Concepts
APM v2 is built on a small set of objects. This page defines them once, so the rest of the documentation can use them precisely.
| Term | What it is |
|---|---|
| Entity | A service or database APM v2 monitors, each with its own health model. Entities are what the catalog lists and what you open to drill into. |
| Signal | A data source reporting for an entity - Spans, Profiling, or Infra. The catalog's Signal column shows which are active. |
| Span | A single timed operation in a distributed trace - one unit of work, such as an HTTP handler or a database call. |
| Trace | The full set of spans for one request as it moves across your services. |
| Operation | A class of span, grouped by name - for example an endpoint (GET /cart) or a database statement (SELECT). Metrics aggregate spans by operation. |
| Transaction | A request that enters a service, identified by its entry-point operation (the root span). Transactions are the service's incoming work. See Transactions. |
| Span metric | A metric Coralogix derives from your spans - the RED metrics that power the catalog, charts, and health. See Span metrics. |
| RED metrics | The three golden signals: Rate (requests), Errors, and Duration (latency). |
| Health policy | A rule that contributes to an entity's health state - apdex, error rate, latency, log errors, cases, or SLOs. See Service health. |
| Case | An operational issue linked to an entity, from Coralogix Cases. |
| Apdex | A score from 0 to 1 that measures user satisfaction with a service's response time against a threshold. See Apdex score. |
Entities, signals, and health
An entity is the thing you monitor - a service or a database. Every entity carries a health state derived from its health policies, and reports one or more signals (spans, profiling, infrastructure) that populate its telemetry. The catalog lists your entities; opening one takes you into its drilldown.
Spans, operations, and transactions
These three describe your traffic at increasing levels of aggregation:
- A span is one operation instance inside a trace.
- An operation groups spans of the same kind - every
GET /cart, or everySELECTagainst a table. - A transaction is a request that enters a service - its root operation - together with the segments and spans beneath it.
For databases, the equivalent of a transaction is an operation: a class of query, such as a SELECT against a given table.
Span metrics and RED
Coralogix reads your spans and derives span metrics - counters and histograms for requests, errors, and duration (RED). These power the catalog, the overview widgets, and the health model, so you read golden signals without querying raw traces. An entity needs span metrics to appear in the catalog; an account needs compact span metrics on services and databases to access APM v2.
Next steps
Get your services reporting in the onboarding tutorial.