Application Real-Time Monitoring Service (ARMS) collects trace data so you can track how a request moves through a distributed system. A trace captures the complete path of a request from start to finish. When a request flows through your services, ARMS records all service interactions and assembles them into a single trace that shows the full call sequence.
Benefits
In a distributed system, a single request typically touches multiple services. When a request times out, fails, or throws an exception, pinpointing the root cause is difficult without visibility into the full call chain. Traces give O&M engineers that visibility:
Troubleshooting: Traces expose the complete request path and the execution status of every service involved, so you can identify failures quickly.
Performance optimization: Analyzing per-span durations reveals execution bottlenecks, giving you a clear target for optimization.
System monitoring: Traces provide real-time visibility into system behavior, helping O&M engineers assess service health and resource utilization.
Terms
Trace
A trace captures the complete execution of a request or transaction, from the moment it enters the system to its final response. For example, a user action that triggers calls across three microservices produces one trace that records the entire journey.
Each trace is a tree of spans. ARMS assigns every trace a unique trace ID that persists throughout the request's lifecycle. All spans belonging to the same request share this trace ID, so you can query every related span in one place when debugging.
The span at the root of the tree — the root span — has no parent. It marks the start of the trace. Every other span has a parent span ID that links it to the span that triggered it.
Span
A span is the basic unit of a trace. It represents a single logical operation — such as a method call, a program block invocation, a remote procedure call (RPC), or a database query.
Each span carries:
A unique span ID
Start and end timestamps
A parent span ID (absent on the root span)
Spans nest inside one another to form the trace tree, mirroring the actual service call hierarchy. A span with no parent span ID is the root span and marks the entry point of the trace.