This presentation is about IIS 7.0, its new architecture and how it integrates with ASP.NET.

2. Introduction

IIS 7.0 – Modular Architecture

IIS 7.0 – Extensible Architecture

IIS 6.0 – Technical Architecture (Refresher)

IIS 7.0 – Technical Architecture

 IIS 7.0 and ASP.NET Request Processing
IIS 7.0 and ASP.NET Integration

 Classic Mode
 Integrated Mode (Benefits, Compatibility, App Pools, etc)
IIS 7.0 and ASP.NET Breaking Changes (Optional)

Top changes in IIS 7.0 (Optional)


3. Prior versions of IIS

 Had to install all of the IIS functionalities
 IIS 6.0 was secure (features were turned off)
 The problems?
 The bits got installed anyways (increased foot-print).
 Service Packs had to be installed, even for the features
which are not being used (increased maintenance).
 The administrators had to maintain the features which
were never used (increased maintenance).
 Reason?
 Web server architecture was monolithic! (all or nothing)

4. New version of IIS to rescue!

 IIS 7.0 is modular.
 3 functional areas
 40+ role services (also referred as “features”).
 IIS 7.0 allows you to choose from those features while
installing IIS.
 Benefits?
 Thin web server with the features which are really
needed.
 Decreased “foot-print” of your web server.
 Less maintenance – Administrators need not maintain
features which are not needed.

5. 
Web Server
Functional
Area
ASP.NET
Role
Service

6.  Prior versions of IIS
 Write ISAPI filters and extensions
 Extensibility code does not run in the managed
environment, hence no access to .NET classes.
 IIS 7.0 to rescue (once again!)
 Native modules
 C++
 New Object Oriented APIs
 Managed modules
 Any .NET language
 Can access all of the .NET classes

7.  Couple of important concepts / components in IIS 6.0
 App Pools
 Application Isolation Modes
 HTTP.sys
 WWW (aka W3SVC) Service

8.  App Pools
 Used for isolating applications from one another and from the
web server process
 New way of implementing application isolation
 Application Isolation Modes
 Worker Process Isolation mode (default, important to
understand)
 Multiple App Pools
 Health Monitoring
 Worker Process Recycling
 Web Garden (Pool with more than one Worker Processes)
 Pool Identity
 IIS 5.0 Isolation mode
 Low Isolation (runs in the web service process!)
 Medium Isolation (shared process)
 High Isolation (separate process altogether)

9.  HTTP.sys
 Kernel level device driver.
 Receives requests; forwards to IIS; returns response.
 Maintains queues; performs caching
 WWW Service (aka W3SVC Service)
 HTTP administration and configuration
 Process (and App Pool) management
 Performance monitoring

10.  Re-written from scratch – hence new concepts and
new architecture.
 Important architectural components in IIS 7.0
 Protocol Listeners (HTTP.sys, etc)
 WWW Service (aka W3SVC Service)
 Windows Process Activation Service (WAS)
 Modules

11.  Protocol Listeners
 Receives requests; forwards to IIS; returns response.
 Maintains queues; performs caching
 More listeners available for other protocols (e.g.
NetTcpActivator in WCF for net.tcp)
 WWW Service (aka W3SVC Service)
 Compared to IIS 6.0, the responsibilities have been reduced.
 Listener adapter for HTTP.sys
 Configures HTTP.sys (at load time)
 Updates HTTP.sys whenever the configuration changes
 Notifies WAS whenever a request enters the request queue
 Does not manage the application pools and the worker
processes.

12.  Windows Process Activation Service (WPAS) (WAS)
 Manage application pools and worker processes (for
both the HTTP and non-HTTP protocols)
 Can be used without W3SVC! (e.g. web service over TCP)
 Loads configuration stored in applicationHost.config
 Monitors configuration for any changes.
 Informs listener adapters (such as W3SVC) if
configuration changes.

13.  Modules
 New concept in IIS 7.0 – borrowed from ASP.NET.
 Most of the web server functionality is built as Modules.
 Two types
 Native
 Managed
 Benefits
 Plug-and-Play modules according to your needs.
 Reduce attack surface and memory foot-print.
 Customize a server to a specific role in your organization
(application server, web server, ftp server, etc).
 Write custom modules (C++ or any .NET language) to
replace existing modules or to introduce new features.

