外文翻譯--基于asp的web技術(shù)介紹

1、<p>　　基于ASP的web技術(shù)介紹</p><p>　　利用ASP開(kāi)發(fā)Web應(yīng)用程序首先必須確立Web應(yīng)用的體系結(jié)構(gòu)。目前在應(yīng)用中常用到的有兩種：C/S體系結(jié)構(gòu)和B/S體系結(jié)構(gòu)。</p><p>　　C/S體系結(jié)構(gòu)即client/server，客戶端/服務(wù)器端。</p><p>　　兩層的客戶/服務(wù)器結(jié)構(gòu)。</p><p>　　

2、客戶/服務(wù)器（Client/Server）模型是一種良好的軟件體系結(jié)構(gòu)，是網(wǎng)絡(luò)的最佳應(yīng)用模式之一。從技術(shù)上看，它本身是一個(gè)邏輯概念，是指將一個(gè)應(yīng)用分解成多個(gè)任務(wù)分別執(zhí)行，共同完成整個(gè)應(yīng)用任務(wù)的功能。網(wǎng)絡(luò)各站點(diǎn)主機(jī)上資源（硬件、軟件、數(shù)據(jù)）分步不均衡，在客戶/服務(wù)器結(jié)構(gòu)下，無(wú)資源的客戶機(jī)通過(guò)向有資源的服務(wù)器發(fā)出請(qǐng)求，并得到資源請(qǐng)求，從而適應(yīng)網(wǎng)絡(luò)中資源分布的不均衡性。采用這種結(jié)構(gòu)能綜合各種計(jì)算機(jī)協(xié)同工作，各盡其能，實(shí)現(xiàn)對(duì)計(jì)算機(jī)系統(tǒng)的規(guī)模優(yōu)化

3、（Rightsizing）和規(guī)模縮小化(Downsizing)。如下圖：</p><p>　　從技術(shù)角度講，“客戶機(jī)”和“服務(wù)器”都是邏輯的概念，其含義是：將計(jì)算機(jī)網(wǎng)絡(luò)應(yīng)用分成兩大部分，其中一部分支持多個(gè)用戶共享的功能與資源，它由服務(wù)器來(lái)實(shí)現(xiàn)；另一部分是面向每個(gè)用戶的，由客戶機(jī)來(lái)實(shí)現(xiàn)，也就是說(shuō)，客戶機(jī)通常執(zhí)行前臺(tái)功能，通過(guò)用戶界面實(shí)現(xiàn)人機(jī)對(duì)話，或是執(zhí)行用戶特定的應(yīng)用程序。而服務(wù)器通常執(zhí)行后臺(tái)功能，管理共享的外設(shè)，

4、接受并回答用戶的請(qǐng)求等。對(duì)于一臺(tái)計(jì)算機(jī)來(lái)說(shuō)，它可以具有雙重功能，在某一時(shí)刻充當(dāng)服務(wù)器，而在另一時(shí)刻又成為客戶機(jī)。</p><p>　　客戶/服務(wù)器類型把計(jì)算機(jī)分為兩類，提供服務(wù)的一方稱為服務(wù)器，請(qǐng)求服務(wù)的一方稱為客戶。為了能夠提供服務(wù)，服務(wù)器一方必須具有一定的硬件和相應(yīng)的服務(wù)器軟件；同樣，客戶一方也必須具有一定的硬件和相應(yīng)的客戶軟件。</p><p>　　在服務(wù)器和客戶之間必須有一個(gè)協(xié)議，

5、雙方根據(jù)這個(gè)協(xié)議進(jìn)行通信。</p><p>　　將客戶/服務(wù)器模型應(yīng)用于Internet服務(wù)， 客戶與服務(wù)器之間的關(guān)系并不是一成不變的。有的Internet節(jié)點(diǎn)一方面提供服務(wù)，另一方面也從別的節(jié)點(diǎn)處獲得服務(wù)；甚至在一次對(duì)話過(guò)程中，雙方的角色也可能互換。如在進(jìn)行文件傳輸時(shí)，如果把提供文件的一方稱為服務(wù)器，把獲取文件的一方稱為客戶，則在使用get 或mget命令從另一個(gè)節(jié)點(diǎn)取文件時(shí)，可以認(rèn)為自己使用的及其是客戶機(jī)，在

6、使用put 或mput命令向另一個(gè)節(jié)點(diǎn)發(fā)送文件時(shí)又可以認(rèn)為自己使用的機(jī)器是服務(wù)器。</p><p>　　多層的客戶/服務(wù)器結(jié)構(gòu)</p><p>　　隨著企業(yè)應(yīng)用的擴(kuò)展，最近又出現(xiàn)了一種新的多層體系結(jié)構(gòu)，它把客戶端應(yīng)用分為兩部分：客戶應(yīng)用和服務(wù)器應(yīng)用?？蛻魬?yīng)用是原來(lái)客戶應(yīng)用的一部分，另一部分被移入服務(wù)器應(yīng)用中。新的客戶應(yīng)用負(fù)責(zé)用戶界面和簡(jiǎn)單固定的業(yè)務(wù)邏輯，新的服務(wù)器應(yīng)用駐留核心的、易變的業(yè)務(wù)

