如何增強ASP程序性能(4)

技巧16：在任何可能時使用Server.Transfer，而不要用Response.Redirect

　　Response.Redirect告訴瀏覽器請求另一個不同的頁面，這常常用於引導用戶到登錄頁面或者出錯處理頁面。由於重定向強迫了一個新頁面請求，結果是瀏覽器必須要與Web服務器循環2次，並且Web服務器必須處理一個額外的請求。IIS5.0引進了一個新功能Server.Transfer，它執行在同一服務器上的頁面傳輸，這將避免額外的瀏覽器－Web服務器的數據循環，形成良好的系統性能，對於用戶也有較好的響應時間。

技巧17：避免使用服務器變量

　　存取服務器變量導致Web站點建立一個特殊的請求並收集所有的服務器變量，而並不是你要求的那個變量。這類似於在文件夾中取回一個特殊的文件，要想取回一個文件，就得首先獲取所在文件夾的信息。

　　不要存取非法的Request對象（比如Request（"Data"）），對於那些不在Request.Cookies、Request.Form、Request.QueryString或者Request.ClientCertificate中的項目，隱含就指向了Request.ServerVariables變量，而這些變量要比其他集合對象慢得多。

技巧18：調整Web服務器

　　有幾個IIS調整參數可以提高站點性能。比如，對於IIS4.0，我們經常發現提高ASP ProcessorThreadMax參數能夠產生重大的效果，特別是在那些要等待後臺資源比如數據庫或中間件產品的站點。在IIS5.0中，你可以發現調整ASP線程通道要比調整AspProcessorThreadMax效果更佳。

最佳的配置設定取決於應用程序代碼、支持的硬件設備以及客戶端的工作量。發現最佳配置的唯一方法就是測試。

相關參考資源

Optimizing ASP scripts

• Developing Scalable Web Applications
• Got Any Cache? by Nancy Winnick Cluts
• Maximizing the Performance of Your Active Server Pages by Nancy Winnick Cluts
• 15 Seconds: Performance Section
• Enhancing Performance in ASP - Part I by Wayne Plourde
• When is Better Worse? Weighing the Technology Trade-Offs by Nancy Winnick Cluts
• Speed and Optimization Resources by Charles Carroll

Tuning IIS

• The Art and Science of Web Server Tuning with Internet Information Services 5.0
• Leveraging ASP in IIS 5.0 by J.D. Meier
• Tuning IIS 4.0 for High Volume Sites by Michael Stephenson
• Tuning Internet Information Server Performance by Mike Moore
• Navigating the Maze of Settings for Web Server Performance Optimization by Todd Wanke
• Managing Internet Information Server 4.0 for Performance by Hans Hugli

ADO and SQL Server

• Top Ten Tips: Accessing SQL Through ADO and ASP by J.D. Meier
• Improve the Performance of your MDAC Application by Suresh Kannan
• Pooling in the Microsoft Data Access Components by Leland Ahlbeck and Don Willits
• SQL Server: Performance Benchmarks and Guides
• Improving the Performance of Data Access Components with IIS 4.0 by Leland Ahlbeck
• Microsoft Data Access Components (MDAC) and ActiveX Data Objects (ADO) Performance Tips by Leland Ahlbeck
• Microsoft SQL Server 7.0 Practical Performance Tuning and Optimization - The Server Perspective by Damien Lindauer
• Microsoft SQL Server 7.0 Practical Performance Tuning and Optimization - The Application Perspective by Damien Lindauer
• Accessing Recordsets over the Internet by Dino Esposito

ASP components and threading models

• ASP Component Guidelines by J.D. Meier
• Q243548: INFO: Design Guidelines for VB Components under ASP
• Threading Models Explained by Nancy Winnick Cluts
• So Happy Together? Using ActiveX components with Active Server Pages by Nancy Winnick Cluts
• Developing Active Server Components with ATL by George Reilly
• Agility in Server Components by Neil Allain
• Building High-Performance Middle-Tier Components with C++ by Jon Flanders
• Active Server Pages and COM Apartments by Don Box
• House of COM: Active Server Pages by Don Box
• House of COM: Contexts by Don Box
• House of COM: Performance Trade-offs of the Windows 2000 Component Execution Environment by Don Box
• Building COM Components That Take Full Advantage of Visual Basic and Scripting by Ivo Salmre
• Component Design Principles for MTS

Dictionary components

• Creating a Page Cache Object by Robert Coleridge
• Abridging the Dictionary Object: The ASP Team Creates a Lookup-Table Object by Robert Carter
• Caprock Dictionary
• Site Server Commerce Edition includes a dictionary component

Session state

• Q175167: HOWTO: Persisting Values Without Sessions
• Q157906: HOWTO: How To Maintain State Across Pages with VBScript
• XML-based Persistence Behaviors Fix Web Farm Headaches by Aaron Skonnard
• House of COM: Stateless Programming by Don Box

Performance and scalability

• Blueprint for Building Web Sites Using the Microsoft Windows DNA Platform
• Server Performance and Scalability Killers by George Reilly
• Microsoft Visual Studio Scalability Center
• Fitch & Mather Stocks 2000
• Tuning the FMStocks Application
• High-Performance Visual Basic Apps by Ken Spencer
• Duwamish Books, Phase 4
• Top Windows DNA Performance Mistakes and How to Prevent Them by Gary Geiger and Jon Pulsipher
• Building from Static HTML to High-Performance Web-Farms by Shawn Bice

Tools

• Microsoft Web Application Stress Tool
• I Can？ Stress It Enough -- Load Test Your ASP Application by J.D. Meier
• Windows DNA Performance Kit
• Monitoring Events in Distributed Applications Using Visual Studio Analyzer by Mai-lan Tomsen

Books

• Professional Active Server Pages 3.0, Wrox Press. (Especially Chapter 26: Optimizing ASP Performance, by George Reilly and Matthew Gibbs)
• Microsoft Internet Information Services 5.0 Resource Guide (bundled with Windows 2000 Server Resource Kit, Microsoft Press.
• Microsoft Internet Information Server Resource Kit (for IIS 4.0), Microsoft Press.
• Programming Distributed Applications with COM and Microsoft Visual Basic 6.0 by Ted Pattison, Microsoft Press.
• Effective COM by Don Box, Keith Brown, Tim Ewald, and Chris Sells; Addison-Wesley.
• Developing Web Usability: The Practice of Simplicity by Jakob Nielsen, New Riders.

ASP Web sites

• Microsoft TechNet for IIS
• LearnASP.com
• 4GuysFromRolla.com
• 15Seconds.com
• AspToday.com
• Asp101.com
• AspLists.com. Many specialized mailing lists including:
  • Fast Code!
  • ASP Advanced
  • Not Newbie
  • State Management
  • Scalability
  • Visual Basic Components
  • XML
  • C++/ATL Component Building
• UseIt.com: Web Usability

ASP style

• ASP Best Practices by George Reilly
• ASP Quick Lessons by Charles Carroll
• Planning for ASP by John Meade
• ASP Guidelines by J.D. Meier

XML

• Inside XML Performance by Chris Lovett
• Inside MSXML3 Performance by Chris Lovet