1. SQL Server 2005 Query Notifications
in ASP.NET 2.0 & ADO.NET 2.0
Julie Lerman
The Data Farm

2. About Me Independent Software Developer
20+ years development experience
Microsoft .NET MVP
ASPInsider
INETA Speaker
Various publications & conferences
Blogs: thedatafarm.com/blog blog.ziffdavis.com/devlife
Founder and leader of Vermont .NET
Vermont Software Developer Alliance Board

3. Agenda SQL Server 2005 Query Notifications ADO.NET 2.0 Notifications
ASP.NET 2.0 Cache Invalidation

4. Query Notifications New feature in SQL Server 2005
Works with SQL Server Service Broker
Enables asynchronous database apps
Uses queues as first class objects
T-SQL can interact with the queues
Transactional Message Processing
Reliable Distributed Processing
*Not* Notification Services

5. How they work SQL Server Query from Client Data
Notification Flag
Change
Detection for
rowset DML
SQL Server Service Broker
Message
Queue
Services
Listener
Application
SQL Server 2005

6. Uses Queries that do not change frequently
Queries that need to stick around for a while
Look-up Tables
When details of change are unimportant
Only reports that “something has changed”
Web Applications
Page level or middle tier
Windows Apps
Server tier (e.g. remoting or web services)
Client side: no more than 10 concurrent users

7. Query Rules Use explicit columns in command text
Required for Change Detection internals
“select *” will not work
Use two-part names to reference tables
e.g.: owner.tablename or schema.tablename
NO!
UNION, Outer Joins, TOP, DISTINCT, COUNT*, aggregates (AVG, MAX, etc.), INTO, more... (see resources for list)
TEMP, table variables, multiple views, system tables/views, queues, more....

8. ALTER DATABASE mydb SET ENABLE_BROKER
SQL Server Rules
Enable Service Broker on database
SQL Server security has this off by default
ALTER DATABASE mydb SET ENABLE_BROKER
Database Compatibility Level = 90
Older databases (e.g. pubs) might be 80 or lower
sp_dbcmptlevel or Database/Properties/Options
Permissions for non-admins
One time setup per account

9. Non-Admin setup TSQL sql_dependencey_subscriber role in SQL Server
EXEC sp_addrole 'sql_dependency_subscriber’
Permissions needed for users to Start
GRANT CREATE PROCEDURE to startUser
GRANT CREATE QUEUE to startUser
GRANT CREATE SERVICE to startUser
GRANT REFERENCES on CONTRACT:: [ to startUser
GRANT VIEW DEFINITION TO startUser
Permissions needed for users to Execute
GRANT SELECT to executeUser
GRANT SUBSCRIBE QUERY NOTIFICATIONS TO executeUser
GRANT RECEIVE ON QueryNotificationErrorsQueue TO executeUser
GRANT REFERENCES on CONTRACT:: [ to executeUser
EXEC sp_addrolemember 'sql_dependency_subscriber', 'executeUser'
*Sushil Chordia on blogs.msdn.com/dataworks

10. ADO.NET 2.0 Integration SqlDependency class
[System.Data.SqlClient namespace]
Uses SqlQueryNotificationService in MSDB database
SqlNotificationRequest class
[System.Data.Sql namespace]
Requires you to write your own listener
Works with DataReaders & DataAdapters

11. SQLDependency: Basic Functionality
Demonstration
SQLDependency: Basic Functionality

12. SqlDependency Steps SqlDependency.Start(Connection) Create SqlCommand
Only needed once per app
e.g. in Global.ASAX
Create SqlCommand
Create SqlDependency
Attach SqlDependency to SqlCommand
Execute SqlCommand
Create delegate to listen for OnChange
and/or SqlDependency.Changed property

13. The Plumbing Data Change SqlDep Start SQL Connection Service Broker
creates queue
creates service
creates sproc for cleanup
“something changed!”
Data Container
Query w/ Depend
Application
SQL Server 2005

14. SqlDependency.Start Creates static non-pooled connection
Creates default queues and services
Optional
Create your own custom services & queues in SQL Server and pass the queue name as a parameter with Start
SqlDependency.Start(connString) or
SqlDependency.Start(connString,”myQueue”,”myService”)

