In-process mode is the default session state mode and is specified using the InProc SessionStateMode enumeration value. In-process mode stores session state values and variables in memory on the local Web server. It is the only mode that supports the Session_OnEnd event. For more information about the Session_OnEnd event, see Session-State Events.

Caution
If you enable Web-garden mode by setting the webGarden attribute to true in the processModel element of the application's Web.config file, do not use InProc session state mode. If you do, data loss can occur if different requests for the same session are served by different worker processes.

StateServer mode stores session state in a process, referred to as the ASP.NET state service, that is separate from the ASP.NET worker process or IIS application pool. Using this mode ensures that session state is preserved if the Web application is restarted and also makes session state available to multiple Web servers in a Web farm.

To use StateServer mode, you must first be sure the ASP.NET state service is running on the server used for the session store. The ASP.NET state service is installed as a service when ASP.NET and the .NET Framework are installed. The ASP.Net state service is installed at the following location:

systemroot\Microsoft.NET\Framework\versionNumber\aspnet_state.exe

To configure an ASP.NET application to use StateServer mode, in the application's Web.config file do the following:

• Set the mode attribute of the sessionState element to StateServer.

• Set the stateConnectionString attribute to tcpip=serverName:42424.

  Note
  To improve the security of your application when using StateServer mode, it is recommended that you protect your stateConnectionString value by encrypting the sessionState section of your configuration file. For details, see Encrypting Configuration Information Using Protected Configuration.

The following example shows a configuration setting for StateServer mode where session state is stored on a remote computer named SampleStateServer:

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<configuration> <system.web> <sessionState mode="StateServer" stateConnectionString="tcpip=SampleStateServer:42424" cookieless="false" timeout="20"/> </system.web> </configuration>

Note
Objects stored in session state must be serializable if the mode is set to StateServer. For information on serializable objects, see the SerializableAttribute class.

To use StateServer mode in a Web farm, you must have the same encryption keys specified in the machineKey element of your Web configuration for all applications that are part of the Web farm. For information on how to create machine keys, see article 313091, "How to create keys by using Visual Basic .NET for use in Forms authentication," in the Microsoft Knowledge Base at http://support.microsoft.com.

SQLServer mode stores session state in a SQLВ Server database. Using this mode ensures that session state is preserved if the Web application is restarted and also makes session state available to multiple Web servers in a Web farm.

Note
Objects stored in session state must be serializable if the mode is SQLВ Server. For information on serializable objects, see the SerializableAttribute class.

To use SQLServer mode, you must first be sure the ASP.NET session state database is installed on SQLВ Server. You can install the ASP.NET session state database using the Aspnet_regsql.exe tool, as described later in this topic.

To configure an ASP.NET application to use SQLServer mode, do the following in the application's Web.config file:

• Set the mode attribute of the sessionState element to SQLServer.

• Set the sqlConnectionString attribute to a connection string for your SQLВ Server database.

  Note
  to improve the security of your application when using SQLServer mode, it is recommended that you protect your sqlConnectionString value by encrypting the sessionState section of your configuration file. For details, see Encrypting Configuration Information Using Protected Configuration.

The following example shows a configuration setting for SQLServer mode where session state is stored on a SQLВ Server named "SampleSqlServer":

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<configuration> <system.web> <sessionState mode="SQLServer" sqlConnectionString="Integrated Security=SSPI;data source=SampleSqlServer;" /> </system.web> </configuration>

Note

If you specify a trusted connection to your SQLВ Server in the configuration file using the sessionState element's sqlConnectionString attribute, the SessionStateModule will connect to SQLВ Server using SQLВ Server integrated security. The connection will be made using the ASP.NET process identity or the user credentials supplied for the identity configuration element, if they exist. You can specify that the IIS impersonated identity be used instead by specifying <identity impersonate="true" /> and setting the useHostingIdentity attribute of the sessionState configuration element to false. For more information on the ASP.NET process identity, see Configuring ASP.NET Process Identity and ASP.NET Impersonation.

To configure SQLServer mode for a Web farm, in the configuration file for each Web server, set the sessionState element's sqlConnectionString attribute to point to the same SQLВ Server database. The path for the ASP.NET application in the IIS metabase must be identical on all Web servers that share session state in the SQLВ Server database. For information on steps to resolve the issue when application paths differ between servers, see article 325056, "PRB: Session State Is Lost in Web Farm If You Use SqlServer or StateServer Session Mode," in the Microsoft Knowledge Base at http://support.microsoft.com.

