We are trying to identify the user executing dashboard on load query so that we can personalize the content.
We are familiar using abap user exit EXIT_SAPLRRS0_001 that we code to set sy-uname to bex variable variable ZVAR_BO_USERID
The bex variable is defined as user exit and ready for manual input. This works as expected in BEx Web - the BW user id is filled in bex prompt variable ZVAR_BO_USERID
So, we created olap connection on this bex query using SSO authentication.
The problem:
When we add this bex query as olap connection in dashboard as query browser, and run thru the wizard, it prompts to select an entry for ZVARUSERID.
If we select an entry, say LLEWIS, this is the value returned in the dashboard in runtime instead of the user executing the dashboard
(BW sy-uname), i.e Logged on user ESMITH gets value LLEWIS. Seems this selection is retained in query browser as the input value for the dsahboard in runtime???? If in query browser, we do not enter a value for the bex variable, the query browser loops endlessly and we see this in BW SM50 and must kill the query browser wizard,
A quick dsahboard example hopefully shows the problem
In the Dashboard query browser, I last edit of the olap conneciton, I had to enter a value for the Bex query value for variable ZVAR_BO_USERID, else the wizard will just spin forever, so here I selected userid WSHAW and saved query. I mapped query columns to spreadsheet, then to text component.
When I run the dashboard from the BOE server I am logged into BI Luanch pad as Lee Lewis,
The query runs on load, but returns the query information for userid WSHAW and not the sy-uname (LLEWIS) as expected from the BW user exit - EXIT_SAPLRRS0_001.
Tried using a prompt in dashboard query designer, but since this is on load, we don't have any values to pass to Bex, again the goal being to identify the user that is executing the Bex query via SSO OLAP connectin from dashboards..
Are BW user exits supported in Dashboards BI4 SP04 Patch5?
ugh! I thought we had it! Any help is appreciated, even you can confirm this is impossible! 
Sincerely
Lee Lewis