What is the difference between the OpenTelemetry SDK and the Collector? [Advanced]
Answer
The OpenTelemetry SDK runs in or beside the application to create telemetry, while the Collector is a separate service or agent that receives, processes, and exports telemetry. The SDK is for instrumentation; the Collector is for pipeline control.
Technical explanation
SDKs implement APIs, sampling, span creation, metric readers, resource attributes, and exporters inside the application process.
The Collector supports receivers, processors, exporters, and extensions for routing, batching, filtering, enrichment, and sampling.
Using the Collector prevents every application from needing direct credentials and backend-specific configuration.
Hands-on example
Example: application SDK exports OTLP to a local Collector agent. The agent batches and forwards to a gateway Collector. The gateway performs tail sampling, PII filtering, tenant routing, and exports to observability backends. App teams only configure service name and endpoint.
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