What is the OpenTelemetry Protocol (OTLP) and how does it compare to other protocols like Jaeger and Zipkin?

Think of telemetry protocols like languages for shipping packages. Jaeger's protocol is like a specialized courier that only delivers letters (traces) using a specific packaging format (Thrift). Zipkin's protocol is another courier for letters but uses different packaging (JSON). OTLP is like a universal shipping system that delivers letters (traces), packages (metrics), and large crates (logs) using the same standardized container format. If you send a richly labeled package via the Jaeger courier, some labels might fall off because Jaeger's format does not support them. OTLP preserves every label because the format was designed for it.

OTLP is defined as a Protocol Buffers schema with three sub-protocols: one for traces, one for metrics, and one for logs. It supports two transport mechanisms: gRPC (on port 4317 by default) and HTTP/protobuf (on port 4318). The gRPC transport provides streaming, bidirectional communication, and built-in backpressure handling. The HTTP transport is simpler and works better through proxies, load balancers, and firewalls that may not support HTTP/2. Both transports serialize data identically using Protocol Buffers, which is significantly more compact than JSON (typically 3-5x smaller on the wire) and faster to serialize and deserialize.

The key advantage of OTLP over Jaeger and Zipkin protocols is semantic fidelity. OpenTelemetry's data model includes rich concepts like span events (structured logs attached to spans), span links (connecting causally related traces that are not parent-child), resource attributes (describing the entity producing telemetry), and instrumentation scope (identifying which library generated the data). When you export via OTLP, all of these concepts are preserved exactly. When you export via the Jaeger exporter, span events get converted to Jaeger logs (losing some structure), span links may be partially supported, and instrumentation scope is dropped. When you export via the Zipkin exporter, the data loss is even greater because Zipkin's model is simpler: no native span events, no span links, and annotations replace structured attributes.

For teams running services like payments-api, user-auth-service, and checkout-service on the OpenTelemetry SDK, the recommendation is clear: always use OTLP as the primary export protocol. Configure SDKs to send OTLP to the OpenTelemetry Collector, then let the Collector export to whatever backend you use. If your backend is Jaeger, the Collector's Jaeger exporter handles the translation. This means you never compromise your SDK-side data model for a backend's protocol limitations, and switching backends requires only a Collector configuration change, not an application code change.

Performance-wise, OTLP with gRPC transport is the fastest option for high-throughput environments. In benchmarks, OTLP/gRPC handles 2-3x more spans per second than the Jaeger Thrift compact protocol on the same hardware, primarily due to Protocol Buffers' efficient binary serialization versus Thrift's overhead. OTLP/HTTP is slightly slower than gRPC but still faster than Zipkin's JSON format. The batch processing built into the OpenTelemetry SDK's BatchSpanProcessor amortizes connection overhead across thousands of spans, making OTLP even more efficient in practice. For the order-processing-service handling 10,000 requests per second, the difference between OTLP and Zipkin JSON can mean the difference between 2% and 8% CPU overhead for telemetry export.