params is for GET-style URL parameters, and data is for POST-style body information. It is perfectly legal to provide both types of information in a request, and your request does so too, but you encoded the URL parameters into the URL already.

Your raw post contains JSON data though. Requests can handle JSON encoding for you, and it'll set the correct Content-Type header too; all you need to do is pass in the Python object to be encoded as JSON into the json keyword argument.

You could split out the URL parameters as well:

params = {'sessionKey': '9ebbd0b25760557393a43064a92bae539d962103', 'format': 'xml', 'platformId': 1}

Then post your data with:

import requests

url = 'http://192.168.3.45:8080/api/v2/event/log'

data = {"eventType": "AAS_PORTAL_START", "data": {"uid": "hfe3hf45huf33545", "aid": "1", "vid": "1"}}
params = {'sessionKey': '9ebbd0b25760557393a43064a92bae539d962103', 'format': 'xml', 'platformId': 1}

requests.post(url, params=params, json=data)

The json keyword is new in Requests version 2.4.2; if you still have to use an older version, encode the JSON manually using the json module and post the encoded result as the data key; you will have to explicitly set the Content-Type header in that case:

import requests
import json

headers = {'content-type': 'application/json'}
url = 'http://192.168.3.45:8080/api/v2/event/log'

data = {"eventType": "AAS_PORTAL_START", "data": {"uid": "hfe3hf45huf33545", "aid": "1", "vid": "1"}}
params = {'sessionKey': '9ebbd0b25760557393a43064a92bae539d962103', 'format': 'xml', 'platformId': 1}

requests.post(url, params=params, data=json.dumps(data), headers=headers)

params is for GET-style URL parameters, data is for POST-style body information. It is perfectly legal to provide both types of information in a request, and your request does so too, but you encoded the URL parameters into the URL already.

Your raw post contains JSON data though. requests can handle JSON encoding for you, and it'll set the correct Content-Type header too; all you need to do is pass in the Python object to be encoded as JSON into the json keyword argument.

You could split out the URL parameters as well:

params = {'sessionKey': '9ebbd0b25760557393a43064a92bae539d962103', 'format': 'xml', 'platformId': 1}

then post your data with:

import requests

url = 'http://192.168.3.45:8080/api/v2/event/log'

data = {"eventType": "AAS_PORTAL_START", "data": {"uid": "hfe3hf45huf33545", "aid": "1", "vid": "1"}}
params = {'sessionKey': '9ebbd0b25760557393a43064a92bae539d962103', 'format': 'xml', 'platformId': 1}

requests.post(url, params=params, json=data)

The json keyword is new in requests version 2.4.2; if you still have to use an older version, encode the JSON manually using the json module and post the encoded result as the data key; you will have to explicitly set the Content-Type header in that case:

import requests
import json

headers = {'content-type': 'application/json'}
url = 'http://192.168.3.45:8080/api/v2/event/log'

data = {"eventType": "AAS_PORTAL_START", "data": {"uid": "hfe3hf45huf33545", "aid": "1", "vid": "1"}}
params = {'sessionKey': '9ebbd0b25760557393a43064a92bae539d962103', 'format': 'xml', 'platformId': 1}

requests.post(url, params=params, data=json.dumps(data), headers=headers)

To perform GET requests with URL query string:

import requests

params = {
    'action': 'subscribe',
    'callbackurl': '',
    'comment': '',
    'oauth_consumer_key': '',
    'oauth_nonce': '',
    # more key=value pairs as appeared in your query string
}
r = requests.get("http://wbsapi.withings.net/notify", params=params)

With that cleared, now you just need to follow the workflow documented on http://www.withings.com/en/api/oauthguide and implement them

1. Upon receiving your OAuth Key and OAuth Secret, perform a GET request with the following endpoint and query string which will give you back token:

   https://oauth.withings.com/account/request_token? oauth_callback=http%3A%2F%2Fexample.com%2Fget_access_token &oauth_consumer_key=c331c571585e7c518c78656f41582e96fc1c2b926cf77648223dd76424b52b &oauth_nonce=f71972b1fa93b8935ccaf34ee02d7657 &oauth_signature=J8xzgFtHTsSRw8Ejc8UDV2jls34%3D &oauth_signature_method=HMAC-SHA1 &oauth_timestamp=1311778988 &oauth_version=1.0

