Publish/subscribe

The IEC61499 is an open standard for distributed control and automation. The interface between control software and hardware or communications is achieved by means of the so-called Service Interface Function Blocks (SIFB). This paper presents the guidelines to build communication SIFBs based on the emerging OMG DDS (Data Distribution Service) middleware. This specification implements in a very efficient way the Publisher/Subscriber paradigm providing significant QoS configuration possibilities. These characteristics make DDS suitable for implementing the communications among time-critical devices. By using these DDS-SIFBs within IEC61499 code generation tools, the designers of the distributed applications will be allowed to use this powerful technology in the new distributed applications.

Publish-subscribe middleware allows the components of a distributed application to subscribe for event notifications and provides the infrastructure enabling event routing from sources to subscribers. This model decouples publishers from subscribers, and in principle makes it amenable to highly dynamic environments. Nevertheless, publish-subscribe systems exploiting a distributed event dispatcher are typically not able to rearrange dynamically their operations to adapt to changes impacting the topology of the dispatching infrastructure. In this work, we first describe two solutions available in the literature that constitute the extremes of the reconfiguration spectrum in terms of the number of nodes potentially affected by the reconfiguration. They differ essentially in the tradeoffs between simplicity and efficiency. Then, we introduce our contribution as a new algorithm that strikes a balance between the aforementioned solutions by tolerating frequent reconfigurations at the cost of moderate overhead.

Despite the availability of the sensor and smartphone devices to fulfill the ubiquitous computing vision, thestate-of-the-art falls short of this vision. We argue that the reason for this gap is the lack of an infrastructure to task/utilize these devices for collaboration and coordination. We propose that Twitter can provide an "open" publish-subscribe infrastructure for sensors and smartphones, and pave the way for ubiquitous crowd-sourced sensing and collaboration applications. We design and implement a crowd-sourced sensing and collaboration over Twitter, and showcase our system in the context of two applications: a crowd-sourced weather radar, and a participatory noise-mapping application. Our results from real-world Twitter experiments give insights into the feasibility of this approach and outlines the research challenges in sensor/smartphone integration to Twitter.

Reliable delivery of messages is an important problem that needs to be addressed in distributed systems. In this paper we present our strategy to enable reliable delivery of messages in the presence of link and node failures. This is facilitated by a specialized repository node. We then present our strategy to make this scheme even more failure resilient, by incorporating support for repository redundancy. Each repository functions autonomously. The scheme enables updates to the redundancy scheme depending on the failure resiliency requirements. If there are N available repositories, reliable delivery guarantees will be met even if N-1 repositories fail.

Description/Abstract In this paper we present our A/V collaboration system based on our XGSP collaboration framework and NaradaBrokering messaging middleware. Using publish/subscribe event model, this system can provide videoconferencing services to heterogeneous endpoints such as H. 323, SIP and Access Grid. This paper discusses the common a/v collaboration model shared by all kinds of A/V conferencing clients and introduces the details about how to implement such a model based on publish/subscribe ...

We report on a fruitful combination of applying academic experience with formal modelling and verification techniques to an industrial case study. The goal of the case study was to investigate a priori, i.e. before implementation, the effects of adding a lightweight and easy-to-use publish/subscribe (event) notification service to thinkteam r ○ —an asynchronous and dispersed groupware system which was developed by think3. Researchers from the Formal Methods and Tools (FM&T) group of ISTI–CNR—with a longstanding experience in research on the development and application of formal methods, notations, and software tools for the specification, design, and verification of complex computer systems— therefore teamed up with think3—a global provider of integrated product development solutions that provides mechanical design and Product Data Management (PDM) software catering the product management needs of design processes in the manufacturing industry. The technical details of this joint re...

Users of modern digital libraries (DLs) can keep themselves up-to-date by searching and browsing their favorite collections, or more conveniently by resorting to an alerting service. The alerting service notifies its clients about new or changed documents. Proprietary and mediating alerting services fail to fluidly integrate information from differing collections. So far, no sophisticated service has been proposed that is integrated with the digital library software and covers heterogeneous and distributed collections. This paper ...

