lifetime, provide recommendations to application developers and may optimize the energy consumed by the WSN applications. While measurement is a known and precise strategy for power consumption evaluation, it is very costly, tedious and may be unfeasible considering the (usual) large number of WSN nodes. Furthermore, due to the inherent dynamism of WSNs, the instrumentation required by measurement techniques makes difficult their use in several different scenarios. In this context, this paper presents an approach for evaluating the power consumption of WSN applications by using simulation models along with a set of tools to automate the proposed approach. Starting from a programming language code, we automatically generate consumption models used to predict the power consumption of WSN applications. In order to evaluate the proposed approach, we compare the results obtained by using the generated models against ones obtained by measurement.

An Integrated Approach for Model Driven Process Modeling and Enactment

The adoption of MDA in software development is increasing and is widely recognized as an important approach for building software systems. However, theres a lack of standard terminology and notation addressing design aspects of an MDA process. The available MDA tools and environments are particularly focused in defining and executing model transformations, while a development process involves other important definitions which should be carried out during the process enactment. This paper presents an integrated approach for MDA process modeling and enactment based on specializations of some SPEM 2 concepts. To support and evaluate our approach a tool was developed and applied in two case studies.

Incorporating Security Requirements into Service Composition: From Modelling to Execution

Despite an increasing need for considering security requirements in service composition, the incorporation of security requirements into service composition is still a challenge for many reasons: no clear identification of security requirements for composition, absence of notations to express them, difficulty in integrating them into the business processes, complexity of mapping them into security mechanisms, and the complexity inherent to specify and enforce complex security requirements. We identify security requirements for service composition and define notations to express them at different levels of abstraction. We present a novel approach consisting of a methodology, called Sec-MoSC, to incorporate security requirements into service composition, map security requirements into enforceable mechanisms, and support execution. We have implemented this approach in a prototype tool by extending BPMN notation and building on an existing BPMN editor, BPEL engine and Apache Rampart. We showcase an illustrative application of the Sec-MoSC toolset.

Adaptive web service composition

Web services have played an important role in the development of distributed systems. In particular, the possibility of composing already implemented web services in order to provide a new functionality is an interesting approach for building distributed applications and business processes. The possibility of dynamically composing web services is also apparent. Current approaches address to this point, but they do not adopt established specifications, like WS-BPEL, as they usually propose modifications in the rules of business process specifications by imposing more difficulties to implement the system. This paper proposes a policy-driven approach for enabling web service adaptability through a semantic modification in the invocation primitive of WS-BPEL, whilst mantains its syntax unaffected. Hence, programmers may define dynamic web service compositions without changing the source code. The approach has been applied to a loan approval system in order to illustrate it.

Improving Transparent Adaptability in Web Service Composition

Web services have played an important role in the development of distributed systems. In particular, the possibility of composing already implemented Web services in order to provide a new functionality is an interesting approach for building distributed applications and business processes. The possibility of dynamically composing web services is also apparent. Current approaches address to this point, but they do not adopt established specifications, like WS-BPEL, as they usually propose modifications in the rules of business process specifications by imposing more difficulties to implement the system. This paper proposes a new approach for improving policy-driven web service adaptability through a semantics modification in the invocation primitive, whilst it keeps the syntax unaffected. Hence, programmers may define dynamic Web service compositions without changing the source code. The approach was applied to a loan approval system in order to illustrate it.