J2EE中间件的开发与应用

在黑龙江联通大客户管理系统中，如何将现在和未来的业务逻辑转换成通用或专用的J2EE中间件是一个很棘手的问题。因此，一些用JavaBean，KJB，TagLib，JDBC技术开发的中间件便应运而生。本文通过介绍与大客户系统有相似业务概念的用户回访系统的设计实现．说明中间件的通用性设计的重要性及优点。     

基于中间件的运行时监测与分析框架

运行时刻软件的监测与分析不仅可以提高软件质量,也是软件自适应性的基础.本文提出了基于模式的声明式约束描述方法,以此为基础,在J2EE中间件PKUAS上开发了运行时监测与分析框架,其最大的特点是探针的灵活部署和监测面向业务逻辑的约束.最后,阐述了框架的实现和相关实验的效果.     

多种措施为机关网络护航

这天，大家都正常上班，网管值班人员按常规检查机房各个服务器是否工作正常。碰巧，在检查过程中发现有台业务应用服务器的某关键应用程序没有开启，这将直接导致全省系统内无法访问该服务器——该关键业务应用瘫痪。经过仔细检查，发现该服务器的相关中间件（WebSphere）以及数据库（Oracle）莫名的丢失了，这直接导致业务应用程序无法启动，并造成部分数据丢失。     

基于J2EE架构的企业应用集成中EJB组件的开发

EJB是实现J2EE架构业务逻辑层商务功能的可重用组件。首先详细介绍了企业应用集成中的几个基本概念，如软件架构的多层C／S模式、J2EE架构、J2EE架构中的EJB组件等。给出了EJB组件的开发示例。最后指出用EJB组件实现J2EE架构中的业务逻辑层具有简单易行安全高效的特点。     

MVC和UML在教学管理系统中的研究与应用

MVC(模型-视图-控制器)是一种优秀的编程模型,它可以把用户界面设计、流程控制和事务逻辑进行分离。文中结合南京邮电大学教学平台建设的实践,研究了MVC模式和UML(统一建模语言)在教学管理系统中应用,探索了一种把MVC和UML相结合的方法,提出了基于多层网络应用框架的教学管理系统,即客户应用层、J2EE(Java 2平台企业版)服务器中W eb处理层、J2EE服务器中处理各种复杂教学事务的业务逻辑层、存储数据和文件的企业信息层。其中,业务逻辑层是整个系统的重点,它包含6个EJB(企业Java组件)。实践表明,这种多层结构的软件系统有着良好的推广价值和应用前景。     

RFID中间件系统关键模块的设计与实现

在分析RFID中间件系统功能的基础上,阐述了基于J2EE技术的RFID中间件系统的构建方法,介绍了系统结构和软件设计.提出了RFID中间件系统中关键模块的一种设计思想和实现方法,充分体现了JAVA2企业版分布式计算平台的优越性.     

SOA架构下基于JBI的企业服务总线技术

针对目前J2EE应用服务器只能基于自身特定的传输协议接收和处理消息,不同的J2EE容器之间很难相互通信的现状,提出在面向服务架构（SOA）T,基于Java业务集成（JBI）架构思想,通过配置可插拔的方式实现一种将不同类型的服务集成起来的全新J2EE容器,同时采用完全实现JBI标准的ServiceMix开源项目,作为企业服务总线（ESB）实现Java业务集成。     

网络化教学系统的设计

本文开发了一个基于J2EE规范的面向教学培训的通用系统,展示了基于Struts框架结构的表现页面,探讨了基于Spring和Struts的集成结合的业务逻辑表现。使用J2EE框絮技术可以减少重复代码的使用,提高系统的可扩展性,由于实现了框架与业务逻辑之间的松耦合,提高了其通用性。     

ECS业务监测系统的快速构建

电子渠道系统拥有宽泛、复杂的业务范围,需要相应的业务监测系统作为支撑,以确定软硬件系统、服务器及各种业务的状态,完成用户交互和业务处理.本文结合中国联通ECS的业务监测需求,提出了一种结合开源搜索引擎、插件和J2EE架构的快速构建系统方案,并开发了以数据采集为基础,实现综合监测、业务系统监测和日志监测的交费充值业务可视化监测系统.该系统容易部署,便于操作,可为类似系统的构建提供有益的案例参考.     