An Unmanned Aerial Vehicle is a non-piloted airplane designed to operate in dangerous and repetitive situations. With the advent of UAV's civil applications, UAVs are emerging as a valid option in commercial scenarios. If it must be economically viable, the same platform should implement a variety of missions with little reconfiguration time and overhead. This paper presents a middleware-based architecture specially suited to operate as a flexible payload and mission controller in a UAV. The system is composed of low-cost computing devices connected by network. The functionality is divided into reusable services distributed over a number of nodes with a middleware managing their lifecycle and communication. Some research has been done in this area; yet it is mainly focused on the control domain and in its realtime operation. Our proposal differs in that we address the implementation of adaptable and reconfigurable unmanned missions in low-cost and low-resources hardware.

Publish/subscribe is a distributed interaction paradigm well adapted to the deployment of scalable and loosely coupled systems. Apache Kafka and RabbitMQ are two popular open-source and commercially-supported pub/sub systems that have been around for almost a decade and have seen wide adoption. Given the popularity of these two systems and the fact that both are branded as pub/sub systems, two frequently asked questions in the relevant online forums are: how do they compare against each other and which one to use? In this paper, we frame the arguments in a holistic approach by establishing a common comparison framework based on the core functionalities of pub/sub systems. Using this framework, we then venture into a qualitative and quantitative (i.e. empirical) comparison of the common features of the two systems. Additionally, we also highlight the distinct features that each of these systems has. After enumerating a set of use cases that are best suited for RabbitMQ or Kafka, we try to guide the reader through a determination table to choose the best architecture given his/her particular set of requirements.

RESUMEN: Se presenta la especificación de cuatro patrones arquitectónicos que permiten modelar los mecanismos de interacción en sistemas distribuidos utilizando un Lenguaje de Descripción Arquitectónica (ADL) denominado "RAPIDE". Las descripciones obtenidas poseen un alto nivel de abstracción y formalismo, por tener los ADLs una semántica bien definida, siendo posible la producción de simulaciones de la arquitectura a partir de ellas. Tales simulaciones pueden ser utilizadas por un especialista para analizar el comportamiento de los patrones respecto a la especificación inicial de requisitos y así tomar decisiones en cuanto a las situaciones en las cuales es conveniente aplicarlos. Palabras clave: Arquitectura del software, sistemas distribuidos, ADL, RAPIDE, patrones ABSTRACT: This paper presents the specification of four architectural patterns used for modeling the interaction mechanisms of distributed systems using the RAPIDE Architecture Description Language. The descriptions obtained have a high level of abstraction and formality, since their semantics is well defined, thus facilitating simulations of the architectural behavior. Such simulations may be used by the specialist in order to analyze the pattern behavior regarding initial requirement specifications, for selecting the most convenient pattern in a particular architecture.

Content-based publish-subscribe is emerging as a communication paradigm able to cope with the needs of scalability, flexibility, and reconfigurability typical of highly dynamic distributed applications. However, very few efforts address dynamic changes in the topology of the publish-subscribe distributed dispatching infrastructure-a fundamental challenge in mobile computing scenarios. In this chapter we illustrate the problems posed by mobility in the context of publish-subscribe, discuss protocols and integrated solutions proposed by our research group, and survey the state of the art in this research area. * G. Cugola and G.P. Picco ([cugola,picco]@elet.polimi.it) are with

In the past decade, new communication schemes have been designed and retrofitted into substations by utilities to integrate data from relays and Intelligent Electronic Devices (IEDs) and capitalize on the protection, control, metering, fault recording and communication functions available in digital devices. The introduction of IEC 61850 has made it possible and justifiable to integrate station IEDs on a high-speed peer-to-peer communication network (ethernet) through standardization. However, more advances are needed in order to establish an open and standard working environment allowing for more functions to be developed. In this paper, the authors propose a real-time publisher/subscriber communication model as a means of satisfying the unique behavior and communications needs of the IEC 61850 protocol. The authors provide a detailed design and implementation detail of this model along with interesting performance results. The target audience for this paper includes power system protection and automation engineers and technicians as well as research personnel who have at least a basic understanding of the IEC 61850 international standard and other technology mechanisms addressed in this paper.

In this paper we present a scalable networking middleware designed for multiplayer and massively multiplayer games. We argue that objects can implement an ideal interface between the game logic and the communication middleware. This allows the game developer to maintain current design techniques and apply object-oriented decomposition to partition the game state. Game objects are mapped to duplicated ob-jects, our units of distribution and replication of state. Sophisticated, load-balanced, multidimensional interest management is applied to du-plicated objects to communicate only relevant updates to player nodes. Optimization of message sending using state prediction techniques is performed at the attribute level of objects. At the lowest level, dupli-cated objects communicate using a network engine that provides remote method invocation and publish/subscribe capabilities. We outline the ar-chitecture of two implementations of our middleware: one designed for experiments in an acade...

