Load-balancing data distribution in publish/subscribe mode

To improve data distribution efficiency a load-balancing data distribution LBDD method is proposed in publish/subscribe mode.In the LBDD method subscribers are involved in distribution tasks and data transfers while receiving data themselves.A dissemination tree is constructed among the subscribers based on MD5 where the publisher acts as the root. The proposed method provides bucket construction target selection and path updates furthermore the property of one-way dissemination is proven.That the average out-going degree of a node is 2 is guaranteed with the proposed LBDD.The experiments on data distribution delay data distribution rate and load distribution are conducted. Experimental results show that the LBDD method aids in shaping the task load between the publisher and subscribers and outperforms the point-to-point approach.

An SDN-Based Publish/Subscribe-Enabled Communication Platform for IoT Services

Publish/subscribe paradigm paves a way to integrate and serve many scalable, inter-operable Internet of Things(IoT) applications. The increasing IoT applications require new properties of publish/subscribe communication model, for example, strict quality of service(Qo S) guarantees, supporting a large number of widely distributed devices, etc. Software Defined Networking(SDN) enables personalized programming and individualized QoS supports for different applications. The combination of the two will have a good prospect. In this paper, we present an IoT-oriented communication platform which combines the publish/subscribe paradigm with SDN, aiming at establishing an IoT ecosystem to facilitate IoT services/applications accessing internet. We design the interaction logic of topic-based publish/subscribe middleware, and describe the setup and maintenance of topology information as well as event routing in detail, considering the characteristics of SDN. Finally, we exemplify its practicability with a deployed District Heating Control and Information Service System(DHCISS) and validity the effectiveness with some experiments.

Cross-Layer QoS Enabled SDN-Like Publish/Subscribe Communication Infrastructure for IoT

Publish/subscribe paradigm is often adopted to create the communication infrastructure of the Internet of Things(IoT)for many clients to access enormous real-time sensor data.However,most current publish/subscribe middlewares are based on traditional ossified IP networks,which are difficult to enable Quality of Service(QoS).How to design the next generation publish/subscribe middleware has become an urgent problem.The emerging Software Defined Networking(SDN)provides new opportunities to improve the QoS of publish/subscribe facilities for delivering events in IoT owing to its customized programmability and centralized control.We can encode event topics,priorities and security policies into flow entries of SDN-enabled switches to satisfy personalized QoS needs.In this paper,we propose a cross-layer QoS enabled SDN-like publish/subscribe communication infrastructure,aiming at building an IoT platform to seamlessly connect IoT services with SDN networks and improving the QoS of delivering events.We first present an SDN-like topic-oriented publish/subscribe middleware architecture with a cross-layer QoS control framework.Then we discuss prototype implementation,including topic management,topology maintenance,event routing and policy management.In the end,we use differentiated services and cross-layer access control as cross-layer QoS scenarios to verify the prototype.Experimental results show that our middleware is effective.

Providing Delay-Guaranteed Multicast Transmission Services for an SDN-Based Publish/Subscribe System

Providing end-to-end delay guarantees in traditional Internet is a complex task due to the distributed nature of TCP/IP protocols. Software Defined Networking(SDN) gives a new dimension to improve QoS(Quality of Service) as it can benefit from its flexibility, programmability and centralized view. In this paper, we provide delay-guaranteed data transmission service instead of "best efforts" service for a topic-based publish/subscribe system by means of exploring these specific features of SDN. We attribute this routing problem in such conditions to Delay-Constraint Lowest Cost Steiner Tree(DCLCST) problem. To solve it, we compute the shortest delay paths from source node to every subscribe node and the shortest cost paths from every subscribe node to any other node using dijkstra algorithm. Then we construct a delay-constraint least cost steiner tree for per-topic based on these paths as multicast tree. We also present experimental results to demonstrate the effectiveness of the algorithms and methods we proposed.

Embedding Authentication &Authorization in Discovery Protocols for Standard Based Publish/Subscribe Middleware: A Performance Evaluation

Standard based Pub/Sub middleware, such as OMG Data Distribution Service (DDS), could assume a key role in supporting computer communications requiring continuous state information updating, deterministic deadline to data delivering and real time information adjourning. This kind of capability could be well ex-ploited by Peer-To-Peer (P2P) systems, Internet-wide as long as private ones, like in Public Safety or Civil Protection Communication Systems;but Pub/Sub specifications, and DDS/RTPS (Real Time Publish Sub-scribe) as well, usually do not provide Authentication & Authorization (AA) mechanisms. In the present work two important novelties are assessed: a possible scheme to implement AA in DDS/RTPS networks and a time performance evaluation study about embedded Authentication in RTPS.

