Publish-subscribe Architecture Research Articles

Agent-Based Coordinated Control of Power Electronic Converters in a Microgrid

This paper presents the implementation of an agent-based architecture suitable for the coordination of power electronic converters in stand-alone microgrids. To this end, a publish-subscribe agent architecture was utilized as a distributed microgrid control platform. Over a distributed hash table (DHT) searching overlay, the publish-subscribe architecture was identified based on a numerical analysis as a scalable agent-based technology for the distributed real-time coordination of power converters in microgrids. The developed framework was set up to deploy power-sharing distributed optimization algorithms while keeping a deterministic time period of a few tens of milliseconds for a system with tens of converters and when multiple events might happen concurrently. Several agents participate in supervisory control to regulate optimum power-sharing for the converters. To test the design, a notional shipboard system, including several converters, was used as a case study. Results of implementing the agent-based publish-subscribe control system using the Java Agent Development Framework (JADE) are presented.

Constrained Optimization of Multicast Routing for Wide Area Control of Smart Grid

Wide area control (WAC) is highly desirable for maintaining the stability of large-scale smart grid. It requires the support of real-time data communications with low latency, which leads to the consideration of the multicast technique for routing of data packets of various measurements, control signals, and commands. While the feasibility of multicast in WAC communications has been investigated, there is a lack of a general framework to formulate and solve the multicast routing problem, particularly for WAC. To tackle this problem, this paper presents a systematic approach to constrained optimization of multicast routing in WAC over wide area networks (WANs) with a publish-subscribe architecture. To fulfil the requirements of real-time WAC communications, the optimization is formulated to minimize the end-to-end delay over WANs subject to bandwidth constraints. Then, the constrained optimization is solved theoretically by using Lagrangian Relaxation. The theoretic results are implemented in an iterative bandwidth-constrained minimum Steiner tree algorithm. Simulations are conducted to demonstrate the approach presented in this paper.

Connected-Vehicle Data Exchanges and Positioning Computing Based on the Publish-Subscribe Paradigm

Connected vehicles for safety and traffic efficient applications require device-to-device connections supporting one-to-many and many-to-many communication, precise absolute and relative positioning and distributed computing. Currently, the 5.9 GHz Dedicated Short Range Communications (DSRC) and 4G-Long-Term Evolution (LTE) are available for connected vehicle services. But both have limitations in reliability or latency over large scale field operational tests and deployment. This paper proposes the device-to-device (D2D) connectivity framework based on publish-subscribe architecture, with Message Queue Telemetry Transport (MQTT) protocol. With the publish-subscribe communication paradigm, road mobile users can exchange data and information in moderate latency and high reliability manner, having the potential to support many Vehicle to Everything (V2X) applications, including vehicle to vehicle (V2V), vehicle to roadside infrastructure (V2I), and vehicle to bicycle (V2B). The D2D data exchanges also facilitate computing for absolute and relative precise real-time kinematic (RTK) posi-tioning. Vehicular experiments were conducted to evaluate the performance of the proposed publish-subscribe MQTT protocols in term of latency and reliability. The latency of data exchanges is measured by One-trip-time (OTT) and the reliability is measured by the packet loss rate (PLR). Our results show that the latency of GNSS raw data exchanges between vehicles through 4G cellular networks at the rate of 10 Hz and the data rates of 10 kbps are less than 300 ms while the reliability is over 96%. Vehicular positioning experiments have also shown that vehicles can exchange raw GNSS data and complete mov-ing-base RTK positioning with the positioning availability of 98%.

Storage management in DONA content routers

Information-centric networking (ICN) as an emerging paradigm for the future introduces a radical change in internet communications. It allows information access regardless of their location and it defines innovative concepts such as forwarding, name-based routing, security and caching. Many ICN architectures have been proposed over the past few years such as DONA, NetInf, CCN, NDN, publish-subscribe architecture, etc. In this paper, we focus especially on DONA, one of the first ICN architecture, and we analyse the required memory space to store routing states. Our study shows that today's technologies are not able to satisfy the content routing needs. Thus, we propose an enhancement of DONA called BADONA to deal with this problem. It uses the Bloom filter to drastically reduce the usage of the memory space. We evaluate our proposal performances and compare it with two ICN solutions: CCN and DHTChord to find out how these models scale when they are deployed over large networks. The obtained simulation results show that our solution reduces considerably the memory usage, and the decreasing ratio reaches the value of 40 with the standard Bloom filter version. Moreover, BADONA outperforms the other existing schemes.

