I wish to know the possible ways to find out the count of all currently logged in users across all the SharePoint site collections in a farm.
For example (users logged into sites)
John - http://webapp1/sites/portal
Jack - http://webapp1/sites/portal
The output desired from a program/script is it can give me the total unique visitors with active sessions across all these site collections
Things I have tried so far
IIS Log Parser way
SQL Queries to the content database of the web application
SELECT COUNT(DISTINCT tp_login) AS USERCOUNT
WHERE tp_ExternalTokenLastUpdated > '2012-03-31'
AND tp_Token != 'NULL'
Both the above ways are bound by limitations like parsing IIS logs from multiple WFEs and manually querying all content databases becomes an overhead.Additionally I am not really sure if either of them are the right approach for achieving this.
I read a good number of webpages from Google and the only definite conclusion I have is there are no out of the box way in SharePoint to achieve this. Please somebody guide me here.