7、邏輯。因此其結(jié)構(gòu)就變成了新的（Client應(yīng)用+Server應(yīng)用）/Server結(jié)構(gòu)。如下圖所示：</p><p>　　這種結(jié)構(gòu)解決了傳統(tǒng)Client/Server的可擴(kuò)展問(wèn)題，既減少了客戶端業(yè)務(wù)邏輯，又降低了客戶端對(duì)硬件的要求。同時(shí)，由于把許多業(yè)務(wù)邏輯集中到了單一的應(yīng)用服務(wù)器上，應(yīng)用系統(tǒng)的維護(hù)工作也被集中到了一起，消除了傳統(tǒng)Client/Server結(jié)構(gòu)中軟件分發(fā)的問(wèn)題。這種結(jié)構(gòu)即被稱為B/S體系結(jié)構(gòu)。<

8、/p><p>　　B/S體系結(jié)構(gòu)即Browser/Server，瀏覽器/服務(wù)器端。本質(zhì)上，Browser/Server也是一種Client/Server結(jié)構(gòu)，它是一種由傳統(tǒng)的二層Client/Server結(jié)構(gòu)發(fā)展而來(lái)的三層Client/Server結(jié)構(gòu)在Web上應(yīng)用的特例。 </p><p>　　在Browser/Server的系統(tǒng)中，用戶可以通過(guò)瀏覽器向分布在網(wǎng)絡(luò)上的許多服務(wù)器發(fā)出

9、請(qǐng)求。Browser/Server結(jié)構(gòu)極大的簡(jiǎn)化了客戶機(jī)的工作，客戶機(jī)上只需安裝、配置少量的客戶端軟件即可， 服務(wù)器將擔(dān)負(fù)更多的工作，對(duì)數(shù)據(jù)庫(kù)的訪問(wèn)和應(yīng)用程序的執(zhí)行將在服務(wù)器上完成。 </p><p>　　在Browser/Server三層體系結(jié)構(gòu)下，表示層(Presentatioon)、功能層(Business Logic)、數(shù)據(jù)層(Data Service)被割成三個(gè)相對(duì)獨(dú)立的單元：</p&g

10、t;<p>　　第一層　表示層：Web瀏覽器。</p><p>　　在表示層中包含系統(tǒng)的顯示邏輯，位于客戶端。它的任務(wù)是由Web瀏覽器向網(wǎng)絡(luò)上的某一Web服務(wù)器提出服務(wù)請(qǐng)求，Web服務(wù)器對(duì)用戶身份進(jìn)行驗(yàn)證后用HTTP協(xié)議把所需的主頁(yè)傳送給客戶端，客戶機(jī)接受傳來(lái)的主頁(yè)文件，并把它顯示在Web瀏覽器上。 </p><p>　　第二層　功能層：具有應(yīng)用程序擴(kuò)展功能的Web

11、服務(wù)器。</p><p>　　在功能層中包含系統(tǒng)的事務(wù)處理邏輯，位于Web服務(wù)器端。它的任務(wù)是接受用戶的請(qǐng)求，首先需要執(zhí)行相應(yīng)的擴(kuò)展應(yīng)用程序與數(shù)據(jù)庫(kù)進(jìn)行連接，通過(guò)SQL等方式向數(shù)據(jù)庫(kù)服務(wù)器提出數(shù)據(jù)處理申請(qǐng)，而后等數(shù)據(jù)庫(kù)服務(wù)器將數(shù)據(jù)處理的結(jié)果提交給Web服務(wù)器，再由Web服務(wù)器傳送回客戶端。</p><p>　　第三層　數(shù)據(jù)層：數(shù)據(jù)庫(kù)服務(wù)器。 </p><p&g

12、t;　　在數(shù)據(jù)層中包含系統(tǒng)的數(shù)據(jù)處理邏輯，位于數(shù)據(jù)庫(kù)服務(wù)器端。它的任務(wù)是接受Web服務(wù)器對(duì)數(shù)據(jù)庫(kù)操縱的請(qǐng)求，實(shí)現(xiàn)對(duì)數(shù)據(jù)庫(kù)查詢、修改、更新等功能，把運(yùn)行結(jié)果提交給Web服務(wù)器。</p><p>　　仔細(xì)分析不難看出，三層的Browser/Server體系結(jié)構(gòu)是把二層Client/Server結(jié)構(gòu)的事務(wù)處理邏輯模塊從客戶機(jī)的任務(wù)中分離出來(lái)，由單獨(dú)組成的一層來(lái)負(fù)擔(dān)其任務(wù)，這樣客戶機(jī)的壓力大大減輕了，把負(fù)荷均衡地分配給了

13、Web服務(wù)器，于是由原來(lái)的兩層的Client/server結(jié)構(gòu)轉(zhuǎn)變成三層的Browser/Server結(jié)構(gòu)。這種三層體系結(jié)構(gòu)如下圖所示。</p><p>　　這種結(jié)構(gòu)不僅把客戶機(jī)從沉重的負(fù)擔(dān)和不斷對(duì)其提高的性能的要求中解放出來(lái)，也把技術(shù)維護(hù)人員從繁重的維護(hù)升級(jí)工作中解脫出來(lái)。由于客戶機(jī)把事務(wù)處理邏輯部分分給了功能服務(wù)器，使客戶機(jī)一下子“苗條”了許多，不再負(fù)責(zé)處理復(fù)雜計(jì)算和數(shù)據(jù)訪問(wèn)等關(guān)鍵事務(wù)，只負(fù)責(zé)顯示部分，所以維

