Ah, I see. It’s a common misconception, you are mixing Client Relevance with Session Relevance. Client Relevance, which is much more common, evaluates…on the client. In Fixlets, Tasks, Analyses, Global Properties, etc., Client Relevance is running on the BigFix Client and has access to the operating system, hardware, etc.
Session Relevance, running from Web Reports, the Web Reports QNA page, REST API, Console Debugger, or Console Dashboards, use the same language constructs but don’t have access to any real device - it can only report on the data that has been previously rolled up from a client. Session Relevance is where we can reference objects like ‘bes fixlets’, ‘bes computers’, and ‘bes properties’.
What you would need, then, is to first create properties in an Analysis (or Global Properties) that the clients can report up to the server; and then you can use Session Relevance to correlate results across your deployment.
For instance, you could create an Analysis in your Master Action Site named “Client Timings”. Add two properties to it -
“First Registration Time” - with relevance of
minimum of subscribe times of sites
“OS Boot Time” - with relevance of
boot time of operating system
Then, in your REST API query, Web Reports dashboard, etc. you could report these directly via the “Explore -> Computers” page and add these Columns, or filter with a Session Relevance query like
(names of computers of it, values of it) of results of bes properties whose (name of it = "OS Boot Time)
If you want to retrieve multiple property results in one query, there are some ways to craft the query that make a huge difference in performance, so I’d suggest reading Efficient Session Relevance Query for Computer Properties especially if you want to retrieve both the First Registration Time and the OS Boot Time in a single report.