The Service Layer: A gRPC Superset

Reaktor's Service layer is a transport-agnostic, typed RPC system that surpasses gRPC in flexibility. It defines six transport modes that all share the same typed Request/Response contract.

Transport Modes

Transport	Wire Protocol	Use Case	Platform Support
HTTP	HTTP/1.1, HTTP/2, HTTP/3	Client-to-server RPC, REST APIs, public endpoints.	All (Android, iOS, JVM, JS, Workers).
LOCAL	In-process function call	Service-to-service within the same graph. Mock implementations.	All platforms.
PEER	Reaktor Mesh DataChannel	P2P RPC between two mesh peers.	All platforms with Mesh support.
PUBSUB	GCP Pub/Sub message	Async event-driven communication and cross-service notifications.	JVM, Workers.
QUEUE	Task Queue (GCP Tasks, Cloudflare Queues)	Background job processing with guaranteed delivery.	Workers, JVM.
WORKFLOW	Durable workflow (Cloudflare Workflows)	Multi-step, long-running processes with checkpointing and retry.	Workers, JVM.

The Service Contract

Every service operation is a typed pair: Request → Response. A single Service class defines both the client and server sides of every operation.

• Server Definition: Service.server(PostHandler, "/users") { request -> ... } defines the handler logic.
• Client Definition: Service.client(PostHandler, "/users") auto-generates the HTTP client call.
• Transport Transparency: You can switch from HTTP to LOCAL for testing, or to PEER for P2P, by changing only the ServiceEndpoint.

Interceptor / Middleware System

Services support a composable interceptor chain that runs on both client and server execution phases.

• Authentication: Validates JWT tokens on the server and attaches them to the client.
• Caching: Checks ObjectStore before invoking a handler. Cache hits return directly.
• Telemetry: Wraps every invocation in an OpenTelemetry span for automated tracing.
• Rate Limiting: Tracks and limits requests per principal from reaktor-auth.
• Validation: Automatically validates incoming requests against Schema DSL rules.