Combining the characteristics of current network computing environment,research on new generation middleware technology which is suitable for open and mobile networking environments was presented.Based on the analysis to the key characteristics of today’s network environment,new technical requirements for new generation middleware were identified.Subsequently,some key challenges such as context-awareness,environmental adaptation,open coordination,service discovery and pervasive interoperability for new generation middleware were discussed in detail.Further,some real solutions were showed as well.

Recent advances in wireless networking technologies and mobile computing devices have engendered a new paradigm of computing, mobile computing. In the meantime, applications on these mobile devices also present some challenges to software designers. In order to cope with these challenges, many research efforts have been focused on a new middleware system that can support the requirements imposed by mobility. In this paper, we investigate some key issues in mobile middleware systems and introduce several basic concepts related to mobile middleware. In addition, we also discuss the technical requirements that mobile middleware systems have to meet. Finally, we conclude the paper and present the future research direction of mobile middleware system.

Workflow instance migration is a typical and important problem in the research of workflow evolution. Underlying the definitions of the extended-task-structures based workflow, some rules, conditions and an algorithm for workflow instance migration are presented, which are suited to generic dynamic changes. By the comparisons with other similar research works, the advantages of the approach in terms of applicability, universality, correctness and practicality are illustrated.

对象管理组织制定的CORBA规范是分布对象计算的中间件标准,允许客户透明的访问远地对象,同时支持异构系统的互操作.IDL编译器是分布计算环境的基本开发工具.灵活、高效、可维护的IDL编译器对于分布对象系统的实现意义重大.文中首先讨论目前IDL编译器的设计方法及存在问题;其次给出了一种新的IDL编译器体系结构;最后给出了结论.

1 前言目前传统中间件在技术上已基本发展成熟,在国内外占有最大的市场份额.但传统中间件是一种以"过程"为基础的编程技术.新一代面向对象中间件在符合CORBA规范2.X的前提下,提出了一种"构件化"的思想,它保证不同产品相互之间能够实现互操作[1,2].为满足新的面向对象应用的需要,同时保持向前兼容传统中间件的应用,本文提出了一种全新的思路和实现,将消息中间件作为ORB的底层通信协议,即保持应用不变,"核心"向前推移,提供给用户一个高性能的分布式计算平台.

In complex and diversified application context, flexibility is one of the key issues of workflow technology. As an important approach to improve the flexibility of system,reflection is also available to Workflow Management System (WfMS) .This paper reifies the workflow process and its management respectively from structural and behavioral aspects,and as a result,a reflective model of workflow is designed. A model of Meta-Object Protocol (MOP) is proposed to abstract and program on meta-level, including protocol declaration, meta-object association, protocol selection and meta-object management. The typical instance evolution example shows that reflection is effective to improve the flexibility and adaptability of WfMS. The implementation of reflection is presented in the paper.

对象管理组织制定的CORBA规范是分布对象计算的中间件标准,允许客户透明地访问远地对象,同时支持异构系统的互操作.作为ORB的重要组成部分,IDL编译器是分布计算环境的基本开发工具.该文首先讨论IDL编译器的地位和作用;其次给出了模式概念和种类;第三,分析了IDL编译器设计面临的问题及如何应用模式解决这些问题.最后给出了结论.

1 引言 以CORBA为代表的对象中间件在企业应用中越来越发挥着重要的作用,但日趋增多的应用领域如:电子商务、多媒体与实时系统、移动计算等,及新CORBA标准都对中间件开发者提出了新的挑战.只有协调好统一的体系结构、广泛而灵活的适应性及优化的性能这三方面问题,产品才能快速适应各种应用领域的需求,同时保持良好的性能.

1 引言 现代软件系统必须能快速灵活地适应需求变化,换言之,系统要有灵活性和可重构性.同样,对中间件也如此.以往的研究表明,反省(Reflection)己被公认为是增加语言或系统灵活性与开放性的一种重要技术.近年来它开始向分布系统延伸,一些成果已初步证明了反省对提高分布系统,特别是中间件的灵活性是行之有效的.

1 引言 全球性的竞争使得从头开发和维护复杂的中间件显得日益困难.在过去的几年中,对分布对象计算中间件,尤其是CORBA的需求迅速增长,基于CORBA的企业级应用发展迅猛.但是,由于目前的CORBA规范缺乏标准的服务员交互模型,使用现有的CORBA中间件开发企业级应用仍显得过于复杂,开发周期较长,产生的软件的可重用性和灵活性也较差.于是,OMG提出了对CORBA构件模型CCM(CORBA Compo nent Model)的提议征求RFP(Request For Proposals),相应的提案已于最近被采纳,并将出现在CORBA3.0规范中.采用CCM后,应用编程人员将有可能用更小的工作量集成实现服务和应用所必需的具有更强可移植性的构件.CCM标准不仅大大增强了服务器软件的可重用性,而且为CORBA应用的动态配置提供了更大的灵活性.

Rapid evolution of e-bussiness expects a kind of integrated enterprise computing platform, which can assemble information, applications and persons. So a new technology called portal emerges and becomes prevalent. The concept, architecture and some primary services of portal are analyzed and discussed in the paper, as well as some associated technologies. Consequently, we reveal the technology