Installing the Session State Database Using the Aspnet_regsql.exe Tool

To install the session state database on SQLВ Server, run the Aspnet_regsql.exe tool located in the systemroot\Microsoft.NET\Framework\versionNumber folder on your Web server. Supply the following information with the command:

• The name of the SQLВ Server instance, using the -S option.

• The logon credentials for an account that has permission to create a database on SQLВ Server. Use the -E option to use the currently logged-on user, or use the -U option to specify a user ID along with the -P option to specify a password.

• The -ssadd command-line option to add the session state database.

  By default, you cannot use the Aspnet_regsql.exe tool to install the session state database on SQLВ Server Express Edition. In order to run the Aspnet_regsql.exe tool to install a SQLВ Server Express Edition database, you must first enable the Agent XPs SQLВ Server option using T-SQL commands like the following:

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  EXECUTE sp_configure 'show advanced options', 1 RECONFIGURE WITH OVERRIDE GO EXECUTE sp_configure 'Agent XPs', 1 RECONFIGURE WITH OVERRIDE GO EXECUTE sp_configure 'show advanced options', 0 RECONFIGURE WITH OVERRIDE GO

  You must run these T-SQL commands for any instance of SQLВ Server Express Edition where the Agent XPs option is disabled.

By default, the Aspnet_regsql.exe tool will create a database named ASPState containing stored procedures that support SQLServer mode. Session data itself is stored in the tempdb database by default. You can optionally use the -sstype option to change the storage location of session data. The following table specifies the possible values for the -sstype option:

Option	Description
t	Stores session data in the SQLВ Server tempdb database. This is the default. If you store session data in the tempdb database, the session data is lost if SQLВ Server is restarted.
p	Stores session data in the ASPState database instead of in the tempdb database.
c	Stores session data in a custom database. If you specify the c option, you must also include the name of the custom database using the -d option.

For example, the following command creates a database named ASPState on a SQLВ Server instance named "SampleSqlServer" and specifies that session data is also stored in the ASPState database:

aspnet_regsql.exe -S SampleSqlServer -E -ssadd -sstype p

Note

If you are running ASP.NET 1.0 or ASP.NET 1.1, the Aspnet_regsql.exe tool does not provide the option to store session data in the ASPState database. However, you can obtain scripts to store session state in a persistent database. For details, see article 311209, "HOW TO: Configure ASP.NET for Persistent SQL Server Session State Management" in the Microsoft Knowledge Base at http://support.microsoft.com.

In SQLServer mode, you can configure several computers running SQLВ Server to work as a failover cluster, which is two or more identical computers running SQLВ Server that store data for a single database. If one computer running SQLВ Server fails, another server in the cluster can take over and serve requests without session-data loss. To configure SQLВ Server mode for a failover cluster, you must specify -sstype p when you execute the Aspnet_regsql.exe tool so that session state data is stored in the ASPState database instead of the tempdb database. Storing session state in the tempdb database is not supported for a SQLВ Server cluster. For more information about setting up SQLВ Server mode for a failover cluster, see article 323262, "How to use ASP.NET session state SQL Server Mode in a failover cluster" in the Microsoft Knowledge Base at http://support.microsoft.com.

Custom mode specifies that you want to store session state data using a custom session state store provider. When you configure your ASP.NET application with a Mode of Custom, you must specify the type of the session state store provider using the providers sub-element of the sessionState configuration element. You specify the provider type using an add sub-element and include both a type attribute that specifies the provider's type name and a name attribute that specifies the provider instance name. The name of the provider instance is then supplied to the customProvider attribute of the sessionState element to configure ASP.NET session state to use that provider instance for storing and retrieving session data.

The following example shows elements from a Web.config file that specify that ASP.NET session state use a custom session state store provider:

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<configuration> <connectionStrings> <add name="OdbcSessionServices" connectionString="DSN=SessionState;" /> </connectionStrings> <system.web> <sessionState mode="Custom" customProvider="OdbcSessionProvider"> <providers> <add name="OdbcSessionProvider" type="Samples.AspNet.Session.OdbcSessionStateStore" connectionStringName="OdbcSessionServices" writeExceptionsToEventLog="false" /> </providers> </sessionState> </system.web> </configuration>

For more information on custom session state store providers, see Implementing a Session-State Store Provider.

Note

A custom session state store provider will access any secured resource, such as SQLВ Server, using the ASP.NET process identity or the user credentials supplied to the identity configuration element, if they exist. You can specify that the IIS impersonated identity be used instead by specifying <identity impersonate="true" /> and setting the useHostingIdentity attribute of the sessionState configuration element to false. For more information on the ASP.NET process identity, see Configuring ASP.NET Process Identity and ASP.NET Impersonation.

Reference

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