Auctions have been a popular trading paradigm for centuries but have gained new interest through world-wide trading on the Internet. Many B2C sites are embracing reverse auctions, in which a potential buyer posts her maximum bid, as an additional service to registered customers. In all these cases the efficient notification of the participants is essential. In this paper we develop the notion of a metaauction that allows a potential buyer to roam automatically across auction sites and we identify critical communication and notification requirements of the next generation of Internet-scale trading systems. To cope with the scale, distribution and availability requirements these systems must leverage intelligent information dissemination and caching techniques. In the context of a meta-auction formerly independent systems must act in the role of component information systems. One of the main challenges is to provide communication protocols that allow efficient and transparent cooperation in distributed heterogeneous environments. Today's information systems are limited in their growth and interaction potential because the typical client-server and n-tier system architectures are solely based on a request/response interaction; second, the user-initiated query metaphor from the database domain is the primary means for information acquisition; and third, many assumptions about the meaning of data and notifications provided and exchanged through the Internet are left implicit.

The completely decoupled interaction model offered by the publish/subscribe communication paradigm perfectly suits the interoperability needs of todays large-scale, dynamic, peer-to-peer applications. The unmanaged environments, where these applications are expected to work, pose a series of problems (potentially wide number of partipants, low-reliability of nodes, absence of a centralized authority, etc.) that severely limit the scalability of existing approaches which were originally thought for supporting distributed applications built on the top of static and managed environments. In this paper we propose an architecture for implementing the topic-based publish/subscribe paradigm in large scale peer-to-peer systems. The architecture is based on clustering peers subscribed to the same topic. The major novelty of this architecture lies in the mechanism employed to bring events from the publisher to the cluster (namely outer-cluster routing). The evaluation shows that this mechanism for outer-cluster routing has a probability to bring events to the destination cluster very close to 1 while keeping small the involved number of outof-cluster peers. Finally, the overall architecture is shown to be scalable along several fundamental dimensions like number of participants, subscriptions, and to exhibit a fair load distribution (load distribution closely follows the distribu- *

Recent trends in data-centric systems have motivated significant standardization efforts, such as the Data Distribution Service (DDS) to enable data dissemination with guaranteed Quality of Service (QoS). However, clear design guidelines and techniques for the support of reliable and scalable DDS-based deployments, especially for (mobile) data intensive services, such as Internet-wide information dissemination for breaking news or financial analysis services, are still missing. After an analysis of main DDS fault-tolerance and scalability deployment issues, this paper proposes a novel solution with two core original contributions: i) DDScompliant routing substrate to facilitate reliable data dissemination between mobile devices; ii) relay-based DDS support infrastructure with limited overhead to enable scalable Internet-wide data dissemination. Our solution, especially tailored for mobile computing scenarios, is lightweight and requires neither persistency nor heavy operations at mobile device side. Reported experimental results confirm that our proposal can guarantee desired scalability requirements with a limited network, CPU, and memory resource overhead.

A Real-Time Wireless Distributed Embedded System (RTWDES) is formed by a large quantity of small devices with certain computing power, wireless communication and sensing/actuators capabilities. These types of networks have become popular as they have been developed for applications which can carry out a vast quantity of tasks, including home and building monitoring, object tracking, precision agriculture, military applications, disaster recovery, industry applications, among others. For this type of applications a middleware is used in software systems to bridge the gap between the application and the underlying operating system and networks. As a result, a middleware system can facilitate the development of applications and is designed to provide common services to the applications. The development of a middleware for sensor networks presents several challenges due to the limited computational resources and energy of the different nodes. This work is related with the design, implementation and test of a micro middleware for RTWDES; the proposal incorporates characteristics of a message oriented middleware thus allowing the applications to communicate by employing the publish/subscribe model. Experimental evaluation shows that the proposed middleware J Intell Robot Syst provides a stable and timely service to support different Quality of Service (QoS) levels.

