DEVT1-56: ASP.NET Best Practices

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Best Practices for ASP.NET Development
Joe Healy 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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Agenda

• 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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Language and Code PracticesCode Performance

• .NET Common Language Runtime (CLR) provides big
  runtime performance wins
• 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 and JScript
• 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

• Transitions between managed and unmanaged
  code can be expensive
• With methods having complicated structures as
  arguments and return types
• Use chunky over chatty APIs
• Apartment threaded components are must b e
  handled appropriately in ASP.NET
• ASP.NET now uses MTA thread pool by default. If
  not deal with MTA pool 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
• Generate early bound .NET wrappers for COM
  components (using TLBIMP.exe)
• Note this does not remove aspcompattrue
  requirement for apartment components

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Language and Code Practicesinterop
Recommendations

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

bad!!!! Public Sub New() mathtest New
STATest.MathClass() End Sub good!!! Private
Sub Page_Load() Handles MyBase.Load mathtest
New STATest.MathClass() End Sub
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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
• Caching Techniques
• Deployment Best Practices
• Measurement Techniques

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

• 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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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 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
Code Behind, User Controls Components
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Agenda

• 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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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
• Caching Techniques
• Deployment Best Practices
• Measurement Techniques

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Caching TechniquesDesign for Caching

• Leverage the built-in ASP.NET built-in caching
  features
• Output Caching
• Fragment Caching
• Cache API
• Recommendation
• Specifically design your pages around these
  features can lead to massive perf wins

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Caching TechniquesOutput Caching

• Caches the static result of an ASP.NET page
• Declarative lt_at_ OutputCache gt directive
• Optional Output Cache APIs can also be called
• 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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Caching TechniquesFragment Caching

• 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
• Additional Features
• VaryByControl Varies cached items by controls
• VaryByCustom Allows user cache key method

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Caching TechniquesCache API

• Caching output isnt always possible
• Cache API allows objects to be cached
• in memory Hashtable
• System.Web.Caching.Cache class
• Page intrinsic property (Cache)
• Features
• Dependencies (key, file, time)
• Unused items automatically expire
• Supports Callbacks

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Demonstration 5Caching Techniques Output
CachingCustom Caching
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Agenda

• 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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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
• Caching Techniques
• 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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Measurement TechniquesDesigning Scalable
Applications

• Quantify performance for a range of load
  conditions
• Request/sec using different loads (100, 250, 500,
  750, 1000, etc concurrent clients)
• Identify maximum client load that fits into
  acceptable TTFB/TTLB response time range
• Use ASP.NET Caching to cache page output
• Design pages to maximize use of cache

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Demonstration 6Measurement 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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