Configure ASP.NET Session State at runtime

Question

We have an ASP.NET web site that uses SQL Server session state. The state is configured in Web.config like:

<sessionState mode="SQLServer" sqlConnectionString="data source=TheServer;
    User ID=TheUser;password=ThePassword;" cookieless="false" timeout="480"/>

But there are three environments (development / staging / production). All the other connection strings are configured like:

<configuration>
    <connectionStrings>
        <add name="Development_Db1" connectionString="..."/>
        <add name="Production_Db1" connectionString="..."/>
    </connectionStrings>
</configuration>

At runtime, we pick one to connect to the database based on hostname. Unfortunately, the Session State connection string appears to be hard coded in web.config.

Is there a way to configure SQL Server session state at runtime, or make it refer to a connection string from the connectionStrings section?

So basically you have information of all environments in one config file? Do you not want to use one file per environment? — GôTô
@GôTô: Yes, all information for all environments is in one config file. Working on a relatively old system here, my job is to swap it from in-process to sqlserver state. — Andomar
This is a good question in general, but I don't like the idea of keeping all the connection strings in one place. Too much chance that production writes to development environment or vice versa... — D'Arcy Rittich
@RedFilter I agree completely. I've worked in scenarios before trying to reference production and development environments from the same place, and it's easy to mess things up. — Andy

Andomar Andomar · Accepted Answer · 2011-01-23T00:48:54

As it turned out, there was a fairly easy way of doing this. Session State provides a feature called Partitioning, where you can spread your state over multiple SQL Servers. You can provide a function to select the SQL Server based on the session id (SID). The trick is that you can use this feature with ONE server, just to choose the server dynamically.

The web.config configuration looks like:

<sessionState mode="SQLServer" 
              partitionResolverType="YourNamespace.PartitionResolver" 
              cookieless="false" 
              timeout="60" />

The function that chooses the SQL Server looks like:

public class PartitionResolver : IPartitionResolver
{
    public void Initialize() {}

    // The key is a SID (session identifier)
    public String ResolvePartition(Object key)
    {
        return <grab your config here>;
    }
}

This approach allowed us to continue using one web.config for both production and development.

Configure ASP.NET Session State at runtime

3 Answers