In this paper we describe SelectCast, a self-repairing multicast overlay routing facility for supporting publish/subscribe applications. SelectCast is a peer-to-peer protocol, and leverages Astrolabe, a secure distributed information management system. SelectCast uses replication to recover quickly from transient failures, as well as Astrolabe's aggregation facilities to recover from long-term failures or adapt to changes in load or QoS requirements. In order to evaluate the scalability and performance of SelectCast, and compare these with other multicast facilities, we built a multicast testing facility on NetBed. This paper reports latency and load results for Se-lectCast, compared to both native IP multicast and Yoid.

Connectors in distributed architecture play an important role. Software engineers meet more and more challenges of designing connectors. Particularly, in a distributed MVC architecture, there are many issues in the design of connectors such as: how to apply the architecture pattern to design of connector in distributed MVC system; how to make the connectors of MVC become loosely coupled. With the aim of resolving the problems, this paper proposes a layered model to design connectors in distributed MVC architecture. And then, a design example of a complicated message-based MVC is given by using this model.

Managing multi-tenant edge devices with heterogeneous capabilities scattered across an urban area requires significant communication and computing power, which is challenging when devices are also resource-constrained. These devices play a crucial role in smart city monitoring systems by notifying various municipal organizations about a wide range of ongoing complex events. Some recent approaches in complex event processing use a publish-subscribe architectural pattern to decouple simple event producers from complex event consumers. However, they did not fully address communication efficiency or diverse quality of service (QoS) requirements in aggregating events. This paper proposes a new architecture that integrates the publish-subscribe architectural pattern with software-defined network technology for urban monitoring applications. The architecture enhances monitoring applications with capabilities of distributed processing and detection of complex events. It also enables application developers to define QoS requirements and supports the TESLA complex event specification language. The main focus of our work is on energy and network efficiency. The simulation results demonstrate significant improvements in energy consumption and data packet traffic compared to three close baselines.

This paper presents a novel adaptation mechanism that allows every node of a gossip-based broadcast algorithm to adjust the rate of message emission 1) to the amount of resources available to the nodes within the same broadcast group and 2) to the global level of congestion in the system. The adaptation mechanism can be applied to all gossip-based broadcast algorithms we know of and makes their use more realistic in practical situations where nodes have limited resources whose quantity changes dynamically with time without decreasing the reliability.

Considerable research has been performed in applying run-time reconfigurable component models to the domain of wireless sensor networks. The ability to dynamically deploy and reconfigure software components has clear advantages in sensor network deployments, which are typically large in scale and expected to operate for long periods in the face of node mobility, dynamic environmental conditions and changing application requirements. To date, research on component and binding models for sensor networks has primarily focused on the development of specialized component models that are optimized for use in resource-constrained environments. However, current approaches impose significant overhead upon developers and tend to use inflexible binding models based on remote procedure calls. To address these concerns, we introduce a novel component and binding model for networked embedded systems (LooCI). LooCI components are designed to impose minimal additional overhead on developers. Furthermore, LooCI components use a novel event-based binding model that allows developers to model rich component interactions, while providing support for easy interception, re-wiring and advanced features like distributed garbage collection and generic fault tolerance. A prototype implementation of our component and binding model has been realised for the SunSPOT platform. Our preliminary evaluation shows that LooCI has an acceptable memory footprint and imposes minimal overhead on developers.

Narada is a distributed event brokering system designed to run on a large network of cooperating broker nodes. Narada supports heterogeneous client configurations that scale to arbitrary size and incorporates efficient routing algorithms to optimize disseminations to clients. Narada is failure resilient and guarantees delivery in the presence of failures. In this paper we provide an overview of the Narada event brokering system. The paper also describes the Java Message Service compliance process and support for peer-to-peer interactions in Narada. Finally, the paper outlines issues and entry points for supporting Web Services within Narada

The software components of embedded control systems get extremely complex as they are designed into distributed systems consisting of a large number of inexpensi ve microcontrollers interconnected by low-bandwidth real-time networks such as the controller area network (CAN). While recently emerging middleware technologies such as CORBA and DCOM address the complexity of distributed programming, they cannot be directly applied to distributed control system design due to their excessive resource demand and inadequate communication models. In this paper, we propose a CORBA-based middleware design for CANbased distributed embedded control systems. Our design goal is to minimize its resource need and make it support group communication without losing the IDL (interface definition language) level compliance to the OMG standards. To achieve this, we develop a transport protocol on the CAN and a group communication scheme based on the well-known publisher/subscriber model. The protocol effectively realizes subject-based addressing and supports anonymous publisher/subscriber communication. We also customize the method invocation and message passing protocol, referred to as the general inter-ORB protocol (GIOP), of CORBA so that CORBA method invocations are efficiently serviced on a low-bandwidth network such as the CAN. This customization includes packed data encoding and variable-length integer encoding for compact representation of IDL data types. We have implemented our CORBA-based middleware on the mArx real-time operating system we have developed at Seoul National University. Our experiments clearly demonstrate that it is feasible to use CORBA in developing distributed embedded control systems possessing severe resource limitations. Our design clearly demonstrates that it is feas ible to use a CORBA-based middleware in developing distributed embedded systems on real-time networks possessing severe resource limitations.