A Real-Time-Enabled, Blackboard-Based, Publish/Subscribe Architecture for Wireless Sensor Nodes

Wireless sensor network nodes have only limited resources concerning memory and battery life-time. Mem- ory can be efficiently used by sharing data, and the life-time of a battery can be extended, when the node has long power saving sleep-phases. We propose a publish/subscribe architecture that achieves these two aims. The results of our work are of great interest for sensor application developers, giving them now the opportu- nity to use our architecture for sharing data among different applications on the node as well as the different layers of the operating system. We introduce a blackboard which is used for centrally storing published val- ues, like measured data from a monitored sensor. This makes it possible to share stored data without monitoring the sensors once again, which is advantageously concerning power consumption, memory space, and reaction time. Beside the proposed publish/subscribe method for sensor nodes with its notification possibili- ties, our architecture fulfills also real-time requirements. We show how the well-known sensor operating system MANTIS OS can be extended by a real-time enabled, blackboard-based publish/subscribe architect- ture. This architecture and first of all its implementation is of special interest for cross layer optimization of sensor applications. Cross-layer approaches benefit from our architecture because the available implementa- tion can be used as an efficient framework for central storing and managing of shared values.

Research of Publish and Subscribe Model Based on WS-Notification

WS-Notification bundle of standards, WS-BaseNotification, WS-Topics, and WS-BrokeredNotification, can be used as a general purpose publish/subscribe interface for Service Oriented Architectures. We provide an overview of the WS-Notification specification and describe a modified publish and subscribe model based on WS-Notification. The model is an adaptive policy-driven notification framework that can help enterprises to meet the flexibility and respon-siveness requirements of the enterprise. With the modified publish/subscribe model, information consumers can dy-namically and declaratively create and configure entities on their behalves to manage their distribution requirements.

基于LCM的分布式嵌入式消息通信中间件设计

为了满足工业控制计算机在野外作业装备的分布式嵌入式系统任务迁移需求,设计了一种网络通信中间件方案。基于LCM的发布订阅模式框架以及中心节点的消息通信中间件,从而强化了LCMLite的多线程处理能力和消息通信中间件功能。该中间件能够促进任务迁移过程中各参与方之间的互动流程,并解决应用任务迁移后的网络通信续接和消息丢失问题。据测试结果,对于需要处理大量消息流量的场景,该网络通信中间件在消息传输方面的时间消耗非常少。

一种基于语义的P2P网格资源发现模型

网格环境中资源的有效管理和发现在网格研究中占有十分重要的地位。文章提出了一种基于语义和P2P技术的新的网格资源发现模型——Semantic-basedPeertoPeerGrid(简称SPTOPGrid)。该模型采用P2P技术进行资源检索,每个peer节点都能提供资源描述和某个知识领域的本体库(ontology);采用publish/subscribe模式进行资源分发;利用语义知识库进行资源的匹配,进行智能化的资源搜索,能够适应网格资源的复杂性、异构性和动态性,具有良好的扩展性。

Modelling and Verification of Real-Time Publish and Subscribe Protocol Using UPPAAL and Simulink/Stateflow

Real-Time Publish and Subscribe (RTPS) protocol is a protocol for implementing message exchange over an unreliable transport in data distribution service (DDS). Formal modelling and verification of the protocol provide stronger guarantees of its correctness and efficiency than testing alone. In this paper, we build formal models for the RTPS protocol using UPPAAL and Simulink/Stateflow. Modelling using Simulink/Stateflow allows analyzing the protocol through simula-tion, as well as generate executable code. Modelling using UPPAAL allows us to verify properties of the model stated in TCTL (Timed Computation Tree Logic), as well as estimate its performance using statistical model checking. We further describe a procedure for translation from Stateflow to timed automata, where a subset of major features in Stateflow is supported, and prove the soundness statement that the Stateflow model is a refinement of the translated timed automata model. As a consequence, any property in a certain fragment of TCTL that we have verified for the timed automata model in UPPAAL is preserved for the original Stateflow model.

SecSPS: A Secure and Privacy-Preserving Framework for Smart Parking Systems

Smart parking systems are a crucial component of the “smart city” concept, especially in the age of the Internet of Things (IoT). They aim to take the stress out of finding a vacant parking spot in city centers, due to the increasing number of cars, especially during peak hours. To realize the concept of smart parking, IoT-enabling technologies must be utilized, as the traditional way of developing smart parking solutions entails a lack of scalability, compatibility with IoT-constrained devices, security, and privacy awareness. In this paper, we propose a secure and privacy-preserving framework for smart parking systems. The framework relies on the publish/subscribe communication model for exchanging a huge volume of data with a large number of clients. On one hand, it provides functional services, including parking vacancy detection, real-time information for drivers about parking availability, driver guidance, and parking reservation. On the other hand, it provides security approaches on both the network and application layers. In addition, it supports mutual authentication mechanisms between entities to ensure device/ data authenticity, and provide security protection for users. That makes our proposed framework resilient to various types of security attacks, such as replay, phishing, and man-in-the-middle attacks. Finally, we analyze the performance of our framework, which is suitable for IoT devices, in terms of computation and network overhead.

