Best Practices for ASP.NET Development Ammar Abuthuraya Developer & Platform Lead Microsoft Corporation

What we will cover  Designing ASP.NET Web forms  Use code-behind for best performance and scalability  ASP.NET caching techniques  State management options  Recommendations for communicating with COM components from ASP.NET

Session Prerequisites Level 300  Understand.NET architecture  Working knowledge of either VB.NET or C#  Knowledge of ASP.NET application architecture  Knowledge of ASP

So Why This Presentation?  You know how to build ASP applications and use the same techniques to build ASP.NET applications  You want to leverage the power and capabilities of ASP.NET  You want to use ASP.NET to build high- performance, scalable, web-based applications

Demonstrations  Language best practices  Server Control design practices  Component & user control design  State management recommendations  Caching techniques  Measuring performance

Agenda  Language and Code Practices  Server Control Design Practices  Component and User Control Usage Practices  State Management Recommendations  Deployment Best Practices  Measurement Techniques

Language and Code Practices Code Performance .NET Common Language Runtime (CLR) provides big runtime performance wins  Further optimize by native code generation using NGEN.EXE  No perf difference in.NET languages  Equivalent code written in VB and C# provides equivalent performance at runtime

Language and Code Practices Binding in VB.NET  Early binding in VB performs better than late binding ‘ VB Late Binding Example Dim j, obj obj = New System.Collections.ArrayList() for j = 0 To i obj.Add(j) obj.Add(j)Next ‘ VB Early Binding Example Dim j as integer, obj As ArrayList obj = New System.Collections.ArrayList() for j = 0 To i obj.Add(j) obj.Add(j)Next

Language and Code Practices Language Recommendations  Avoid using late binding in VB  Explicitly declare all variable types (Dim a as Long)  Avoid late bound methods on Object type  Use  Requires all variables to be declared (DIM required)  Still enables late bound code to exist though   Disallows any late bound code to be used

Language and Code Practices COM interop Issues  Apartment threaded components are particularly expensive in ASP.NET  ASP.NET now uses MTA thread pool by default that has very bad perf side effects when running STA components  This affects all VB6( STA) components!

Language and Code Practices interop Recommendations  Ideally migrate COM code to.NET  Alternatively structure APIs to be less “chatty” and more “chunky” in usage  Use COM interop through System.Runtime.interopServices  If using apartment components, mark page to run in STA compat mode: 

Language and Code Practices interop Recommendations  Be careful not to declare any STA component in “constructor” of page: Dim MyComponent as New MySTAComponent() 'Bad! Dim MyComponent as New MySTAComponent() 'Bad!</script> Dim MyComponent as MySTAComponent Dim MyComponent as MySTAComponent Sub Page_Load(Sender as Object, E as EventArgs) Sub Page_Load(Sender as Object, E as EventArgs) MyComponent = New MySTAComponent() MyComponent = New MySTAComponent() End Sub End Sub</script>

Demonstration 1 Language Best Practices Early binding vs. Late Binding Using COM objects in ASP.NET

Agenda  Language and Code Practices  Server Control Design Practices  Component and User Control Usage Practices  State Management Recommendations  Deployment Best Practices  Measurement Techniques

Server Control Design Practices Optimizing Server Control Rendering  Server controls provide a very clean programming model abstraction  Recommended way to build ASP.NET pages  Server controls do more rendering/postback work than old-style code  Should understand what this work is and optimize for it accordingly  Two areas to think about and optimize:  Rendering Content  ViewState Postback

Server Control Design Practices Optimizing Server Control Rendering  Server controls encapsulate rendering markup logic at runtime  Handle style and automatic uplevel/downlevel functionality management  individual server controls each add slight additional rendering cost  Additional allocations for style management  Additional allocations for control itself  Net take: the more individual server controls on page, the more this overhead can be noticed  Need to be especially aware of this w/ composite list controls that generate multiple controls per data row

Server Control Design Practices Optimizing Use of Viewstate  ASP.NET allows pages/controls to maintain state across round trips by storing state within hidden “viewstate” field  Disabled with “EnableViewState” attribute  Some downsides:  increases network payload  Performance overhead to serialize this  Recommendation:  Always review your usage of this feature  Always disable if you are not doing postback  Disable on per control basis if possible  Use to track usage size

Server Control Design Practices Data Validation Techniques  Leverage client side scripting capabilities to perform validations  Perform validation on both server & client side to avoid validation bypass  Make appropriate use of the RequiredFieldValidator  Use RegularExpressionValidator for validating complex field types like Credit Card

Server Control Design Practices Data Binding Best Practices  Multiple ways to do data access with.NET  SQL vs. OLEDB ADO.NET Provider  DataReaders vs. DataSets  Recommendations:  Always use SQL Data Provider for Microsoft ® SQL Server ™ data access  Use DataReaders for ASP.NET data access and use DataSets only when data caching or with web services

Demonstration 2 Server Control Design Practices Optimizing Server Control Rendering Optimizing Use of Viewstate Data Validation Best Practices Data Binding Best Practices

Agenda  Language and Code Practices  Server Control Design Practices  Component and User Control Usage Practices  State Management Recommendations  Deployment Best Practices  Measurement Techniques

Component & User Control Practices Improving User Experience  ASP.NET built-in caching features  Output Caching  Fragment Caching  Caches the static result of an ASP.NET page  Use the directive to control caching behavior