14、護(hù)人員不再為程序的維護(hù)工作奔波于每個(gè)客戶機(jī)之間，而把主要精力放在功能服務(wù)器上程序的更新工作。這種三層結(jié)構(gòu)層與層之間相互獨(dú)立，任何一層的改變不影響其它層的功能。它從根本上改變了傳統(tǒng)的二層Client/Server體系結(jié)構(gòu)的缺陷，它是應(yīng)用系統(tǒng)體系結(jié)構(gòu)中一次深刻的變革。 </p><p>　　兩種體系結(jié)構(gòu)的對(duì)比 </p><p>　　Browser/Server體系結(jié)構(gòu)與Cl

15、ient/Server體系結(jié)構(gòu)相比不僅具有Client/Server體系結(jié)構(gòu)的全部?jī)?yōu)點(diǎn)，而且又有Clinet/Server體系結(jié)構(gòu)所不具備的獨(dú)特優(yōu)勢(shì)：</p><p>　　開(kāi)放的標(biāo)準(zhǔn)：Client/Server所采用的標(biāo)準(zhǔn)只要在內(nèi)部統(tǒng)一就可，它的應(yīng)用往往是專用的。Browser/Server所采用的標(biāo)準(zhǔn)都是開(kāi)放的、非專用的，是經(jīng)過(guò)標(biāo)準(zhǔn)化組織所確定的而非單一廠商所制定，保證了其應(yīng)用的通用性和跨平臺(tái)性。</p&

16、gt;<p>　　較低的開(kāi)發(fā)和維護(hù)成本：Client/Server的應(yīng)用必須開(kāi)發(fā)出專用的客戶端軟件，無(wú)論是安裝、配置還是升級(jí)都需要在所有的客戶機(jī)上實(shí)施，極大地浪費(fèi)了人力和物力。Browser/Server的應(yīng)用只需在客戶端裝有通用的瀏覽器即可，維護(hù)和升級(jí)工作都在服務(wù)器端進(jìn)行，不需對(duì)客戶端進(jìn)行任何改變，故而大大降低了開(kāi)發(fā)和維護(hù)的成本。 </p><p>　　使用簡(jiǎn)單，界面友好：Client/

17、Server用戶的界面是由客戶端軟件所決定的，其使用的方法和界面各不相同，每推廣一個(gè)Client/Server系統(tǒng)都要求用戶從頭學(xué)起，難以使用。Browser/Server用戶的界面都統(tǒng)一在瀏覽器上，瀏覽器易于使用、界面友好，不須再學(xué)習(xí)使用其它的軟件，一勞永逸的解決了用戶的使用問(wèn)題。</p><p>　　客戶端消腫：Client/Server的客戶端具有顯示與處理數(shù)據(jù)的功能，對(duì)客戶端的要求很高，是一個(gè)“胖”客戶機(jī)

18、。Browser/Server的客戶端不再負(fù)責(zé)數(shù)據(jù)庫(kù)的存取和復(fù)雜數(shù)據(jù)計(jì)算的等任務(wù)，只需要其進(jìn)行顯示，充分發(fā)揮了服務(wù)器的強(qiáng)大作用，這樣就大大的降低了對(duì)客戶端的要求，客戶端變得非?！笆荨薄?#160;</p><p>　　系統(tǒng)靈活：Client/Server系統(tǒng)的三部分模塊中有一部分需改變就要關(guān)聯(lián)到其它模塊的變動(dòng)，使系統(tǒng)極難升級(jí)。Browser/Server系統(tǒng)的三部分模塊各自相對(duì)獨(dú)立，其中一部分模塊改變時(shí)其它模塊不

19、受影響，系統(tǒng)改進(jìn)變得非常容易，且可以用不同廠家的產(chǎn)品來(lái)組成性能更佳的系統(tǒng)。</p><p>　　保障系統(tǒng)的安全性：在Client/Server系統(tǒng)中由于客戶機(jī)直接與數(shù)據(jù)庫(kù)服務(wù)器進(jìn)行連接，用戶可以很輕易的改變服務(wù)器上的數(shù)據(jù)，無(wú)法保證系統(tǒng)的安全性。Browser/Server系統(tǒng)在客戶機(jī)與數(shù)據(jù)庫(kù)服務(wù)器之間增加了一層Web服務(wù)器，使兩者不再直接相連，客戶機(jī)無(wú)法直接對(duì)數(shù)據(jù)庫(kù)操縱，有效地防止用戶的非法入侵。</p&g

20、t;<p>　　三層的Browser/Server體系結(jié)構(gòu)具有許多傳統(tǒng)Client/Server體系結(jié)構(gòu)不具備的優(yōu)點(diǎn)，而且又緊密的結(jié)合了Internet/Intranet技術(shù)，是技術(shù)發(fā)展的大勢(shì)所趨，它把應(yīng)用系統(tǒng)帶入了一個(gè)嶄新的發(fā)展時(shí)代。由此我們選擇B/S架構(gòu)作為系統(tǒng)開(kāi)發(fā)的體系結(jié)構(gòu)。</p><p>　　什么是C/S和B/S</p><p>　　要想對(duì)“C/S”和“B/S”技術(shù)