14.  Differences between Native and Managed Modules
Native Modules Managed Modules
C++ Any .NET language
Difficult to develop Easy to develop
Use this for migrating old ISAPI Use this for add new “features” or
components over to IIS 7.0 enhancements to IIS 7.0
Unrestricted access to server Don’t have unrestricted access to
resources server resources; .NET and
ASP.NET security applies
Need to be registered with IIS No need to register with IIS
<globalModules> node
Admin rights are needed to Admin rights are not needed to
install/enable/un-install install/enable/un-install

15.  IIS 7.0 Request Processing

16.  Classic Mode
 Integrated Mode
 Benefits
 Compatibility
 App Pools
 Enable ASP.NET services for all content
 Enhanced ASP.NET API
 Runtime Integration
 Request Processing
 ASP.NET Breaking Changes

17.  Classic Mode
 Just like IIS 6.0 Worker
Process Isolation Mode.
 Integration is based on
aspnet_isapi.DLL.
 ASP.NET content (.aspx, etc)
are processed by ASP.NET
runtime.
 Non ASP.NET content (.htm, etc)
are processed by IIS.
 Major drawback
 ASP.NET services are not available to non-ASP.NET content
 When to use?
 While porting an IIS 6.0 application that does not work in the Integrated
Mode. (not recommended)

18.  Integrated Mode
 Integrates ASP.NET runtime
with the core server.
 One consolidated pipe-line.
 Similar to ASP.NET pipe-line
in IIS 6.0.
 Adds new events
 Modules subscribe to events
 IIS core engine calls modules
whenever the events occur.

19.  Integrated Mode – Benefits
 ASP.NET services are available to all
of the content including.asp pages!
 Fully extend IIS with ASP.NET
 No need to write ISAPI
 Now ASP.NET modules
 Directly plug into the server pipe-line.
 Execute in all stages of the request
processing pipe-line.
 Be executed in any order respective to
the native modules! (Very important –
for example, could replace the
Basic Authentication provided by IIS)

20.  Integrated Mode – Benefits
 Unified Server Runtime
 Eliminates the duplication of
features in IIS and ASP.NET.
 Tighter integration allows many
features to be unified.
 Unified configuration for IIS and
ASP.NET modules and handlers
 Custom Errors
 Tracing
 Output Caching

21.  Integrated Mode – Compatibility
 Existing and new applications can
run side-by-side.
 Existing applications in Classic mode.
 New applications in Integrated mode.
 What is an existing application is
run in Integrated mode?
 Might or might not work (Depends!)
 Configuration changes b/c of the
configuration unification.
 Code changes b/c of the new
runtime architecture and breaking
changes.
 IIS 7.0 is helpful! Shows detailed errors.

23.  Integrated Mode – What to fix?
 HTTP Modules
 HTTP Error 500.22
 Reason
 Web.config contains <httpModules>.
 Fix
 Remove <httpModules>.
 Add<system.webServer>/modules.
 Or use appcmd to do it for you.
 appcmd migration config
quot;Default Web Site/App Namequot;
-section:httpModules

24.  Integrated Mode – What to fix?
 HTTP Handlers
 HTTP Error 500.23
 Reason
 Web.config contains <httpHandlers>.
 Fix
 Remove <httpHandlers>.
 Add<system.webServer>/handlers.
 Or use appcmd to do it for you.
 appcmd migration config
quot;Default Web Site/App Namequot;
-section:httpHandlers

25.  Integrated Mode – What to fix?
 Impersonation
 HTTP Error 500.24
 Reason?
 <identity impersonate=“true”/>
could be problematic. Impersonated
identity is unavailable until
PostAuthenticateRequest stage.
 Fix
 Change the code written in
BeginRequest and
AuthenticateRequest events to not
access the impersonated identity.
 See if the code could be moved to
PostAuthenticateRequest stage.

