How to integrate tcl (Project Open) and xero API using oauth 1?

Question

I tried with the help of twitter api call into my tcl program, but it's not working. I want to call Xero API into tcl programming using OAuth 1.0a.

::http::register https 443 [list ::tls::socket -ssl2 0 -ssl3 0 -tls1 1]
set handle [::http::geturl https://api.xero.com/api.xro/2.0/Contacts ]
set body [::http::data $handle]

It gives me a following error.

invalid command name "::tls::socket"
while executing
"::http::geturl https://api.xero.com/api.xro/2.0/Contacts "
("uplevel" body line 3)
   invoked from within
 "uplevel {
     ::http::register https 443 [list ::tls::socket -ssl2 0 -ssl3 0 -tls1 1]