Reliable delivery of events (or messages, where the terms messages and events are used interchangeably) is an important problem that needs to be addressed in distributed systems. Increasingly, interactions between entities within a distributed system are encapsulated in events. In this paper we present our strategy to enable reliable delivery of events in the presence of link and node failures. We then present our strategy to make this scheme even more failure resilient, by incorporating support for replicated reliable ...

Semantic web service technology has a high potential for integrating heterogeneous applications. Web service capabilities are impossible to be used without having a precise service discovery mechanism. The increase in the precision of this mechanism depends upon taking QoS specification of services in service discovery process into account. Since using linguistic quantities in non-functional attribute description is popular, fuzzy logic is appropriate for being used in representation of non-functional attribute description. In this paper, a fuzzy logic-based framework is proposed which allows publication and subscription of semantic web services alongside with maintaining its consistency with standard UDDI and application of fuzzy synthetic evaluation and multi-objective decision-making algorithms. This framework allows increasing the consistency of interpreting request and service by natural language process (NLP) and thesaurus approaches on one hand and deferring interpretation time of non-functional aspects of published service on the other hand. Moreover, the proposed framework does not try to decrease subjectivity of discovery/publication request and attempts to find the most matched service to consumer's subjective request by separately taking individual consumer's preferences into account.

Well adapted to the loosely coupled nature of distributed interaction in large-scale applications, the publish/subscribe communication paradigm has recently received increasing attention. With systems based on the publish/subscribe interaction scheme, subscribers register their interest in an event, or a pattern of events, and are subsequently asynchronously notified of events generated by publishers. Many variants of the paradigm have recently been proposed, each variant being specifically adapted to some given application or network model. This paper factors out the common denominator underlying these variants: full decoupling of the communicating entities in time, space, and synchronization. We use these three decoupling dimensions to better identify commonalities and divergences with traditional interaction paradigms. The many variations on the theme of publish/subscribe are classified and synthesized. In particular, their respective benefits and shortcomings are discussed both in terms of interfaces and implementations.

In this paper, we discuss one of the most important issues in Sensor-Grid, i.e., to develop a fast and flexible content-based publish/subscribe information dissemination (CBPSID) system for automatic fusion, interpretation, sharing and delivery of huge sensor data to consumers as the entire Sensor-Grid environment is very dynamic. Existing works to develop the CBPSID system in Sensor-Grid mostly focus on reducing the effort to define and maintain subscriptions and to handle the difficulty of dynamic changes of publishers and consumers data. However, the performance of a CBPSID system in Sensor-Grid is bounded by the expensive matching/evaluation cost of events. Existing event-matching algorithms are not very efficient, especially for interval range predicates or overlapping predicates in subscriptions which are practical in Sensor-Grid as well as other application areas. So in this paper we discuss the above challenge and propose a dynamic and fast event-matching algorithm called CGIM for the CBPSID system in Sensor-Grid. The algorithm supports range predicates or overlapping predicates very well and provides single and composite event matching. It uses two approaches, called SGIM and DGIM, to group the subscriptions by the predicates and dynamically identifies appropriate number of groups considering different statistical distributions of subscriptions at run time. Also, we present an experimental evaluation of the proposed algorithm in a Sensor-Grid based u-Healthcare scenario using synthetic workloads and compare its performance with existing algorithms. The experimental results show that our algorithm significantly reduces the evaluation cost (on average using SGIM by 79% and DGIM by 88%) comparing with others and guarantees the scalability with respect to the number of subscriptions as well as the number of predicates and events. In addition, further experiments were conducted by applying the CGIM algorithm in other application areas, e.g. in the publish/subscribe system for online job sites, to show its diverse utilization and scalability.

