Is it possible that you over thinking this? DNN is a wonderful portal solution that handles presentation and module creation. SplendidCRM is a wonderfully extensible business system and database. In my opinion, all that is required is pass through authentication and a method of linking DNN portals to unique SplendidCRM databases.
I've recently created a hosted solution that does just that. It is implemented as a DNN security role, a DNN "Portal Integration" module, and some tweaks to the SplendidCRM authentication process.
In my integration, users who are members of the "SplendidCRM Users" security role in DNN see an "Intranet Apps" page with a link to SplendidCRM. They click the link, which handles the handshake between DNN and SplendidCRM. It also manages the SplendidCRM database association. It works great.
In my implementation, all non-customer facing SplendidCRM interaction is left untouched (raw SplendidCRM). All customer facing interaction is done through DNN modules with a very specific purpose. DNN modules interact with SplendidCRM, through the same T-SQL used by SplendidCRM. This eliminates the need for a full SplendidCRM and DNN integration. In my opinion, you get the best of both products without too tightly integrating them and losing their distinct personalities.
I'm offering integrated SplendidCRM and DotNetNuke sites at http://netsphere.developitnow.com. If you're looking for a solution, it's available. If you're looking for a guide to doing it yourself, you might consider doing what I've done.
I have an instant one way sync of DNN Users to Splendid Contacts which uses Database Triggers. It also includes DNN Roles to sync to Splendid so that DNN Roles are searchable on the Splendid side. The original project called for a two way sync of the Contacts and Users portion, but was never completed. It could be completed by myself or someone else if anyone is interested.
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