From Flow Logic to static type systems for coordination languages

Coordination languages are often used to describe open-ended systems. This makes it challenging to develop tools for guaranteeing the security of the coordinated systems and the correctness of their interaction. Successful approaches to this problem have been based on type systems with dynamic checks; therefore, the correctness properties cannot be statically enforced. By contrast, static analysis approaches based on Flow Logic usually guarantee properties statically. In this paper, we show how the insights from the Flow Logic approach can be used to construct a type system for statically ensuring secure access to tuple spaces and safe process migration for an extension of the language Klaim.     

支持JSR286和WSRP2.0规范的Portlet协作的设计

JSR286规范定义了本地Portlet之间的协作方式,WSRP2.0规范定义了远程Portlet之间的协作方式,但两者并未深入涉及远程Portlet和本地Portlet之间的协作问题,降低了Portlet的交互能力。针对这点不足,在WSRP2.0规范定义的事件分发及状态分发等协作机制基础上,设计了一个消费者门户主导的联邦协作框架。在该框架中,通过协作信息转换和协作服务作为中介,通过消息队列进行消息存储、消息验证和消息处理,实现了Portlet容器和代理容器的松散耦合,并支持远程Portlet和远程Portlet之间、远程Portlet和本地Portlet之间、本地Portlet和本地Portlet之间的协作。该框架与JSR286规范和WSRP2.0规范兼容,满足WSRP2.0模块的可插拔性,并具有良好的可扩展性和可移植性。     

What affects information systems development team performance? An exploratory study from the perspective of combined socio-technical theory and coordination theory

Quality is an important factor in information systems development (ISD), and ISD team performance closely relates to quality. To better understand ISD teams, we empirically tested a model on ISD team performance by combining socio-technical theory and coordination theory. Using existing empirical studies and data collected from three well-known ISD companies in China, our research results identified influential characteristics of ISD team performance, and revealed similarities and differences between China’s ISD team performance and those in other countries. By the results, we find that knowledge sharing and major do not affect team performance. The compensation satisfaction to job performance is not significant in China, either. Our research provides suggestions for building and supporting ISD teams that could lead to performance improvements.     

Coordination of split deliveries in one-warehouse multi-retailer distribution systems

In this paper, we consider a distribution system where a warehouse is responsible for replenishing the inventories at multiple retailers by a fleet of vehicles of limited capacity. If a distribution policy of the system involves split deliveries, that is, the inventory of at least one retailer is replenished by using multiple vehicle routes, the coordination of the deliveries can further reduce the inventory cost of the retailer. We consider the coordination where two split deliveries are realized by direct shipping and multiple-stop shipping, respectively. To the best of our knowledge, this kind of coordination was never studied in the literature but can find its application in inventory routing problems. This paper proposes and analyses a class of coordination policies for the split deliveries which can reduce the inventory costs of the retailers without increasing transportation costs. A non-linear programming model is established for formulating the class of polices. Because the optimal coordination policy corresponding to an optimal solution of the model may be hard to find and/or implement, two simple but effective coordination policies are proposed. The inventory cost savings realized by the two policies are evaluated analytically and algorithmically. Our theoretical analysis and computational experiments show that both policies are effective. Under certain conditions, they can save 50% of the inventory costs at the retailers without increasing transportation costs.     

Group awareness tools: It’s what you do with it that matters

This study examined the effect of using a group awareness tool on online collaboration. Furthermore, we examined whether the effect of using a group awareness tool on online collaboration is mediated by group awareness (i.e., students’ awareness of their group members’ levels of participation). To answer these questions, we determined how often and how long 107 secondary education students used the Participation-tool (PT), a group awareness tool designed to visualize group members’ relative contribution to the online collaborative process. Our analyses show that duration of PT use (how long students displayed the tool on their screens) significantly predicted group members’ participation in the online dialogue, their participation when writing collaborative texts, equality of participation within the group, and coordination and regulation of activities in the relational space (i.e., discussing the collaboration process with group members). No effect of using the PT on group performance was found. Mediation analyses showed that the effect of using the PT is only partially mediated by group awareness: an indirect effect of using the PT, via enhanced awareness of participation, on student participation during chat discussions and the collaborative writing process was found.     

Agent-based negotiation and decision making for dynamic supply chain formation

Modern businesses are facing the challenge of effectively coordinating their supply chains from upstream to downstream services. It is a complex problem to search, schedule, and coordinate a set of services from a large number of service resources under various constraints and uncertainties. Existing approaches to this problem have relied on complete information regarding service requirements and resources, without adequately addressing the dynamics and uncertainties of the environments. The real-world situations are complicated as a result of ambiguity in the requirements of the services, the uncertainty of solutions from service providers, and the interdependencies among the services to be composed. This paper investigates the complexity of supply chain formation and proposes an agent-mediated coordination approach. Each agent works as a broker for each service type, dedicated to selecting solutions for each service as well as interacting with other agents in refining the decision making to achieve compatibility among the solutions. The coordination among agents concerns decision making at strategic, tactical, and operational level. At the strategic level, agents communicate and negotiate for supply chain formation; at the tactical level, argumentation is used by agents to communicate and understand the preferences and constraints of each other; at the operational level, different strategies are used for selecting the preferences. Based on this approach, a prototype has been implemented with simulated experiments highlighting the effectiveness of the approach.     

Coordination components for collaborative virtual environments

This paper deals with the behavior of virtual environments from the collaboration point-of-view, in which actors (human or virtual beings) interact and collaborate by means of interdependent tasks. In this sense, actors may realize tasks that are dependent on tasks performed by other actors, while the interdependencies between tasks (through resource management and temporal relations) delineate the overall behavior of a virtual environment. Our main goal is to propose an approach for the coordination of those behaviors. Initially a generic study of possible interdependencies between collaborative tasks is presented, followed by the formal modeling (using Petri Nets) of coordination mechanisms for those dependencies. In order to implement such mechanisms, an architecture of reusable and pluggable coordination components is also introduced. These components are used in an implementation of a multi-user videogame. The presented approach is a concrete step to create virtual societies of actors that collaborate to reach common goals without the risk of getting involved in conflicting or repetitive tasks.     

城市群区域公共基础设施网络的协调模式浅析

针对现在我国城市化发展进程,城市群的发展已迫在眉睫,本文主要分析了城市群区域公共基础设施网络体系的协调发展对城市群经济建设的重要性,以及协调发展的模式,并对我国未来城市群发展的方针提出自己的看法。     

Java多线程同步机制的应用分析

在一个程序中代码段从单独的并发的线程当中访问了同一个对象,这个代码段是临界区。对“临界区”要进行保护,Java语言采用管程机制,提供同步语法对临界区进行保护。只要了解了同步内部的实现机制,编写出安全高效的多线程程序会更加灵活。利用Java多线程同步机制,可以协调管理由访问冲突所产生的一系列问题。将这种机制运用到售票系统中来解决具体的实际问题,得到了令人满意的结果。     

电化学聚合研究进展

电化学聚合是近年来发展起来的一种新型的聚合方法，它除了可以合成一些常用方法所不能合成的聚合物外，还能改变某些聚合物的性能．现已广泛用于导电高分子的研究中．并具有潜在的工业化前景。本文从机理及应用方面综述了电化学聚合方法的研究进展。