This document provides an overview and introduction to Microsoft's AppFabric distributed caching platform. It discusses what AppFabric is, why a distributed cache is useful, how to configure an AppFabric client and server, how to manage a cache cluster, and considerations around concurrency and high availability. The document also outlines some common caching patterns like cache-aside and discusses how AppFabric compares to other caching solutions.

1. The Need For Speed
A Developer’s Guide to
Distributed Caching with
Velocity AppFabric
Phil Pursglove
@philpursglove
http://philpursglove.blogspot.com
http://www.philippursglove.com/Velocity

2. Agenda
• What is AppFabric?
• Why a Distributed Cache?
• Configuring a client
• Configuring a server
• Managing a cache
• Concurrency
• High availability / load balancing

3. Caching Review
• .NET 1.1
– ASP.NET Cache
• .NET 2.0
– SqlCacheDependency
– Enterprise Library Caching Application
Block
• .NET 4.0
– System.Runtime.Caching assembly
– AppFabric

4. Cache-Aside
• The cache-aside pattern
– See if the item you want is in the cache
– If it isn’t (a cache miss),
• Go and get it i.e. from the DB
• Put it in the cache
– If it is,
• Cast it to the desired type and return it

5. What is AppFabric?
• A combination of two projects:
– A distributed cache
• One logical cache shared across a number of physical
servers
• Already being used by:
– MSDN Forums
– Xbox Live
– MSN
• A session state provider
• In .NET 4.0, a cache provider
– A workflow host
• v1 released June 2010

6. How Do I Get AppFabric?
• For Devs:
– Web Platform Installer, under the Products tab
– Requires SQL Express
• If you want to use SQL Server, download the installer
• For IT Pros:
– Download the installer from
http://tinyurl.com/appfabric10installer

7. Why a Distributed Cache?
• Bigger cache
– Many physical servers contribute to one
logical cache
• High availability
– Multiple servers = fault tolerance
• Increased throughput
– Many servers available to fulfil requests

8. Terminology
• Cluster
– A number of servers running Velocity
– Not related to Windows clustering
• Cache
– A named cache on a cluster
• Region
– A named part of a cache associated to a
single server

9. What Data Can I Cache In
AppFabric?
• Any serializable .NET object
– Reference Data (Shared Read)
• e.g. Product categories
– Activity Data (Exclusive Write)
• e.g. Shopping Basket
– Resource Data (Read and Write)
• e.g. product stock data

10. Configuring the AppFabric
Client
• Two assembly references to add:
– Microsoft.ApplicationServer.Caching.Client.dll
– Microsoft.ApplicationServer.Caching.Core.dll
• Cache hosts can be hard-coded or in
web.config/app.config
• Clients
– Routing vs Simple
– Local caches

11. Using AppFabric 1
• Add/Remove
• Concurrency
– Optimistic
• Version based
– Pessimistic
• Lock based

12. Using AppFabric 2
• Regions
– Live inside a cache
– Tie a group of cached objects to a specific node

– But adds extra options (Tags) for retrieving the
object 

13. Configuring an AppFabric
Server
• Cluster configuration can be held:
– On a network share (XML Provider)
– In a SQL Server DB (SQL Provider)
• Integrated Security only 
– AppFabric servers must be inside a
domain

14. Managing An AppFabric
Cluster
• Powershell integration
– Can start/stop a whole cluster or
individual servers
– Create new named caches
• But not regions 
– Get cache statistics
• MDCAdmin tool
– WPF app sitting on top of Powershell

15. AppFabric 1.1
• CTP 1 released Aug 2011
• New session state and output cache
providers
• Read-through/write behind cache
– Inherit from DataCacheStoreProvider

16. Summary
• v1 is worth looking at as a session
state provider
– The end of sticky load-balancing 
• v1.1’s new model makes it much more
usable

17. Questions?
phil@philippursglove.com
http://philpursglove.blogspot.com
http://www.philippursglove.com/Velocity
@philpursglove
http://slideshare.net/philpursglove

18. References
• Documentation on MSDN
– http://tinyurl.com/msdnappfabric
• Velocity team blog
– http://blogs.msdn.com/velocity
– http://blogs.msdn.com/endpoint
• AppFabric blog for IT Pros
– http://blogs.technet.com/appfabric/
• TechEd videos
– http://tinyurl.com/velocityteched
• Mix 09 video
– http://tinyurl.com/velocitymixvideo
• Mix 10 video
– http://tinyurl.com/velocitymix10video
• ARCCast Video
– http://tinyurl.com/velocityscotthavideo
• ScottHa on Velocity
– http://tinyurl.com/velocityhanselminutes
• Deep Fried Bytes on AppFabric
– http://tinyurl.com/deepfriedappfabric

19. References
• AppFabric coverage on StackOverflow
– http://tinyurl.com/stackoverflowvelocity
– http://tinyurl.com/stackoverflowappfabric
• DotNetRocks
– http://tinyurl.com/dotnetrocksappfabric
• Other .NET distributed caches
– NCache - http://tinyurl.com/ncache
– Memcached - http://tinyurl.com/smoe
– Oracle Coherence – http://tinyurl.com/oraclecoherence
– SharedCache – http://codeplex.com/sharedcache
• Extensions Project
– http://tinyurl.com/mscacheext
• Admin Tool
– http://mdcadmintool.codeplex.com/