Design and Implementation of a Hardware Versatile Publish-Subscribe Architecture for the Internet of Things

A variety of contemporary technologies are being framed within the Internet of Things (IoT) architecture, including publish/subscribe (pub/sub) systems. In IoT, things, such as objects, machines, vehicles, and wireless sensors, have to communicate with other things or humans and exchange information based on Internet connectivity. With the integration of pub/sub mechanism with IoT, these things can “publish” their presence to a specific node, which can be named a broker or router, while things that “subscribe” to that node are able to receive information based on publishers’ content. In order to perceive a sound and efficient pub/sub structure in IoT, high performance processing and interoperability are valid requirements. This paper presents a versatile architecture of a broker, named X2CBBR, that can operate in IoT with different pub/sub systems. X2CBBR: 1) adopts XML-based publication data and XPath-based subscription data to yield interoperability; 2) processes both XML data and XPath queries in hardware (instead of software) to boost processing performance; 3) employs a hardware-based matching mechanism that exploits subscription commonalities; and 4) makes use of four different operation modes as a method for accepting or limiting acceptance of either publications or subscriptions. While maintaining the total decoupling feature between publishers and subscribers, the broker switches from an operation mode to another to keep traffic under control. Moreover, its content-based routing mechanism avoids redundant subscription and notification data. Finally, the broker can effectively operate in either centralized or distributed systems. The results obtained through a prototype hardware implementation targeting an FPGA demonstrate the high-efficiency of the broker/router in multiple scenarios.

Architecting Feasible Deployment Alternatives for Publish-Subscribe Systems

Publish-Subscribe is one of the important patterns for developing scalable distributed systems. Usually, the deployment of the publishers and subscribers to the nodes can be done in many different ways, whereby each deployment alternative will have a different impact on the performance. The many possible architecture design alternatives tend to trade-off with respect to execution cost and communication cost. Unfortunately, for the human engineer it is not tractable to define a feasible configuration in case of large number of nodes and participants. In this paper we propose a generic method to assist the architect by automatically deriving feasible deployment alternatives of Publish-Subscribe based distributed systems. The approach is based on the so-called capacitated task allocation problem (CTAP) in which constraints on memory capacity and processing power are applied to manage the trade-offs between the total execution cost and total communication cost to derive feasible design alternatives. The method is supported by our tool framework (Deploy-PS) that provides an integrated development environment for modeling the Publish-Subscribe deployment architecture, modeling the physical resources and the performance requirements, and the selection and generation of the feasible deployment architecture alternatives.

The Design of Real-time Transmission

Some network services, such as Vehicle tele-operations, remote monitor requires time critical services. The publish-subscribe architecture has been designed to provide message transmission task. The paper presents a publish-subscribe communication model with QoS parameter indicator. The fair scheduling strategy guarantees the real-time service. The implementation of real-time publish-subscribe communication protocol is built on the top of standard UDP stack. It offers practical advantages for applications with time-critical data flows, which can provide control of timing requirement and reliability.

A Semantic Publish-Subscribe Architecture for the Internet of Things

This paper presents a publish-subscribe architecture designed to support information level interoperability in smart space applications in the Internet of Things (IoT). The architecture is built on top of a generic SPARQL endpoint where publishers and subscribers use standard SPARQL Updates and Queries. Notifications about events [i.e., changes in the resource description framework (RDF) knowledge base] are expressed in terms of added and removed SPARQL binding results since the previous notification, limiting the network overhead and facilitating notification processing at subscriber side. A novel event detection algorithm, tailored on the IoT specificities (i.e., heterogeneous events need to be detected and continuous updates of few RDF triples dominate with respect to more complex updates), is presented along with the envisioned application design pattern and performance evaluation model. Eventually, a reference implementation is evaluated against a benchmark inspired by a smart city lighting case. The performance evaluation results show the capability to process up to 68k subscriptions/s triggered by simple single-lamp updates and up to 3.8k subscriptions/s triggered by more complex updates (i.e., 10 to 100 lamps).

Publish-Subscribe Architecture for Delivering Assistance to Visually Impaired People

Visually impaired people face many difficulties in everyday tasks. In this paper we present a distributed architecture for delivering Assistive Technologies that can help a user in such tasks. The architecture allows a user using a internet enabled device to send images, video and GPS location to remote “Helpers” that can send messages back with helpful instructions or tips. The Helpers can be programs running on a remote server or real people invited by the user. The architecture is based on a publish-subscribe paradigm using MQTT protocol. A system, based on the proposed architecture, was implemented with a collision detector, a scene classifier and a object recognized. A qualitative analysis of experiments have shown positive results and pointed out some improvements.