基于Struts、Hibernate实现的办公一体化管理系统

随着J2EE平台在各个领域的广泛应用,多层Web结构在军队的各个领域已经逐渐普及。J2EE设计中出现了一些开源而又免费的应用框架,为轻量级的办公一体化实现提供了快速而又经济的方案;Struts框架和Hibernate持久化框架是其中的典型代表。     

Selective Message Forwarding in Delay Tolerant Networks

It is challenging to deliver messages in a network where no instant end-to-end path exists, so called delay-tolerant network (DTN). Node encounters are used for message forwarding. In this paper, we propose a DTN routing protocol SMART. SMART utilizes the travel companions of the destinations (i.e. nodes that frequently meet the destination) to increase the delivery opportunities while limiting message overhead to a bounded number. Our approach differs from related work in that it does not propagate node encounter history nor the delivery probabilities derived from the encounter history. In SMART, a message source injects a fixed number of message copies into the network to forward the message to a companion of the destination, which only forwards the message to a fixed number of the destination’s companions. Our analysis and simulation results show that SMART has a higher delivery ratio and a smaller delivery latency than the schemes that only use controlled opportunistically-forwarding mechanism and has a significantly smaller routing overhead than a pure flooding scheme.     

Message Drop Control Buffer Management Policy for DTN Routing Protocols

In delay tolerant network interruptions will occur continuously because there is no end-to-end path exists for the longer period of time from source to destination. In this context, delays can be immensely large due to its environment contrails e.g. wildlife tracking, sensor network, deep space and ocean networks. Furthermore, larger replication of messages put into the network is to increase delivery probability. Due to this high buffer occupancy storage space and replication result in a huge overhead on the network. Consequently, well-ordered intelligent message control buffer drop policies are necessary to operate on buffer that allows control on messages drop when the node buffers are near to overflow. In this paper, we propose an efficient buffer management policy which is called message drop control source relay (MDC-SR) for delay tolerant routing protocols. We also illustrate that conventional buffer management policy like Drop oldest, LIFO and MOFO be ineffective to consider all appropriate information in this framework. The proposed MDC-SR buffer policy controls the message drop while at the same time maximizes the delivery probability and buffer time average and reduces the message relay, drop and hop count in the reasonable amount. Using simulations support on an imitation mobility models Shortest Path Map Based Movement and Map Route Movements, we show that our drop buffer management MDC-SR with random message sizes performs better as compared to existing MOFO, LIFO and DOA.     

DFEMD: Delay Tolerant Fast Emergency Message Dissemination Routing Protocol

In vehicular ad-hoc network, vehicles are move very speedy thus their topology is changing frequently and intermittent connectivity occur often. The intermittent connectivity network (delay and disruption-tolerant network) resulting is end to end path is absent. In this intermittent network connectivity areas, during emergency event occurs, emergency rescue message (Example: Fire, Accident, etc.,) are sent to a rescue team is most necessary. Due to these constraints, general ad hoc protocol approaches is not suitable and, as a result, alternative protocol must be deliberated. This leads to the make a specific protocol mechanisms able to deliver both fast and trustworthiness in-order delivery emergency message needed. Thus we introduce the DFEMDR protocol, it follow the vehicular delay tolerant network (VDTN) common technique store carry-forward method and message replicas. This paper describes an efficient Delay tolerant Fast Emergency Message Dissemination Routing Protocol, called DFEMD routing protocol. This protocol enables in VDTN, the source node broadcast an emergency message to all available node in its communication range. The source node allocates a message replicas and message time to live to the neighbour nodes (forwarded node) based on that node has credence value. Credence value is calculated to all nodes based on two values; the first value is visited level estimation, it is calculated based on the number of nodes previously visited by the node. The second value is Destination Reaches Level Estimation (DLE); it is calculated based on the number of times the node successfully delivered the message to the destination. Finally, each node credence value is calculated, from this visited level and destination reaches level estimation values. Finally, the trust authority received emergency messages and evaluate the trustworthiness of message based on message reputation value or message confidence value.

