# Semantic conventions for SignalR server metrics

LLMS index: [llms.txt](/llms.txt)

---

**Status**: [Stable][DocumentStatus]

This article defines semantic conventions for SignalR metrics emitted by .NET components and runtime.


## Metric: `signalr.server.connection.duration`

This metric SHOULD be specified with [`ExplicitBucketBoundaries` advisory parameter](https://github.com/open-telemetry/opentelemetry-specification/blob/v1.54.0/specification/metrics/api.md#instrument-advisory-parameters) of `[ 0.01, 0.02, 0.05, 0.1, 0.2, 0.5, 1, 2, 5, 10, 30, 60, 120, 300 ]`.

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| Name | Instrument Type | Unit (UCUM) | Description | Stability | Entity Associations |
| -------- | --------------- | ----------- | -------------- | --------- | ------ |
| `signalr.server.connection.duration` | Histogram | `s` | The duration of connections on the server. [1] | ![Stable](https://img.shields.io/badge/-stable-lightgreen) | |

**[1]:** Meter name: `Microsoft.AspNetCore.Http.Connections`; Added in: ASP.NET Core 8.0

**Attributes:**

| Key | Stability | [Requirement Level](/docs/specs/semconv/general/attribute-requirement-level/) | Value Type | Description | Example Values |
| --- | --- | --- | --- | --- | --- |
| [`signalr.connection.status`](/docs/specs/semconv/registry/attributes/signalr.md) | ![Stable](https://img.shields.io/badge/-stable-lightgreen) | `Recommended` | string | SignalR HTTP connection closure status. | `app_shutdown`; `timeout` |
| [`signalr.transport`](/docs/specs/semconv/registry/attributes/signalr.md) | ![Stable](https://img.shields.io/badge/-stable-lightgreen) | `Recommended` | string | [SignalR transport type](https://github.com/dotnet/aspnetcore/blob/main/src/SignalR/docs/specs/TransportProtocols.md) | `web_sockets`; `long_polling` |

---

`signalr.connection.status` has the following list of well-known values. If one of them applies, then the respective value MUST be used; otherwise, a custom value MAY be used.

| Value | Description | Stability |
| --- | --- | --- |
| `app_shutdown` | The connection was closed because the app is shutting down. | ![Stable](https://img.shields.io/badge/-stable-lightgreen) |
| `normal_closure` | The connection was closed normally. | ![Stable](https://img.shields.io/badge/-stable-lightgreen) |
| `timeout` | The connection was closed due to a timeout. | ![Stable](https://img.shields.io/badge/-stable-lightgreen) |

---

`signalr.transport` has the following list of well-known values. If one of them applies, then the respective value MUST be used; otherwise, a custom value MAY be used.

| Value | Description | Stability |
| --- | --- | --- |
| `long_polling` | LongPolling protocol | ![Stable](https://img.shields.io/badge/-stable-lightgreen) |
| `server_sent_events` | ServerSentEvents protocol | ![Stable](https://img.shields.io/badge/-stable-lightgreen) |
| `web_sockets` | WebSockets protocol | ![Stable](https://img.shields.io/badge/-stable-lightgreen) |

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## Metric: `signalr.server.active_connections`

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| Name | Instrument Type | Unit (UCUM) | Description | Stability | Entity Associations |
| -------- | --------------- | ----------- | -------------- | --------- | ------ |
| `signalr.server.active_connections` | UpDownCounter | `{connection}` | Number of connections that are currently active on the server. [1] | ![Stable](https://img.shields.io/badge/-stable-lightgreen) | |

**[1]:** Meter name: `Microsoft.AspNetCore.Http.Connections`; Added in: ASP.NET Core 8.0

**Attributes:**

| Key | Stability | [Requirement Level](/docs/specs/semconv/general/attribute-requirement-level/) | Value Type | Description | Example Values |
| --- | --- | --- | --- | --- | --- |
| [`signalr.connection.status`](/docs/specs/semconv/registry/attributes/signalr.md) | ![Stable](https://img.shields.io/badge/-stable-lightgreen) | `Recommended` | string | SignalR HTTP connection closure status. | `app_shutdown`; `timeout` |
| [`signalr.transport`](/docs/specs/semconv/registry/attributes/signalr.md) | ![Stable](https://img.shields.io/badge/-stable-lightgreen) | `Recommended` | string | [SignalR transport type](https://github.com/dotnet/aspnetcore/blob/main/src/SignalR/docs/specs/TransportProtocols.md) | `web_sockets`; `long_polling` |

---

`signalr.connection.status` has the following list of well-known values. If one of them applies, then the respective value MUST be used; otherwise, a custom value MAY be used.

| Value | Description | Stability |
| --- | --- | --- |
| `app_shutdown` | The connection was closed because the app is shutting down. | ![Stable](https://img.shields.io/badge/-stable-lightgreen) |
| `normal_closure` | The connection was closed normally. | ![Stable](https://img.shields.io/badge/-stable-lightgreen) |
| `timeout` | The connection was closed due to a timeout. | ![Stable](https://img.shields.io/badge/-stable-lightgreen) |

---

`signalr.transport` has the following list of well-known values. If one of them applies, then the respective value MUST be used; otherwise, a custom value MAY be used.

| Value | Description | Stability |
| --- | --- | --- |
| `long_polling` | LongPolling protocol | ![Stable](https://img.shields.io/badge/-stable-lightgreen) |
| `server_sent_events` | ServerSentEvents protocol | ![Stable](https://img.shields.io/badge/-stable-lightgreen) |
| `web_sockets` | WebSockets protocol | ![Stable](https://img.shields.io/badge/-stable-lightgreen) |

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[DocumentStatus]: /docs/specs/otel/document-status