21、發(fā)展變化有所了解，首先必須搞清楚三個(gè)問(wèn)題。</p><p><b>　　什么是C/S結(jié)構(gòu)。</b></p><p>　　C/S （Client/Server）結(jié)構(gòu)，即大家熟知的客戶機(jī)和服務(wù)器結(jié)構(gòu)。它是軟件系統(tǒng)體系結(jié)構(gòu)，通過(guò)它可以充分利用兩端硬件環(huán)境的優(yōu)勢(shì)，將任務(wù)合理分配到Client端和Server端來(lái)實(shí)現(xiàn)，降低了系統(tǒng)的通訊開(kāi)銷。目前大多數(shù)應(yīng)用軟件系統(tǒng)都是Client

22、/Server形式的兩層結(jié)構(gòu)，由于現(xiàn)在的軟件應(yīng)用系統(tǒng)正在向分布式的Web應(yīng)用發(fā)展，Web和Client/Server 應(yīng)用都可以進(jìn)行同樣的業(yè)務(wù)處理，應(yīng)用不同的模塊共享邏輯組件；因此，內(nèi)部的和外部的用戶都可以訪問(wèn)新的和現(xiàn)有的應(yīng)用系統(tǒng)，通過(guò)現(xiàn)有應(yīng)用系統(tǒng)中的邏輯可以擴(kuò)展出新的應(yīng)用系統(tǒng)。這也就是目前應(yīng)用系統(tǒng)的發(fā)展方向。</p><p>　　傳統(tǒng)的C／S體系結(jié)構(gòu)雖然采用的是開(kāi)放模式，但這只是系統(tǒng)開(kāi)發(fā)一級(jí)的開(kāi)放性，在特定的應(yīng)

23、用中無(wú)論是Client端還是Server端都還需要特定的軟件支持。由于沒(méi)能提供用戶真正期望的開(kāi)放環(huán)境，C/S結(jié)構(gòu)的軟件需要針對(duì)不同的操作系統(tǒng)系統(tǒng)開(kāi)發(fā)不同版本的軟件， 加之產(chǎn)品的更新?lián)Q代十分快，已經(jīng)很難適應(yīng)百臺(tái)電腦以上局域網(wǎng)用戶同時(shí)使用。而且代價(jià)高， 效率低。如我院使用的上海超蘭公司“案件統(tǒng)計(jì)”管理軟件就是典型的C／S體系結(jié)構(gòu)管理軟件。</p><p><b>　　什么是B/S結(jié)構(gòu)。</b>&

24、lt;/p><p>　　B/S（Browser/Server）結(jié)構(gòu)即瀏覽器和服務(wù)器結(jié)構(gòu)。它是隨著Internet技術(shù)的興起，對(duì)C/S結(jié)構(gòu)的一種變化或者改進(jìn)的結(jié)構(gòu)。在這種結(jié)構(gòu)下，用戶工作界面是通過(guò)WWW瀏覽器來(lái)實(shí)現(xiàn)，極少部分事務(wù)邏輯在前端（Browser）實(shí)現(xiàn)，但是主要事務(wù)邏輯在服務(wù)器端（Server）實(shí)現(xiàn)，形成所謂三層3-tier結(jié)構(gòu)。這樣就大大簡(jiǎn)化了客戶端電腦載荷，減輕了系統(tǒng)維護(hù)與升級(jí)的成本和工作量，降低了用戶的總

25、體成本（TCO）。以目前的技術(shù)看，局域網(wǎng)建立B/S結(jié)構(gòu)的網(wǎng)絡(luò)應(yīng)用，并通過(guò)Internet/Intranet模式下數(shù)據(jù)庫(kù)應(yīng)用，相對(duì)易于把握、成本也是較低的。它是一次性到位的開(kāi)發(fā)，能實(shí)現(xiàn)不同的人員，從不同的地點(diǎn)，以不同的接入方式（比如LAN, WAN, Internet/Intranet等）訪問(wèn)和操作共同的數(shù)據(jù)庫(kù)；它能有效地保護(hù)數(shù)據(jù)平臺(tái)和管理訪問(wèn)權(quán)限，服務(wù)器數(shù)據(jù)庫(kù)也很安全 。目前我院內(nèi)網(wǎng)（Intranet）、外網(wǎng)（Internet）和北京東

26、方清大公司“案件、辦公管理軟件”就是B/S 結(jié)構(gòu)管理軟件，干警在局域網(wǎng)各工作站通過(guò)WWW瀏覽器就能實(shí)現(xiàn)工作業(yè)務(wù)。特別是在JAVA這樣的跨平臺(tái)語(yǔ)言出現(xiàn)之后，B/S架構(gòu)</p><p><b>　　管理軟件主流技術(shù)。</b></p><p>　　管理軟件技術(shù)的主流技術(shù)與管理思想一樣，也經(jīng)歷了三個(gè)發(fā)展時(shí)期。首先，界面技術(shù)從上世紀(jì)DOS字符界面到Windows圖形界面（或圖形

