opentelemetry-dotnet/docs/metrics/extending-the-sdk/README.md

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# Extending the OpenTelemetry .NET SDK
* [Building your own exporter](#exporter)
* [Building your own reader](#reader)
* [Building your own exemplar](#exemplar)
* [References](#references)
## Exporter
OpenTelemetry .NET SDK has provided the following built-in metric exporters:
* [Console](../../../src/OpenTelemetry.Exporter.Console/README.md)
* [InMemory](../../../src/OpenTelemetry.Exporter.InMemory/README.md)
* [OpenTelemetryProtocol](../../../src/OpenTelemetry.Exporter.OpenTelemetryProtocol/README.md)
* [Prometheus](../../../src/OpenTelemetry.Exporter.Prometheus/README.md)
Custom exporters can be implemented to send telemetry data to places which are
not covered by the built-in exporters:
* Exporters should derive from `OpenTelemetry.BaseExporter<Metric>` (which
belongs to the [OpenTelemetry](../../../src/OpenTelemetry/README.md) package)
and implement the `Export` method.
* Exporters can optionally implement the `OnShutdown` method.
* Exporters should not throw exceptions from `Export` and
`OnShutdown`.
* Exporters are responsible for any retry logic needed by the scenario. The SDK
does not implement any retry logic.
* Exporters should avoid generating telemetry and causing live-loop, this can be
done via `OpenTelemetry.SuppressInstrumentationScope`.
* Exporters receives a batch of `Metric`, and each `Metric`
can contain 1 or more `MetricPoint`s.
* Exporters should use `ParentProvider.GetResource()` to get the `Resource`
associated with the provider.
```csharp
class MyExporter : BaseExporter<Metric>
{
public override ExportResult Export(in Batch<Metric> batch)
{
using var scope = SuppressInstrumentationScope.Begin();
foreach (var metric in batch)
{
Console.WriteLine($"Export: {metric.metric}");
foreach (ref readonly var metricPoint in metric.GetMetricPoints())
{
Console.WriteLine($"Export: {metricPoint.StartTime}");
}
}
return ExportResult.Success;
}
}
```
A demo exporter which simply writes metric name, metric point start time
and tags to the console is shown [here](./MyExporter.cs).
Apart from the exporter itself, you should also provide extension methods as
shown [here](./MyExporterExtensions.cs). This allows users to add the Exporter
to the `MeterProvider` as shown in the example [here](./Program.cs).
## Reader
Not supported.
## Exemplar
Not supported.
## References