2. Then you need to authorize the token you received with the following request which will give you the user_id:

   https://oauth.withings.com/account/authorize? oauth_callback=http%3A%2F%2Fexample.com%2Fget_access_token &oauth_consumer_key=c331c571585e7c518c78656f41582e96fc1c2b926cf77648223dd76424b52b &oauth_nonce=369f9ceb2f285ac637c9a7e9e98019bd &oauth_signature=OR9J9iEl%2F2yGOXP2wk5c2%2BWtYvU%3D &oauth_signature_method=HMAC-SHA1 &oauth_timestamp=1311778988 &oauth_token=5bb105d2292ff43ec9c0f633fee9033045ed4643e9871b80ce586dc1bf945 &oauth_version=1.0

3. Then you need to request the access_token by hitting this endpoint with some more query string:

   https://oauth.withings.com/account/access_token? oauth_consumer_key=c331c571585e7c518c78656f41582e96fc1c2b926cf77648223dd76424b52b &oauth_nonce=7acd22371fc56fd8a0aaf8416f79f84f &oauth_signature=jmj1g%2FB3rYR2DCpWp86jB5YVHIM%3D &oauth_signature_method=HMAC-SHA1 &oauth_timestamp=1311778988 &oauth_token=5bb105d2292ff43ec9c0f633fee9033045ed4643e9871b80ce586dc1bf945 &oauth_version=1.0 &userid=831

4. Now you have everything needed to perform the aforementioned request in your question, and others, example directly from the documentation:

   http://wbsapi.withings.com/measure? action=getmeas &oauth_consumer_key=c331c571585e7c518c78656f41582e96fc1c2b926cf77648223dd76424b52b &oauth_nonce=accbac1b7ee2b86b828e6dc4a5a539b2 &oauth_signature=XfobZMboIg2cRyNKAvyzONHHnKM%3D &oauth_signature_method=HMAC-SHA1 &oauth_timestamp=1311842514 &oauth_token=887557411788d5120537c6550fbf2df68921f8dd6f8c7e7f9b441941eb10 &oauth_version=1.0 &userid=831

Again, everything can be done without explicit oauth library as you can finish the workflow with requests.get and query string built from a dict feed into the params argument of the method.

I truly hope this helps you achieve your goal.

You cannot use requests for this; the library builds such URLs if passed a Python structure for the parameters, but does not offer any tools to parse them. That's not a goal of the project.

Stick to the urllib.parse method to parse out the parameters. Once you have a dictionary or list of key-value tuples, just pass that to requests to build the URL again:

try:
    # Python 3
    from urllib.parse import urlparse, parse_qs
except ImportError:
    # Python 2
    from urlparse import urlparse, parse_qs

o = urlparse(url)
query = parse_qs(o.query)
# extract the URL without query parameters
url = o._replace(query=None).geturl()

if 'token' in query:
    query['token'] = 'NEW_TOKEN'

requests.get(url, params=query)

You can get both the urlparse and parse_qs functions in both Python 2 and 3, all you need to do is adjust the import location if you get an exception.

Demo on Python 3 (without the import exception guard) to demonstrate the URL having been built:

>>> from urllib.parse import urlparse, parse_qs
>>> url = "http://httpbin.org/get?token=TOKEN_TO_REPLACE&param2=c"
>>> o = urlparse(url)
>>> query = parse_qs(o.query)
>>> url = o._replace(query=None).geturl()
>>> if 'token' in query:
...     query['token'] = 'NEW_TOKEN'
... 
>>> response = requests.get(url, params=query)
>>> print(response.text)
{
  "args": {
    "param2": "c", 
    "token": "NEW_TOKEN"
  }, 
  "headers": {
    "Accept": "*/*", 
    "Accept-Encoding": "gzip, deflate", 
    "Host": "httpbin.org", 
    "User-Agent": "python-requests/2.5.1 CPython/3.4.2 Darwin/14.1.0"
  }, 
  "origin": "188.29.165.245", 
  "url": "http://httpbin.org/get?token=NEW_TOKEN&param2=c"
}