Problem with POST request with http_poller plugin

Hi,
I'm using Logstash to import data from a http web-service. It uses post method to retrieve data.
Now whenever I'm using the following format in my conf file, its throwing the following error: "Invalid url post".
My conf file sytax is as follows:
input {
http_poller{
urls => {
method => post
url => "https://zausvdisadey1:8243/services/SimpleProxy"
body => 'request xml body here'
}
request_timeout => 60
# Supports "cron", "every", "at" and "in" schedules by rufus scheduler
schedule => { cron => "* * * * * UTC"}
codec => "plain"
# A hash of request metadata info (timing, response headers, etc.) will be sent here
metadata_target => "http_poller_metadata"
}
}
output {
stdout { }
}

Please quote the full error message. Have you tried making the exact same request with e.g. curl?