``` { version: 4,

info: { reason: <string>, // what triggered this ping: "saved-session", "environment-change", "shutdown", ... revision: <string>, // the Histograms.json revision timezoneOffset: <integer>, // time-zone offset from UTC, in minutes, for the current locale previousBuildId: <string>, // null if this is the first run, or the previous build ID is unknown

sessionId: <uuid>,  // random session id, shared by subsessions
subsessionId: <uuid>,  // random subsession id
previousSessionId: <uuid>, // session id of the previous session, null on first run.
previousSubsessionId: <uuid>, // subsession id of the previous subsession (even if it was in a different session),
                              // null on first run.

subsessionCounter: <unsigned integer>, // the running no. of this subsession since the start of the browser session
profileSubsessionCounter: <unsigned integer>, // the running no. of all subsessions for the whole profile life time

sessionStartDate: <ISO date>, // hourly precision, ISO date in local time
subsessionStartDate: <ISO date>, // hourly precision, ISO date in local time
sessionLength: <integer>, // the session length until now in seconds, monotonic
subsessionLength: <integer>, // the subsession length in seconds, monotonic

addons: <string>, // obsolete, use ``environment.addons``

},

processes: {...}, simpleMeasurements: {...},

// The following properties may all be null if we fail to collect them. histograms: {...}, keyedHistograms: {...}, chromeHangs: {...}, // removed in firefox 62 threadHangStats: [...], // obsolete in firefox 57, use the 'bhr' ping log: [...], // obsolete in firefox 61, use Event Telemetry or Scalars gc: {...}, fileIOReports: {...}, lateWrites: {...}, addonDetails: {...}, UIMeasurements: [...], // Android only slowSQL: {...}, slowSQLstartup: {...}, } ```

``` { type: <string>, // "main", "activation", "optout", "saved-session", ... id: <UUID>, // a UUID that identifies this ping creationDate: <ISO date>, // the date the ping was generated version: <number>, // the version of the ping format, currently 4

application: { architecture: <string>, // build architecture, e.g. x86 buildId: <string>, // "20141126041045" name: <string>, // "Firefox" version: <string>, // "35.0" displayVersion: <string>, // "35.0b3" vendor: <string>, // "Mozilla" platformVersion: <string>, // "35.0" xpcomAbi: <string>, // e.g. "x86-msvc" channel: <string>, // "beta" },

clientId: <UUID>, // optional environment: { ... }, // optional, not all pings contain the environment payload: { ... }, // the actual payload data for this ping type } ```

Message Queuing Telemetry Transport MQTT protocol -> publish-subscribe network protocol that transports messages between devices, usually through TCP/IP

Protocol defines 2 network entities:

1. message broker -> receives messages from clients and then sends them to any clients subscribed to topic.
2. a number of clients ->

<table style="border: 1px solid black;"> <tr> <th style="border: 1px solid black;"> MQTT un-encrypted port </th> <th style="border: 1px solid black;"> MQTT encrypted port </th> </tr> <tr> <td style="border: 1px solid black;">**1883** </td> <td style="border: 1px solid black;">**8883** </td> </tr> </table>