27、用戶界面GUI），直至Browser瀏覽器界面三個(gè)不同的發(fā)展時(shí)期。其次，今天所有電腦的瀏覽器界面，不僅直觀和易于使用，更主要的是基于瀏覽器平臺(tái)的任何應(yīng)用軟件其風(fēng)格都是一樣的，使用人對(duì)操作培訓(xùn)的要求不高，而且軟件可操作性強(qiáng)，易于識(shí)別；再者，平臺(tái)體系結(jié)構(gòu)也從過(guò)去單用戶發(fā)展到今天的文件／服務(wù)器（F／S）體系、客戶機(jī)／服務(wù)器（C／S）體系和瀏覽器／服務(wù)器（B／S）體系</p><p>　　C/S和B/S 之比較</

28、p><p>　　C/S和B/S是當(dāng)今世界開(kāi)發(fā)模式技術(shù)架構(gòu)的兩大主流技術(shù)。C/S是美國(guó) Borland公司最早研發(fā)，B/S是美國(guó)微軟公司研發(fā)。目前，這兩項(xiàng)技術(shù)以被世界各國(guó)所掌握，國(guó)內(nèi)公司以C/S和B/S技術(shù)開(kāi)發(fā)出產(chǎn)品也很多。這兩種技術(shù)都有自己一定的市場(chǎng)份額和客戶群，各家企業(yè)都說(shuō)自己的管理軟件架構(gòu)技術(shù)功能強(qiáng)大、先進(jìn)、方便，都能舉出各自的客戶群體，都有一大群文人墨客為自己搖旗吶喊，廣告滿天飛，可謂仁者見(jiàn)仁，智者見(jiàn)智<

29、/p><p>　　C/S架構(gòu)軟件的優(yōu)勢(shì)與劣勢(shì) </p><p>　　（1）應(yīng)用服務(wù)器運(yùn)行數(shù)據(jù)負(fù)荷較輕。</p><p>　　最簡(jiǎn)單的C/S體系結(jié)構(gòu)的數(shù)據(jù)庫(kù)應(yīng)用由兩部分組成，即客戶應(yīng)用程序和數(shù)據(jù)庫(kù)服務(wù)器程序。二者可分別稱為前臺(tái)程序與后臺(tái)程序。運(yùn)行數(shù)據(jù)庫(kù)服務(wù)器程序的機(jī)器，也稱為應(yīng)用服務(wù)器。一旦服務(wù)器程序被啟動(dòng)，就隨時(shí)等待響應(yīng)客戶程序發(fā)來(lái)的請(qǐng)求；客戶應(yīng)用程序運(yùn)行在用戶自己的電

30、腦上，對(duì)應(yīng)于數(shù)據(jù)庫(kù)服務(wù)器，可稱為客戶電腦，當(dāng)需要對(duì)數(shù)據(jù)庫(kù)中的數(shù)據(jù)進(jìn)行任何操作時(shí)，客戶程序就自動(dòng)地尋找服務(wù)器程序，并向其發(fā)出請(qǐng)求，服務(wù)器程序根據(jù)預(yù)定的規(guī)則作出應(yīng)答，送回結(jié)果，應(yīng)用服務(wù)器運(yùn)行數(shù)據(jù)負(fù)荷較輕。</p><p>　?。?）數(shù)據(jù)的儲(chǔ)存管理功能較為透明。</p><p>　　在數(shù)據(jù)庫(kù)應(yīng)用中，數(shù)據(jù)的儲(chǔ)存管理功能，是由服務(wù)器程序和客戶應(yīng)用程序分別獨(dú)立進(jìn)行的，前臺(tái)應(yīng)用可以違反的規(guī)則，并且通常把

31、那些不同的（不管是已知還是未知的）運(yùn)行數(shù)據(jù)，在服務(wù)器程序中不集中實(shí)現(xiàn)，例如訪問(wèn)者的權(quán)限，編號(hào)可以重復(fù)、必須有客戶才能建立定單這樣的規(guī)則。所有這些，對(duì)于工作在前臺(tái)程序上的最終用戶，是“透明”的，他們無(wú)須過(guò)問(wèn)（通常也無(wú)法干涉）背后的過(guò)程，就可以完成自己的一切工作。在客戶服務(wù)器架構(gòu)的應(yīng)用中，前臺(tái)程序不是非?！笆菪　?，麻煩的事情都交給了服務(wù)器和網(wǎng)絡(luò)。在C/S體系的下，數(shù)據(jù)庫(kù)不能真正成為公共、專業(yè)化的倉(cāng)庫(kù)，它受到獨(dú)立的專門管理。</p>

