Federated protocol adapters

Model adapters and protocol adapters solve different extension problems. ModelAdapter contains survival-model-specific target and prediction logic; FederatedProtocol determines what clients exchange and how the server updates. Version 0.7.0 contains four protocol adapters.

Protocol	Models	Exchange	Intended use
FedAvg	all seven adapters	model parameters	default sample-weighted baseline
FedProx	all seven adapters	model parameters	reduce local drift under heterogeneous client data
FedOpt	all seven adapters	model parameters	adaptive Adam, Yogi, or Adagrad server updates
WebDISCO-style	linear CoxPH only	aggregated risk-set statistics	pooled Breslow Cox objective without parameter averaging

High-level use

from federated_survival import FederatedSurvival

model = FederatedSurvival(
    model="DeepSurv",
    protocol="FedProx",
    protocol_params={"mu": 0.01},
    n_clients=5,
    global_rounds=20,
    local_steps=2,
).fit(frame)

FedOpt defaults to a FedAdam server update:

model = FederatedSurvival(
    model="LogisticHazard",
    protocol="FedOpt",
    protocol_params={
        "optimizer": "adam",  # adam, yogi, or adagrad
        "server_lr": 0.01,
        "beta1": 0.9,
        "beta2": 0.99,
        "tau": 1e-3,
    },
).fit(frame)

The survival-specific risk-set-statistics protocol is selected separately:

model = FederatedSurvival(
    model="CoxPH",
    protocol="WebDISCO-style",
    protocol_params={"max_iter": 50, "tolerance": 1e-7},
    n_clients=5,
    client_fraction=1.0,
).fit(frame)

WebDISCO-style is an independent Python implementation of distributed Breslow Cox risk-set aggregation. It is not the original WebDISCO web service. It requires horizontal partitions, full participation, a bias-free linear CoxPH model, and no client-update perturbation. The reported communication quantity is an analytical float64 payload estimate and excludes protocol framing and transport overhead.

Register a third-party protocol

from federated_survival import FederatedProtocol, register_federated_protocol

class MyProtocol(FederatedProtocol):
    name = "MyProtocol"

    def aggregate(
        self, global_state, client_states, client_weights, *, round_index
    ):
        ...

register_federated_protocol(MyProtocol.name, MyProtocol)

Third-party protocols should declare ProtocolCapabilities, validate their supported models and partition geometry, reset persistent server state in begin_run, and report protocol-specific metadata.

One-command protocol smoke test

federated-survival run \
  --config federated_survival/examples/four_protocol_smoke.json \
  --output results/four_protocol_smoke

This configuration executes 22 cells: seven models under each of FedAvg, FedProx, and FedOpt, plus CoxPH under WebDISCO-style. Results, failures, the resolved configuration, and a run manifest are written to the output folder.