DEVT156: ASP'NET Best Practices

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

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Session Prerequisites

• Understand .NET architecture
• Working knowledge of either VB.NET or C
• Knowledge of ASP.NET application architecture
• Knowledge of ASP

Level 300
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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

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Demonstrations

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

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Agenda

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

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Language and Code PracticesCode 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

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Language and Code PracticesBinding 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) 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) Next
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Language and Code PracticesLanguage
Recommendations

• Avoid using late binding in VB
• Explicitly declare all variable types (Dim a as
  Long)
• Avoid late bound methods on Object type
• Use lt_at_ Page LanguageVB Explicittrue gt
• Requires all variables to be declared (DIM
  required)
• Still enables late bound code to exist though
• lt_at_ Page LanguageVB Stricttrue gt
• Disallows any late bound code to be used

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Language and Code PracticesCOM 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!

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Language and Code Practicesinterop
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.interopServ
  ices
• If using apartment components, mark page to run
  in STA compat mode
• lt_at_ Page ASPCompattrue gt

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Language and Code Practicesinterop
Recommendations

• Be careful not to declare any STA component in
  constructor of page

lt_at_ Page LanguageVB ASPCompattrue
gt ltscript languageVB runatservergt Dim
MyComponent as New MySTAComponent()
'Bad! lt/scriptgt lt_at_ Page LanguageVB
ASPCompattrue gt ltscript languageVB
runatservergt Dim MyComponent as
MySTAComponent Sub Page_Load(Sender as
Object, E as EventArgs) MyComponent
New MySTAComponent() End Sub lt/scriptgt
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Demonstration 1Language Best Practices Early
binding vs. Late Binding Using COM objects in
ASP.NET
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Agenda

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

15
Server Control Design PracticesOptimizing 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 lt gt code
• Should understand what this work is and optimize
  for it accordingly
• Two areas to think about and optimize
• Rendering Content
• ViewState Postback

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Server Control Design PracticesOptimizing 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

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Server Control Design PracticesOptimizing 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 lt_at_ Page Tracetrue gt to track usage size
  

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Server Control Design PracticesData 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

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Server Control Design PracticesData 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

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Demonstration 2Server Control Design Practices
Optimizing Server Control RenderingOptimizing
Use of ViewstateData Validation Best
PracticesData Binding Best Practices
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Agenda

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

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Component User Control PracticesImproving User
Experience

• ASP.NET built-in caching features
• Output Caching
• Fragment Caching
• Caches the static result of an ASP.NET page
• Use the lt_at_ OutputCache gt directive to control
  caching behavior

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Component User Control PracticesImproving 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)

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Component User Control PracticesImproving User
Experience

• Caching the entire page isnt always possible
• Partial page personalization, etc.
• Fragment Caching allows caching regions of a page
  by using user controls (.ascx)
• User controls define lt_at_ OutputCache gt directive

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Component User Control PracticesCoding
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

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Component User Control PracticesOptimizing
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

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Component User Control PracticesOptimizing
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.

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Demonstration 3Component User Control Best
Practices Buffered OutputFragment Caching
Custom Caching Code Behind, User Controls
ComponentsData Flow Across TiersOptimizing
Postback
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Agenda

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

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State Management Recommendationsin 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

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State Management RecommendationsOut 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

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State Management RecommendationsConfiguring
Session State

• Session state can be configured via the
  ltsessionStategt 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

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Demonstration 4State Management Best Practices
State ManagementSession State in A State Server
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Agenda

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

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Deployment Best PracticesLogical 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 shouldnt assume that a client will
  always return to the same machine
• Be careful of assumptions regarding statics and
  application state

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Deployment Best PracticesPhysical 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

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Deployment Best PracticesISA for DMZ
Configurations
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Agenda

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

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Measurement TechniquesOverview 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

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Measurement TechniquesKey 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

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Measurement TechniquesStress 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

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Measurement TechniquesStress 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

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Measurement TechniquesDesigning 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

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Demonstration 5Measurement TechniquesPerformanc
e Measurement
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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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for More information

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• msdn.microsoft.com

47
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