CTU June 2011 - Things that Every ASP.NET Developer Should Know

Things that Every ASP.NET
Developer should know

Darren Sim
Microsoft MVP (ASP.NET / IIS)
Member, Microsoft Developer Guidance Web Advisory Council
Director, Singapore Software Quality Testing Board (SGTQB)

AGENDA

HTTP and Web Server Fundamentals

Debugging and Analysis Tools

Development Techniques

Patterns & Practices

Fundamentals

• Internet is based on TCP/IP

• World Wide Web is based on HTTP
– HTTP based on Request/Response paradigm
– Header and body
– Stateless
– Specification @ http://www.ietf.org/rfc/rfc2068.txt

Http Request

GET http://localhost:99/default.aspx HTTP/1.1
Accept: */*
Accept-Language: en-us
UA-CPU: x86
Accept-Encoding: gzip, deflate
User-Agent: Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 6.0; SLCC1; .NET CLR 2.0.50727; .NET
CLR 3.0.04506; .NET CLR 1.1.4322; InfoPath.2; .NET CLR 3.5.21022)
Host: localhost:99
Proxy-Connection: Keep-Alive
Pragma: no-cache

Http Response

HTTP/1.1 200 OK
Cache-Control: private
Content-Type: text/html; charset=utf-8
Server: Microsoft-IIS/7.0
X-AspNet-Version: 2.0.50727 Header
X-Powered-By: ASP.NET
Date: Sun, 07 Mar 2010 19:22:19 GMT
Content-Length: 686

<head><title> Home Page </title></head>
<body class="basic">
<form name="form1" method="post" action="default.aspx" id="form1">
<div>
<input type="hidden" name="__VIEWSTATE" id="__VIEWSTATE"
value="/wEPDwULLTE0MDkxNzYwNDNkZKn1tb3qjzVWNrSAgGULkE4nvHPg" />
</div> Body
<div style="background-color:Blue">
<h3>Home</h3>
</div>
</form>
</body>
</html>

How we connect to the internet?

ISP

IIS Architecture

Configuration Application Pool

SvcHost.exe w3wp.exe

WWW Windows
Publishing Process
Service Activation
(W3SVC) Service (WAS)

User Mode
Kernel Mode

HTTP.sys

Configuration File

Site Application
Machine.config Root web.config
web.config web.config
<system.Web> <system.Web>

Applicationhost.config
<system.webServer> <system.webServer>

*Web.config has a 100Kb file size limit.

Fiddler

• Tracing tool specifically for HTTP
• Shows complete request and response (not packets)
• Can save archive of session
• Can be used on own machine (ipv4.fiddler, ipv6.fiddler)
• Can create own GET requests
• Can decrypt SSL traffic!

Microsoft Network Monitor

• General network tracing tool for many protocols
• Hooks into network adapters
• See network frames at multiple levels
• Apply filters for specific protocols, IP addresses, etc

Free download at http://www.microsoft.com/downloads/en/details.aspx?FamilyID=983b941d-06cb-
4658-b7f6-3088333d062f&displaylang=en

IIS Log Files

• Time Taken (execute, queue, and time to client – IIS 7/6)
• Sub-status codes are very useful for indicating the exact problems
• Log entries are made AFTER the page execution is complete
• Log file entries are always in GMT
• Setup cookie, referrer, bytes sent

Log Parser

• Utility to query IIS log files, event logs, etc
• Query syntax nearly identical to SQL
• Write series of queries for site health (HTTP status, time taken, file
sizes, down pages, orders, etc)
• ASP.NET Response.AppendToLog( )

Download Log Parser at http://tinyurl.com/5uoxz

Performance Culprits
Problem Statement

• HTTP requests are the biggest web performance killer
• Reduce Requests, massively improve performance

Performance Culprits
Solution

• Combine all Javascript into one file
• Combine all CSS into one file
• Using MSAjax CDN instead of your own

Reduce & Avoid Requests

• Avoid Response.Redirect
– Invokes an extra client side HTTP Request

• Use Server.Transfer instead

Reduce Page Size

• The smaller the page, the quicker the download

• Especially important in these areas
– Mobile Applications (Windows Mobile, IPhone, 3G Data Card)
– Non Broadband Users
– Many offices have less capacity than broadband
– Developing Countries

Reduce Page Size

• Most Browsers support HTTP Compression
– GZIP & Deflate
– IE, Firefox etc
• Drastically reduces page size
• Steps
– Browser Passes Accept-Encoding in Request Header
– Data is compressed and sent to browser
– Browser decompresses html

• Only GET is compressed, POST IS NOT Compressed

HTTP Compression

• Server evaluates the “Accept-Encoding” header for request,
compresses resulting response
• largeGridView.aspx - 41 frames down to 7
• Implemented in February 2003 when about 3% of Fortune 1000 web
sites utilized
• Used 53% less bandwidth, ~25% faster Keynote measurements
• Now use IIS Compression (free)

