《阅读翻译mobiledatabase》由会员分享，可在线阅读，更多相关《阅读翻译mobiledatabase（6页珍藏版）》请在金锄头文库上搜索。
1、Mobile database From Wikipedia, the free encyclopediaA mobile database is a database that can be connected to by a mobile computing device over a mobile network. The client and server have wireless connections. A cache is maintained to hold frequent data and transactions so that they are not lost du
2、e to connection failure. A database is a structured way to organize information. This could be a list of contacts, price information or distance travelled.1The use of laptops, mobiles and PDAs is increasing and likely to increase in the futurecitation needed with more and more applications residing
3、in the mobile systems. While those same analysts cant tell us exactly which applications will be the most popular, it is clear that a large percentage will require the use of a database of some sort. Many applications such as databases would require the ability to download information from an inform
4、ation repository and operate on this information even when out of range or disconnected.An example of this is a mobile workforce. In this scenario user would require to access and update information from files in the home directories on a server or customer records from a database. This type of acce
5、ss and work load generated by such users is different from the traditional workloads seen in clientserver systems of today. With the advent of mobile databases, now users can load up their smart phones or PDAs with mobile databases to exchange mission-critical data remotely without worrying about ti
6、me or distance. Mobile databases let employees enter data on the fly. Information can be synchronized with a server database at a later time.Need for mobile databases Mobile users must be able to work without a wireless connection due to poor or even non-existent connections. Applications must provi
7、de significant interactivity. Applications must be able to access local device/vehicle hardware, such as printers, bar code scanners, or GPS units (for mapping or Automatic Vehicle Location systems). Bandwidth must be conserved (a common requirement on wireless networks that charge per megabyte or d
8、ata transferred). Users dont require access to truly live data, only recently modified data. Limited life of power supply(battery) The changing topology of networkIf your application meets any of those requirements, the chances are good that you will be required to build a mobile database applicatio
9、n with synchronizaMobile database system architectureFor any mobile architecture, things to be considered are: Users are not attached to a fixed geographical location Mobile computing devices: low-power, low-cost, portable Wireless networks Mobile computing constraints Three partiesMobile databases
10、typically involve three parties: fixed hosts, mobile units, and base stations. Fixed hosts perform the transaction and data management functions with the help of database servers. Mobile units are portable computers that move around a geographical region that includes the cellular network (or cells)
11、 that these units use to communicate to base stations. (Note that these networks need not be cellular telephone networks.) Base stations are two-way radios, installations in fixed locations, that pass communications with the mobile units to and from the fixed hosts. They are typically low-power devi
12、ces such as mobile phones, portable phones, or wireless routers.When a mobile unit leaves a cell serviced by a particular base station, that station transparently transfers the responsibility for the mobile units transaction and data support to whichever base station covers the mobile units new loca
13、tion. ProductsSybase Inc.s SQL Anywhere dominates the mobile-database field, with about 68 percent of the mobile database market. IBMs DB2 Everyplace is a relational database and enterprise synchronization server that extends enterprise applications to mobile devices. Microsoft SQL Server Compact an
14、d Oracle9i Lite are similar mobile databases. Products from lesser-known vendors, such as SQLBase from Gupta Technologies LLC of Redwood Shores, Calif., HanDBase from DDH Software Inc. of Lake Worth, Fla.and Cellica Database from Cellica Corporation NY, might serve your needs equally well. On Apples
15、 iOS, the DataGlass Mobile Database Client line of products by impathic offers file-based access to Microsoft Access databases and client-server access to Sybase, Microsoft SQL Server, IBM DB2, MySQL, Oracle, and PostgreSQL. Sybases SQL AnywhereSQL Anywhere offers enterprise-caliber databases that s
16、cale from 64-bit servers with thousands of users down to small handheld devices. SQL Anywheres data exchange technologies extend information in corporate applications and enterprise systems to databases running in mission-critical frontline environments. Design and management tools within SQL Anywhere enable developers to implement and deploy frontline applications and equip administrators to easily manage and suppo
