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System Observability: Logging, Metrics & Tracing (ELK + OpenTelemetry) · Lesson

Signals and Semantic Conventions

Learn the three OpenTelemetry signals, how they share resources and context, and why semantic conventions make telemetry portable across tools.

Signals and Semantic Conventions is a free System Observability: Logging, Metrics & Tracing (ELK + OpenTelemetry) lesson on CoddyKit — lesson 4 of 4. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the System Observability: Logging, Metrics & Tracing (ELK + OpenTelemetry) learning path, one of 4 lessons in the course, and your progress syncs across the web and the CoddyKit app.

The Three Signals

OpenTelemetry defines three signals of telemetry: traces, metrics, and logs. One specification and SDK produce all three in a consistent way.

Traces

Traces capture the path of a request across services as a tree of spans, answering where time went and what failed.

span: GET /checkout
  span: query inventory
  span: charge payment

Metrics

Metrics are numeric measurements aggregated over time: counters, gauges, and histograms that answer how much and how often.

http.server.duration histogram
http.server.active_requests gauge

Logs

Logs are timestamped records of discrete events. In OTel they can be correlated with traces by carrying the same trace and span IDs.

{ "body": "order placed", "trace_id": "a9f...c1" }

The Resource

A Resource describes the entity producing telemetry, such as a service or host. It is attached to all three signals so they share identity.

resource:
  service.name: checkout
  service.version: 1.4.0

Shared Context

All signals can carry the same context. A log and a metric exemplar can point back to the trace that produced them, enabling correlation.

What Are Semantic Conventions?

Semantic conventions are agreed names for common attributes. Everyone uses http.request.method instead of inventing their own key.

Why Conventions Matter

Standard names let any backend understand your data. Dashboards, alerts, and tools work out of the box because the keys are predictable.

  • Portability across vendors
  • Reusable dashboards
  • Automatic correlation

Common Attribute Examples

Conventions cover HTTP, databases, messaging, and more.

http.request.method = "GET"
http.response.status_code = 200
db.system = "postgresql"

Resource vs Span Attributes

Resource attributes describe the producer and rarely change. Span attributes describe a single operation and vary per request.

resource: service.name (static)
span: http.route, user.tier (per request)

Signals Together

Combining the three signals with shared resources and conventions gives full observability: metrics show what is wrong, traces show where, and logs show why.

Quick Check

Identify the purpose of semantic conventions.

Recap

You learned the three OTel signals (traces, metrics, logs), how a shared Resource and context tie them together, and how semantic conventions standardize attribute names for portability and correlation across any backend.

Frequently asked questions

Is the “Signals and Semantic Conventions” lesson free?

Yes — the full text of “Signals and Semantic Conventions” is free to read here on the web, and the System Observability: Logging, Metrics & Tracing (ELK + OpenTelemetry) course includes 4 lessons in total. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the System Observability: Logging, Metrics & Tracing (ELK + OpenTelemetry) course, upgrade to CoddyKit PRO.

What will I learn in “Signals and Semantic Conventions”?

Learn the three OpenTelemetry signals, how they share resources and context, and why semantic conventions make telemetry portable across tools. You practise System Observability: Logging, Metrics & Tracing (ELK + OpenTelemetry) with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.

Do I need any experience to start System Observability: Logging, Metrics & Tracing (ELK + OpenTelemetry)?

No prior experience is required. System Observability: Logging, Metrics & Tracing (ELK + OpenTelemetry) on CoddyKit is structured for beginners through advanced learners; this is — lesson 4 of 4, so you can start here or from the beginning and move at your own pace.

How long does the “Signals and Semantic Conventions” lesson take?

Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.

Can I write and run code in this System Observability: Logging, Metrics & Tracing (ELK + OpenTelemetry) lesson?

Yes. Every System Observability: Logging, Metrics & Tracing (ELK + OpenTelemetry) lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.

All lessons in this course

  1. The OpenTelemetry Standard
  2. OTel Collectors and Exporters
  3. Instrumenting Apps with OTel SDKs
  4. Signals and Semantic Conventions
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