Events and logs api (#2676)

This PR is a follow up to the OTEP [Events and Logs API](https://github.com/open-telemetry/oteps/blob/main/text/0202-events-and-logs-api.md). It describes the specification for an Events and Logs API and also defines semantic conventions for attributes to be used for Events that are represented using Log Records.

For non-trivial changes, follow the [change proposal
process](../CONTRIBUTING.md#proposing-a-change) and link to the related issue(s)
and/or [OTEP(s)](https://github.com/open-telemetry/oteps), update the
[`CHANGELOG.md`](../CHANGELOG.md), and also be sure to update
[`spec-compliance-matrix.md`](../spec-compliance-matrix.md) if necessary.


Related [OTEP(s)](https://github.com/open-telemetry/oteps) #

[Events and Logs API](https://github.com/open-telemetry/oteps/blob/main/text/0202-events-and-logs-api.md)

semantic_conventions/logs/events.yaml

@@ -0,0 +1,32 @@
+groups:
+  - id: event
+    prefix: event
+    brief: >
+        This document defines attributes for Events represented using Log Records.
+    attributes:
+      - id: name
+        type: string
+        requirement_level: required
+        brief: >
+          The name identifies the event.
+        examples: ['click', 'exception']
+      - id: domain
+        brief: >
+          The domain identifies the context in which an event happened. An event name is unique only within a domain.
+        type:
+          allow_custom_values: true
+          members:
+            - id: browser
+              value: 'browser'
+              brief: 'Events from browser apps'
+            - id: device
+              value: 'device'
+              brief: 'Events from mobile apps'
+            - id: k8s
+              value: 'k8s'
+              brief: 'Events from Kubernetes'
+        requirement_level: required
+        note: |
+          An `event.name` is supposed to be unique only in the context of an
+          `event.domain`, so this allows for two events in different domains to
+          have same `event.name`, yet be unrelated events.

specification/logs/semantic_conventions/README.md

@@ -6,6 +6,10 @@ The following semantic conventions for logs are defined:
 
 * [Log Media](media.md): Semantic attributes that may be used in describing the source of a log.
 
+The following semantic conventions for events are defined:
+
+* [Events](events.md): Semantic attributes that must be used to represent Events using log data model.
+
 Apart from semantic conventions for logs, [traces](../../trace/semantic_conventions/README.md), and [metrics](../../metrics/semantic_conventions/README.md),
 OpenTelemetry also defines the concept of overarching [Resources](../../resource/sdk.md) with their own
 [Resource Semantic Conventions](../../resource/semantic_conventions/README.md).

specification/logs/semantic_conventions/events.md

@@ -0,0 +1,27 @@
+# Semantic Convention for event attributes
+
+**Status**: [Experimental](../../document-status.md)
+
+This document describes the attributes of standalone Events that are represented
+by `LogRecord`s. All standalone Events have a name and a domain. The Event domain
+is a namespace for event names and is used as a mechanism to avoid conflicts of
+event names.
+
+<!-- semconv event -->
+| Attribute  | Type | Description  | Examples  | Requirement Level |
+|---|---|---|---|---|
+| `event.name` | string | The name identifies the event. | `click`; `exception` | Required |
+| `event.domain` | string | The domain identifies the context in which an event happened. An event name is unique only within a domain. [1] | `browser` | Required |
+
+**[1]:** An `event.name` is supposed to be unique only in the context of an
+`event.domain`, so this allows for two events in different domains to
+have same `event.name`, yet be unrelated events.
+
+`event.domain` 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 |
+|---|---|
+| `browser` | Events from browser apps |
+| `device` | Events from mobile apps |
+| `k8s` | Events from Kubernetes |
+<!-- endsemconv -->