RunBefore class final

A reflective annotation that declares that the annotated interceptor, filter, or handler should execute before one or more specified targets within the JetLeaf request processing pipeline.

Overview

The RunBefore annotation is part of JetLeaf’s interceptor ordering system, allowing developers to define explicit execution precedence between different interceptors or filters.

When JetLeaf builds the interceptor chain for a given request, it uses these annotations to sort components deterministically—ensuring that certain interceptors (e.g. logging, metrics, security) execute in a specific order.

Usage Example

@RunBefore([AuthInterceptor, 'metrics_interceptor'])
class LoggingInterceptor implements HandlerInterceptor {
  @override
  Future<bool> preHandle(req, res, handler) async {
    print('Incoming request: ${req.getUri()}');
    return true;
  }
}

In this example:

• The LoggingInterceptor will always run before both AuthInterceptor and the interceptor registered under the pod name 'metrics_interceptor'.

Supported Target Types

• Type references (e.g. AuthInterceptor)
  → JetLeaf resolves these based on class types.
• String pod names (e.g. 'security_interceptor')
  → Used when the interceptor is registered dynamically or under a dependency injection pod.

Framework Integration

During interceptor registration, JetLeaf reads all RunBefore and RunAfter annotations and computes an execution graph.

It then uses topological sorting to produce a stable and deterministic interceptor order.

Example of Combined Usage

@RunBefore([AuthInterceptor])
class MetricsInterceptor {}

@RunAfter([MetricsInterceptor])
class AuthInterceptor {}

The framework will always ensure: MetricsInterceptor → AuthInterceptor

Design Notes

• Used only at class-level, enforced via @Target({TargetKind.classType}).
• Extends ReflectableAnnotation for runtime resolution through JetLeaf’s reflection system.
• The ordering is advisory, meaning if a referenced interceptor isn’t registered, the system skips it gracefully.

Related Annotations

• RunAfter — declares execution ordering after another target.

Summary

The RunBefore annotation provides fine-grained control over interceptor execution order, improving modularity and predictability in complex request pipelines.