基于嵌入式数据库的移动计算数据访问

本文分析了移动计算环境下移动终端对数据访问的需求,认为关系数据库兼容性、安全性和完善的数据同步特性是实现企业级移动计算数据访问的关键。在此基础上提出了基于开源嵌入式关系数据库Apache Derby的解决方案,并给出了应用实例。     

移动环境下支持实时事务处理的数据预取

随着移动通信技术的迅速发展,人们提出了新的应用要求:在移动环境下处理实时事务.而移动通信带宽有限性引起较大的数据访问延迟,有时甚至由于网络传输的断接使得事务得不到所需要的数据,数据预取能够很好地解决这个问题.已有的移动环境下数据预取没有考虑到数据的流行性和事务的时间特性.该文分析影响实时事务数据预取的因素,首先考虑数据易变性、活跃性等因素,获得高价值预取数据集合;然后考虑访问预取数据的事务优先级、数据流行性等因素,构造预取数据的选择函数,通过该函数在前面选取的集合中筛选出对满足实时事务截止期更有价值的数据对象进行预取.实验表明,该数据预取策略能降低移动实时事务满足截止期的比率,更好地支持移动实时事务处理.     

移动客户机中缓存技术的应用研究

在移动计算环境中,移动性和断接性是它的最主要的两个特点.为了支持断接操作,数据时常需要先存储到移动客户机中.缓存技术成为移动计算环境中的重要技术.本文研究了基于广播技术中客户机端缓存的管理技术,讨论了缓存管理的粒度问题、缓存一致性策略和缓存替换策略三个关键问题.     

移动计算环境中数据广播访问时间优化算法

移动计算是近年来新兴的一个研究热点，具有极大的市场潜力和需求，数据广播是提高移动计算系统可伸缩性的一项重要技术，本文对无线移动计算环境中数据广播的平均访问时间优化进行了研究和实验，首先分析了平均访问时间的理论最小值，然后提出了向理论最小值逼近的NASA 算法，实验表明NASA算法具有良好的性能，优于MDS等其他调度方法。     

移动数据库的并行数据分发控制技术研究

移动计算环境中上下行通信链路资源有限,通信链路频繁断连。数据移动终端用户如何能在移动计算环境中高效的访问数据,保证数据的实时性是文章的研究重点。通过提出一种基于并发控制的数据广播技术,来保证移动数据终端对数据的访问效率、时效性等性能的要求。实验结果表明数据访问的效率、时效性得到了提高。     

基于移动计算环境的智能客户端的研究

频繁断连性、通信不对称性、用户数据访问模式多变性、移动终端能源有限性是移动计算环境的典型特征。如何能在如此"苛刻"的条件下保证数据访问的高效性、时效性和安全性是研究的重点。文章详细分析了智能客户端技术在移动计算环境中特点和优势,在此基础上,提出了实现智能客户端的一些关键问题及其解决方案,最后对智能客户端的安全性问题作了介绍。     

基于移动终端位置特征信息的终端缓存的数据压缩方法

大数据技术的蓬勃发展对相应设备提出了更高的要求,尤其在移动自组织网络中,移动终端始终受到计算能力、存储空间和网络带宽的限制。笔者设计了一种基于移动终端位置特征信息的无损数据压缩方法,利用移动终端提取当前位置特征信息,建立位置信息与对应特征词汇的云端数据库,对移动终端的缓存数据进行周期性数据压缩、数据去重和数据还原操作,有效减轻了移动终端的存储负担,提升了移动自组织网络的运行效率。     

移动数据库中基于数据广播缓存一致性的研究

随着移动设备的普及以及移动基础设施的迅速发展,移动计算环境日益成熟。数据广播技术作为移动环境中的重要技术得到广泛的研究,本文着重的介绍了数据广播中缓存一致性的相关问题以及各种广播技术解决缓存一致性的特点。     

连接中断计算环境下移动数据的处理模型

无线网络中断和弱连接现象,常导致用户在访问远程数据时访问中断和数据丢失,并正成为移动计算发展的一个瓶颈。基于这种现状,提出一种在无线网络出现连接暂时中断时移动计算环境下移动数据的处理模型,以解决上述问题。为提高用户访问数据的可靠性,即在出现网络连接中断时使用户能够在离线情况下继续操作且不会丢失数据,该模型在移动终端提供语义缓存功能,并能在连接恢复时立即执行被滞后的操作。     

数据访问中间件在移动学习平台的研究与设计

随着无线通信技术和手机、PDA等移动终端的发展,移动学习成为一种新型的学习方式.为了解决移动终端能访问传统的网络学习资源,本论文提出设计基于XML的数据访问中间件模型,方便异构平台之间数据库访问.     

