feat(framework:cc): Update C++ SDK for Flower 1.27.0 inflatable objects protocol

examples/quickstart-cpp/CMakeLists.txt

@@ -1,12 +1,14 @@
 cmake_minimum_required(VERSION 3.16)
+# Allow CMake 4.x to configure dependencies built with older cmake_minimum_required
+set(CMAKE_POLICY_VERSION_MINIMUM 3.5)
 project(SimpleCppFlowerClient VERSION 0.10
   DESCRIPTION "Creates a Simple C++ Flower client that trains a linear model on synthetic data."
   LANGUAGES CXX)
 set(CMAKE_CXX_STANDARD 17)
 option(USE_LOCAL_FLWR "Use local Flower directory instead of fetching from GitHub" OFF)
 
 ######################
-### Download gRPC 
+### Download gRPC
 
 include(FetchContent)
 FetchContent_Declare(
@@ -58,16 +60,19 @@ target_link_libraries(flwr
   ${_REFLECTION}
   ${_GRPC_GRPCPP}
   ${_PROTOBUF_LIBPROTOBUF}
+  ssl
+  crypto
 )
 
 target_include_directories(flwr PUBLIC
   ${FLWR_INCLUDE_DIR}
+  ${grpc_SOURCE_DIR}/third_party/boringssl-with-bazel/src/include
 )
 
 ######################
 ### FLWR_CLIENT
 file(GLOB FLWR_CLIENT_SRCS src/*.cc)
-set(EXECUTABLE_NAME flwr_client)
+set(EXECUTABLE_NAME flower-supernode)
 add_executable(${EXECUTABLE_NAME} ${FLWR_CLIENT_SRCS})
 
 target_include_directories(${EXECUTABLE_NAME} PUBLIC

examples/quickstart-cpp/Dockerfile

@@ -0,0 +1,42 @@
+FROM ubuntu:22.04
+
+ARG DEBIAN_FRONTEND=noninteractive
+
+# Install system dependencies
+RUN apt-get update && apt-get install -y \
+    build-essential \
+    cmake \
+    git \
+    curl \
+    wget \
+    autoconf \
+    libtool \
+    pkg-config \
+    python3 \
+    python-is-python3 \
+    python3-pip \
+    && rm -rf /var/lib/apt/lists/*
+
+# Install Flower and Python dependencies for the server
+RUN pip3 install --no-cache-dir \
+    flwr \
+    numpy \
+    hatchling
+
+WORKDIR /app
+
+# Copy proto definitions and C++ SDK source
+COPY framework/proto /app/framework/proto
+COPY framework/cc /app/framework/cc
+
+# Copy the quickstart-cpp example
+COPY examples/quickstart-cpp /app/examples/quickstart-cpp
+
+# Build the C++ client (this fetches gRPC ~v1.43.2 and generates protos)
+WORKDIR /app/examples/quickstart-cpp
+RUN cmake -S . -B build -DUSE_LOCAL_FLWR=ON \
+    -DCMAKE_BUILD_TYPE=Release \
+    -DFETCHCONTENT_QUIET=OFF \
+    && cmake --build build -j$(nproc)
+
+WORKDIR /app/examples/quickstart-cpp

examples/quickstart-cpp/README.md

@@ -4,10 +4,7 @@ dataset: [Synthetic]
 framework: [C++]
 ---
 
-# Flower Clients in C++ (under development)
-
-> [!WARNING]\
-> This example is compatible with `flwr<1.13.0`. We are currently updating it to the newer `flwr run` way of running Flower Apps.
+# Flower Clients in C++
 
 In this example you will train a linear model on synthetic data using C++ clients.
 
@@ -19,31 +16,49 @@ Many thanks to the original contributors to this code:
 - Francisco José Solís (code re-organization)
 - Andreea Zaharia (training algorithm and data generation)
 
-## Install requirements
+## Option 1: Run with Docker (recommended)
 
-You'll need CMake and Python with `flwr` installed.
+The easiest way to test the C++ client is with Docker Compose, which builds the
+client and runs the full federated learning setup automatically.
 
-### Building the example
+```bash
+cd examples/quickstart-cpp
+docker compose up --build
+```
 
-This example provides you with a `CMakeLists.txt` file to configure and build the client. Feel free to take a look inside it to see what is happening under the hood.
+This starts the SuperLink, two C++ SuperNode clients, and the Python ServerApp.
+
+To clean up:
+
+```bash
+docker compose down
+```
+
+## Option 2: Run locally
+
+### Install requirements
+
+You'll need CMake, a C++17 compiler, and Python with `flwr` and `numpy` installed.
+
+### Building the example
 
 ```bash
-cmake -S . -B build
+cmake -S . -B build -DUSE_LOCAL_FLWR=ON
 cmake --build build
 ```
 
