Mobile Objects as Mobile Processes

Obliq is a lexically scoped, distributed, object-based programming language. In Obliq, the migration of an object is proposed as creating a clone of the object at the target site, whereafter the original object is turned into an alias for the clone. Obliq has only an informal semantics, so there is no proof that this style of migration is safe, i.e., transparent to object clients. In previous work, we introduced Ø, an abstraction of Obliq, where, by lexical scoping, sites have been abstracted away. We used Ø in order to exhibit how the semantics behind Obliq's implementation renders migration unsafe. We also suggested a modified semantics that we conjectured instead to be safe. In this paper, we rewrite our modified semantics of Ø in terms of the π-calculus, and we use it to formally prove the correctness of object surrogation, the abstraction of object migration in Ø.     

Mobile networking through Mobile IP

Mobile IP is a proposed standard protocol that builds on the Internet Protocol by making mobility transparent to applications and higher level protocols like TCP. Mobile IP (RFC 2002) is a standard proposed by a working group within the Internet Engineering Task Force; it allows the mobile node to use two IP addresses: a fixed home address and a care-of address that changes at each new point of attachment. The article presents the Mobile IP standard in moderate technical detail and points the reader toward a wealth of further information. Is also describes how Mobile IP will change with IP version 6, the product of a major effort within the IETF to engineer an eventual replacement for the current version of IP. Although IPv6 will support mobility to a greater degree than IPv4, it will still need Mobile IP to make mobility transparent to applications and higher level protocols such as TCP. There is a great deal of interest in mobile computing and apparently in Mobile IP as a way to provide for it. A quick Web search for items related to Mobile IP returned over 60,000 hits-impressive even given the notorious lack of selectivity for such procedures. Mobile IP forms the basis either directly or indirectly of many current research efforts and products. The Cellular Digital Packet Data (CDPD), for example, has created a widely deployed communications infrastructure based on a previous draft specification of the protocol. In addition, most major router vendors have developed implementations for Mobile IP     

移动计算

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基于Mobile Agent的嵌入式移动数据库

随着移动计算技术的发展,移动数据库逐步走向应用,在嵌入式操作系统中移动数据库更显示出其优越性。移动环境中所具有移动性、频繁断接收、低带宽、电池电量有限性等特性,决定了移动数据库中计算环境不同于分布式数据库,给移动数据库研究提出了许多新的要求。该文从分析移动数据库特点、体系结构;介绍移动数据库系统中一些关键性技术;Agent技术及移动Agent在移动数据库中的应用。     

基于Mobile Agent的嵌入式移动数据库

随着移动计算技术的发展,移动数据库逐步走向应用,在嵌入式操作系统中移动数据库更显示出其优越性。移动环境中所具有移动性、频繁断接收、低带宽、电池电量有限性等特性,决定了移动数据库中计算环境不同于分布式数据库,给移动数据库研究提出了许多新的要求。该文从分析移动数据库特点、体系结构;介绍移动数据库系统中一些关键性技术;Agent技术及移动Agent在移动数据库中的应用。     

移动运营商的移动互联网发展路径探究

移动互联网的快速增长催生了巨大的"信息消费"产业图景,但也导致了移动通信网业分离和专业细分的趋势。移动运营商应摆脱"网络运营商"的观念束缚,自身定位为"数字社会的综合服务提供商",主动分拆自己拥有的价值创造环节,成立独立经营实体,融入移动互联网的发展大潮。     

一种针对移动全覆盖问题的节点移动策略

在传感网和物联网的大力发展过程中,覆盖问题始终是该领域关注的核心问题.目前在诸多应用中,网络部署受各类影响因素的制约以及传感设备自身条件的限制,无法实现监测区域的完全覆盖.但如果借助某些特定的移动设备并按照有针对性的移动策略实施移动覆盖,就可以实现监测区域内的补全覆盖.基于此应用提出了一类新的覆盖问题——移动全覆盖问题,即在网络稀疏覆盖的环境下,利用移动节点的移动覆盖实现监测区域的全覆盖问题.针对该问题提出了分而治之的节点移动策略.首先,按照移动节点通信半径将整个监测区域划分成多个子区域;其次,以四叉树分层遍历的策略作为移动节点在子区域间的移动方案;最后,针对每个子区域内静态节点的覆盖状况制定相应的区域内的移动策略.实验结果表明采用本文提出的移动策略可以实现在移动节点移动较小距离的前提下达到整个区域的全覆盖,从而解决了稀疏网络环境下的全覆盖问题.     

移动软交换--移动核心网的技术变革

从全球范围来看，移动运营商对软交换进展的关注甚为密切，不仅引入了移动软交换，而且不再不遗余力地对移动交换机进行改造。例如，美国某家运营商可以将媒体网关放在德克萨斯州的基站上，呼叫服务器放在达拉斯，这些不同模块间的连接可以通过IP网络进行，管理可以集中进行。彩铃就是利用软交换的一种典型业务，正受到用户的很大欢迎。     

移动定位技术和移动定位系统

移动终端的位置是移动互联网中的关键信息.本文从移动定位技术、典型的移动定位系统及当前研究热点等方面对其进行了阐述.     