MOOS-IvP를 이용한 무인잠수정 제어기 개발의 효용성

This paper demonstrates the benefit of using MOOS-IvP in the development of control system for Unmanned Underwater Vehicles(UUV). The demand for autonomy in UUVs has significantly increased due to the complexity in missions to be performed. Furthermore, the increased number of sensors and actuators that are interconnected through a network has introduced a need for a middleware platform for UUVs. In this context, MOOS-IvP, which is an open source software architecture, has been developed by several researchers from MIT, Oxford University, and NUWC. The MOOS software is a communication middleware based on the publish-subscribe architecture allowing each application to communicate through a MOOS database. The IvP Helm, which is one of the MOOS modules, publishes vehicle commands using multi-objective optimization in order to implement autonomous decision making. This paper explores the benefit of MOOS-IvP in the development of control software for UUVs by using a case study with an auto depth control system based on self-organizing fuzzy logic control. The simulation results show that the design and verification of UUV control software based on MOOS-IvP can be carried out quickly and efficiently thanks to the reuse of source codes, modular-based architecture, and the high level of scalability.

An DDS based Architecture in Supporting of Data Centric Wireless Sensor Network Environments

Wireless sensor networks (WSNs) have emerged as one of the most promising technology to provide a wide variety of industrial applications. However, it is still failing to respond in a timely fashion service. In contrast to existing studies, we propose a more practical standard known as Data Distribution Service (DDS), as a middleware standard for interoperable Data Centric Publish-Subscribe (DCPS) architecture with real-time data distribution capabilities, and a candidate for standards based realizations of equally data centric WSN environments. Especially, this paper aims to evaluate on customized design features for real-time WSNs of an applicable and supportive architecture of DDS-based middleware. In the meantime, to integrate the underlying heterogeneous WSN and DDS, a supportive wireless protocol design is required and, thus, those features could be taken into account in designing the protocol.

Manufacturing Systems Integration Using Real Time QoS-Aware Middleware

In recent years, there has been a growth in the amount of data used to improve the production processes. As a result, the cross communication and interaction between components has increased and became a key property of modern production system. To reduce the cost of communication and to increase the efficiency of these systems, middleware technology such as CORBA, COM+, Java RMI, and Web services are being used. Middleware is becoming more and more the essential factor in improving current Manufacturing Process Automation and Control Systems, and their applications have witnessed an increased demand in real time Manufacturing Distributed Applications. In this paper, we propose publish-subscribe middleware architecture based on the Data Distribution System (DDS) open standard. The proposed architecture aims to seamlessly integrate the existing heterogeneous manufacturing systems, such as SCADA system, DCS, PLCs, and databases; and improve the communication and real time data delivery among system components; also, it provides a QoS support layer between the communicating components. Furthermore, the proposed architecture is implemented and evaluated by intensive experiments.

A publish-subscribe architecture and component-based programming model for medical device interoperability

Medical devices historically have been monolithic units --- developed, validated, and approved by regulatory authorities as standalone entities. Modern medical devices increasingly incorporate connectivity mechanisms that offer the potential to stream device data into electronic health records, integrate information from multiple devices into single customizable displays, and coordinate the actions of groups of cooperating devices to realize "closed loop" scenarios and automate clinical workflows. In this paper, we describe a publish-subscribe architecture for medical device integration based on the Java Messaging Service. We provide a overview of a model-based development environment that we have built for rapidly programming device coordination scenarios. We assess the extent to which this framework is capable of supporting and complementing the Integrated Clinical Environment that has been proposed by the Medical Device Plug and Play Interoperability Project The implementation of this framework is freely available and open source. One of the primary goals of the framework is to provide researchers in acadaemia, industry, and government with an open test bed for exploring development, quality assurance, and regulatory issues related to medical device interoperability.

Karma2

The increasing ability for the sciences to sense the world around us is resulting in a growing need for datadriven e-Science applications that are under the control of workflows composed of services on the Grid. The focus of our work is on provenance collection for these workflows that are necessary to validate the workflow and to determine quality of generated data products. The challenge we address is to record uniform and usable provenance metadata that meets the domain needs while minimizing the modification burden on the service authors and the performance overhead on the workflow engine and the services. The framework is based on generating discrete provenance activities during the lifecycle of a workflow execution that can be aggregated to form complex data and process provenance graphs that can span across workflows. The implementation uses a loosely coupled publish-subscribe architecture for propagating these activities, and the capabilities of the system satisfy the needs of detailed provenance collection. A performance evaluation of a prototype finds a minimal performance overhead (in the range of 1% for an eight-service workflow using 271 data products).