     

Message trust‐based secure multipath routing protocol for opportunistic networks

Opportunistic networks (OppNets) are composed of wireless nodes opportunistically communicating with each other. These networks are designed to operate in a challenging environment characterized by high delay, intermittent connectivity, and no guarantee of fixed path between the sender and the destination nodes. One of the most vital issues in designing and maintaining practical networks over a time period is the security of the messages flowing in OppNets. This paper proposes a new method called message trust‐based secure multipath routing protocol (MT‐SMRP) for opportunistic networks. Various routing protocols such as ProPHet, Epidemic, and HiBOp, to name a few, have been proposed for OppNets, but none of these have applied a secure multipath routing technique. The proposed MT‐SMRP scheme relays the message to the destination through the disjoint paths, each applying a soft‐encryption technique to prevent message fabrication attacks. Simulations are conducted using the Haggle Infocom'06 real mobility data traces, showing that when time‐to‐live is varied, (1) the proposed MT‐SMRP scheme outperforms D‐MUST by 18.10%, 7.55%, 3.275%, respectively, in terms of delivery probability, messages dropped, and average latency; (2) it also outperforms SHBPR by 21.30%, 7.44%, and 4.85%, respectively, in terms of delivery probability, messages dropped, and average latency. Under similar performance metrics, the performance of MT‐SMRP is also shown to be better than that of D‐MUST and SHBPR when the buffer size (respondents. the message generation interval) is varied.     

基于AMQP的校园消息总线系统的设计与实现

针对传统数字化校园应用间强耦合与复杂的依赖关系,设计并实现了一种基于AMQP的校园消息总线系统,将消息总线作为数字化校园应用间的消息中间件,简化了应用系统的开发逻辑,并减少了应用间的耦合关系。该系统的实际应用表明,该结构适用于数字化校园的建设,使数字化校园各应用更易于管理与扩展。     

Enhanced fuzzy logic‐based spray and wait routing protocol for delay tolerant networks

Delay tolerant networks are a class of ad hoc networks that enable data delivery even in the absence of end‐to‐end connectivity between nodes, which is the basic assumption for routing in ad hoc networks. Nodes in these networks work on store‐carry and forward paradigm. In addition, such networks make use of message replication as a strategy to increase the possibility of messages reaching their destination. As contact opportunities are usually of short duration, it is important to prioritize scheduling of messages. Message replication may also lead to buffer congestion. Hence, buffer management is an important issue that greatly affects the performance of routing protocols in delay tolerant networks. In this paper, Spray and Wait routing protocol, which is a popular controlled replication‐based protocol for delay tolerant networks, has been enhanced using a new fuzzy‐based buffer management strategy Enhanced Fuzzy Spray and Wait Routing, with the aim to achieve increased delivery ratio and reduced overhead ratio. It aggregates three important message properties namely number of replicas of a message, its size, and remaining time‐to‐live, using fuzzy logic to determine the message priority, which denotes its importance with respect to other messages stored in a node's buffer. It then intelligently selects messages to schedule when a contact opportunity occurs. Because determination of number of replicas of a message in the network is a difficult task, a new method for estimation of the same has been proposed. Simulation results show improved performance of enhanced fuzzy spray and wait routing in terms of delivery ratio and resource consumption. Copyright © 2014 John Wiley & Sons, Ltd.     