-## Run the `Flower SuperLink`, the two clients, and the `Flower ServerApp` in separate terminals
+### Run the SuperLink, two clients, and the ServerApp in separate terminals
 
 ```bash
 flwr-superlink --insecure
 ```
 
 ```bash
-build/flwr_client 0 127.0.0.1:9092
+build/flower-supernode 0 127.0.0.1:9092
 ```
 
 ```bash
-build/flwr_client 1 127.0.0.1:9092
+build/flower-supernode 1 127.0.0.1:9092
 ```
 
 ```bash

examples/quickstart-cpp/client.py

@@ -0,0 +1,22 @@
+"""Placeholder ClientApp for C++ quickstart.
+
+The actual clients are C++ SuperNodes that connect via gRPC.
+This file satisfies the Flower app configuration requirement.
+"""
+import flwr as fl
+
+
+def client_fn(context) -> fl.client.Client:
+    """Placeholder client factory for the C++ quickstart.
+
+    The actual clients for this example are implemented in C++ and connect to
+    the server via gRPC. This Python client placeholder exists only to satisfy
+    the Flower app configuration requirements and must not be started.
+    """
+    raise RuntimeError(
+        "This Python ClientApp is a placeholder for the C++ quickstart. "
+        "Use the C++ SuperNode clients instead of starting this client."
+    )
+
+
+app = fl.client.ClientApp(client_fn=client_fn)

examples/quickstart-cpp/docker-compose.yml

@@ -0,0 +1,75 @@
+services:
+  # Builds the C++ client binary and Python server dependencies
+  cpp-build:
+    build:
+      context: ../..
+      dockerfile: examples/quickstart-cpp/Dockerfile
+    image: flower-quickstart-cpp
+
+  # Flower SuperLink (manages FL lifecycle, runs ServerApp as subprocess)
+  superlink:
+    image: flower-quickstart-cpp
+    depends_on:
+      cpp-build:
+        condition: service_completed_successfully
+    command: flower-superlink --insecure
+    ports:
+      - "9091:9091"
+      - "9092:9092"
+      - "9093:9093"
+    working_dir: /app/examples/quickstart-cpp
+    networks:
+      - flwr-network
+
+  # C++ SuperNode client 0
+  client-0:
+    image: flower-quickstart-cpp
+    depends_on:
+      superlink:
+        condition: service_started
+    command: >
+      bash -c "sleep 4 && ./build/flower-supernode 0 superlink:9092"
+    working_dir: /app/examples/quickstart-cpp
+    networks:
+      - flwr-network
+
+  # C++ SuperNode client 1
+  client-1:
+    image: flower-quickstart-cpp
+    depends_on:
+      superlink:
+        condition: service_started
+    command: >
+      bash -c "sleep 8 && ./build/flower-supernode 1 superlink:9092"
+    working_dir: /app/examples/quickstart-cpp
+    networks:
+      - flwr-network
+
+  # Submit the ServerApp run to the SuperLink
+  runner:
+    image: flower-quickstart-cpp
+    depends_on:
+      superlink:
+        condition: service_started
+      client-0:
+        condition: service_started
+      client-1:
+        condition: service_started
+    command:
+      - bash
+      - -c
+      - |
+        mkdir -p /root/.flwr
+        cat > /root/.flwr/config.toml << 'EOF'
+        [superlink.local-deployment]
+        address = "superlink:9093"
+        insecure = true
+        EOF
+        sleep 12 && flwr run . local-deployment
+    working_dir: /app/examples/quickstart-cpp
+    networks:
+      - flwr-network
+
+networks:
+  flwr-network:
+    driver: bridge

examples/quickstart-cpp/pyproject.toml

@@ -0,0 +1,28 @@
+[build-system]
+requires = ["hatchling"]
+build-backend = "hatchling.build"
+
+[project]
+name = "quickstart-cpp"
+version = "1.0.0"
+description = "Quickstart C++ with Flower"
+license = "Apache-2.0"
+requires-python = ">=3.9"
+dependencies = [
+    "flwr>=1.27.0",
+    "numpy>=1.26.0",
+]
+
+[tool.hatch.build.targets.wheel]
+packages = ["."]
+
+[tool.flwr.app]
+publisher = "flwrlabs"
+
+[tool.flwr.app.components]
+serverapp = "server:app"
+clientapp = "client:app"
+
+[tool.flwr.app.config]
+num-server-rounds = 3
+

examples/quickstart-cpp/src/main.cc

@@ -5,7 +5,7 @@ int main(int argc, char **argv) {
   if (argc != 3) {
     std::cout << "Client takes 2 mandatory arguments as follows: " << std::endl;
     std::cout << "./client  CLIENT_ID  SERVER_URL" << std::endl;
-    std::cout << "Example: ./flwr_client 0 '127.0.0.1:8080'" << std::endl;
+    std::cout << "Example: ./flower-supernode 0 '127.0.0.1:9092'" << std::endl;
     return 0;
   }
 

framework/cc/flwr/CMakeLists.txt

@@ -1,4 +1,6 @@
 cmake_minimum_required(VERSION 3.16)
+# Allow CMake 4.x to configure dependencies built with older cmake_minimum_required
+set(CMAKE_POLICY_VERSION_MINIMUM 3.5)
 project(flwr VERSION 1.0
   DESCRIPTION "Flower Library that packages gRPC and other dependencies"
   LANGUAGES CXX)
@@ -71,10 +73,13 @@ endmacro()
 # Using the above macro for all proto files
 GENERATE_AND_COPY(transport)
 GENERATE_AND_COPY(node)
-GENERATE_AND_COPY(task)
-GENERATE_AND_COPY(fleet)
 GENERATE_AND_COPY(error)
-GENERATE_AND_COPY(recordset)
+GENERATE_AND_COPY(recorddict)
+GENERATE_AND_COPY(message)
+GENERATE_AND_COPY(heartbeat)
+GENERATE_AND_COPY(run)
+GENERATE_AND_COPY(fab)
+GENERATE_AND_COPY(fleet)
 
 add_library(flwr_grpc_proto STATIC ${ALL_PROTO_FILES})
 
@@ -97,7 +102,8 @@ add_library(flwr ${FLWR_SRCS})
 
 target_include_directories(flwr PUBLIC
   $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include>
+  $<BUILD_INTERFACE:${grpc_SOURCE_DIR}/third_party/boringssl-with-bazel/src/include>
 )
 
-# Link gRPC and other dependencies
-target_link_libraries(flwr PRIVATE flwr_grpc_proto)
+# Link gRPC and other dependencies (ssl/crypto from BoringSSL for node auth)
+target_link_libraries(flwr PRIVATE flwr_grpc_proto ssl crypto)