Hi

I am trying to get NHibernate working with WCF. Originally I was hoping to be able to create a contract that implemented methods of ISession.

Unfortunately, this seems not to work, as the CreateCriteria method requires a generic Type parameter. I get this error:

There was an error while trying to serialize parameter http://tempuri.org/:persistentClass. The InnerException message was 'Type 'System.RuntimeType' with data contract name 'RuntimeType:http://schemas.datacontract.org/2004/07/System' is not expected

Is the only way for me to create my custom objects on the server and pass them to the client?

I would really appreciate anyone with experience of getting NHibernate working with WCF giving me some pointers here!

Thanks,
Mark.

I did that in one project i.e. using nhibernate and WCF together. Make sure all your mapped classes allow serialisation or implement ISerializeable. By all I mean ALL those which have to pass between server and client.

.Net will serialise nested objects also and if any class does not allow serialisation, it will cause exception to be thrown.

I am also trying to setup a WCF + NHibernate system. I found this quite useful. http://lunaverse.wordpress.com/2007/05/09/remoting-using-wcf-and-nhibernate/

Thanks for the responses.

One thing that occurred to me: If the ISession exsists on the server, surely this is where the object cache will exist too?

To me, one of the big benefits of using an ORM is to have objects cached on the client.

Having only used one other ORM, DevExpress persistent objects, this supported having the data serialized via a service contract but in all other respects, the caching/lazy loading logic sat on the Client. Unfortunately, the DevExpress tool is far from mature in other respects!

To put it simply: I don't want a SQLServer or Oracle connection string on the client because I don't want the security/firewall/DB admin/Politics issues of the client PC talking straight to the database - it needs to go via an application-specific Remoting/WCF/WebService channel, but it still needs to have all the benefits of ORM performances :)