Transcript Building Scalable and Reliable Web Applications

Building Scalable and
Reliable Web Applications
Vineet Gupta
Technology Evangelist
Microsoft Corporation
http://spaces.msn.com/members/vineetgupta
Agenda
IIS 6.0 and ASP.Net Architecture
Reliability
State Management
Caching
Other Cool Stuff
Agenda
IIS 6.0 and ASP.Net Architecture
Reliability
State Management
Caching
Other Cool Stuff
Rearchitecting IIS
A review of IIS5
DLLHost.EXE
INETINFO.EXE
DLLHost.EXE
ISAPI
Extensions
DLLHost.EXE
ISAPI
Extensions
ISAPI
Extensions
ISAPI Filters and
Extensions
Metabase
user
kernel
WinSock 2.0
TCP/IP
IIS 6.0 Architecture
Goal: Enable complete app
isolation from other Web
apps and core Web server
Web service in INETINFO
split out to do this:
Multiple W3wp.exe files
web
web
web
app
app
Web
app
App
Kernel
Http.sys: Kernel mode
listener and request router
WAS: Config and process
manager
W3wp.exe: Where Web apps
are processed
WAS
W3wp.exe
W3wp.exe
W3wp.exe
Http.sys
Process Model Contrast
IIS5 to IIS6 – Making it more robust
AppPool 1
INETINFO
WAS
metabase
AppPool 2
Worker
Process
Worker
Process
Worker
Process
App1
App2
App2
Filters
Filters
Filters
Requests
User Mode
Kernel Mode
HTTP.SYS
TCP/IP
Connections
ASP.Net on IIS 6
.NET Application Domains vs. Application Pools
Application domains
Lightweight CLR unit of isolation
One app domain per IIS application
Combine with W3wp.exe files to
achieve high scalability and isolation
ASP.NET manages app domains
independently
Recycled within a single process
Can have private components,
session variables , etc.
App pool
WAS
App pool
W3wp.exe
W3wp.exe
ASP.NET
ASP.NET
Http.sys
Application Pool
W3wp.exe
ASP.NET
App
App
App
Domain
App
Domain
App
Domain
App
Domain
App
Domain
App
Domain
Domain
Domain
Demo
Application Pools
Agenda
IIS 6.0 and ASP.Net Architecture
Reliability
State Management
Caching
Other Cool Stuff
Application Pools
Application Isolation in Processes
Can create 1 or more
application pools
Each served by 1 or
more processes.
Each worker process
serves only 1 pool.
Reqs routed directly to
pool by HTTP.sys
Isolate apps based
on:
Site/Customer
Functionality
Reliability
Recycling
What is it and Why use it?
What is it?
Periodically restart
applications based on:
Uptime
# of requests
Scheduled time
Memory consumption
On-demand
Why use it?
Refresh apps to ensure
availability
Prevent bad apps from
taking over the system
No interruption in
Service!!
Recycling
Overlapping Recycle
New Worker
Process
Web Proc.
Core DLL
ISAPI Exts &
Filters
Old Worker
Process
Web Proc.
Core DLL
ISAPI Exts &
Filters
user
kernel
HTTP.SYS
Request
Ready for
Shut down
Recycle
WAS
startup
ready
Demo
Process Recycling
Agenda
IIS 6.0 and ASP.Net Architecture
Reliability
State Management
Caching
Other Cool Stuff
Increasing .NET Scale & Performance
Attributes of Scalable Web Applications
Stateless
Application code and components can be
restarted cheaply; session state is
managed externally in some sort of state
store
Low initialization costs
Applications should avoid doing heavy
processing at startup or assume that they
will run for a long time
Increasing .NET Scale & Performance
Attributes of Scalable Web Applications (2)
Can have multiple instances
All the components and classes of an
application should be able to have multiple
instances in separate processes without
namespace or locking issues
Expect administrator-imposed limits
Your application is likely to have
CPU limits
Memory limits
Processor affinity imposed
Making Applications More Reliable
Web Farm Session State
Session state can be stored in an external
process
ASPState Service
Microsoft® SQL Server™ 2000
Big reliability wins
Session state survives crashes/restarts
Enables Web farm deployment
Session state can now be shared across a Web
farm of ASP.NET servers
Applications no longer tied to one computer
Design your apps to be recycled!
Demo
Managing State
Agenda
IIS 6.0 and ASP.Net Architecture
Reliability
State Management
Caching
Other Cool Stuff
Dynamic Kernel Caching
With
Cache
Without
Cache
Database
Database
User Application
User Application
ASP.NET/CLR
ASP.NET/CLR
W3WP.EXE (IIS6.0)
W3WP.EXE (IIS6.0)
User
Kernel
User
Kernel
HTTP.SYS
Cache
Network Stack
Request
Response
HTTP.SYS
Cache
Network Stack
Request
Response
ASP.Net 2.0 Caching Improvements
Data Caching
Data-set based data-sources can be
easily cached
Just set EnableCaching to true on datasource control
Also set CacheDuration, CacheExpirationPolicy
SQL Cache Invalidation for Stale Data
SQL 7, 2000 use a custom change table, a
DB trigger and a polling mechanism by
ASP.Net
SQL 2005 uses Service Broker
ASP.Net 2.0 Caching Improvements
Post-Cache Substituion
Output Cache an entire page except XXX
XXX must be a simple string
Use Response.WriteSubstitution with
callback
Or Use Substitution Control with
associated Callback method
Demo
Caching
Agenda
IIS 6.0 and ASP.Net Architecture
Reliability
State Management
Caching
Other Cool Stuff
Resource Optimization in IIS 6
Idle Timeout and Demand Start
Idle timeout
Timeout and shutdown idle processes if process is
idle for given period of time.
Frees resources for active applications.
Apps still available even if worker process idles
out and is shut down!
Demand start
Only start worker process if there is demand for
the application pool.
Application considerations
Use idle timeout to free up resources for other
heavy-use applications.
Consider disabling idle timeout if starting an
application takes a long time.
View State Improvements
More efficient
serialization format
reduces state size
Splitting View State
into Control State
and UI State
Site Compilation
Pre-Compile your website
Use aspnet_compiler.exe
Endpoints reduced to empty files (aspx)
No request-time compilation
/bin contains compiled assemblies for
entire site
Demo
Cool Stuff 
Agenda
IIS 6.0 and ASP.Net Architecture
Reliability
State Management
Caching
Other Cool Stuff
Recommendations
Move to IIS 6 and ASP.Net 2.0
Design Apps for Recycling
Design Stateless Apps
Or think out-of-proc state management
Use Caching wherever you can!
Questions?
http://spaces.msn.com/members/vineetgupta
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© 2006 Microsoft Corporation. All rights reserved.
This presentation is for informational purposes only. Microsoft makes no warranties, express or implied, in this summary.