26.  Integrated Mode – App Pools
 Use IIS 6.0 Worker Process isolation
mode.
 Underlying mechanism for
implementing Classic and
Integrated modes in IIS 7.0!
 An application pool specifies
 Pool type (Classic vs Integrated)
 .NET Framework Version

28.  Integrated Mode – App Pools
 Change ASP.NET mode for a pool
 Why?
 To create the appropriate pipe-line.
 How
 Use the Administration tool.
 Use appcmd
 Sets the app pool mode to Integrated
 appcmd set apppool “app pool name”
/managedPipelineMode:Integrated
 Lists properties that can be set on an
app pool
 appcmd set apppool “app pool name”
/?
 Manually change the
applicationHost.config file.

29.  Integrated Mode – App Pools
 Change app pool for an application
 Why?
 Allows you to run your application under a
specific ASP.NET version or a different mode.
(Don’t use aspnet_regiis to configure
the ASP.NET version in IIS 7.0)
 How?
 Use the Administration tool.
 Use appcmd
 Sets the app pool mode to Integrated
appcmd set apppool “app pool name”
/managedPipelineMode:Integrated
 Lists properties that can be set on an app
pool
appcmd set apppool “app pool name” /?
 Manually change the
applicationHost.config file.

30.  Integrated Mode – Enable ASP.NET
services for all of the content
 Not enabled by default.
 For backwards compatibility
Run this module only for
the managed requests

31.  Integrated Mode – Enable ASP.NET
services for all of the content
 What are Pre-Conditions?
 Answers to some questions.
 IIS 7.0 configures itself based on
the answers.
 Pre-Conditions specify.
 Process Bitness – bitness32, bitness64
 Managed Extensibility Style –
integratedMode, ISAPIMode
 .NET Framework Version –
runtimeVersionv1.1 ,
runtimeVersionv2.0
 Managed Code Execution –
managedHandler

32.  Integrated Mode – Enable ASP.NET
services for all of the content
 How?
 Change each and every module entry
and remove the managedHandler
pre-condition (tedious).

33.  Integrated Mode – Enable ASP.NET
services for all of the content
 How?
 Or set the
runAllManagedModulesForAllRequests
attribute for the <modules> section
to true.

34.  Integrated Mode – Enhanced
ASP.NET APIs
 APIs are backwards compatible –
allows existing code to run in IIS.
 New APIs have been added; couple
of existing APIs have been changed.
 HttpResponse.Headers
 Allows changing the response headers
generated by other applications.
 HttpRequest.Headers
 Now writeable! Allows modules to
manipulate the incoming request
headers (e.g. dynamically change the
Accept-Language header).
 HttpRequest.ServerVariables
 Now writeable! Could be used for passing
information to other application frameworks,
such as PHP.

35.  Breaking Changes
 Passport Authentication
 ASP.NET Error 500
 Reason
 Passport auth not supported on Vista
and Windows Server 2008.
 Applies to both Classic and Integrated
modes.
 Fix
 Don’t use Passport authentication!

36.  Breaking Changes
 Query String > 2048
 HTTP Error 404.15
 Reason
 This is the default limit.
 Applies to both Classic and Integrated
modes.
 Fix
 Change maxQueryString attribute.

37.  Breaking Changes
 HttpContext.Current.Request and
HttpContext.Current.Response in
Application_Start in global.asax
 ASP.NET YSOD
 Generates error if code tries to access
these properties.
 Reason
 Application initialization tied to the
arrival of 1st request – design flaw!
couples the application initialization
with the 1st request.
 Fix
 Write a module and move code in the
BeginRequest stage for performing one
time initialization.

38.  Top changes in IIS 7.0
 Simple configurable command line setup
 Great compatibility
 Most of the applications will work.
 Classic mode allows for easy app migration.
 IIS 6.0 meta-base compatibility layer for existing scripts
 No more meta-base
 Clear text schema
 IIS settings are stored in applicationHost.config
 Meta-base for SMTP/FTP/NNTP
 Delegated configuration
 Administrators can now delegate IIS settings to application owner.
 Settings defined in web.config file in application directory.

39.  Top changes in IIS 7.0
 Appcmd and other new management options
 Manage via the UI
 Manage via the command line (replaces adsutil.vbs, iisapp.vbs, etc).
 Command line management of sites, applications, vdir, app pool,
etc.
 Failed Request Tracing
 Request Filtering

40. IIS 7.0 Architecture and Integration with ASP.NET