Linking WebCenter Spaces to UCM and Discussions

I'm working for a day now on linking the three products together (WCS, UCM and Discussions)
Unfortunately, still no luck :(
Problem:
When I start all processes (HTTP server for UCM, UCM, WLS Admin server, WLS_Services and WLS_Spaces), navigate to WebCenter Spaces and login as weblogic all seems fine.
However, when I try to upload a document, I get the following error in my WLS_Spaces log:

(System Error: Could not find the parameter 'dDocType'.)
oracle.webcenter.doclib.internal.view.DoclibIdcException: Oracle Content Server error: Unable to execute service COLLECTION_CHECKIN_NEW and function validateCheckinData.
(System Error: Could not find the parameter 'dDocType'.)
at oracle.webcenter.doclib.internal.view.CISRepositoryLogic.createDocument(CISRepositoryLogic.java:615)
.
.
.

Followed by some stack trace I'll won't bother you with.
In the browser I see the message:
Messages for this page are listed below.
Unable to upload the document.
The document no longer exists.
Click the Refresh icon to see the latest content.

The problem for this problem was (as always?!?!?) a small thing:
There was no default value defined for the document type.
With a fresh install, UCM gets shipped with a number of ACME Example document types.
WebCenter adds a document type named DOCUMENT
However, no document type is selected as default. Therefore, like the error states, there is no dDocType during the checkin.
The solution is simple:

• Go to the UCM site
• Open Administration
• Open Folder Configuration
• Click System Default Information Field Configuration
• Set the Type to DOCUMENT - Document type
• While you're there, set the Security Group to Personal Spaces

Second issue:
When I click on the discussion forums icon (in the left navigation) i get the message in the browser:
failure to authenticate the user weblogic, due to: Session is locked for user weblogic

which might be caused by the WARNING in the spaces diagnostics log:

[2010-09-30T11:56:36.348+02:00] [WLS_Spaces] [WARNING] [] [oracle.webcenter.collab.forum.internal.model.gateway.ForumGatewayManager] [tid: [ACTIVE].ExecuteThread: '0' for queue: 'weblogic.kernel.Default (self-tuning)'] [ecid: 0000IhY4KrZFg4WFLzRL8A1Cd5uA000000,0] [APP: webcenter] oracle.webcenter.collab.share.LoginFailedException: failure to authenticate the user weblogic, due to: service 'oracle.webcenter.collab.forum' disabled by 1 hung threads[[
service : oracle.webcenter.collab.forum
resource : null
source : oracle.webcenter.collab.share.Session$1@1b7e45 (oracle.webcenter.collab.share.Session$1)
submission : 3
]]

This issue was a bit more complex.
It had to do with the configuration of the Web Service Security between WebCenter and the Discussion application.
I can supply the solution in the post, but perhaps it's better to point you to the original blog post from Andrejus Baranovskis that I followed.
Beware for all the parameters you need in the different steps.
Easiest is to only change the passwords ;)

I'ld like to thank George Maggessy for thinking along with me.