32、;<p>　?。?） C/S架構(gòu)的劣勢(shì)是高昂的維護(hù)成本且投資大。</p><p>　　首先，采用C/S架構(gòu)，要選擇適當(dāng)?shù)臄?shù)據(jù)庫(kù)平臺(tái)來(lái)實(shí)現(xiàn)數(shù)據(jù)庫(kù)數(shù)據(jù)的真正“統(tǒng)一”，使分布于兩地的數(shù)據(jù)同步完全交由數(shù)據(jù)庫(kù)系統(tǒng)去管理，但邏輯上兩地的操作者要直接訪問(wèn)同一個(gè)數(shù)據(jù)庫(kù)才能有效實(shí)現(xiàn)，有這樣一些問(wèn)題，如果需要建立“實(shí)時(shí)”的數(shù)據(jù)同步，就必須在兩地間建立實(shí)時(shí)的通訊連接，保持兩地的數(shù)據(jù)庫(kù)服務(wù)器在線運(yùn)行，網(wǎng)絡(luò)管理工作人員既要對(duì)

33、服務(wù)器維護(hù)管理，又要對(duì)客戶端維護(hù)和管理，這需要高昂的投資和復(fù)雜的技術(shù)支持，維護(hù)成本很高，維護(hù)任務(wù)量大。</p><p>　　其次，傳統(tǒng)的C/S結(jié)構(gòu)的軟件需要針對(duì)不同的操作系統(tǒng)系統(tǒng)開(kāi)發(fā)不同版本的軟件，由于產(chǎn)品的更新?lián)Q代十分快，代價(jià)高和低效率已經(jīng)不適應(yīng)工作需要。在JAVA這樣的跨平臺(tái)語(yǔ)言出現(xiàn)之后，B/S架構(gòu)更是猛烈沖擊C/S，并對(duì)其形成威脅和挑戰(zhàn)。</p><p>　　B/S架構(gòu)軟件的優(yōu)勢(shì)與劣

34、勢(shì)</p><p>　?。?）維護(hù)和升級(jí)方式簡(jiǎn)單。</p><p>　　目前，軟件系統(tǒng)的改進(jìn)和升級(jí)越來(lái)越頻繁，B/S架構(gòu)的產(chǎn)品明顯體現(xiàn)著更為方便的特性。對(duì)一個(gè)稍微大一點(diǎn)單位來(lái)說(shuō)，系統(tǒng)管理人員如果需要在幾百甚至上千部電腦之間來(lái)回奔跑，效率和工作量是可想而知的，但B/S架構(gòu)的軟件只需要管理服務(wù)器就行了，所有的客戶端只是瀏覽器，根本不需要做任何的維護(hù)。無(wú)論用戶的規(guī)模有多大，有多少分支機(jī)構(gòu)都不會(huì)增

35、加任何維護(hù)升級(jí)的工作量，所有的操作只需要針對(duì)服務(wù)器進(jìn)行；如果是異地，只需要把服務(wù)器連接專網(wǎng)即可，實(shí)現(xiàn)遠(yuǎn)程維護(hù)、升級(jí)和共享。所以客戶機(jī)越來(lái)越“瘦”，而服務(wù)器越來(lái)越“胖”是將來(lái)信息化發(fā)展的主流方向。今后，軟件升級(jí)和維護(hù)會(huì)越來(lái)越容易，而使用起來(lái)會(huì)越來(lái)越簡(jiǎn)單，這對(duì)用戶人力、物力、時(shí)間、費(fèi)用的節(jié)省是顯而易見(jiàn)的，驚人的。因此，維護(hù)和升級(jí)革命的方式是“瘦”客戶機(jī)，“胖”服務(wù)器。</p><p>　　（2）成本降低，選擇更多。&

36、lt;/p><p>　　大家都知道windows在桌面電腦上幾乎一統(tǒng)天下，瀏覽器成為了標(biāo)準(zhǔn)配置，但在服務(wù)器操作系統(tǒng)上windows并不是處于絕對(duì)的統(tǒng)治地位。 現(xiàn)在的趨勢(shì)是凡使用B/S架構(gòu)的應(yīng)用管理軟件，只需安裝在Linux服務(wù)器上即可，而且安全性高。所以服務(wù)器操作系統(tǒng)的選擇是很多的，不管選用那種操作系統(tǒng)都可以讓大部分人使用windows作為桌面操作系統(tǒng)電腦不受影響，這就使的最流行免費(fèi)的Linux操作系統(tǒng)快速發(fā)展起來(lái)，

37、Linux除了操作系統(tǒng)是免費(fèi)的以外，連數(shù)據(jù)庫(kù)也是免費(fèi)的，這種選擇非常盛行。</p><p>　　比如說(shuō)很多人每天上“新浪”網(wǎng)，只要安裝了瀏覽器就可以了，并不需要了解“新浪”的服務(wù)器用的是什么操作系統(tǒng)，而事實(shí)上大部分網(wǎng)站確實(shí)沒(méi)有使用windows操作系統(tǒng)，但用戶的電腦本身安裝的大部分是windows操作系統(tǒng)。</p><p>　?。?） 應(yīng)用服務(wù)器運(yùn)行數(shù)據(jù)負(fù)荷較重。</p>&

38、lt;p>　　由于B/S架構(gòu)管理軟件只安裝在服務(wù)器端（Server）上，網(wǎng)絡(luò)管理人員只需要管理服務(wù)器就行了，用戶界面主要事務(wù)邏輯在服務(wù)器（Server）端完全通過(guò)WWW瀏覽器實(shí)現(xiàn)，極少部分事務(wù)邏輯在前端（Browser）實(shí)現(xiàn)，所有的客戶端只有瀏覽器，網(wǎng)絡(luò)管理人員只需要做硬件維護(hù)。但是，應(yīng)用服務(wù)器運(yùn)行數(shù)據(jù)負(fù)荷較重，一旦發(fā)生服務(wù)器“崩潰”等問(wèn)題，后果不堪設(shè)想。因此，許多單位都備有數(shù)據(jù)庫(kù)存儲(chǔ)服務(wù)器，以防萬(wàn)一。</p>&l