HTTP Compression (cont…)

• IIS 7
– Can control when to stop using if CPU usage is too high
– Minimum default file size is 256K
– Only static compression is on by default

Detailed article about enabling IIS 6 compression at http://tinyurl.com/yjdo7w

Content Expirations

• Client asks “if-modified-since”
• Small content files it is just as expensive to see if modified as to
receive content
• Setup expiration times for content folders
• Avoid requests for files that seldom change (.js, .css, images, etc)
• Rename the file if need to override browser caching

Ajax Minifier

• Microsoft Ajax Minifier (Codeplex.com)
• Minimize CSS and JavaScript files
– Remove whitespace, comments, excessive semicolons, etc
• Command line, .dll, and build tasks
• jQuery-1.4.2.js minimized 55.5%
• Test after minimize!
• MSBuild Extension Pack (version #)

ETags

• Used for cache validation
• IIS sends the ETag header in response for static files
– hash:changeNumber
• IIS 6
– changeNumber – specific to server
– Set to 0 with Metabase Explorer, http://tinyurl.com/2agsbtc

• IIS 7
– changeNumber - 0 by default
– Completely remove header with HttpModule

CSS Sprite

• Combine small images into a single image
• Use CSS to “index” into the larger image

• Often 70-95% of time taken for a user is time requesting components
(images, .css, .js)
• Reduce the number of requests

**Free CSS Sprite generator at http://spritegen.website-performance.org/

Tracing

• Setup ASP.NET to save information about recent requests

• <trace enabled="true" pageOutput="false" localOnly="false"
requestLimit="2" mostRecent="true" />

• /Trace.axd

Error Page Configurations

• <deployment retail=”true” /> (machine.config only)
– <customErrors mode=”On” />
– <compilation debug=”false” />
– <tracing enabled=“false” />

• External config files (no restart)

Global.asax Application_Error( )

• Every ASP.NET web site should have this coded to ensure that
unhandled exceptions are caught and logged

• HKLMSystemCurrentControlSetServicesEventLogApplication and
add key for source

• Use <customErrors mode=“On” /> to redirect to a down page

Validation Controls

• OWASP Top 10
– XSS (Cross Site Scripting)
– SQL Injection

• All input from web controls needs to be verified
• Leverage client validation for user experience but must validate on the server

• Common validators
– RequiredFieldValidator
– RangeValidator
– RegularExpressionValidator
– CompareValidator
– CustomValidator

Caching

– Data caching (Cache), cut 50% of our SQL queries which was 72,080,000
less queries each month!
– Substitution
– Output caching (shared)

– Don’t cache page (set specific cache ability)
• Response.Cache.SetCacheability(System.Web.HttpCacheability.NoCache);

Yahoo! A List Browsers
Win XP Win 7 Mac 10.6.† iOS 3.† iOS 4.† Android 2.2.†

Safari 5.† A-grade

Chrome † (latest
A-grade
stable)

A-grade (upon GA A-grade (upon GA
Firefox 4.†
release) release)

Firefox 3.6.† A-grade A-grade A-grade

A-grade (upon GA
IE 9.0
release)

IE 8.0 A-grade A-grade
IE 7.0 A-grade
IE 6.0 A-grade

Safari for iOS A-grade A-grade

WebKit for Android
A-grade
OS

Complete list available at http://developer.yahoo.com/yui/articles/gbs/

Reference Model to Guide Architecture Projects

Model for Web 2.0

Users

Client applications/runtimes

Connectivity/reachability

Services

Capabilities

Basic Service-Consumer Pattern

Consumed
via
internet
Service Client Applications

Provides View

Offered as
Interface

Capability

Landscape leading to hybrid platforms

Web 2.0 Reference Architecture (basic)

Web 2.0 Reference Architecture (detailed)

Components of a pattern (basic)

Components of a pattern (detailed)

Patterns for Web 2.0

• The Service-Oriented Architecture Pattern
• The Software as a Service (SaaS) Pattern
• The Participation-Collaboration Pattern
• The Asynchronous Particle Update Pattern
• The Mashup Pattern
• The Rich User Experience Pattern

Patterns for Web 2.0 (cont…)

• The Synchronized Web Pattern
• The Collaborative Tagging Pattern
• The Declarative Living and Tag Gardening Pattern
• The Semantic Web Grounding Pattern
• The Persistent Rights Management (PRM) Pattern
• The Structured Information Pattern

Resources & Readings

Performance Management
http://www.sitepoint.com/books/aspnetant1/aspnetant1-sample.pdf

ASP.NET Developer Guidance Map
http://www.darrensim.com

itsme@darrensim.com http://www.facebook.com/darrensim http://www.twitter.com/darrensim

CTU June 2011 - Things that Every ASP.NET Developer Should Know

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