I am using below IronPython code for request web method with GET. It's worked with POST method. Then I change the post method into GET request.Method = "GET" and there after this example not work for GET method.
from System.Net import WebRequest
from System.IO import StreamReader
from System.Text import Encoding
def UrlOpen(uri, parameters=None):
    request = WebRequest.Create(uri)
    if parameters is not None:
        request.ContentType = "application/x-www-form-urlencoded"
        #request.Method = "POST" #work for post
        request.Method = "GET"   #not work for get method
        bytes = Encoding.ASCII.GetBytes(parameters)
        request.ContentLength = bytes.Length
        reqStream = request.GetRequestStream()
        reqStream.Write(bytes, 0, bytes.Length)
        reqStream.Close()
    response = request.GetResponse()
    result = StreamReader(response.GetResponseStream()).ReadToEnd()
    return result
print(UrlOpen("http://localhost:89/api/","data=1"))
PHP Code for web service just:
<?php
echo $_POST["data"];        
?>
It's displayed below error on Python console after changing request.Method = "GET" 
Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "<string>", line 9, in UrlOpen
SystemError: Cannot send a content-body with this verb-type.
 
    