Creating comments and nodes with Services 3.x and JSON I'm having trouble getting services to recognize a POST to /comment.json.
I have a similar issue with creating nodes as well. 

The following is the error I get:
HTTP/1.1 406 Not Acceptable: Missing required argument comment

This message comes from the file: /services/server/rest_server/includes/RESTServer.inc
Specifically, the lines:

  elseif (!isset($info['optional']) || !$info['optional']) {
    return services_error(t('Missing required argument !arg', array(
      '!arg' =&gt; $info['name'],
    )), 406);
  }


basically, it seems to think the "comment" argument is missing (and it's not optional).

This is one of many bits of JSON I've given it (posting a comment to node 8801)

{name:"test",language:"und",cid:"0",pid:"0",uid:"17593",nid:"8801",
comment:{subject:"Subject of the comment, if not entered it will be auto-generated",
comment_body:
{und:[
[{value:"value of the field comment in the comment, remember that in D7 we can create fields for comments too", format: "full_html"}]
]}}}


It's perfectly valid (based on other online JSON checks).  It also matches what I see in the services test examples at /services/test/functional/ServivesResourceCommentTests.test

however, I always get the same error message.
This seems similar to:  Drupal 7 services json node object

which is also unresolved.  Can someone help me with the proper JSON formatting?  Really, all I want to do is pass it something like:

{ nid : 8081 , uid : 17593 ,comment:{comment_body:"test",subject:"test"}}


my http headers seem ok and user/login worked fine.
The following JSON appears to be the minimum you need to post a comment:

{
  "nid":"1",
  "subject":"Comment Subject Text",
  "comment_body":{
    "und":[{
      "value":"Comment body text"
    }]
  }
}


Since there is no user, commenting on this "example.com/node/1" needs to be turned on and permissions for anonymous users to post comments need to be set.