Mobile E-Witness

This paper describes the design, implementation and experimental evaluation of a system prototype, named Mobile E-Witness (MEW), which enables the acquisition and remote storage of multimedia (i.e., audio and video) data streams. In essence, MEW consists of a mobile device, incorporating a camera and a microphone, which can be “worn” (i.e., it can be carried without causing any impediment) by public officers, such as policemen and health care operators, in order to record the events these officers witness while on duty. MEW transmits the audio and video data recordings it takes to a remote storage service which maintains these recordings for future replay. Thus, for example, an event recording can be used as an impartial testimony to resolve disputes concerning the relative responsibilities of those participating to the recorded event, including the officers themselves (hence the name Mobile E-Witness). The infrastructure MEW uses for communications with the remote storage service consists of the wired and wireless communication infrastructures publicly available in metropolitan areas, including the Internet. MEW utilizes these infrastructures in order to (1) ensure that sufficient bandwidth for multimedia data transmission is available, (2) guarantee highly available communications, (3) limit the power consumption for the multimedia transmission and, finally, (4) limit the electromagnetic radiation emanation of the device worn by the public officers. We have carried out an experimental evaluation of a MEW prototype in the city of Bologna. The results of this evaluation, reported in this paper, confirm the potential of our system.

与移动节点无关的Mobile IP架构

在WLan中,移动节点MN(Mobile Node)在Access Point(AP)间的漫游通常是通过二层网络实现。随着网络扩大,二层的广播包会降低系统性能。RFC3344提出的MobileIP架构使得三层网络的漫游成为可能,但是,RFC3344作为一种通用的解决方案,直接集成到WLan中,其定义的一些服务与802.11定义的服务在功能上存在重叠。同时,RFC3344要求MN提供相关的支持,这限制了协议适用范围。在RFC3344的基础上,提出了一种MobileIP在WLan中的实现方式,通过对DHCP消息过滤,实现对MN位置的跟踪。此实现基于在Internet中广泛使用的服务,同时独立于MN的实现,具有很好的实用价值。     

Mobile computing

The problems, limitations, and potential advantages of mobile computing systems are discussed. It is suggested that the constraints violate many of the assumptions upon which today's distributed systems are based. A key requirement of mobile computing systems will be the ability to access critical data regardless of location, which implies interdependence between the elements of a mobile computing system. The Coda file system, which is an effort to provide transparency of environment to mobile computing systems, is reviewed     

基于移动Agent的无线应用软件测试系统

介绍了基于移动Agent技术实现的用于测试与网络相关的无线应用软件的测试系统,并提出了将系统的弱移动机制改造成为强移动的新思路用以提高测试环境的真实性。利用了对源程序插入代码来捕捉和恢复程序状态的方法,加入的代码在程序需要捕捉状态时捕捉到程序状态信息并在重新运行时恢复状态。实现了在不修改Java虚拟机的情况下基于Java的移动Agent强迁移。     

移动环境下基于移动代理的应用框架设计

随着网络技术的发展和移动设备的普及，用户希望能随时随地对资源进行访问。但是，由于移动网络连接带宽低且移动单元本身资源贫乏，移动环境为分布应用开发提出了新的挑战。移动代理技术以其节省带宽、异步性等特征，为移动计算提供了良好的解决方案。本文首先讨论了移动代理系统的设计，然后提出一个基于移动代理的移动应用框架
架，最后给出了相应的应用实例。     

Mobile supercomputers

We need mobile supercomputers that provide massive computational performance from the power in a battery. These supercomputers will make our personal devices much easier to use. They will perform real-time speech recognition, video transmission and analysis, and high bandwidth communication. And they will do so without us having to worry about where the next electrical outlet will be. But to achieve this functionality, we must rethink the way we design computers. Rather than worrying solely about performance, with the occasional nod to power consumption and cost, we need to judge computers by their performance-power-cost product. This new way of looking at processors will lead us to new computer architectures and new ways of thinking about computer system design.     

Mobile payments

The increasing deployment of wireless networks and the widespread popularity of handheld devices have led to numerous applications ranging from mobile banking to location-based tracking to mobile advertising. With nearly 300 million mobile users worldwide expected to be purchasing content on wireless devices by 2005, many of these emerging services would greatly benefit from infrastructure support for mobile payments. Many emerging services would greatly benefit from infrastructure support for mobile payments.     

Mobile graphics

Mobile phones form a ubiquitous graphics platform; over half of the world population uses them. This special issue presents solutions that overcome some of the inherent limitations of these compact computing devices and make use of the fact that they are available at all times, not just at your desk.     

移动计算环境下的移动事务解决方案

由于移动计算环境的复杂性、网络条件多样性、频繁断接等特性使得移动终端发出的事务具有传统事务不具备的异构性、移动性、长事务性和易错性。通过对XML Web Services原理和队列通信机制的分析,本文构建了一个基于XML Web服务的客户/移动终端服务代理层/服务器的三层体系结构,并在移动终端服务代理层设置了可用于存储不同事务类型的事务队列。此解决方案支持事务在移动计算环境下的传输。     

Mobile agents

A lot of agents are executing on the Web, and some of them are starting to move around. While most agents are static (existing as a single process or thread on one host), others can pick up and move their code and data to a new host where they resume executing