hi, everybody

I added a formula field to an object with this content:

HYPERLINK("https://na3-api.salesforce.com/secur/frontdoor.jsp?sid=" & GETSESSIONID() & "&retURL=/servlet/servlet.Integration?lid=01r500000009WP3⁣=1&param=a_parameter", "open")

This place a link that open a web-tab in my apeexchange app with a s-control.
My cuestion is:
how can I get the value of the parameter "param" (a_parameter) in the s-control placed in the web-tab?

thanks in advance

please, anybody knowns how to call a method defined in an Apex package, using java API?
thanks