Module session_window 

Session Window Operators

Implementation of session windows for stream processing.

Session windows are dynamic windows that group events by activity periods separated by gaps. Unlike tumbling and sliding windows which have fixed boundaries, session windows grow with activity and close after inactivity.

Key Characteristics

• Dynamic boundaries: Sessions start with the first event and extend with each new event within the gap period
• Per-key tracking: Each key maintains independent session state
• Gap-based closure: Sessions close when no events arrive within the gap
• Session merging: Late data can merge previously separate sessions

Example

Gap: 30 seconds

Events: [t=0] [t=10] [t=20]  ...gap...  [t=100] [t=110]
        |<---- Session 1 ---->|          |<- Session 2 ->|
        [0, 50)                          [100, 140)

Usage

use laminar_core::operator::session_window::SessionWindowOperator;
use laminar_core::operator::window::CountAggregator;
use std::time::Duration;

// Create a session window with 30-second gap
let operator = SessionWindowOperator::new(
    Duration::from_secs(30),    // gap timeout
    CountAggregator::new(),
    Duration::from_secs(60),    // allowed lateness
);

Structs

ArchivedSessionId

An archived SessionId

ArchivedSessionIndex

An archived SessionIndex

ArchivedSessionMetadata

An archived SessionMetadata

SessionId

Unique identifier for a session instance.

SessionIdResolver

The resolver for an archived SessionId

SessionIndex

Index of all active sessions for a single key.

SessionIndexResolver

The resolver for an archived SessionIndex

SessionMetadata

Metadata for a single session within a key’s session index.

SessionMetadataResolver

The resolver for an archived SessionMetadata

SessionMetrics

Session metrics for monitoring.

SessionWindowOperator

Creates the standard session output schema. Session window operator.