Event Sourcing¶
Fowler, M. (2005). Event Sourcing. martinfowler.com.
Cited by¶
10 citations across 10 artifacts.
Each citation links to the sentence it supports in the citing article.
Primes¶
- Event-Centered Modeling
- In software it is event sourcing, where application state is not stored directly but computed by replaying an append-only log of events — the same wiring as the historiographic case on a different substrate.
This sourceDefines event sourcing — application state computed by replaying an append-only log of immutable events, with snapshots and projections — the software instance of event-centered modeling.
Supported in partVerified against the work's full text
Fowler describes event sourcing as storing every change as an event and rebuilding application state by replaying the log; he also allows storing current state alongside.
“Complete Rebuild: We can discard the application state completely and rebuild it by re-running the events from the event log”
- In software it is event sourcing, where application state is not stored directly but computed by replaying an append-only log of events — the same wiring as the historiographic case on a different substrate.
- Immutability
- The concept crystallized in computer science—where the immutable object, the persistent data structure, and the append-only log are now standard building blocks—but the same write-once discipline governs executed legal instruments, the unalterable accounting journal, content-addressed version-control commits, and append-only distributed ledgers.
This sourceArticulates the append-only event log as the authoritative record across software systems, treating apparent change as appended events and current state as a derivation by replay—the same write-once discipline that recurs in ledgers and audit trails.
Supported in partVerified against the work's full text
Fowler supports the append-only event log in software and its fit with accounting audit, but not the wider cross-domain claim about legal instruments, commits and ledgers.
“the event log is a purely additive structure that requires minimal locking.”
- The concept crystallized in computer science—where the immutable object, the persistent data structure, and the append-only log are now standard building blocks—but the same write-once discipline governs executed legal instruments, the unalterable accounting journal, content-addressed version-control commits, and append-only distributed ledgers.
- Logging
- The pattern supports the log-determinism inference: if a system's behaviour is a function only of the log plus deterministic processing, then replaying the log reproduces the behaviour
This sourceDescribes recording all state changes as an ordered append-only event log so that replaying the log deterministically reconstructs current state.
SupportedVerified against the work's full text
Fowler says state is purely derivable from the event log and rebuilt by re-running events, and that external query results must be recorded to ensure consistent replay.
“Since an application state is purely derivable from the event log, you can cache it anywhere you like.”
- The pattern supports the log-determinism inference: if a system's behaviour is a function only of the log plus deterministic processing, then replaying the log reproduces the behaviour
- Identity-Preserving Modification
- This composition logic underwrites event-sourced architectures in software, amendment chains in law, and history reconstruction in medicine and cultural heritage, all of which solve the same problem — how to know the current state's warrant — by following the chain back to the originating event.
This sourceArchitectural pattern of storing the full ordered sequence of state-changing events against an identifier and reconstructing current state by replaying them.
Supported in partVerified against the work's full text
Fowler supports event sourcing in software (state as a replayable event log) but says nothing about law, medicine, cultural heritage or a shared warrant problem.
“Event Sourcing ensures that all changes to application state are stored as a sequence of events.”
- This composition logic underwrites event-sourced architectures in software, amendment chains in law, and history reconstruction in medicine and cultural heritage, all of which solve the same problem — how to know the current state's warrant — by following the chain back to the originating event.
Mechanisms¶
- Audit Log Review
- Its strength is answering why, not just what: by replaying an event-sourced
This sourceUses the event history to reconstruct past states and understand how the current discrepancy arose.
- Its strength is answering why, not just what: by replaying an event-sourced
- Deviation Event Log
- Six weeks later, a reliability review queries the log for every `checkout-api` deviation of the quarter, sees they cluster on Friday deploys, and — crucially — each old fact still names the baseline version live at the time, so a since-changed expectation does not silently rewrite what counted as a deviation back then.
This sourceExplains that a stored event sequence can be queried to inspect and reconstruct application-state history.
- Six weeks later, a reliability review queries the log for every `checkout-api` deviation of the quarter, sees they cluster on Friday deploys, and — crucially — each old fact still names the baseline version live at the time, so a since-changed expectation does not silently rewrite what counted as a deviation back then.
- Event-Sourced Projection
- It misleads when the log grows large and replay becomes slow — a cold rebuild can take hours without periodic snapshots to start from.
This sourceLarge event histories can make reconstruction from a blank state slow; a saved snapshot provides a faster replay starting point.
- It misleads when the log grows large and replay becomes slow — a cold rebuild can take hours without periodic snapshots to start from.
- Occupancy Ledger
- The ledger's strength is that it makes turnover reconstructable: because it is an append-only log
This sourceStores state-changing events in sequence so earlier states and the path of changes can be reconstructed from the event log.
- The ledger's strength is that it makes turnover reconstructable: because it is an append-only log
- Ratchet Event Log
- It is the disciplined-provenance idea behind an event-sourced system, where current state is derivable from the ordered log of events.
This sourceDefines event sourcing as storing every state change in an ordered event sequence from which application state can be rebuilt.
- It is the disciplined-provenance idea behind an event-sourced system, where current state is derivable from the ordered log of events.
- Snapshot Plus Replay
- If a projector bug corrupts state, snapshotting bakes the bug in, and every future rebuild resumes from the poisoned state instead of re-deriving cleanly from the log — the very fault an event-log model is supposed to be able to heal by replay.
This sourceExplains that an event-sourced system can reconstruct state and repair consequences of past processing errors by replaying its event log.
- If a projector bug corrupts state, snapshotting bakes the bug in, and every future rebuild resumes from the poisoned state instead of re-deriving cleanly from the log — the very fault an event-log model is supposed to be able to heal by replay.
Verification¶
Does it exist? Not checked yet. This entry carries no identifier to resolve. It was extracted from the citation as written in the article, normalized, and deduplicated against the rest of the registry.
Does it back the claim? Read against the text for 4 of 10 citations: 1 supported, 3 supported in part. Each verdict is shown under its citation below, with what in the work backs the sentence.
Support is checked per citation rather than per work — the same source can be cited soundly in one article and wrongly in another. Per-citation recording began recently, so a citation with no recorded check is a gap in the record rather than evidence it went unchecked.
See how references were verified.
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