Energy-Efficient Content-Based Routing in Internet of Things

The?convergence of the Internet, sensor networks, and Radio Frequency Identification (RFID) systems has ushered to the concept of Internet of Things (IoT) which is capable of connecting daily things, making them smart through sensing, reasoning, and cooperating with other things. Further, RFID technology enables tracking of an object and assigning it a unique ID. IoT has the potential for a wide range of applications relating to healthcare, environment, transportation, cities… Moreover, the middleware is a basic component in the IoT architecture. It handles heterogeneity issues among IoT devices and provides a common framework for communication. More recently, the interest has focusing on developing publish/subscribe middleware systems for the IoT to allow asynchronous communication between the IoT devices. The scope of our paper is to study routing protocols for publish/subscribe schemes that include content and context-based routing. We propose an Energy-Efficient Content-Based Routing (EECBR) protocol for the IoT that minimizes the energy consumption. The proposed algorithm makes use of a virtual topology that is constructed in a centralized manner and then routes the events from the publishers to the intended interested subscribers in a distributed manner. EECBR has been simulated using Omnet++. The simulation results show that EECBR has a significant performance in term of the energy variance compared to the other schemes.

An Authentication Method of Distinguishing Proxy's Secure Accident Responsibility

The publish/subscribe （pub/sub） paradigm has asynchronous, loosely-coupled and many-to-many communication properties and is widely used in the application of large-scale distributed computing environment. There is the problem that is mutual trustable between network proxies in terms of pub/sub systems and the problem which is hardly to distinguish accident responsibility while the accident happens in Kerberos based on symmetrical encryption algorithm. A proxy identity authentication algorithm based on RSA encryption is proposed to solve the problem of mutual trust between proxies, and the security of the messages is guaranteed through certificate delegation. The algorithm can distinguish accident responsibility. The feasibility analysis, security analysis and efficiency analysis of the algorithm are carried out.

Establishment of the Secure Channel between Broker Nodes in Pub/Sub System

The paper mainly discusses the integrity of the forwarded subscription message guaranteed by secure channel which encrypted in data communication by using data encryption standard （DES） algorithm and chaos code algorithm between broker nodes in the routing process of the contentbased publish/subscribe system. It analyzes the security of the secure channel encrypted with data communication by DES algorithm and chaos code algorithm, and finds out the secure channel can be easily attacked by known plain text. Therefore, the paper proposes the improved algorithm of message encryption and authentication, combining encryption and the generation of the message authentication code together to finish scanning at one time, which enhances both the secure degree and running efficiency. This secure channel system has a certain reference value to the pub/sub system requiring highly communication security.

HHR:Hierarchical Hybrid Routing Scheme for Information-Centric Network

Publish/subscribe(pub/sub) paradigm is the main communication model for Information-Centric Network(ICN) proposals.A key issue for pub/sub system is how to route the content objects to the correct subscribers,and ICN is no exception.ICN network would be divided into core domain and many edge domains as today's internet does.HHR(Hierarchy Hybrid Routing scheme) is presented for ICN:A Chord-like routing scheme is used in core domain,while edge domains routing structure can be classified into three categories,Local Routing(LR),Delivery of Local Publication to Core domain(DLPC),and Remote Publication Routing into edge domain(RPR).LR can be decided by each edge domain,which determined by many factors,such as locality characteristic for pub/sub information and local policies.A hierarchical routing algorithm is proposed to solve DLPC and RPR simultaneously.Simulation results demonstrate that HHR can be fast deployed,and can be applied in large scale network or dynamic subscription environment.

Publish/subscribe based information dissemination over VANET utilizing DHT

A vehicular ad-hoc network （VANET） can be visualized as a network of moving vehicles communicating in an asynchronous and autonomous fashion. Efficient and scalable information dissemination in VANET applications is a major challenge due to the movement of vehicles which causes unpredictable changes in network topology. The publish/subscribe communication paradigm provides decoupling in time, space, and synchronization between communicating entities, and presents itself as an elegant solution for information dissemination for VANET like environments. In this paper, we propose our approach for information dissemination which utilizes publish/subscribe and distributed hash table （DHT） based overlay networks. In our approach, we assume a hybrid VANET consisting of stationary info-stations and moving vehicles. These info-stations are installed at every major intersection of the city and vehicles can take the role of publisher, subscriber, or broker depending upon the context. The info-stations form a DHT based broker overlay among themselves and act as rendezvous points for related publications and subscriptions. Further, info-stations also assist in locating vehicles that have subscribed to information items. We consider different possible deployments of this hybrid VANET with respect to the number of info-stations and their physical connectivity with each other. We perform simulations to assess the performance of our approach in these different deployment scenarios and discuss their applicability in urban and semi-urban areas.

