Understanding the Atmosphere Protocol

The Atmosphere Framework uses a really simple communication protocol between its supported client and the core server component. By default, Atmosphere attach, to the request URI, a list of query string that are used by the core server component. It can also set those value as requests headers if required. The mandatory key/value lists are:

• X-Atmosphere-Framework = version The lowest Atmosphere's version supported
• X-Cache-Date = This header is used to retrieve lost events on the server side. Lost events happens when the browser reload the page, when the connection gets closed or any I/O related issue. The client always first set that value to 0, and after always use the value send back by the server, as a response's header. If the server's value cannot be retrieved, the value should be set to 0 and the server will figure out which events to send back.
• X-Atmosphere-Transport: sse|websocket|long-polling|streaming|ajax|jsonp The transport used for that connection.
• X-Atmosphere-tracking-id: value Originally set to 0, this value will be set by the server in order to uniquely track the client.
• _timeStamp a unique value starting with _ . This is required to prevent browsers from caching request.

For example, a request may looks like

T 127.0.0.1:57618 -> 127.0.0.1:8080 [AP]
GET /chat?X-Atmosphere-tracking-id=e24de98c-6624-c552-5572-6edbffd270e3&
X-Atmosphere-Framework=1.0&X-Atmosphere-Transport=long-polling&X-Cache-Date=134183423411&_=1341834834155 HTTP/1.1.
Host: 127.0.0.1:8080.
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.7; rv:13.0) Gecko/20100101 Firefox/13.0.
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8.
Accept-Language: en-us,en;q=0.5.
Accept-Encoding: gzip, deflate.
Connection: keep-alive.
Referer: http://127.0.0.1:8080/.
Cookie: nikio.guid=890066de-f3ad-4e33-a96a-a80c6fc1d4a7.