Trace a complete request

Overview

W3C trace context ties messages, events and child operations together. OpenTelemetry exports the activity tree; the monitor provides a different retained/queryable view. Child work should inherit causal context without reusing the parent's span ID.

Trace context connects work across boundaries

A trace identifies the overall request and spans identify individual operations within it. A child tool/database call should retain the causal trace while receiving its own span identity. FabrCore's ActivitySources/meters must be registered with the exporter before the viewer can display them. Application-specific work can add child Activity spans.

A trace and a monitor answer different questions

OpenTelemetry exports causal timing and diagnostics to your chosen backend. Retained monitoring provides queryable message/model records with its own retention and coverage. Missing data can mean an unregistered source, sampling, exporter failure or a different silo, not that the operation never ran. Use the request ID and timing to correlate these views.

Trace one investigation

1. Register the documented FabrCore ActivitySources/meters with an OpenTelemetry exporter and optional Aspire development viewer.
2. Stamp/propagate message trace context through the supported helpers. Create child Activity spans for application-specific HTTP or database operations.
3. Run SR-1042 through the assistant and a specialist, then inspect the parent/child relationships and model attribution.

// In your Program.cs, after AddFabrCoreServer:
builder.Services.AddOpenTelemetry()
    .WithTracing(tracing => tracing
        .AddSource("FabrCore.*")              // pick up every FabrCore ActivitySource
        .AddHttpClientInstrumentation()       // optional but recommended
        .AddAspNetCoreInstrumentation()       // optional for server
        .AddOtlpExporter(o =>                 // OR .AddJaegerExporter() / .AddConsoleExporter()
        {
            o.Endpoint = new Uri("http://localhost:4317");
        }))
    .WithMetrics(metrics => metrics
        .AddMeter("FabrCore.*")               // FabrCore meters (Host.Extensions, Host grains, SDK, ...)
        .AddOtlpExporter());

public class MyAgent : FabrCoreAgentProxy
{
    private static readonly ActivitySource Source = new("MyCompany.MyAgent");

    public override async Task<AgentMessage> OnMessage(AgentMessage message)
    {
        using var activity = Source.StartActivity("search-docs");
        activity?.SetTag("query.length", message.Message?.Length ?? 0);

        var result = await DoTheWork(message);

        var response = message.Response();
        response.Message = result;
        // Grain will StampFromActivity before returning to the caller; optional here.
        return response;
    }
}

Go deeper

Explore the related documentation.

• FabrCore Telemetry
• FabrCore Monitoring
• FabrCore Verifiable Execution
• FabrCore Testing
• OpenTelemetry exporter setup
• Creating child spans in your agent