This document discusses techniques for writing scalable ASP.NET applications, including caching output, objects, and data; managing paging; reducing network loads by optimizing viewstate and using compression; and distributed caching options like Velocity, NCache, and memcached. It provides an overview of these techniques and resources for further information.

1. “This One Goes Up To 11”
or
How to write scalable ASP.NET
Phil Pursglove
phil@philippursglove.com
http://diaryofadotnetdeveloper.blogspot.com
http://www.philippursglove.com/ScalableASPNET
http://twitter.com/philpursglove

2. About Me
• Senior .NET Developer
• MBCS
• MCSD
• VBUG East Anglia Co-ordinator
• Written for VB Developer and SQL
Server Pro

3. Agenda
• Increasing server performance
– Caching
• Output caching
• Donut caching
• Object caching
• Velocity
– Paging
• Reducing network loads
– Managing ViewState
– Compression

4. What is Scalability?
• “The ability to handle growing amounts of
work in a graceful manner” Wikipedia
• Scalability != Performance
• What affects scalability?
• Everything you see today applies to .NET
2.0 and higher

5. Increasing Server
Performance

6. Why Cache?
• Because there’s a credit crunch!
• Building a page is an expensive
process
– Database calls across servers
– Web Service calls
– AD lookups
• Returning a stored page from a cache
is much cheaper!

7. Caching 1: OutputCache
• Caches the rendered HTML from your page
– Duration is in seconds
– VaryByParam allows you to cache several
versions
– Location means you can cache on the web
server, client, downstream machines or all of
these
– CacheProfiles mean you have fine config-based
control
– Cached pages can be removed with
HttpResponse.RemoveOutputCachedItem
• Composite scripts are outputcached for you
automatically

8. Caching 2: Donut Caching
• aka Post-Cache Substitution
• Inject dynamic content into a cached
page before it is returned to the client
– <asp:substitution>
– Must use static methods with a
HttpContext

9. Caching 3: Caching API
• Store objects in memory and pull them out
when you need them
• Currently System.Web.Cache
– But in .NET 4.0 moving to System.Data.Cache
• For data objects, you have to use DataSets
and DataTables, not DataReaders

10. Caching 3: CacheDependency
• Objects in the cache can be dependent on
other objects
– When the dependency changes, the cached item
is removed
– Not very useful in .NET 1.1
• .NET 2.0 introduced SqlCacheDependency
– Cached objects can be dependent on SQL tables
– Enable using the ASPNET_REGSQL tool
– Or programmatically with the
SqlCacheDependencyAdmin object
– Can integrate with OutputCaching

11. Caching 4: Velocity
• Velocity
– Distributed cache
• One logical cache split across several servers
• PowerShell management console
– CTP3 released April 09
– CTP4 September 09
• V1 Q4 09?
– Microsoft.Data.Caching

12. Caching 4: Velocity
• Version 1
– Will not have dependencies
– Most appropriate to use for session state
• The future
– Writethrough
– Automatic caching?
• See also NCache and memcached

13. Paging
• Default GridView paging behaviour reads the
entire dataset every time
– For 100 rows this probably isn’t going to matter
– For 1 000 000 rows this probably isn’t so good
• Write your own paging mechanism
• For custom paging DataGrids are better than
GridViews
• In SQL 2005 the ROW_NUMBER function is
your friend!
• LINQ
– Skip

14. Reducing Network Loads

15. ViewState 1
Viewstate Size
Object
in bytes
HTML Table 52
DataList 6628
Repeater 6600
DataGrid 10592
GridView 10928

16. ViewState 2
• Taming Viewstate
– Can be disabled per-control
– ZIP it up and put the zipped version on the
page
– Keep it on the web server

17. Compression 1
• All modern browsers will accept
compressed content
– Content is compressed on the server /
decompressed by the browser
– Can be enabled in IIS
or
– Use the HttpCompress library

18. Compression

19. Compression 2
• JavaScript Compression
– JSMin (http://tinyurl.com/jscriptmin)
– jQuery is pre-minified for you
• CSS Compression
– Icey’s CSS Compressor
(http://tinyurl.com/csscompressor)
– Written in PHP

20. Summary
• Cache is King!
• Paging is good for your pages!
• Viewstate doesn’t have to be evil!

21. Any Questions?

22. Resources
• Books
– Essential ASP.NET by Fritz Onion
– The ASP.NET 2.0 Cookbook by Michael Gittel & Geoffrey LeBlond
– The ASP.NET Anthology by Scott Allen et al
• PodCasts
– http://www.dotnetrocks.com/default.aspx?showNum=24
– http://www.dotnetrocks.com/default.aspx?showNum=367
• MSDN White Paper on .NET Performance &
Scalability
– http://msdn.microsoft.com/en-us/library/ms998530.aspx
• Strangeloop Networks Scaling Appliance
– http://www.strangeloopnetworks.com/products/AS1000/

23. Resources
• Velocity
– http://blogs.msdn.com/velocity
– http://www.hanselman.com/blog/HanselminutesPodcast116DistributedCac
hingWithMicrosoftsVelocity.aspx
– http://videos.visitmix.com/MIX09/T59F
• NCache
– http://www.alachisoft.com/ncache/
• memcached
– http://www.danga.com/memcached/
• Donut Caching
– http://tinyurl.com/donutcaching
• HttpCompress Library
– http://www.blowery.org/code/HttpCompressionModule.html