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用C＋＋实现OODB中对象多版本 总被引：1，自引：0，他引：1
作者利用Ｓｙｂａｓｅ作底层的数据存储，在Ｃ＋＋中扩展了永久类，实现了ＯＯＤＢ的一个重要功能，文中讨论的是在此基础上，利用Ｃ＋＋语言重载能力，和关系数据库便于集合操作的特性，扩展我版本类，实现ＯＯＤＢ对象多版本。 相似文献
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需求工程知识库／ＰＬ——ＲＫＢ／ＰＬ（ｒｅｑｕｉｒｅｍｅｎｔ—ｅｎｇｉｎｅｅｒｉｎｇｋｎｏｗｌｅｄｇｅｂａｓｅ／ＰＬ）是保持Ｃ＋＋原有风格对Ｃ＋＋进行的持久性扩充．为支持对象的持久性,ＲＫＢ／ＰＬ在Ｃ＋＋对象类的基础上扩充了以约束声明加强对象状态的用户监控;引入簇来表达对象类的集合含义;引入集合、簇、簇闭包的遍历机制来支持对象查询．为支持这些语言机制,ＲＫＢ／ＰＬ具有一个由一组ｂｕｉｌｄ—ｉｎ对象类层次、类型信息库及接口函数、系统状态表以及系统服务函数等构成的运行时系统．本文讨论了ＲＫＢ／ＰＬ中这些机制的表示、相应的运行时系统的组成以及它们的主要实现技术．ＲＫＢ／ＰＬ已成功地用于实现“软件需求获取助手ＦＲＡ”系统的需求工程知识库子系统． 相似文献
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对象持久化技术是一种数据存储方法,其目的是为了使程序开发者更加方便的访问数据.对象持久化技术解决了面向对象技术和关系数据库技术的不匹配问题,使得程序员从数据库细节中解放出来,让程序员有更多的精力去处理事务逻辑. 相似文献
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通过实例介绍了利用Hibernate实现对象持久化的过程,并对持久化过程中对象创建的时序和状态进行了分析。采用Hibernate进行持久化有利于提高开发的灵活性,有利于提高数据访问效率。 相似文献
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Hibernate是一个对象持久化工具,它通过其强大的O/R映射功能将Java对象同存放于关系数据库中的数据进行映射,避免了开发人员使用大量的SQL语句通过JDBC的方式对数据库进行操作,可以有效地提高开发的效率. 相似文献
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本文介绍了在应用面向对象方法设计的学校人事管理系统中如何使用Java的对象序列化机制实现对象持久化,以及如何进行对象数据管理。 相似文献
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随着近年来嵌入式应用的复杂化和多样化,工业界和学术界提出来用内存数据库满足嵌入式系统对数据处理性能不断提升的要求.然而,现有的内存数据库需要在磁盘或闪存等外存上持久化存储真实的数据库备份,并且以I/O操作的方式将数据库的更新操作同步回外存,有极大的性能开销.此外,这类数据库即便直接部署在新型非易失性内存（non-volatile memory,简称NVM)中,也因为缺乏内存中的持久化机制而不能脱离外存.针对现有内存数据库的不足,提出一套面向NVM的持久化内存数据库设计方案.该方案直接用数据库独立管理NVM,持久化存储NVM的空间信息以及内存数据库的元数据.依据该方案,在典型的内存数据库Redis的基础上实现了可在NVM上持久化的内存数据库.实验结果表明,该方案与既有Redis的持久化方案AOF相比,数据库的启动速度可提高2 400倍,关闭速度可提高5倍,set操作的速度可提高58倍,delete操作的速度可提升34倍. 相似文献
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POTENTIAL is a virtual database machine based on general computing platforms,especially parllel computing platforms.It provides a complete solution to high-performance database systems by a ‘virtual processor virtual data bus virtual memory‘ architecture.Virtual processors manage all CPU resources in the system,on which various operations are running.Virtual data bus is responsible for the management of data transmission between associated operations.which forms the higes of the entire system.Virtual memory provides efficient data storage and buffering mechanisms that conform to data reference behaviors in database systems.The architecture of POTENTIAL is very clear and has many good features,including high efficiency,high scalability,high extensibility,high portability,etc. 相似文献
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Interrupt strategy of an operating system can help computer to tackle with urgent orimportant events,and to run programs in a reasonable fashion in order to achieve a satisfactoryperformance.But a sophisticated strategy will cause an amount of system costs.In this paperwe introduce the concept of “layered interrupt priorities”which will care both the system costsand the response capability.This strategy can be applied in timesharing systems,realtimesystems,or multiprocessor systems.At the end of the paper we exploit the advantages of thisstrategy using data acquired by simulation of a real computer system. 相似文献
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Jirong WEN;Hong CHEN;Shan WANG 《计算机科学技术学报》2000,15(6):527-541
POTENTIAL is a virtual database machine based on general computing platforms, especially parallel computing platforms. It provides a complete solution to high-performance database systems by a 'virtual processor + virtual data bus + virtual memory' architecture. Virtual processors manage all CPU resources in the system, on which various operations are running. Virtual data bus is responsible for the management of data transmission between associated operations, which forms the hinges of the entire system.... 相似文献
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EuLisp has an integrated object system with reflective capabilities. We discuss some example applications which use these facilities to experiment with some advanced and powerful concepts, namely, finalization, virtual shared memory and persistence. A secondary goal is to attempt to illustrate the additional possibilities of metaobject programming over non-metalevel techniques. 相似文献
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Recent explosive growth in physical memory configurations inverts the problem faced by traditional operating systems, which were built around the assumption of limited physical memory and plentiful virtual memory. With the introduction of the Pentium Pro, there is an aberration in the historical trend towards increased virtual space. Such processors have 36‐bit physical and 32‐bit logical addressing; with traditional algorithms, the smaller virtual space limits the number of concurrent processes as well as the total physical memory usable by an application. To address these problems, two general principles can be applied to any operating system to reduce its virtual memory needs: first, multiplexing different physical addresses over the same virtual—as opposed to multiplexing different virtual over the same physical, where the optimization was to share the physical memory across multiple processes; second, optimize virtual consumption by kernel pagepool data, by organizing data structures to extend their physical memory reach using the same amount of virtual space. Copyright © 2000 John Wiley & Sons, Ltd. 相似文献
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DMM:A dynamic memory mapping model for virtual machines 总被引：2，自引：0，他引：2
CHEN HaoGang WANG XiaoLin WANG ZhenLin ZHANG BinBin LUO YingWei & LI XiaoMing 《中国科学:信息科学(英文版)》2010,(6):1097-1108
Memory virtualization is an important part in the design of virtual machine monitors(VMM).In this paper,we proposed dynamic memory mapping(DMM) model,a mechanism that allows the VMM to change the mapping between a virtual machine's physical memory and the underlying hardware resource while the virtual machine is running.By utilizing DMM,the VMM can implement many novel memory management policies,such as Demand Paging,Swapping,Ballooning,Memory Sharing and Copy-On-Write,while preserving compatibility with va... 相似文献