What is the proper URL to get flag service? I'm running Drupal 7 with the Services module and the Flag Service modules installed  but I'm having trouble trying to figure out how to Get countall for a particular post ? Can anyone please tell me what URL I should use ?

URL to get all posts : http://webaddess/rest/events

URL to get one Post : http://webaddess/rest/node/3591
I had to implement this for DrupalGap/jDrupal:

https://github.com/dontmcyn/flag/blob/master/flag.js#L282

Essentially you make a POST to ?q=rest/flag/countall.json and send along the following data:

var data = {
  flag_name: 'my_flag_name',
  entity_id: 123
}


You may have to JSON.stringify(data) before sending it. And you are right, pass along an X-CSRF-Token header in the POST call, the value of the token can be retrieved here: ?q=services/session/token