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(submitting-customping)=
# Submitting custom pings (deprecated)
:::{important}
Legacy Telemetry collection APIs are now deprecated.
Please use Glean instead.
:::
Custom pings can be submitted from JavaScript using:
```js
TelemetryController.submitExternalPing(type, payload, options)
```
- `type` - a `string` that is the type of the ping, limited to `/^[a-z0-9][a-z0-9-]+[a-z0-9]$/i`.
- `payload` - the actual payload data for the ping, has to be a JSON style object.
- `options` - optional, an object containing additional options:
: - `addClientId`- whether to add the client id and profile group id to the ping, defaults to `false`
- `addEnvironment` - whether to add the environment data to the ping, defaults to `false`
- `overrideEnvironment` - a JSON style object that overrides the environment data
`TelemetryController` will assemble a ping with the passed payload and the specified options.
That ping will be archived locally for use with Shield and inspection in `about:telemetry`.
If preferences allow the upload of Telemetry pings, the ping will be uploaded at the next opportunity (this is subject to throttling, retry-on-failure, etc.).
:::{important}
Every new or changed data collection in Firefox needs a [data collection review](https://wiki.mozilla.org/Firefox/Data_Collection) from a Data Steward.
:::
## Submission constraints
When submitting pings on shutdown, they should not be submitted after Telemetry shutdown.
Pings should be submitted at the latest within:
- the [observer notification](https://developer.mozilla.org/docs/Observer_Notifications#Application_shutdown) `"profile-before-change"`
- the {ref}`AsyncShutdown phase <AsyncShutdown_phases>` `sendTelemetry`
There are other constraints that can lead to a ping submission getting dropped:
- invalid ping type strings.
- invalid payload types: E.g. strings instead of objects.
- oversized payloads: We currently only drop pings >1MB, but targeting sizes of \<=10KB is recommended.
### Tools
Helpful tools for designing new pings include:
- [gzipServer](https://github.com/mozilla/gzipServer) - a Python script that can run locally and receives and saves Telemetry pings. Making Firefox send to it allows inspecting outgoing pings easily.
- `about:telemetry` - allows inspecting submitted pings from the local archive, including all custom ones.
### Designing custom pings
In general, creating a new custom ping means you don't benefit automatically from the existing tooling. Further work is needed to make data show up in re:dash or other analysis tools.
In addition to the [data collection review](https://wiki.mozilla.org/Firefox/Data_Collection), questions to guide a new ping design are:
- Submission interval & triggers:
: - What events trigger ping submission?
- What interval is the ping submitted in?
- Is there a throttling mechanism?
- What is the desired latency? (submitting "at least daily" still leads to certain latency tails)
- Are pings submitted on a clock schedule? Or based on "time since session start", "time since last ping" etc.? (I.e. will we get sharp spikes in submission volume?)
- Size and volume:
: - What’s the size of the submitted payload?
- What's the full ping size including metadata in the pipeline?
- What’s the target population?
- What's the overall estimated volume?
- Dataset:
: - Is it opt-out?
- Does it need to be opt-out?
- Does it need to be in a separate ping? (why can’t the data live in probes?)
- Privacy:
: - Is there risk to leak PII?
- How is that risk mitigated?
- Data contents:
: - Does the submitted data answer the posed product questions?
- Does the shape of the data allow to answer the questions efficiently?
- Is the data limited to what's needed to answer the questions?
- Does the data use common formats? (i.e. can we reuse tooling or analysis know-how)