15. SqlNotificationEventArgs
Notification is not always about a change
Type
Source
Info
One of 18 Enums can be returned
Update
Invalid: Query does not follow rules
Options: Not all SQL Server options are set
more…
Notification returns immediately for problems

16. In the Middle Tier Cache Data at the Application Level
All client sessions get data from that cache
Notification triggers the cache to update

17. SqlDependency in the Middle Tier
Demonstration
SqlDependency in the Middle Tier

18. SqlNotificationRequest
Lower level than SqlDependency
Does not use default queue in SQL Server
Custom Service and Queue must be created in SQL Server in advance
Does not require an application wide “Start”
Definitely for the middle tier

19. SqlNotificationRequest Steps
Create QUEUE & SERVICE in SS2005
Create SqlCommand
Create SqlNotificationRequest
Point request to QUEUE & SERVICE
Attach SqlNotificationRequest to SqlCommand
Execute SqlCommand
Run WAITFOR Query
Handle results of WAITFOR

20. Create Queue & Service CREATE QUEUE myqueue
CREATE SERVICE myservice ON QUEUE myqueue ([ PostQueryNotification])

21. SqlNotificationRequest
Demonstration
SqlNotificationRequest

22. Cache Invalidation 1.x Invalidate triggers with:
File Change
Key Change (pointing to different cache)
Time Based
Database change invalidation
Complicated trickery
Can be done with bells and whistles involving SQL Server TRIGGERS and file dependency
re Jeff Prosise Wicked Code for doing this in 1.x

23. Cache Invalidation 2.0 SqlCacheDependency class
System.Web.Caching namespace
Inherits from System.Web.Caching.CacheDependency
Internals similar to SqlDependency
Plugs into the Output Cache
Two methods
Server-side code using SqlCacheDependency
Client side within <% OutputCache > directive

24. Demonstration
SqlCacheDependency

25. SqlCacheDependency Steps
Similar to SqlDependency
SqlDependency.Start
Create SqlCommand
Create SqlCacheDependency
Attach SqlCacheDependency to command
Execute Command
Add SqlCacheDependency to the Cache of the Response object
Set Cache properties

26. <% OutputCache…>
Remember the SqlDependency.Start
Can be in global.asax
System.Data.SqlClient.SqlDependency.Start(ConfigurationManager.ConnectionStrings[“myConn”].ConnectionString)
SqlDependency=“CommandNotification”
Flags ASP.NET to use SQL Server 2005 Query Notification
Applies to all valid queries related to page
SqlDependency= anything else
Will use polling method to check for changes to database
Requires additional setup in web.config & aspnet_regsql.exe command line tool
Works with SS2005, SS2000, SS7
for pre-sql2005:
<caching>
            <sqlCacheDependency>
                        <databases>
                                    <add name=”Northwind” connectionStringName=”NorthwindConnectionString1” />
                        </databases>             </sqlCacheDependency>
</caching>
And then enable the database and table for notification:
Aspnet_regsql.exe –S <server> -U <user> -P <password> -ed –d Northwind –et –t Products

27. <% OutputCache…>
Demonstration
<% OutputCache…>

28. Conclusion
Query Notification is a powerful feature for ASP.NET Applications
Best target is read-mostly lookup tables
Use in middle with ADO.NET classes
Use at page level with ASP.NET classes

29. Contact Info
Julie Lerman

30. Resources
Query Notifications in ADO.NET 2.0 Bob Beauchemin, MSDN Online April 2005
What’s New in ADO.NET 2.0
Julia Lerman, MSDN Magazine April 2005
Caching Improvements in ASP.NET Whidbey G. Andrew Duthie, MSDN Online Feb 2004
Improved Caching in ASP.NET Stephen Walther, MSDN Online, June 2004
Asynchronous Command Execution in ADO.NET Pablo Castro, MSDN Online, July 2004
ADO.NET 2.0 and System.Xml v.2.0 – The Beta Version Alex Homer, Dave Sussman, Mark Fussell Addison-Wesley, April 2005

31. Please fill out the survey forms
Please fill out the survey forms! They are the key to amazing prizes that you can get at the end of each day
Thank you!