This document discusses techniques for writing scalable ASP.NET applications, including caching output and objects to improve performance, managing viewstate to reduce network loads, using compression, and load balancing across multiple servers. It covers caching techniques like output caching, object caching, donut caching, and Microsoft's new Velocity distributed caching platform. It also discusses paging large result sets and reducing viewstate payload.

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

2. I am…
• Senior .NET Developer
• MCSD
• VBUG East Anglia Co-ordinator
• Used to write for VB Developer and
SQL Server Pro

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

4. What is Scalability?
• “The ability to handle growing amounts
of work in a graceful manner” Wikipedia
• What affects scalability?
• Everything you see this morning
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

8. Caching 2: Caching API
• Store objects in memory and pull them
out when you need them
• For data objects, you have to use
DataSets and DataTables, not
DataReaders

9. Caching 2: 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

10. Caching 3: Velocity
• Velocity
– Distributed cache
• One logical cache split across several servers
• PowerShell management console
– CTP2 released at PDC
– Doesn’t have dependencies – yet
– The future: automatic caching?

11. Caching 3: Velocity

12. Caching 4: 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

13. Paging
• Default GridView paging behaviour reads the
entire dataset every time
– For 100 000 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
in bytes
HTML Table (built in-line) 52
HTML Table (built in code-behind) 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
• 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
• JavaScript Compression
– JSMin (http://tinyurl.com/jscriptmin)
– jQuery is pre-minified for you

18. Compression

19. Load Balancing

20. Load Balancing
• Synchronise machineKey (in
machine.config)
• Don’t use basic Session state
– SQL Server Session State
– ASP.NET State Service
– Velocity ASP.NET Session state

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

22. Any Questions?

23. Enjoy the day!

24. Resources
• DotNetRocks
– http://www.dotnetrocks.com/default.aspx?showNum=24
– http://www.dotnetrocks.com/default.aspx?showNum=367
• 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
• MSDN White Paper on .NET Performance &
Scalability
– http://msdn.microsoft.com/en-us/library/ms998530.aspx

25. Resources
• Velocity
– http://blogs.msdn.com/velocity
– http://www.hanselman.com/blog/HanselminutesPodcast116DistributedCac
hingWithMicrosoftsVelocity.aspx
• Donut Caching
– http://tinyurl.com/donutcaching
• HttpCompress Library
– http://www.blowery.org/code/HttpCompressionModule.html