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主從式資料庫架構 臺北大學統計系 莊東穎 大綱 主從式架構之沿革 主從式資料庫設計 關聯性資料庫管理系統 主從式資料庫工具簡介 系統整合考量 整合性管理 Chapter 2 - 2 TY Juang Web DB 主從式架構之沿革 Chapter 2 - 3 1970 : 主 機 型 資 料 處 理 (Mainframe Database Computing 或 Host-based Computing) 1980 : 檔 案 伺 服 型 資 料 處 理 (PC/File Server Database Computing) 1990 : 主 從 型 資 料 處 理 (Client/Server Database Computing, N-tier Computing) TY Juang Web DB 主機型資料處理 Dumb Terminal 1 Mainframe running RDBMS and application Dumb Terminal 2 Chapter 2 - 4 Dumb Terminal 3 TY Juang Web DB 主機型資料處理(續) 中大型企業之唯一選擇 可靠性高 安全性高 所有作業均由後端主機負責 Chapter 2 - 5 TY Juang Web DB 主機型資料處理(續) 價格昂貴 維護成本高 環境封閉,受制於廠商 架構龐大,複雜 無法隨企業成長而調適 Chapter 2 - 6 TY Juang Web DB 檔案伺服器資料處理 Data sent back to PC for processing PC running application and RDBMS Request for data File Server PC running application and RDBMS Chapter 2 - 7 PC running application and RDBMS TY Juang Web DB 檔案伺服器資料處理(續) 使用第三、四代語言,開發容易 價格低廉 前端機器執行資料管理作業 後端伺服器僅負責資料儲存和分享 Chapter 2 - 8 TY Juang Web DB 檔案伺服器資料處理(續) 使用人數多,則易造成網路阻塞 資料搬移量大,系統表現差 安全性較低 穩定性較差 Chapter 2 - 9 TY Juang Web DB 主從式資料處理 Query result Query Client workstation running application User Interface Business Logic Server running RDBMS Client workstation running application Database Processing Business Logic TY Juang Chapter 2 - 10 Client workstation running application Web DB 為何主從式資料處理成為主流? Affordability 開放性架構(open architecture) 可選擇之廠商眾多 Speed 減少網路傳輸瓶頸 處理速度可媲美主機型資料處理 Chapter 2 - 11 TY Juang Web DB 為何主從式資料處理成為主流? Adaptability 軟硬體可分開採購 更符合實際需要 Simplified Data Access 可使用簡單、易開發之工具 不需使用特定語言 Chapter 2 - 12 TY Juang Web DB 主從式資料庫設計 三個組成元素: 1.客戶端 (presentation,使用者介面) 2.伺服端 (資料庫伺服器) 3.企業邏輯 (Business logic) 企業邏輯:應用程式中資料處理的定義及規則 企業邏輯 客戶端 Chapter 2 - 13 TY Juang 伺服端 Web DB FAT Server: 1: 2: Client issues request to server Server issues response to client Client Fat Server Fat Server Client 1.Issue request to inspect widget supply 5.Receive response from server Chapter 2 - 14 2.Receive request -count number of widgets on hand -if Count=0 then construct high priority request to replenish widget supply if Count>0 and <50 then construct medium priority request to replenish widget supply if Count>50 then construct low priority request to replenish widget supply 3.Issue request to replenish widget supply 4.Issue response TY Juang Web DB FAT client: 1: 2: 3: 4: Client issues request to server Server issues response to client Client issues request to server Server issues response to client Server Fat Client Server logic Fat Client logic 1.Issue request to count widget supply 4.Process response from RDBMS -if Count=0 then construct high priority request to replenish widget supply if Count>0 and <50 then construct medium priority request to replenish widget supply if Count>50 then construct low priority request to replenish widget supply 5.Issue request to replenish widget supply 8.Receive response from RDBMS Chapter 2 - 15 2.Receive request -count number of widgets on hand 3.Issue request 6.Receive response -replenish widget supply 7.Issue response TY Juang Web DB 分層式架構(Tiered Architecture) 什麼是Tier? 定義: A tiered architecture is when a logical section of an application can be divided into categories or tiers. Chapter 2 - 16 TY Juang Web DB 兩層式架構(Two-tiered Architecture) 傳統之主從式架構 將程式分為客戶端 (Client) 及資料庫伺服 端 (Database Server) 客戶端為使用者介面 (一般為GUI) 資料庫伺服端提供所需之資料 Chapter 2 - 17 TY Juang Web DB 兩層式架構(續) Tier 1 Tier 2 GUI (presentation layer) Database (Data Server layer) Chapter 2 - 18 TY Juang Web DB 三層式架構(Three-tiered architecture) Tier 1 GUI (presentation) Chapter 2 - 19 Tier 2 Business logic Tier 3 DBMS TY Juang Web DB 三層式架構(Three-tiered architecture) CGI(Common Gateway Interface) Web server 與應用程式間之溝通管道 CGI程式-在Server上執行 ASP 、PHP 、 VB、 Perl、 C、C++ 、Java 、 JavaScript 、VBScript 、 Active X Chapter 2 - 20 TY Juang Web DB Middleware (DB access) Stand between the client and the server that magically makes the two capable of exchanging data SQL(Structured Query Language) Chapter 2 - 21 1970,IBM Easy to recognize Like Unix,too many versions. ANSI SQL 92 TY Juang Web DB Middleware (Cont.) ODBC(Open DataBase Connectivity) Microsoft invented programmer only need to learn one set of database calls. IDAPI(Independent Database Application Programming Interface) Chapter 2 - 22 Borland,IBM and Novell Like ODBC except for different OS OS/2,Windows,Netware,AIX TY Juang Web DB Middleware (Cont.) JDBC(Java DataBase Connectivity) Chapter 2 - 23 Java programmer only need to learn one set of database calls. TY Juang Web DB