39、t;p>　　Introduction of ASP based on Web Technology</p><p>　　Develop Web application program using ASP the architecture that must first establish Web application. Now in application frequently with to have

40、two: The architecture of C/S and the architecture of B/S. </p><p>　　Client/server and customer end / server hold the architecture of C/S. </p><p>　　The customer / server structure of two floor.

41、</p><p>　　Customer / server ( Client/Server ) model is a kind of good software architecture, it is the one of best application pattern of network. From technology, see that it is a logic concept, denote will

42、 a application many tasks of decomposing difference carry out , common completion is entire to apply the function of task. On each network main computer of web site, resource ( hardware, software and data ) divide into s

43、tep, is not balanced, under customer / server structure, without the client compute</p><p>　　It is most of to divide into computer network application into two, in which the resource and function that part s

44、upports many users to share , it is realized by server; Another part faces every user , is realized by client computer, also namely, client computer is usual to carry out proscenium function , realizes man-machine intera

45、ction through user interface , or is the application program of specific conducted user. And server usually carries out the function of backstage supporter , manages </p><p>　　Customer / server type computer

46、 divide into two kinds, one side who offers service is called as server , asks one side of service to be called as customer. To be able to offer service, server one side must have certain hardware and corresponding serve

47、r software; Also, customer one side must also have certain hardware and corresponding customer software. </p><p>　　There must be a agreement between server and customer, both sides communicate according to t

48、his agreement. </p><p>　　Apply customer / server model in Internet service , the relation between customer and server is not immutable. Some Internet node offers service on the one hand , also gets service o

49、n the other hand from other node; It is even in one time dialogue course, mutual role also exchanges probably. As in carry out file transmission , if be called as one side who offers file server, is called as one side wh

50、o gets file customer, when using get or mget order since another node takes file, can think that w</p><p>　　Multilayer customer / server structure </p><p>　　Along with the development of enterpr

51、ise application, recently, have again arisen a kind of new multilayer architecture, it applies customer end to divide into two minutes: Customer application and server apply. Customer application is the part of original

52、customer application , is another and partial to have been transfered to server to apply. New customer application takes the responsibility for user interface and simple regular business logic and new server application

53、resident core , changea</p><p>　　This kind of structure has solved traditional Client/Server can expand problem, have reduced customer end business logic , and have reduced the requirement of customer end fo

54、r hardware. At the same time because of a lot of business logic concentrations have gone to unitary application server on, the maintenance work of application system had been also concentrated together, have eliminated t

55、he problem in the traditional structure of Client/Server that software distributes. This kind of structu</p><p>　　Browser/Server and browser / server hold the architecture of B/S. On essence, Browser/Serve

56、r is also a kind of structure of Client/Server, it is a kind of from the traditional two levels of structural development of Client/Server come to the three-layer structural special case of Client/Server that applied on

57、Web. </p><p>　　In the system of Browser/Server, user can pass through browser to a lot of servers that spread on network to send request. The structure of Browser/Server is maximum to have simplified the wor

58、k of client computer, on client computer, need to install and deploy few customer end software only , server will bear more work, for database visit and apply program carry out will in server finish. </p><p>

59、;　　Under the three-layer architecture of Browser/Server, express layer ( Presentatioon ) , function layer ( Business Logic ) , data layer ( Data Service ) have been cut the unit of 3 relative independences: </p>&

60、lt;p>　　It is the first layer of to express layer: Web browser. </p><p>　　In expressing layer contain system show logic, locate in customer end. It's task is to suggest by Web browser to the certain a

61、Web server on network that service is asked , after verifying for user identity, Web server delivers needed homepage with HTTP agreement to customer end, client computer accept the homepage file that passed , and show it

62、 in Web browser on. </p><p>　　Second layer function layer: Have the Web server of the application function of program extension. </p><p>　　In function layer contain the systematic handling of ge

63、neral affairs logic, locate in Web server end. It's task is the request concerning accepting user , need to be first conducted and corresponding to expand application program and database to carry out connection , pa

64、sses through the waies such as SQL to database server to put forward data handling to apply for, then etc. database server the result of handling data submit to Web server, deliver again by Web server to return customer

65、end. </p><p>　　The number of plies of 3th according to layer: Database server. </p><p>　　In data layer contain systematic data handling logic, locate in database server end. It's task is to

66、accept the request that Web server controls for database, realization is inquired and modified for database , update etc. function, submit operation result to Web server. </p><p>　　Careful analysis is been e

67、asy to see , the architecture of Browser/Server of three-layer is the handling of general affairs of the two levels of structure of Client/Server logic modular from the task of client computer in split , from the first f

68、loor of individual composition bear the pressure of its task and such client computer have alleviated greatly, distribute load balancedly and have given Web server, so from the structural change of Client/server of origi

