Schema

An Application Event Schema describes the event data that an application can emit. Quent uses it to generate an application-specific, typed instrumentation API.

Entities

An entity is anything you want to emit events about. It typically represents a control-flow or data-flow object in your code, such as a task, request, buffer, or worker. It can also represent a function call, a metric source, or another event-producing concept.

Each entity instance has a universally unique identity represented by a UUID, which keeps its events separate from events emitted by other instances. Processes can assign these identities independently without coordinating through a central allocator, shared counter, or global process state.

Entities exist to group related events around the thing they describe.

Events

An event is something that happens to an entity at a particular point in time, such as a task starting or ending.

For each event, the generated instrumentation API provides a named call that application code uses to emit it. Depending on the target language, this call may be exposed as a method or function.

In statically typed target languages, these generated calls are fully type-safe. The compiler checks that each event receives the expected number and types of attributes. This makes it harder for instrumentation changes to accidentally alter event semantics or break downstream analysis.

In this respect, Quent resembles structured logging: each event has a known name and typed data. Quent can also export events through an end-to-end statically typed pipeline. Exporters do not necessarily need to attach runtime type information to each value, which can reduce runtime work and improve performance.

Events exist to record how an entity behaves over time.

Attributes

An attribute is a typed value captured when an event occurs, such as a task name or result code. Each attribute becomes a typed argument to the generated event call.

Attributes exist to record the details needed to interpret an event.

Records

A field is a named, typed value inside a record. A record is a named, reusable group of fields. The generated API represents a record as a struct in Rust and C++. In Python, records are dictionaries with generated TypedDict type hints.

Records exist to keep related values together and avoid repeating the same field definitions.

Event cardinality

Event cardinality defines how often an event can occur for one entity instance. A once event occurs at most once. A multi event may occur repeatedly.

Cardinality exists to distinguish unique events from repeatable events.