1. The Need For Speed
A Developer’s Guide to Velocity
Phil Pursglove
phil@philippursglove.com
http://diaryofadotnetdeveloper.blogspot.com
http://www.philippursglove.com/Velocity
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
• What is Velocity?
• Why a Distributed Cache?
• Configuring a client
• Configuring a server
• Managing a cache
• Concurrency
• High availability / load balancing

4. What is Velocity?
• A distributed cache
– One logical cache shared across a number of
servers
– Already being used by MSDN Forums
– A session state provider
– In .NET 4.0, a cache provider
• CTP3 released April 2009
– CTP4 coming September 2009
– V1 coming who knows when? Q1 2010?

5. Why a Distributed Cache?
• ASP.NET already has a cache
– In .NET 4.0 it’s moving to
System.Data.Cache
• Enterprise Library has a Caching block
• Caching is per-server

6. What Data Can I Cache In
Velocity
• Any .NET object
– Reference Data
• e.g. Product categories
– Activity Data
• e.g. Shopping Cart
– Resource Data
• e.g. Stock data

7. Configuring the Velocity Server

8. Configuring the Velocity Client
• Four(!) assembly references to add:
– CacheBaseLibrary.dll
– CASBase.dll
– ClientLibrary.dll
– FabricCommon.dll
• Cache hosts can be hard-coded or in
web.config/app.config

9. Using Velocity
• Add/Remove
• Concurrency
– Optimistic
– Pessimistic
• Regions
– Tie a group of cached objects to a specific node
– But adds extra options (Tags) for retrieving the
object

10. Managing A Velocity Cluster
• Powershell integration
– Can start/stop cache hosts in a cluster
– Create new caches
• But not regions

11. What Should I Use It For Now?
• Session state only
– Lack of support for dependencies means it
is not ready for other uses

12. Velocity vNext
• Read-from/write-through
• Dependencies
• Support for output caching

13. Summary
• Velocity is going to be great
… in v2
• v1 is worth looking at as a session
state provider
– The end of sticky load-balancing

14. Questions?
phil@philippursglove.com
http://diaryofadotnetdeveloper.blogspot.com
http://www.philippursglove.com/Velocity
http://twitter.com/philpursglove

15. References
• Velocity team blog
– http://blogs.msdn.com/velocity
• TechEd videos
– http://tinyurl.com/velocityteched
• Mix 09 video
– http://tinyurl.com/velocitymixvideo
• ARCCast Video
– http://tinyurl.com/velocityscotthavideo
• ScottHa on Velocity
– http://tinyurl.com/velocityhanselminutes
• Velocity coverage on StackOverflow (beware, here be Java!)
– http://tinyurl.com/velocitystackoverflow
• Other .NET distributed caches
– NCache - http://tinyurl.com/ncache
– Memcached - http://tinyurl.com/smoe