CoCache

The CoCache extension integrates the CoCache distributed caching framework with Wow's CQRS read model, providing event-driven cache refresh capabilities.

Features

• Event-driven cache refresh: Automatically refresh or evict cache entries when domain events are received
• Two refresh strategies: Evict (remove stale entries) and Set (update with latest state)
• Flexible cache sources: Local QueryService or remote REST API for cache loading

Installation

Add the wow-cocache dependency:

implementation("me.ahoo.wow:wow-cocache")

Cache Refresh Strategies

Evict Strategy

The evict strategy removes stale cache entries when domain events are received, forcing a cache miss on the next read:

class OrderCacheRefresher(
    cache: CoCache<*, OrderState, *>
) : EvictStateCacheRefresher<String, OrderState, Any>(cache)

Set Strategy

The set strategy proactively updates the cache with the latest aggregate state when state events are received:

class OrderCacheRefresher(
    cache: CoCache<*, OrderState, *>,
    converter: StateToCacheDataConverter<OrderState, OrderCacheData>
) : SetStateCacheRefresher<String, OrderState, Any>(cache, converter)

Cache Sources

QueryServiceCacheSource

Uses the local SnapshotQueryService to load aggregate snapshots into cache:

val cacheSource = QueryServiceCacheSource(snapshotQueryService, converter)

QueryApiCacheSource

Uses a remote REST API to load aggregate snapshots, suitable for distributed scenarios:

val cacheSource = QueryApiCacheSource(reactiveSnapshotQueryApi)