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InMemory Transport

RpcInMemoryTransport is a bidirectional in-process transport. Both sides of a connection live in the same Dart isolate — no sockets, no serialization, no ports. It is the default transport for unit tests and for co-located services that run in the same process.

Creating a Pair

final (callerTransport, responderTransport) = RpcInMemoryTransport.pair();

pair() returns two connected transports. Messages sent to one arrive on the other. The returned record is ordered (caller, responder).

Zero-Copy Transfer

RpcInMemoryTransport reports supportsZeroCopy == true. When both sides use the same transport pair, the endpoint skips serialization and passes objects directly by reference — no CBOR encoding, no memory copies. This makes in-process calls as fast as a plain Dart function call.

Zero-copy activates automatically when no codec is provided and the transport supports it. You can also use it explicitly with RpcDataTransferMode.zeroCopy contracts (the default for generated code).

Usage

Testing

The primary use case is fast, hermetic unit tests — no network setup, teardown in microseconds:

late CalculatorContractCaller caller;
late RpcResponderEndpoint server;

setUp(() {
  final (callerTransport, responderTransport) = RpcInMemoryTransport.pair();

  server = RpcResponderEndpoint(transport: responderTransport);
  server.registerServiceContract(CalculatorResponder());
  server.start();

  caller = CalculatorContractCaller(
    RpcCallerEndpoint(transport: callerTransport),
  );
});

tearDown(() async {
  await caller.endpoint.close();
  await server.close();
});

Co-located Services

For services that run in the same process (e.g., a plugin architecture or a monolith with logical service boundaries):

final (callerTransport, responderTransport) = RpcInMemoryTransport.pair();

final authServer = RpcResponderEndpoint(transport: responderTransport);
authServer.registerServiceContract(AuthResponder());
authServer.start();

// Another part of the app holds the caller transport
final authClient = AuthContractCaller(
  RpcCallerEndpoint(transport: callerTransport),
);

Notes

  • Compression is automatically disabled for InMemory transport — zero-copy makes it pointless.
  • Both transports share a StreamController pair; closing either side closes both.
  • supportsZeroCopy returns true only on RpcInMemoryTransport. All network transports return false.