Online Social Networks (OSNs) are taking the world by storm and are urging the development of a new type of ad hoc networks that is Vehicular Social Networks (VSNs). The inclusion of social networks within vehicles has attracted researchers to devise social aware routing protocols and architectures in order to build vehicular social communities and to facilitate human interaction between commuters on the road. However, several issues defy the purpose of VSNs. This paper presents an analysis of the relevant work published in this growing new field, as well as an extension of our research work that tackles the problem of data dissemination in VSNs. We first summarize vehicular social architectures. Then we examine the main social properties of VANET drivers that contribute in the design of socially aware routing algorithms. Moreover, we discuss the open research challenges including privacy concerns. Finally, we present SocialDrive, an online social aware publish/subscribe strategy for vehicles transiting in platoons. We evaluate its performance and we show that it improves the quality of real time communication between commuters in dense networks.

The rapid development of Wireless Sensor Networks (WSN) technologies gave rise to the need for abstraction mechanisms that can simplify the data management tasks. Under this respect, the publish/subscribe paradigms play an important role since they can be used to abstract the WSN in terms that are closer to applicative needs. On the other hand, Data Centric Storage systems (DCS) can provide a low-level support to the implementation of publish/subscribe systems in WSN. In this paper we consider different implementations of publish/subscribe systems, based either on DCS or basic network primitives and we compare the resulting approaches in terms of functionalities and performance.

This paper defines and discusses the implementation of two novel extensions to the Siena Content-based Network (CBN) to extend it to become a Knowledge-based Network (KBN) thereby increasing the expressiveness and flexibility of its publications and subscription. One extension provides ontological concepts as an additional message attribute type, onto which subsumption relationships, equivalence, type queries and arbitrary ontological subscription filters can be applied. The second extension provides for a bag type to be used that allows bag equivalence, sub-bag and super-bag relationships to be used in subscription filters, possibly composed with any of the Siena subscription operators or the ontological operators previously mentioned. The performance of this KBN implementation has also been explored. However, to maintain scalability and performance it is important that these extensions do not break Siena's subscription aggregation algorithm. We also introduce the necessary covering relationships for the new types and operators and examine the subscription matching overhead resulting from these new types and operators.

Distributed content-based publish-subscribe is emerging as a communication paradigm able to meet the demands of highly dynamic distributed applications, e.g., those made popular by mobile computing and peer-to-peer networks. Nevertheless, the available systems implementing this communication model are unable to cope efficiently with dynamic changes to the topology of their distributed dispatching infrastructure, thus effectively hampering applicability in the aforementioned scenarios.

Quality-of-service (QoS)-enabled publish/subscribe (pub/sub) mid-dleware provides powerful support for scalable data dissemination. It is hard, however, to maintain specified QoS properties (such as reliability and latency) in dynamic environments (such as disas-ter relief operations or power grids). For example, managing QoS manually is often not feasible in dynamic systems due to (1) slow human response times, (2) the complexity of managing multiple in-terrelated QoS settings, and (3) the scale of the systems being man-aged. For certain applications the systems must be able to reflect on the conditions of their environment and adapt accordingly. Machine learning techniques provide a promising adaptation ap-proach to maintaining QoS properties of QoS-enabled pub/sub mid-dleware in dynamic environments. These techniques include deci-sion trees, neural networks, and linear logistic regression classifiers that can be trained on existing data to interpolate and extrapolate for new data...

Mission-critical, distributed systems are often designed as a set of distributed, components that interact using publish/subscribe middleware. Currently, in these systems, software components are usually statically allocated to the nodes to fulfil predictability, reliability requirements. However, a static allocation of components has major drawbacks, e.g. the need for quantification of the expenditure of resources to prevent a lack of resources during runtime. A dynamic allocation diminishes the drawbacks of a static allocation by reallocating components during system run-time. The process of dynamic reallocation is considered as a reconfiguration of the system, which can be implemented as an additional functionality of the middleware. In this paper, we propose a new dynamic reconfiguration service for a publish/subscribe middleware that enables dynamic reallocation of components in order to achieve predictable and reliable system behaviour and fulfil deployment requirements. We have built a prototype that validates our research.

