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excerpt from Bill's Notes

Rob Howard – WSV330 – ASP.NET Programming Using Advanced Caching Techniques in ASP.NET Whidbey

 

Program Manager, Web Platform & Tools

 

http://www.asp.net/whidbey to download the slides

http://weblogs.asp.net/rhoward

 

ASP.NET 1.X Output Cache

• Page Output Caching
  • Cache contents of page to memory
  • Reused cached page on subsequent requests
  • Supported HTTP 1.1 Cache semantics
• Partial Page Caching
  • Cached User Control in a page
  • Allowed for portions of page to be cached
  • Time based dependencies
• Programmatic Cache API
  • Cache objects in memory
  • Same cache used for Output Caching
• Dependencies
  • Time, Key, File
  • Remove items when dependency changes
• Removal event 

ASP.NET 2.0 Cache

• Most requested Cache features
  • Support database invalidation
  • Create your own dependencies
• We listened…
  • Added SQL 7/2000/’Yukon’ cache invalidation 

SqlCacheDependency

System.Web.Caching

• SQL 7 & 2000 Support
  • Table change dependencies on SQL 7 & 2000
  • Requires configuration settings
  • One-time setup of SQL Server database
  • Polling model
• SQL Server “Yukon”
  • Result Set dependencies for SQL Yukon
  • Supported through ADO.NET SqlCommand
  • No setup required
  • Notification model 

SQL Yukon – push based model. Yukon will detect when changes occur and will push to ASP.NET … other databases use a polling method.

 

SQL 7 & 2000 require a one-time setup … create a table in the database and some stored procedures. SQL Yukon – no setup required.

 

SQL 7 & 2000

• Table level notifications only
  • Notification when data in table changes
  • Row-level notification is not supported
• Requires one time setup of SQL 7/2000
  • Triggers on tables that participate
  • Stored procedures called to check
• Of Note:
  • Entries in cache table <# of tables in DB
  • Entries in cache = # items in cache table 

New attribute in the output directive – sqldependency=”MyDatabase:Products”

 

In the web.config:

  

  

 

Cache.Insert(cacheKey, dataset, New SqlCacheDependency(“ACME”, “Products”))

 

There is no Oracle cache dependency. We don’t know if we want to build one – all because of time constraints. You can build your own though. Easy to do.

 

Behind the scenes: When we do this polling, we do not do this on your request thread, therefore there is no overhead on the polling.

 

Dim d as New SqlCacheDependency()

 

How does this all work? We use a tool aspnet_regsqlcache.exe – this is going to go away in the beta. Set up your database. Creates table. Trigger created. Created dataset and page and we begin monitoring. You update to a table is causing the trigger to change the SqlCD table and then your asp.net page knows to use the new data.

 

Enabling SQL 7 & 2000

• Alpha – Command Line only
  • Aspnet_regsqlcache.exe
• Beta – Command Line and Wizard
  • Rolled into aspnet_regsql.exe 

Enabling the table and the database are two separate and distinct things.

 

configuration – only for sql server 7 and 2000

• Relates friendly name to connection string
• Control default polling settings 

pollTime attribute causes the refresh of the polling. This is optional.

 

• section
  • Identify connection string 

SQL Server ‘Yukon’

• Granular Notification Support
  • Ex., when data in table changes
  • Ex., when SPROC results change
• Built in feature of the database
  • No triggers or other services to install
  • Pushes changes to subscribers
• ADO.NET SqlCommand
  • Supported by Yukon only

This works in a web garden as well.

 

CacheDependency Changes

• No breaking changes to CacheDependency
  • Backwards compatible with v1.x code
• ASP.NET 2.0 CacheDependency class:
  • New virtual properties/methods 

New APIs

 

ASP.NET 2.0

• Post-Cache Substitution
  • Ouput cache entire page
  • Identify regions that are dynamic
• Uses a PlaceHolder buffer
• New Response.WriteSubstitution()
  • Wires up substitution event on page
  • Adds a substitution buffer to the response
  • Substitution event returns string value to add
• New control
  • Drag and drop anywhere content should go.