I googled for something like this but couldn't find anything. Then I decided to do it server side in ROR.

Here it is how to get UPS and Fedex xml request and response from their test servers.

For Fedex:

track_no = '111111111111'  # This is a test tracking number

# This XML Request body for fedex
xml_req = 

"<TrackRequest xmlns='
                <Password>YOUR_ACC_PASSWORD</Password></UserCredential></WebAuthenticationDetail><ClientDetail>
                <AccountNumber>YOUR_ACC_NUMBER</AccountNumber><MeterNumber>YOUR_ACC_METER_NUMBER</MeterNumber></ClientDetail>
                <TransactionDetail><CustomerTransactionId>ActiveShipping</CustomerTransactionId></TransactionDetail>
                <Version><ServiceId>trck</ServiceId><Major>3</Major><Intermediate>0</Intermediate><Minor>0</Minor></Version>
                <PackageIdentifier><Value>#{track_no}</Value><Type>TRACKING_NUMBER_OR_DOORTAG</Type></PackageIdentifier>
                <IncludeDetailedScans>1</IncludeDetailedScans></TrackRequest>"

path = ""

#this url connects to the test server of fedex
# for live server url is:""

url = URI.parse(path)
http = Net::HTTP.new(url.host,url.port)
http.use_ssl = true
http.verify_mode = OpenSSL::SSL::VERIFY_NONE

response =  http.post(url.path, xml_req)
response_body = response.body
res = response_body.gsub(/<(\/)?.*?\:(.*?)>/, '<\1\2>')
hash = Hash.from_xml(res.to_s)

And that's it! You will get response in hash variable, I converted xml response in to Hash because we can easily use Hash object at our view to display response data.