Add Kafka Gateway transport plugin

.github/workflows/release.yml

@@ -8,12 +8,14 @@ on:
     paths:
       - "rabbitmq/**"
       - "servicebus/**"
+      - "kafka/**"
       - ".github/workflows/release.yml"
   pull_request:
     branches: [ "main" ]
     paths:
       - "rabbitmq/**"
       - "servicebus/**"
+      - "kafka/**"
       - ".github/workflows/release.yml"
   workflow_dispatch:
     inputs:
@@ -34,7 +36,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        plugin: [rabbitmq, servicebus]
+        plugin: [rabbitmq, servicebus, kafka]
         platform: [windows-latest, windows-11-arm, ubuntu-22.04, ubuntu-22.04-arm, macos-26-intel, macos-14]
 
     steps:
@@ -76,29 +78,44 @@ jobs:
               ;;
           esac
 
-          if [ "${{ matrix.plugin }}" = "servicebus" ]; then
-            echo "DIRECTORY=servicebus" >> "$GITHUB_ENV"
-            echo "ARTIFACT_PATH=servicebus/build/ServiceBusPlugin" >> "$GITHUB_ENV"
-            echo "CONFIGURE_ARGS=-DCMAKE_TOOLCHAIN_FILE=${VCPKG_INSTALLATION_ROOT}/scripts/buildsystems/vcpkg.cmake" >> "$GITHUB_ENV"
-            if [ "${{ runner.os }}" = "Linux" ]; then
-              echo "INSTALL_PACKAGES=build-essential cmake git ninja-build pkg-config" >> "$GITHUB_ENV"
-            elif [ "${{ runner.os }}" = "macOS" ]; then
-              echo "INSTALL_PACKAGES=cmake ninja pkg-config" >> "$GITHUB_ENV"
-            else
-              echo "INSTALL_PACKAGES=cmake" >> "$GITHUB_ENV"
-            fi
-          else
-            echo "DIRECTORY=rabbitmq" >> "$GITHUB_ENV"
-            echo "ARTIFACT_PATH=rabbitmq/build/RabbitmqPlugin" >> "$GITHUB_ENV"
-            echo "CONFIGURE_ARGS=" >> "$GITHUB_ENV"
-            if [ "${{ runner.os }}" = "Linux" ]; then
-              echo "INSTALL_PACKAGES=build-essential cmake git" >> "$GITHUB_ENV"
-            elif [ "${{ runner.os }}" = "macOS" ]; then
-              echo "INSTALL_PACKAGES=cmake" >> "$GITHUB_ENV"
-            else
-              echo "INSTALL_PACKAGES=cmake" >> "$GITHUB_ENV"
-            fi
-          fi
+          case "${{ matrix.plugin }}" in
+            servicebus)
+              echo "DIRECTORY=servicebus" >> "$GITHUB_ENV"
+              echo "ARTIFACT_PATH=servicebus/build/ServiceBusPlugin" >> "$GITHUB_ENV"
+              echo "CONFIGURE_ARGS=-DCMAKE_TOOLCHAIN_FILE=${VCPKG_INSTALLATION_ROOT}/scripts/buildsystems/vcpkg.cmake" >> "$GITHUB_ENV"
+              if [ "${{ runner.os }}" = "Linux" ]; then
+                echo "INSTALL_PACKAGES=build-essential cmake git ninja-build pkg-config" >> "$GITHUB_ENV"
+              elif [ "${{ runner.os }}" = "macOS" ]; then
+                echo "INSTALL_PACKAGES=cmake ninja pkg-config" >> "$GITHUB_ENV"
+              else
+                echo "INSTALL_PACKAGES=cmake" >> "$GITHUB_ENV"
+              fi
+              ;;
+            kafka)
+              echo "DIRECTORY=kafka" >> "$GITHUB_ENV"
+              echo "ARTIFACT_PATH=kafka/build/KafkaPlugin" >> "$GITHUB_ENV"
+              echo "CONFIGURE_ARGS=" >> "$GITHUB_ENV"
+              if [ "${{ runner.os }}" = "Linux" ]; then
+                echo "INSTALL_PACKAGES=build-essential cmake git libssl-dev libsasl2-dev zlib1g-dev" >> "$GITHUB_ENV"
+              elif [ "${{ runner.os }}" = "macOS" ]; then
+                echo "INSTALL_PACKAGES=cmake openssl" >> "$GITHUB_ENV"
+              else
+                echo "INSTALL_PACKAGES=cmake" >> "$GITHUB_ENV"
+              fi
+              ;;
+            *)
+              echo "DIRECTORY=rabbitmq" >> "$GITHUB_ENV"
+              echo "ARTIFACT_PATH=rabbitmq/build/RabbitmqPlugin" >> "$GITHUB_ENV"
+              echo "CONFIGURE_ARGS=" >> "$GITHUB_ENV"
+              if [ "${{ runner.os }}" = "Linux" ]; then
+                echo "INSTALL_PACKAGES=build-essential cmake git" >> "$GITHUB_ENV"
+              elif [ "${{ runner.os }}" = "macOS" ]; then
+                echo "INSTALL_PACKAGES=cmake" >> "$GITHUB_ENV"
+              else
+                echo "INSTALL_PACKAGES=cmake" >> "$GITHUB_ENV"
+              fi
+              ;;
+          esac
 