Wireless network extension using mobile IP

Over the last two decades, we have seen a dramatic shift in computing systems, away from the monolithic mainframe and toward increasingly distributed, client-server systems. One of the key elements enabling the success of the distributed computing environment was the interconnecting network technology. High-speed, reliable network hardware and protocols evolved to support client-server applications. Network technology has now progressed to the point that applications are being written to specifically exploit the capabilities of the network. The explosion of World Wide Web applications is the latest example of the fact that the network is now the focus of the distributed computing environment. In a concurrent development, personal computing platforms placed increasingly powerful systems in ever smaller form factors. Users have embraced these advances: Mobile computers, in the form of laptops, palmtops, and personal digital assistants (PDAs), are a significant element of the current computing environment. However, to be fully productive, the mobile computer user requires access to the network. Further, access to a network is not sufficient. Mobile users need access to the same network-the same resources and services and communications capabilities-that they would if they were at their desktops. We refer to this concept of providing home network access to the mobile user as network extension. Addressing many requirements for practical wireless access, this Internet technology aids the development of advanced data services for wireless networks, including the integrated dispatch enhanced network     

A multi-agent based user context Bayesian neural network analysis system

The increasing user mobility demands placed upon IT services necessitates an environment that enables users to access optimal services at any time and in any place. This study presents research conducted to develop a system that is capable of analyzing user IT service patterns and tendencies and provides the necessary service resources by sharing each user’s context information. First, each user’s context information is gathered to provide the multi-agent software training data necessary to describe user operations in a hybrid peer-to-peer (P2P) structured communication environment. Next, the data collected about each user’s mobile device is analyzed through a Bayesian based neural network system to identify the user’s tendency and extract essential service information. This information provides a communication configuration allowing the user access to the best communication service between the user’s mobile device and the local server at any time and in any place, thereby enhancing the ubiquitous computing environment.     

移动计算环境下远程用户体验数据挖掘方法研究

在移动计算环境下,通过对远程用户的体验数据优化挖掘,满足远程用户的个性化需求,提高对远程用户QoS服务质量;传统的数据挖掘方法采用显著特征关联信息提取算法,当远程用户体验数据之间的差异性特征不明显时,挖掘的准确性不好;提出一种基于关联用户自适应链路跟踪补偿的移动计算环境下远程用户体验数据挖掘模型,进行远程用户体验数据挖掘模型的总体设计和数据结构特征分析,对采集的远程用户体验数据进行非线性时间序列分解,对数据序列通过自相关特征匹配和特征压缩实现挖掘数据的指向性信息优化提取,采用关联用户自适应链路跟踪补偿方法实现对数据挖掘误差的控制和补偿,提高了数据挖掘的准确性和有效性;仿真结果表明,采用该挖掘方法进行移动计算环境下远程用户体验数据挖掘的准确度高,实时性较好,满足了移动远程用户的个性化需求,提高了对用户服务的针对性。     

移动网络中心云计算存储数据访问安全自动监测系统设计

为了提高移动网络中心云计算存储数据访问和安全监测能力,提出一种基于深度学习和交叉编译控制的移动网络中心云计算存储数据访问安全自动监测系统设计方法。采用混合属性数据模糊加权聚类方法进行移动网络中心云计算存储数据的优化访问控制模型设计,根据云计算存储数据之间的属性相似度进行离散化数值属性分解,提取移动网络中心云计算存储数据的混合属性特征量,根据最小化云存储数据访问成本为代价进行移动网络中心云计算存储数据访问的安全监测。结合深度学习方法进行数据访问的自适应控制,在交叉编译环境下实现云计算存储数据访问安全自动监测系统开发设计。测试结果表明,采用该方法进行移动网络中心云计算存储数据访问的安全性较好,自动化控制能力较强。     

Shared data allocation in a mobile computing system: exploring local and global optimization

