Glossary

This glossary defines key terms used throughout the Angzarr documentation, organized by category.

Component Types

Term	Abbr	Description
Aggregate	agg	Domain logic. Commands in, events out. Single domain source of truth.
Saga	sag	Domain bridge. Events from one domain, commands to another. Stateless.
Projector	prj	Read model builder. Events in, external output.
Process Manager	pmg	Multi-domain orchestrator. Stateful correlation via correlation ID.
Coordinator	-	Angzarr sidecar handling infrastructure concerns.

DDD & Angzarr Mapping

Important Distinction

Angzarr "domain" ≠ DDD "bounded context". Multiple Angzarr domains may exist within one bounded context.

Term	Description
Domain	Angzarr: aggregate namespace and deployment unit. One domain = one aggregate type.
Bounded Context	DDD: semantic/team boundary. Not directly modeled by Angzarr. May contain multiple domains.
Aggregate Root	Entry point entity. All external references go through the root.

Commands, Events & Notifications

Understanding the differences is critical:

Term	Tense	Persisted	Can Reject	Example
Command	Imperative	No	Yes	CreateOrder
Event	Past	Yes	No	OrderCreated
Notification	Present	No	N/A	CompensationRequired

Event Sourcing

Term	Description
Event Sourcing	State derived by replaying events, not stored directly.
Event Store	Append-only database of events. Source of truth.
Replay	Reconstruct state by applying events from beginning.
Snapshot	Cached state checkpoint to optimize replay.
Sequence Number	Ordered position of event in aggregate timeline.
Upcasting	Transform old event versions at read time.

CQRS

Term	Description
CQRS	Command Query Responsibility Segregation.
Projection	Query-optimized read model built from events.

Angzarr Data Structures

Term	Description
EventBook	Collection of events for an aggregate root.
EventPage	Individual event with sequence and timestamp.
CommandBook	Collection of commands with concurrency metadata.
Cover	Identity/routing: domain, root, correlation, edition.
Target	Subscription filter: domain + event types.

Concurrency & Consistency

Term	Description
Merge Strategy	How to handle concurrent command conflicts.
Correlation ID	Identifier for cross-domain workflows.
Edition	Timeline branching for speculative execution.

Patterns & Architecture

Term	Description
Orchestration	Central coordinator controls workflow vs choreography.
Compensation	Handling failures by emitting undo events.
Sidecar	Container pattern for infrastructure concerns.
CloudEvent	Standardized event envelope for external systems.

Error Handling

Term	Description
Dead Letter Queue	Destination for unprocessable messages.

Terminology Comparison: DDD vs CQRS/ES vs Angzarr

The table below maps terminology across Domain-Driven Design, CQRS/Event Sourcing literature, and Angzarr. Understanding these mappings helps when reading DDD books, CQRS articles, or Angzarr docs.

Core Concepts

Concept	DDD (Evans)	CQRS/ES	Angzarr	Key Differences
Problem space	Domain	-	-	DDD's "domain" is the business problem, not a code construct
Problem partition	Subdomain (core/supporting/generic)	-	-	Business capability analysis; no direct Angzarr equivalent
Semantic boundary	Bounded Context	-	(not modeled)	Angzarr doesn't model bounded contexts; they're organizational
Aggregate namespace	(within BC)	-	Domain	Angzarr domain = one aggregate type; multiple domains may share a BC
Consistency unit	Aggregate	Aggregate	Aggregate	All three: cluster of objects, single transaction, invariant enforcement
Entry point	Aggregate Root	Aggregate Root	Root (in Cover)	Angzarr uses UUID; DDD allows domain-specific IDs
Request to change	-	Command	Command	Imperative, can be rejected
Record of change	Domain Event	Event	Event	Past tense, immutable, persisted
Cross-domain translation	Anti-Corruption Layer	Saga	Saga	Angzarr saga = ACL when crossing BC boundaries; internal coordination otherwise
Stateful workflow	-	Saga / Process Manager	Process Manager	Angzarr distinguishes: PM has state, correlation ID as root
Read model	-	Projection / Read Model	Projection	Query-optimized view built from events
Read model builder	-	Projector / Denormalizer	Projector	Angzarr: events in, external output

Event Sourcing Specifics

Concept	CQRS/ES Literature	Angzarr	Key Differences
Event position	Version / Sequence Number	Sequence	Same concept, Angzarr also uses for idempotency
Event persistence	Event Store	Event Store	Append-only, immutable
State reconstruction	Replay / Rehydration	Replay	Derive state by applying events
Performance optimization	Snapshot	Snapshot	Cached state checkpoint
Schema evolution	Upcasting / Versioning	Upcasting	Transform old events at read time
Event envelope	-	Cover	Angzarr-specific: domain, root, correlation, edition
Event collection	Event Stream	EventBook	Angzarr: all events for one aggregate root
Individual event	Event	EventPage	Angzarr: event + metadata (sequence, timestamp)

Angzarr-Specific Concepts

Angzarr Term	Closest Equivalent	Description
Domain	(none—see note)	Aggregate namespace and deployment unit; one domain = one aggregate type
Cover	-	Identity envelope: domain + root + correlation + edition
Edition	-	Timeline branching for speculative execution
Fact	Event	Event without preceding command; receiving domain assigns sequence; retains source traceability
Notification	-	Transient coordination message (not persisted)
Coordinator	-	Sidecar handling infrastructure (routing, storage, bus)
Target	-	Subscription filter: domain + event types
CommandBook	-	Command collection with concurrency metadata

Domain ≠ Bounded Context

Angzarr "domain" is not equivalent to DDD "bounded context." A bounded context may contain multiple Angzarr domains. See Domain and Bounded Context for details.

Where Terminology Diverges

Situation	DDD Says	CQRS/ES Says	Angzarr Does
Saga output	N/A	Events (typically)	Facts (preferred; receiving domain assigns sequence) or Commands (with compensation)
Cross-context calls	Avoid synchronous	Avoid synchronous	Supported but discouraged; indicates boundary debt
Aggregate size	"Just big enough"	Small, enforce one invariant	Decision-containing; can be larger if cohesive
Domain events	Stay in context	May cross contexts	Integration events cross; domain events are internal
Correlation	N/A	Correlation ID	Correlation ID + PM uses it as aggregate root

Translation Guide

When reading DDD literature:

• "Domain" → the overall problem space (no Angzarr equivalent)
• "Subdomain" → business capability; may map to one or more Angzarr domains
• "Bounded Context" → organizational/team boundary; may contain multiple Angzarr domains; not directly modeled
• "Anti-Corruption Layer" → saga that crosses bounded context boundaries (vs. internal coordination saga)

When reading CQRS/ES articles:

• "Saga" → could be Angzarr Saga (stateless) or Process Manager (stateful)—check if it has state
• "Projection" → Angzarr Projection (the data) built by a Projector (the component)
• "Event Stream" → Angzarr EventBook

When reading Angzarr docs:

• "Domain" → aggregate namespace/deployment unit; NOT equivalent to DDD bounded context
• "Saga" → may be internal coordination (within BC) or ACL (crossing BC)—depends on organizational boundaries
• "Fact" → event without preceding command; receiving domain assigns sequence; retains source traceability
• "Edition" → unique to Angzarr, enables speculative execution