Hi, thanks for your interest in this.
Basically the HTTP retriever or receiver can be used to to get or receive HTTP posts. If you want to make the data points in Mango stable you can specify the Set point URL. This is a URL where you have an HTTP listener. Any time you "Set" the point in Mango, Mango will make an HTTP post to your Set point URL with the value that was updated.
You can easily use two installations of Mango to experiment with this and you can use the Listen for HTTP data feature in the data sources to see the raw data come in from a post.
Thanks,
Joel.