In this paper, we devise data allocation algorithms that can utilize the knowledge of user moving patterns for proper allocation of shared data in a mobile computing system. By employing the data allocation algorithms devised, the occurrences of costly remote accesses can be minimized and the performance of a mobile computing system is thus improved. The data allocation algorithms for shared data, which are able to achieve local optimization and global optimization, are developed. Local optimization refers to the optimization that the likelihood of local data access by an individual mobile user is maximized whereas global optimization refers to the optimization that the likelihood of local data access by all mobile users is maximized. Specifically, by exploring the features of local optimization and global optimization, we devise algorithm SD-local and algorithm SD-global to achieve local optimization and global optimization, respectively. In general, the mobile users are divided into two types, namely, frequently moving users and infrequently moving users. A measurement, called closeness measure which corresponds to the amount of the intersection between the set of frequently moving user patterns and that of infrequently moving user patterns, is derived to assess the quality of solutions provided by SD-local and SD-global. Performance of these data allocation algorithms is comparatively analyzed. From the analysis of SD-local and SD-global, it is shown that SD-local favors infrequently moving users whereas SD-global is good for frequently moving users. The simulation results show that the knowledge obtained from the user moving patterns is very important in devising effective data allocation algorithms which can lead to prominent performance improvement in a mobile computing system.     

Flexible CP-ABE Based Access Control on Encrypted Data for Mobile Users in Hybrid Cloud System

In hybrid cloud computing, encrypted data access control can provide a fine-grained access method for organizations to enact policies closer to organizational policies. This paper presents an improved CP-ABE (ciphertext-policy attribute-based encryption) scheme to construct an encrypted data access control solution that is suitable for mobile users in hybrid cloud system. In our improvement, we split the original decryption keys into a control key, a secret key and a set of transformation keys. The private cloud managed by the organization administrator takes charge of updating the transformation keys using the control key. It helps to handle the situation of flexible access management and attribute alteration. Meanwhile, the mobile user’s single secret key remains unchanged as well as the ciphertext even if the data user’s attribute has been revoked. In addition, we modify the access control list through adding the attributes with corresponding control key and transformation keys so as to manage user privileges depending upon the system version. Finally, the analysis shows that our scheme is secure, flexible and efficient to be applied in mobile hybrid cloud computing.     

A Cloud-Manager-Based Re-Encryption Scheme for Mobile Users in Cloud Environment: a Hybrid Approach

Cloud computing is an emerging computing paradigm that offers on-demand, flexible, and elastic computational and storage services for the end-users. The small and medium-sized business organization having limited budget can enjoy the scalable services of the cloud. However, the migration of the organizational data on the cloud raises security and privacy issues. To keep the data confidential, the data should be encrypted using such cryptography method that provides fine-grained and efficient access for uploaded data without affecting the scalability of the system. In mobile cloud computing environment, the selected scheme should be computationally secure and must have capability for offloading computational intensive security operations on the cloud in a trusted mode due to the resource constraint mobile devices. The existing manager-based re-encryption and cloud-based re-encryption schemes are computationally secured and capable to offload the computationally intensive data access operations on the trusted entity/cloud. Despite the offloading of the data access operations in manager-based re-encryption and cloud-based re-encryption schemes, the mobile user still performs computationally intensive paring-based encryption and decryption operations using limited capabilities of mobile device. In this paper, we proposed Cloud-Manager-based Re-encryption Scheme (CMReS) that combines the characteristics of manager-based re-encryption and cloud-based re-encryption for providing the better security services with minimum processing burden on the mobile device. The experimental results indicate that the proposed cloud-manager-based re-encryption scheme shows significant improvement in turnaround time, energy consumption, and resources utilization on the mobile device as compared to existing re-encryption schemes.     

一种基于Xen的信任虚拟机安全访问设计与实现

结合信任计算技术与虚拟化技术,提出了一种基于Xen的信任虚拟机安全访问机制,为用户提供了一种有效的安全访问敏感数据的模式。其核心思想是利用虚拟机的隔离性,为数据信息应用提供一个专用的隔离环境,同时利用信任计算技术保证该虚拟平台配置状态的可信性。     

高效且可验证的多授权机构属性基加密方案

移动云计算对于移动应用程序来说是一种革命性的计算模式,其原理是把数据存储及计算能力从移动终端设备转移到资源丰富及计算能力强的云服务器.但是这种转移也引起了一些安全问题,例如,数据的安全存储、细粒度访问控制及用户的匿名性.虽然已有的多授权机构属性基加密云存储数据的访问控制方案,可以实现云存储数据的保密性及细粒度访问控制;但其在加密和解密阶段要花费很大的计算开销,不适合直接应用于电力资源有限的移动设备;另外,虽然可以通过外包解密的方式,减少解密计算的开销,但其通常是把解密外包给不完全可信的第三方,其并不能完全保证解密的正确性.针对以上挑战,本文提出了一种高效的可验证的多授权机构属性基加密方案,该方案不仅可以降低加密解密的计算开销,同时可以验证外包解密的正确性并且保护用户隐私.最后,安全分析和仿真实验表明了方案的安全性和高效性.