69、nal two floor the structure of Bro</p><p>　　This kind of structure not only client computer from heavy burden and the requirement of performance that rises continuously for it in liberation come out , also d

70、efend technology people from heavy maintenance upgrading work in free oneself. Since client computer handles general affairs , logic partial minutes have given function server, make client computer right off " slend

71、er " a lot of, do not take the responsibility for handling complex calculation and data again visit etc. crucial general a</p><p>　　The contrast of two architectures</p><p>　　The architectu

72、re of Browser/Server and the architecture of Client/Server compare with all advantages that not only have the architecture of Client/Server and also have the architecture of Clinet/Server the unique advantage that place

73、does not have: </p><p>　　Open standard: The standard adopted by Client/Server only in department unification for but, it's application is often for special purpose. </p><p>　　It is lower to

74、develop and defend cost: It need to be implemented on all client computers that the application of Client/Server must develop the customer end software for special purpose, no matter installation and disposition escalate

75、 still, have wasted manpower and material resources maximumly. The application of Browser/Server need in customer end have general browser , defend and escalate to work in server end go on , need not carry out any change

76、 as customer holds , have reduced the cost of</p><p>　　It is simple to use , interface friendly: The interface of the user of Client/Server is decided by customer end software, interface and the method of it

77、s use are not identical each, per popularize a system of Client/Server ask user study from the beginning, is hard to use. The interface of the user of Browser/Server is unified on browser, browser is easy to use , interf

78、ace friendly, must not study use again other software, the use of a Lao Yong Yi that has solved user problem. </p><p>　　Customer end detumescence: The customer end of Client/Server has the function that show

79、s and handles data , as the requirement of customer end is a client computer " it is fat " very high. The customer of Browser/Server holds the access that not takes the responsibility for database again and the

80、 etc. task of complex data calculation, need it only show , the powerful role that has played server fully is so large to have reduced the requirement for customer end, customer end become very " thin ".</p&

81、gt;<p>　　System is flexible: The 3 minutes of the system of Client/Server, in modular, have the part that need to change to want relation to the change of other modular, make system very difficult upgrading. The 3

82、 minutes of the system of Browser/Server modular relative independence, in which a part of modular change, other modular does not get influence, it is very easy that system improve to become, and can form the system with

83、 much better performance with the product of different manufacturer. </p><p>　　Ensure systematic safety: In the system of Client/Server, directly join with database server because of client computer, user ca

84、n very easily change the data on server, can not guarantee systematic safety. The system of Browser/Server has increased a level of Web server between client computer and database server , makes two not to be directly li

85、nked again, client computer can not be directly controled for database, prevent user efficiently invade illegally. </p><p>　　The architecture of Browser/Server of three-layer has the advantage that a lot of

86、traditional architectures of Client/Server does not have , and is close to have combined the technology of Internet/Intranet, is that the tendency of technical development tends to , it application system tape into one b

87、rand-new develop times. From this us option the configuration of B/S the architecture that develops as system.</p><p>　　what are C/S with B/S </p><p>　　For " C/S " with the technology

88、of " B/S " develop change know , first,must make it clear that 3 problems. </p><p>　　( 1 ) What is the structure of C/S. </p><p>　　C/S ( Client/Server ) structure, the server structure

89、 and client computer that all know well. It is software systematic architecture, through it can hold hardware environment fully using two advantage, realize task reasonable distribution to Client end and Server end , hav

90、e reduced systematic communication expense. Now, the most systems of application software are the two levels of structure of the form of Client/Server , are developing to the Web application of distribution type since cu

91、rrent s</p><p>　　Traditional C ／ S architecture though adopting is open pattern, but this is the openness that system develops a level , in specific application no matter Client end or Server end the softwar

92、e that need to still specify support. Because of the software software that need to develop different edition according to the different system of operating system that can not offer the structure of C/S and the open env

93、ironment of user genuine expectation , besides, the renovation of product is very rapid, i</p><p>　　( 2 ) What is the structure of B/S. </p><p>　　B/S ( Browser/Server ) structure browser and ser

94、ver structure. It is along with the technology of Internet spring up , it is for the structure of improvement or a kind of change of the structure of C/S. Under this kind of structure, user working interface is to realiz

95、e through WWW browser, lose the logic of general affairs very much in front( Browser) realization, but the major logic of general affairs in server end( Server) realization, form the three-layer claimed 3-tier structure.

96、 So, have si</p><p>　　( 3 ) The management software technology of main stream. </p><p>　　The technology of main stream of management software technology is as management thought , have also gone

97、 through 3 develop period. First, interface technology goes to Windows graph interface ( or graph user interface GUI ) from last century DOS character interface, till Browser browser interface 3 differences develop perio

98、d. Secondly, today own the browser interface of computer, is not only visual and is easy to use , what is more major is that any its style of application software based on bro</p><p>　　The comparison of C/S

99、 and B/S</p><p>　　C/S and B/S is the now world two technologies of main stream of developing pattern technical configuration. C/S is that American Borland company researches and develop most early, B/S is th

100、at American Microsoft researches and develop. Now this two technologies with quilt world countries grasp , it is many that domestic company produce article with C/S and the technical development of B/S. This two technolo