Javers Integration

Javers is a popular Java library for auditing and tracking changes to domain objects. FlowWarden Javers connects Javers audit snapshots to FlowWarden’s Change Stream engine, letting you react to audit events in real time with deserialized domain objects and full Javers metadata.

How it works

When you use @JaversSpringDataAuditable on a Spring Data repository, Javers inserts a snapshot document into the jv_snapshots collection every time an entity is saved or deleted. FlowWarden Javers watches this collection via MongoDB Change Streams and delivers events to your handler:

Setup

1. Add dependencies

<dependency>
    <groupId>io.flowwarden</groupId>
    <artifactId>flowwarden-stream-core</artifactId>
    <version>1.0.0-rc.7</version>
</dependency>
<dependency>
    <groupId>io.flowwarden</groupId>
    <artifactId>flowwarden-javers</artifactId>
    <version>1.0.0-rc.3</version>
</dependency>
<dependency>
    <groupId>org.javers</groupId>
    <artifactId>javers-spring-boot-starter-mongo</artifactId>
    <version>7.11.5</version>
</dependency>

2. Audit your repository

@JaversSpringDataAuditable
public interface ProductRepository extends MongoRepository<Product, String> {
}

3. Create a Javers stream handler

@JaversStream(entityType = Product.class)
@Checkpoint(saveEveryN = 1)
public class ProductAuditHandler {

    @OnInitial
    void onCreated(Product product, JaversChangeContext<Product> ctx) {
        log.info("Created '{}' by {}", product.getName(),
            ctx.getCommitMetadata().getAuthor());
    }

    @OnUpdate
    void onUpdated(Product product, JaversChangeContext<Product> ctx) {
        log.info("Updated '{}' — changed: {} (v{})",
            product.getName(), ctx.getChangedProperties(), ctx.getVersion());
    }

    @OnTerminal
    void onDeleted(JaversChangeContext<Product> ctx) {
        log.info("Deleted entity {} by {}",
            ctx.getEntityId(), ctx.getCommitMetadata().getAuthor());
    }
}

Javers snapshot types

Javers defines three snapshot types that map to FlowWarden handler annotations:

Javers Type	FlowWarden Annotation	When it fires
`INITIAL`	`@OnInitial`	First time Javers audits an entity (creation)
`UPDATE`	`@OnUpdate`	Subsequent modifications to an audited entity
`TERMINAL`	`@OnTerminal`	Entity is deleted from the audited repository

Handler signatures

Each handler annotation supports three signature styles:

// Entity + context — full access
@OnInitial
void handle(Product product, JaversChangeContext<Product> ctx) { }

// Context only — useful for @OnTerminal where entity state may be minimal
@OnTerminal
void handle(JaversChangeContext<Product> ctx) { }

// Entity only — simple cases
@OnUpdate
void handle(Product product) { }

JaversChangeContext

The JaversChangeContext<T> gives you access to both Javers audit data and FlowWarden event metadata:

Javers data

Method	Returns	Description
`getSnapshot()`	`CdoSnapshot`	Full Javers snapshot (native Javers type)
`getSnapshotType()`	`SnapshotType`	`INITIAL`, `UPDATE`, or `TERMINAL`
`getCommitMetadata()`	`CommitMetadata`	Author, date, commit ID, custom properties
`getChangedProperties()`	`List<String>`	Property names that changed in this snapshot (empty for `INITIAL`)
`getVersion()`	`long`	Javers version number for this entity
`getEntityId()`	`String`	Entity ID from Javers global ID

FlowWarden data

Method	Returns	Description
`getEventId()`	`String`	Unique FlowWarden event ID
`getClusterTime()`	`Instant`	MongoDB cluster timestamp
`getResumeToken()`	`BsonDocument`	Change Stream resume token
`saveCheckpointNow()`	`void`	Force immediate checkpoint save
`sendToDlq(reason)`	`void`	Manually route to Dead Letter Queue
`addMetadata(key, value)`	`void`	Attach custom metadata to this event
`getMetadata(key, type)`	`Optional<V>`	Retrieve custom metadata by key
`getAllMetadata()`	`Map<String, Object>`	All custom metadata (unmodifiable)

FlowWarden annotations

The FlowWarden policy annotations work on @JaversStream classes, exactly as on a @ChangeStream class:

@JaversStream(entityType = Order.class)
@Checkpoint(saveEveryN = 1)
@RetryPolicy(maxAttempts = 3)
@RestartPolicy(maxAttempts = 30, jitter = true)
@DeadLetterQueue(retentionDays = 30)
public class OrderAuditHandler {

    @OnUpdate
    void onUpdated(Order order, JaversChangeContext<Order> ctx) {
        // If this throws, FlowWarden retries 3 times then sends to DLQ
        externalService.notifyOrderChange(order, ctx.getChangedProperties());
    }
}

@Filter and @Pipeline are not supported on @JaversStream classes. The stream watches the whole snapshot collection and filters by entity type internally, before dispatching to your handlers; filter further inside the handler, using JaversChangeContext (changed properties, commit author, …).

Snapshot collection configuration

The Javers snapshot collection name is resolved in order:

Explicit: @JaversStream(snapshotCollection = "custom_snapshots")
Javers property: javers.snapshotCollectionName from application.yml
Default: jv_snapshots

# application.yml — if you customized the Javers collection name
javers:
  snapshotCollectionName: my_audit_snapshots

If you changed the Javers collection name via properties and don’t set snapshotCollection explicitly on @JaversStream, FlowWarden will auto-detect it from the Javers configuration. Make sure the property is set before the application context initializes.

Entity deserialization

FlowWarden deserializes the Javers state field into your domain object using Spring Data MongoDB’s MongoConverter. This means:

Standard Spring Data annotations (@Field, @Id, etc.) are respected
Custom converters registered with Spring are used
For @OnTerminal events, the entity represents the last known state before deletion

Source on GitHub

Browse the flowwarden-javers source, issues, and releases.

Getting Started

Reference

How it works

Setup

1. Add dependencies

2. Audit your repository

3. Create a Javers stream handler

Javers snapshot types

Handler signatures

JaversChangeContext

Javers data

FlowWarden data

FlowWarden annotations

Snapshot collection configuration

Entity deserialization

Source on GitHub

​How it works

​Setup

​1. Add dependencies

​2. Audit your repository

​3. Create a Javers stream handler

​Javers snapshot types

​Handler signatures

​JaversChangeContext

​Javers data

​FlowWarden data

​FlowWarden annotations

​Snapshot collection configuration

​Entity deserialization

Source on GitHub

How it works

Setup

1. Add dependencies

2. Audit your repository

3. Create a Javers stream handler

Javers snapshot types

Handler signatures

JaversChangeContext

Javers data

FlowWarden data

FlowWarden annotations

Snapshot collection configuration

Entity deserialization