In the information filtering (or publish/ subscribe) paradigm, clients subscribe to a server with continuous queries that express their information needs while information sources publish documents to servers. Whenever a document is published, the continuous queries satisfying this document are found and notifications are sent to appropriate subscribed clients. Although information filtering has been in the research agenda for about half a century, there is a huge paradox when it comes to benchmarking the performance of such systems. There is a striking lack of a benchmarking mechanism (in the form of a large-scale standarised test collection of continuous queries and the relevant document publications) specifically created for evaluating filtering tasks. This work aims at filling this gap by proposing a methodology for automatically creating massive continuous query datasets from available document collections. We intend to publicly release all related material (including the software accompanying the proposed methodology) to the research community after publication.

Internet of Things (IoT) application deployment requires the allocation of resources such as virtual machines, storage, and network elements that must be deployed over distinct infrastructures such as cloud computing, Cloud of Things (CoT), datacenters and backbone networks. For massive IoT data acquisition, a gateway-based data aggregation approach is commonly used featuring sensor/ actuator seamless access and providing cache/ buffering and preprocessing functionality. In this perspective , gateways acting as producers need to allocate network resources to send IoT data to consumers. In this paper, it is proposed a Publish/-Subscribe (PubSub) quality of service (QoS) aware framework (PSIoT-Orch) that orchestrates IoT traffic and allocates network resources between aggregates and consumers for massive IoT traffic. PSIoT-Orch schedules IoT data flows based on its configured QoS requirements. Additionally , the framework allocates network resources (LSP/ bandwidth) over a controlled backbone network with limited and constrained resources between IoT data users and consumers. Network resources are allocated using a Bandwidth Allocation Model (BAM) to achieve efficient network resource allocation for scheduled IoT data streams. PSIoT-Orch adopts an ICN (Information-Centric Network) PubSub architecture approach to handle IoT data transfers requests among framework components. The proposed framework aims at gathering the inherent advantages of an ICN-centric approach using a PubSub message scheme while allocating resources efficiently keeping QoS awareness and handling restricted network resources (bandwidth) for massive IoT traffic.

1 Secure media broadcast over the Internet poses unique security challenges. One important problem for public broadcast Location-Based Services (LBS) is to enforce access control on a large number of subscribers. In such a system a user typically subscribes to a LBS for a time interval (a, b) and a spatial region (x bl , y bl , xtr, ytr) according to a 3-dimensional spatial-temporal authorization model. In this paper, we argue that current approaches to access control using key management protocols are not scalable. Our proposal STauth minimizes the number of keys which needs to be distributed and is thus scalable to a large number of subscribers and the dimensionality of the authorization model. We also demonstrate applications of our algorithm to quantified-temporal access control (using ∀ and ∃ quantifications) and partial order tree based authorization models. We describe two implementations of our key management protocols on two diverse platforms: a broadcast service operating on top of a publish/subscribe infrastructure and an extension to Google maps API to support quality (resolution) based access control. We analytically and experimentally show that the performance and scalability benefits of our approach over traditional key management approaches.

The MObile Teamwork Infrastructure for Organizations Networking (MOTION) 1 service platform that we have designed and implemented addresses an emerging requirement in the daily business of large, distributed enterprises: support for mobile teamwork. Employees are often on the move and use a wide range of computing devices such as WAP phones, PDAs, notebooks and desktop computers. The service architecture that we have developed supports mobile teamwork by providing multi-device service access, XML meta data for information sharing and locating, and the XML Query Language (XQL) for distributed searches and publish/subscribe. We present the solution that we adopted in our prototype, analyze the shortcomings of this approach and based on our evaluation experiences, list the requirements for a publish-subscribe middleware for collaborative mobile working.

Publish/subscribe is considered one of the most important interaction styles for the explosive market of enterprise application integration. Producers publish information on a software bus and consumers subscribe to the information they want to receive from that bus. The decoupling nature of the interaction between the publishers and the subscribers is not only important for enterprise computing products but also for many emerging e-commerce and telecommunication applications. It is often claimed that object-orientation is inherently incompatible with the publish/subscribe interaction style. This flawed argument is due to the persistent confusion between object-orientation as a modeling discipline and the specific request/reply mechanism promoted by CORBA-like middleware systems. This paper describes object-oriented abstractions for publish/subscribe interaction in the form of Distributed Asynchronous Collections (DACs). DACs are general enough to capture the commonalities of various publish/subscribe styles, and flexible enough to allow the exploitation of the differences between these styles. This paper presents Distributed Asynchronous Collections (DACs): object-oriented abstractions for expressing the many diverging publish/subscribe interaction styles.