gnodet opened a new pull request, #25731:
URL: https://github.com/apache/camel/pull/25731
## Summary
_Claude Code on behalf of gnodet_
Introduces a block-scoped **Cache EIP** that provides transparent
read-through caching of route segments, backed by the `KeyValueRepository` SPI
from CAMEL-24463 (#25631).
> **Depends on:** #25631 (CAMEL-24463: KeyValueRepository SPI) — must be
merged first.
## Cache EIP vs Cache Components
Camel includes several cache **components** (`camel-caffeine`,
`camel-ehcache`, `camel-jcache`, `camel-infinispan`, etc.) that provide
endpoint-level cache operations (explicit GET/PUT/INVALIDATE). Those are useful
for fine-grained cache management (bulk ops, invalidation, event listening).
The Cache **EIP** covers the most common use case — _"cache the result of
this expensive block by key with a TTL"_ — without manual plumbing. It is
analogous to `@Cacheable` in Spring:
```java
// Without Cache EIP: 7+ lines of plumbing, tied to one cache technology
from("direct:start")
.setHeader("CamelCaffeineAction", constant("GET"))
.setHeader("CamelCaffeineKey", header("productId"))
.to("caffeine-cache:products")
.choice()
.when(body().isNull())
.to("http://expensive-service";)
.setHeader("CamelCaffeineAction", constant("PUT"))
.to("caffeine-cache:products")
.end();
// With Cache EIP: 2 lines, backend-agnostic
from("direct:start")
.cache(simple("${header.productId}"))
.to("http://expensive-service";)
.end();
```
| Aspect | Cache Components | Cache EIP |
|---|---|---|
| Granularity | Endpoint-level GET/PUT/DELETE | Block-scoped read-through |
| Lines of code | 7+ per cache point | 2 (`.cache(key)` … `.end()`) |
| Backend coupling | Tied to specific component | Backend-agnostic via
`KeyValueRepository` |
| Use case | Fine-grained cache management | Transparent result caching |
## What's Included
### New Files
- **`CacheDefinition`** (`core/camel-core-model`) — Model class extending
`OutputExpressionNode` with options: `keyValueRepository`, `ttl`, `cacheNull`
- **`CacheProcessor`** (`core/camel-core-processor`) — Runtime processor
with read-through caching logic, graceful error handling (cache errors never
propagate)
- **`CacheReifier`** (`core/camel-core-reifier`) — Reifier with
auto-discovery: explicit bean → registry ref → auto-discover single KVR →
auto-create `MemoryKeyValueRepository`
- **`CacheProcessorTest`** (`core/camel-core`) — 7 unit tests covering
hit/miss, TTL expiry, null key bypass, failed exchange not cached, null body
handling, expression clause form
- **`CacheTest.groovy`** (`dsl/camel-yaml-dsl`) — 2 YAML DSL tests
- **`cache-eip.adoc`** — Full EIP documentation with Java/XML/YAML examples
### Modified Files
- **`ProcessorDefinition`** — Added `cache()` and `cache(Expression)` DSL
methods
- **`ProcessorReifier`** — Registered `CacheReifier` for `CacheDefinition`
- **`nav.adoc`** — Added Cache EIP to EIP navigation
- **`camel-4x-upgrade-guide-4_23.adoc`** — Added "New Cache EIP" section
- Generated files: catalog models, XML/YAML schemas, deserializers
## Key Design Decisions
1. **Reuses `KeyValueRepository` SPI** — No new cache-specific SPI. Uses the
same abstraction that backs IdempotentConsumer and Aggregator, providing a
unified key-value layer.
2. **Graceful degradation** — All cache errors (read/write) are caught and
logged, never propagated to the exchange. Failed exchanges are never cached.
3. **Block-scoped pattern** — Follows the same architectural pattern as
CircuitBreaker, Saga, and DoTry (extends `OutputExpressionNode`).
4. **Zero-config default** — Works out of the box with
`MemoryKeyValueRepository` auto-creation; no configuration required for simple
use cases.
## Test Plan
- [x] `CacheProcessorTest` — 7 tests (hit, miss, TTL, null key, failed
exchange, null body, expression clause)
- [x] `CacheTest.groovy` — 2 YAML DSL tests (basic cache, cache with options)
- [x] `mvn clean install -pl core/camel-core -DskipTests` — compilation
verified
- [x] Code formatting verified (`mvn formatter:format impsort:sort`)
- [ ] Full CI build (pending)
🤖 Generated with [Claude Code](https://claude.com/claude-code)
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