Tuna Toksoz's weblog

Castle’s extensibility points provide you many ways to make your life easier. One and most widely used extensibility point is the facilities. By using facilities, you can integrate various other frameworks and technologies easily.

I am going to talk about NHibernate Integration Facility, which is currently lead by me. It was originally written by Hamilton Verissimo, and its current shape is more or less the same as what he wrote.

The purpose of this post is to get feedback and shape the documentation accordingly.

Now, after an historical introduction, lets talk about the facility’s purpose, and in as the first part of the documentation, the configuration.

The purpose
The purpose of this facility to provide an easy way to integrate NHibernate into MicroKernel backed applications. The facility provides a nice way to manage multiple session factories, a good way to manage sessions and it also provides some other structures that can be used to further integrate other frameworks such as Fluent NHibernate. It also plays nicely with other Castle services such as Transaction Management.

The Configuration
Currently, the facility can only be configured via XML, but it provides some extension points that can be used to configure it programmatically. The traditional way of configuring it is as given below. 

<configuration>
    <facilities>
        <facility
          id="nhibernatefacility"
          type="Castle.Facilities.NHibernateIntegration.NHibernateFacility, Castle.Facilities.NHibernateIntegration"
          [optional: configurationBuilder="Your custom configuration builder"] [optional: isWeb="Your custom configuration builder"]>
            <factory id="sessionFactory1">
                <settings>
                    <item key="connection.provider">NHibernate.Connection.DriverConnectionProvider</item>
                    <item key="connection.driver_class">NHibernate.Driver.SqlClientDriver</item>
                    <item key="connection.connection_string">Data Source=.;Initial Catalog=test;Integrated Security=SSPI</item>
                    <item key="dialect">NHibernate.Dialect.MsSql2000Dialect</item>
                    <item key="proxyfactory.factory_class">NHibernate.ByteCode.Castle.ProxyFactoryFactory, NHibernate.ByteCode.Castle</item>
                </settings>
                <assemblies>
                    <assembly>YourAssembly.Name.Here</assembly>
                </assemblies>
            </factory>
        </facility>
    </facilities>
</configuration>

<httpModules>
    <add name="NHibernateSessionWebModule"
             type="Castle.Facilities.NHibernateIntegration.Components.SessionWebModule, Castle.Facilities.NHibernateIntegration"/>
</httpModules>

isWeb: In case of web application, you should set this to true, implement IContainerAccessor in your HttpApplication (the global.asax) also add following lines to your <httpModules> section

As it can bee seen here, it is not very much different from the way we configure NHibernate. What happens behind the scenes are that: Facility creates an NHibernate Configuration, registers the SessionManager, and make those ready to be resolved.

The facility provides you some way to modify the Configuration that is created behind the scenes. The point is called IConfigurationContributor. By implementing classes that derive from that interface and registering them to container, you’ll be able to modify the NHibernate Configuration, just before the SessionFactory is resolved. The interface is simple

public interface IConfigurationContributor
{
    void Process(string name,Configuration config);
}

The name corresponds to the id in the configuration.

You can also Configure NHibernate Configuration via the IConfigurationBuilder interface. Currently, there are 2 built in ConfigurationBuilders, namely DefaultConfigurationBuilder and XmlConfigurationBuilder.
The default one is the one that parses the thing you see above while XmlConfigurationBuilder uses NH’s native xmls.

In the next post, I will hopefully show to integrate FluentNHibernate using custom ConfigurationBuilder

nhibernate, nhibernate integration, castle