面向预警探测系统的分布式消息中问件研究与实现

设计了一种面向作战系统应用的信息分发消息中间件解决方案,对消息分发中间件的体系结构、工作流程和系统实现关键点进行了详细的阐述。该设计根据应用进程需求,选择和切换合适的分发策略,满足作战系统在信息交互的实时性、可靠性以及分组报文传输等方面的不同要求;该设计向上屏蔽网络通信的具体实现和传输策略的选择,使上层应用软件开发从复杂的网络结构、传输逻辑以及异构网络传输平台中解脱出来。     

Message delivery in heterogeneous networks prone to episodic connectivity

We present an efficient message delivery framework, called MeDeHa, which enables communication in an internet connecting heterogeneous networks that is prone to disruptions in connectivity. MeDeHa is complementary to the IRTF’s Bundle Architecture: besides its ability to store messages for unavailable destinations, MeDeHa can bridge the connectivity gap between infrastructure-based and multi-hop infrastructure-less networks. It benefits from network heterogeneity (e.g., nodes supporting more than one network and nodes having diverse resources) to improve message delivery. For example, in IEEE 802.11 networks, participating nodes may use both infrastructure- and ad-hoc modes to deliver data to otherwise unavailable destinations. It also employs opportunistic routing to support nodes with episodic connectivity. One of MeDeHa’s key features is that any MeDeHa node can relay data to any destination and can act as a gateway to make two networks inter-operate or to connect to the backbone network. The network is able to store data destined to temporarily unavailable nodes till the time of their expiry. This time period depends upon current storage availability as well as quality-of-service needs (e.g., delivery delay bounds) imposed by the application. We showcase MeDeHa’s ability to operate in environments consisting of a diverse set of interconnected networks and evaluate its performance through extensive simulations using a variety of scenarios with realistic synthetic and real mobility traces. Our results show significant improvement in average delivery ratio and a significant decrease in average delivery delay in the face of episodic connectivity. We also demonstrate that MeDeHa supports different levels of quality-of-service through traffic differentiation and message prioritization.     

Impact of Bloom Filter on Infection Rate in Epidemic Forwarding for ICNs

Mobile ad hoc routing protocols fails in intermittently connected networks (ICN) (i.e. characterized by short-range communication and absence of connected path from source to destination). However, Epidemic routing techniques ensures eventual message delivery from source to destination even where there is never a connected path or when a network partition exists at the origin of message. Epidemic Routing uses random pair-wise messages exchanges between nodes with goals to maximize message delivery rate, minimize message latency, and the total resources consumed in message delivery. Epidemic routing uses summary vector to avoid useless transmission and redundancy. Further,to make summery vector efficient, epidemic routing can use bloom filter to significantly reduce the useless transmissions associated with the summary vector. However, the challenge for epidemic routing remains opens is to optimal design of summary vector size for finite buffer while keeping the benefits of infinite buffer space. This paper proposes an improved scheme of Bloom filter (named it modified bloom filter MBLF), which is tailored according to epidemic routing. We performed simulation to support our clam and observed that delivery ratio of MBLF with epidemic routing is 19 % higher then the traditional bloom filter. In this paper, we have proposed a bloom filter based epidemic forwarding for ICNs.     

Message Path Delays in Packet-Switching Communication Networks

A communication path (in isolation) in a packet-switching store-and-forward communication network, such as a computer or satellite-communication network, is considered. Messages are assumed to arrive according to a Poisson stream, and messagelengths are considered to be random variables governed by an arbitrary distribution. Message lengths are divided into fixed-length packets which are sent independently over theN-channel communication path in a store-and-forward manner, and are reassembled at the destination terminal. Expressions for the distributions of the message waiting and delay times over the path are derived. Also, we obtain the limiting average message waiting times and required buffer sizes at the individual channels. The overall message waiting time is observed to depend only on the minimal channel capacity. The case of exponentially distributed message lengths serves as an illustrating example.