Thanks for confirming that Associations are supported by Wolfram Programming Cloud. The following screenshot shows the code and error message from the web interface:
This code was runnable in the Mathematica 10 Desktop version. I found that if I removed the carriage return after the "col = <|" input and changed the first line to "col = <| "Posted Date" -> 1," then the input was processed as expected. Interestingly, if I then reintroduced the carriage return bringing the input back to the original, it still processed as expected on subsequent executions.