Component & User Control Practices Improving User Experience  Caching Options:  Duration - Time item exists in the cache  VaryByParam - Varies cache entries by Get/Post params. Name param, separate by semi-colons, supports *  VaryByHeader - Varies cache entries by Http header  VaryByCustom - Override method within Global.asax to custom vary by whatever you want (you control the cache key)

Component & User Control Practices Improving User Experience  Caching the entire page isn’t always possible  Partial page personalization, etc.  Fragment Caching allows caching regions of a page by using user controls (.ascx)  User controls define directive

Component & User Control Practices Coding Patterns in ASP.NET  Common coding patterns:  Spaghetti – include all presentation logic and code in the same page like classic ASP  Code behind – all presentation logic is in the aspx file, which is linked to a separate code behind file  Component – business logic is present in a compiled component, which is invoked for providing various services  There is no perf difference between a dynamically compiled.aspx (“spaghetti”) and “code behind” style page

Component & User Control Practices Optimizing Data Flow Across Tiers  Data exchange across tiers has to be optimized for the deployment scenario  Avoid passing datasets across tiers  Use DataReaders for fast, forward-only access to the data stream  XML is very verbose; suitable for communications with unknown systems

Component & User Control Practices Optimizing Data Flow Across Tiers  Minimize the number of post backs  Leverage client side capabilities to avoid post backs  Control the amount of view state information passed during a post back  Use EnableViewState at page or control level to configure view state usage.

Demonstration 3 Component & User Control Best Practices Buffered Output Fragment Caching & Custom Caching Code Behind, User Controls & Components Data Flow Across Tiers Optimizing Postback

Agenda  Language and Code Practices  Server Control Design Practices  Component and User Control Usage Practices  State Management Recommendations  Deployment Best Practices  Measurement Techniques

State Management Recommendations in Proc Session State  Session state is stored in the ASP.NET worker process  Recycling the process will cause all session state to be lost  Session state performance is maximum in this mode

State Management Recommendations Out of Proc Session State  Session state can be stored in a State server process running on the same machine or a different machine  State can also be stored in a SQL Server database  Restarting the web server does not cause the session state to be lost  More reliable than in process session state but less performant

State Management Recommendations Configuring Session State  Session state can be configured via the element in the web.config file  Change causes ASP.NET application to be restarted, all new sessions will be stored as per the updated session configuration  Out of process session state stores like State Server or SQL Server must be started & configured properly

Demonstration 4 State Management Best Practices State Management Session State in A State Server

Agenda  Language and Code Practices  Server Control Design Practices  Component and User Control Usage Practices  State Management Recommendations  Deployment Best Practices  Measurement Techniques

Deployment Best Practices Logical Design  Design your applications using logical 3-Tier Design Practices:  Pages (.aspx) and User Controls (.ascx)  Reusable Biz Classes in \bin dir (.vb +.cs)  Data within a SQL Database  Design your Web application so that it can be distributed across a Web farm  Your code shouldn’t assume that a client will always return to the same machine  Be careful of assumptions regarding statics and application state

Deployment Best Practices Physical Deployment  Deploy your applications such that the pages and components run in same process  Deploying onto remote servers connected via DCOM or Web Services will almost always hurt your performance/scalability  Leverage Web services only for application to application communication -- not intra app calls  Leverage ISA Server for configurations where a DMZ security zone is required  Enables you to restrict app server access from browser clients

Deployment Best Practices ISA for DMZ Configurations ISA ASP.NET SQL DMZ (firewalled) Browsers

Agenda  Language and Code Practices  Server Control Design Practices  Component and User Control Usage Practices  State Management Recommendations  Deployment Best Practices  Measurement Techniques

Measurement Techniques Overview of Application Center Test  Application Center Test (ACT) is a tool designed for stress testing web servers  The tool assists in determining performance and scalability of a given web site  The tool also collect useful statistical information during the stress test  ACT also exposes a programming interface, which can be used for creating stress test scripts

Measurement Techniques Key Performance indicators  The key performance indicators of a web application are:  Processor utilization  Low value indicates blocking on other resources  ASP.NET  Requests/Sec & Requests Queued  Memory  Pages Faults/Sec – lower the better, high numbers indicate insufficient memory condition

Measurement Techniques Stress Testing  Stress testing is a defensive mechanism to creating scalable web sites  Stress runs will indicate the scalability of the application  Can be used to determine scale of operation, when to add new hardware etc  Stress testing should not be the final step in building a web application. It should be integrated into the development life cycle  Narrow the scope of a stress run to get more accurate, actionable results

Measurement Techniques Stress Testing  Use the web site logs to determine operational load  Stress tools like WAS (“Homer”) allow log files to be “replayed” on a web site and record statistical performance information  Run performance monitoring tools on the live servers to identify scalability issues

Measurement Techniques Designing Scalable Applications  Two ways to quantify Web performance:  Machine Throughput (requests/sec)  Response Time (time to first/last bytes)  Measure performance by stressing server  Utilize multiple client stress machines  Use Application Center Test tool  Measure multiple scenarios:  Simulate end to end scenario walkthroughs of site  Measure individual page performances

Demonstration 5 Measurement Techniques Performance Measurement

Session Summary  in this session we discussed:  Language and Code Practices  Server Control Design Practices  Component and User Control Usage Practices  State Management Recommendations  Caching Techniques  Deployment Best Practices  Measurement Techniques

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