0-4-4-understand-message-queue

name	0.4.4-understand-message_queue
description	[0.4.4] A communication mechanism where messages are placed in a queue by producers and consumed asynchronously by con

understand-message_queue

CALL NUMBER: software_architecture_patterns_and_styles.message_queue : deep_event_driven_archite(8) DEFINITION: A communication mechanism where messages are placed in a queue by producers and consumed asynchronously by consumers, decoupling sender and receiver in time and space.

Invoke this skill to understand message_queue down to its primitives. The RELATIVE ROOT below is the least-fixed-point closure of everything it bundles from — the full import cone, grouped by the lib each prim comes from. Projected from a prover-typed KB (MAP/SWI-Prolog consistency gate): every reference below resolves.

THE RELATIVE ROOT (the import cone, by lib)

from deep_event_driven_archite

• pubsub_message (d1): The payload broadcast by a publisher on a topic; in pub/sub it is typically ephemeral and not persisted beyond active subscriber consumption.
• pubsub_content_filter (d2): A predicate or attribute-based rule applied at the broker or subscriber side to select a subset of messages on a topic for delivery.
• pubsub_message_schema (d2): A structured format (JSON, Avro, Protobuf) defining the shape of messages on a topic, enabling subscribers to deserialize and interpret published events.
• pubsub_subscriber (d3): An entity that expresses interest in one or more topics and receives messages published to those topics; receives only messages matching its subscriptions.
• pubsub_broker (d3): The intermediary component that receives messages from publishers and forwards them to subscribers based on topic subscriptions; may also perform filtering.
• pubsub_dead_letter (d4): A destination for messages that cannot be successfully delivered to any subscriber, capturing failures for later inspection or replay.
• pubsub_subscription (d4): An active registration linking a subscriber to a topic; may be durable (surviving subscriber disconnection) or transient (active only while subscriber is connected).
• pubsub_topic_namespace (d5): A hierarchical or scoped naming scheme for topics (e.g., orders.new, orders.cancelled) that enables subscribers to express interest at varying levels of granularity.

CONSUMERS (what needs this)

claim_check_pattern, dead_letter_queue, dps_014, event_driven_architecture, scatter_gather, work_queue

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Projected from the software architecture patterns and styles KB (211 concepts / 192 relations) — consistency-typed by MAP; the facet list after the colon IS the cross-lib dependency web.

(leaf — this is an actual skill.)