ServiceComposer 5.2 OpenTelemetry support

This is going to be a quick one—ServiceComposer 5.2.0 introduced support for OpenTelemetry.

More details on the OpenTelemetry documentation page.

Tracing can be enabled for composition or scatter/gather:

builder.Services.AddOpenTelemetry()
    .WithTracing(b => b
       .AddSource("ServiceComposer.AspNetCore.ViewModelComposition")
       .AddSource("ServiceComposer.AspNetCore.ScatterGather"));

Each ICompositionRequestsHandler execution produces a child span of the ASP.NET Core HTTP server span. When a handler raises an event via context.RaiseEvent<TEvent>(), the event handling produces a child span of the raising handler’s span. When a handler or event handler throws, the span sets ActivityStatusCode.Error, adds tags, and an exception span event following the OTel exception conventions.

On a smaller scale, when using scatter/gather, each IGatherer execution produces a child span of the ASP.NET Core HTTP server span. When a gatherer throws, the span sets ActivityStatusCode.Error with the same otel.status_code, otel.status_description tags, and exception span event as the composition process does.

Conclusion

I’ve wanted OpenTelemetry support for a very long time, and finally it landed.

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