Towards delivery of situational information in distributed environments

In the distributed environment,robots should be able to provide users with adaptive services automatically according to the situational information changing dynamically which is obtained from both users and their environments.The workflow depends on situational information obtained from physical environments and provides context-aware services automatically based on the information retrieved.And the workflow in the business processes and the distributed computing environments have supported the automation of services by connecting tasks.The workflow needs to specify ubiquitous situational information as state-transition constraints.However,the delivery and use of sensor data in the workflow is a difficult problem for the robot system.In order to bridge the gap between applications and low-level constructs and to acquire raw situational information for the execution of the context-aware workflow in the robot systems,this paper presents an approach which can achieve the sensor data transmission between a sensing server and a robot system easily.

MQTT and blockchain sharding:An approach to user-controlled data access with improved security and efficiency

The rapid growth of the Internet of Things(IoT)has raised security concerns,including MQTT protocol-based applications that lack built-in security features and rely on resource-intensive Transport Layer Security(TLS)protocols.This paper presents an approach that utilizes blockchain technology to enhance the security of MQTT communication while maintaining efficiency.This approach involves using blockchain sharding,which enables higher scalability,improved performance,and reduced computational overhead compared to traditional blockchain approaches,making it well-suited for resource-constrained IoT environments.This approach leverages Ethereum blockchain’s smart contract mechanism to ensure trust,accountability,and user privacy.Specifically,we introduce a shard-based consensus mechanism that enables improved security while minimizing computational overhead.We also provide a user-controlled and secured algorithm using Proof-of-Access implementation to decentralize user access control to data stored in the blockchain network.The proposed approach is analyzed for usability,including metrics such as bandwidth consumption,CPU usage,memory usage,delay,access time,storage time,and jitter,which are essential for IoT application requirements.The analysis demonstrated that the approach reduces resource consumption,and the proposed system outperforms TLS and existing blockchain approaches in these metrics,regardless of the choice of the MQTT broker.Additionally,thoroughly addressing future research directions,including issues and challenges,ensures careful consideration of potential advancements in this domain.

An MID-Based Load Balancing Approach for Topic-Based Pub-Sub Overlay Construction

A large proportion of Internet of Things （loT） applications are internally publish/subscribe in nature, and traditional architecture cannot support them efficiently and flexibly. In essence, supporting efficient publish/subscribe systems requires data-oriented naming and efficient multicast. Since deployment of native IP-based multicast has failed, overlay-based multicast has become the practical choice. Since load balancing between heterogeneous nodes is an important issue, designing an optimal load balancing overlay net- work for publish/subscribe systems is a necessary endeavor. This study focuses on the optimal load balancing overlay design problem for topic-based publish/subscribe systems in a heterogeneous environment （in terms of node processing power, bandwidth, and reachability）. The Minimum Idle Degree （MID） model is introduced to capture the heterogeneity of overlay nodes. Based on the MID model, new node load measures are defined that can accommodate heterogeneous server capacities and capture the node load in publish/subscribe systems more accurately than traditional measures. A new optimization problem, Maximum Minimum Idle Degree Topic-Connected Overlay （MMID-TCO）, is established. This problem is NP-complete and a constant approximation algorithm does not exist for this problem （unless P=NP）. Based on MID metrics, the Maximum Minimum Idle Degree Overlay Design Algorithm （MMID-ODA）, which has polynomial time is introduced. To improve performance, an approach that breaks down the problem into several small-scale problems by exploiting the potential inherent disjoint characteristic in the subscription table is presented. Simulation results show that the proposed algorithm is able to achieve better load balance than MinMax-ODA in a heterogeneous environment.

Covering-Based Routing Algorithms for Cyclic Content-Based P/S Overlays

Content-based routing（CBR） publish/subscribe（P/S） system is an important class of distributed systems.This system differs from classical paradigms as messages are routed based on their content rather than their destination address,so as to provide a fine-granularity event dissemination,and support more flexibility decoupling applications.Covering-based routing is a typical optimization method of CBR and has been widely used as a building block in many distributed P/S systems,for it maintains a compact routing table and reduces the costs of communications and matching computations.So far as we know,this optimization method can only be implemented on acyclic overlay network,but cannot be directly utilized on cyclic networks.As the CBR in cyclic systems becomes a new focus of research,developing covering-based protocols and algorithms for cyclic P/S system is becoming significantly important.This paper contributes the cyclic covering-based routing protocol with corresponding algorithms to support covering-based protocol in cyclic P/S system,and implements it in PADRES,a distributed event management infrastructure based on the publish/subscribe model.