           echo "PLUGIN_NAME=${{ matrix.plugin }}" >> "$GITHUB_ENV"
 

.gitignore

@@ -3,4 +3,7 @@
 .cursor
 
 out/
-build/
+build/
+bin/
+obj/
+Binaries/

README.md

@@ -8,6 +8,7 @@ Official open-source Graftcode Gateway plugins for carrying Graft calls over ext
 |--------|---------|
 | [rabbitmq](rabbitmq/) | RabbitMQ (AMQP 0-9-1), request/reply |
 | [servicebus](servicebus/) | Azure Service Bus (AMQP 1.0), request/reply and one-way |
+| [kafka](kafka/) | Apache Kafka, request/reply (correlation-id) |
 | [observability/opentelemetry](observability/opentelemetry/) | OpenTelemetry / Azure Application Insights connector |
 
 Each plugin has its own README with build and configuration steps. For how the Gateway loads a plugin, see the "Plugin server config" section of the [Graftcode Gateway](https://github.com/grft-dev/graftcode-gateway) README.

kafka/.gitignore

@@ -0,0 +1,9 @@
+build/
+out/
+.vs/
+CMakeUserPresets.json
+cmake-build-*/
+vcpkg/
+vcpkg_installed/
+.cache/
+*.user

kafka/BUILD_NOTES.md

@@ -0,0 +1,5 @@
+# Kafka plugin build notes
+
+- Dependencies: CMake `FetchContent` only (nlohmann/json + librdkafka). No vcpkg.
+- Smoke test links factory exports; full RPC needs a live broker (see docker-compose).
+- First configure needs network/git for FetchContent downloads.

kafka/CMakeLists.txt

@@ -0,0 +1,22 @@
+set(CMAKE_MIN 3.22)
+cmake_minimum_required(VERSION ${CMAKE_MIN})
+set(CMAKE_POLICY_VERSION_MINIMUM ${CMAKE_MIN})
+cmake_policy(VERSION ${CMAKE_MIN})
+
+project("KafkaPlugin" VERSION 1.0.0)
+
+set(CMAKE_CXX_STANDARD 20)
+set(CMAKE_CXX_STANDARD_REQUIRED ON)
+set(CMAKE_POSITION_INDEPENDENT_CODE ON)
+
+add_definitions(-DUNICODE)
+enable_testing()
+
+set(CMAKE_POLICY_DEFAULT_CMP0135 NEW)
+
+if(MSVC)
+    add_compile_options(/utf-8)
+endif()
+
+add_subdirectory("KafkaPlugin")
+add_subdirectory("KafkaPluginTest")

kafka/GraftcodePluginsInterfaces/IServer.h

@@ -0,0 +1,16 @@
+#pragma once
+#include <cstddef>
+
+namespace GraftcodeGateway {
+class IServer {
+public:
+    using byte = unsigned char;
+    using WriteResponseFn = void(*)(void* context, const byte* data, std::size_t size);
+    using ProcessMessageFn = bool(*)(const byte* requestData, std::size_t requestSize, WriteResponseFn writeResponse, void* writeContext);
+
+    virtual ~IServer() = default;
+    virtual void configure(const char* jsonConfig, ProcessMessageFn processMessage) = 0;
+    virtual void start() = 0;
+    virtual void stop() = 0;
+};
+}

kafka/GraftcodePluginsInterfaces/ITransport.h

@@ -0,0 +1,12 @@
+#pragma once
+#include "_common.h"
+
+namespace Hypertube::Native::Interfaces {
+class ITransport {
+public:
+    virtual ~ITransport() = default;
+    virtual int Initialize(byte callingRuntimeNumber, byte calledRuntimeNumber, byte calledRuntimeVersion) = 0;
+    virtual int SendCommand(byte* messageByteArray, int32_t messageByteArrayLen) = 0;
+    virtual int ReadResponse(byte* responseByteArray, int32_t responseByteArrayLen) = 0;
+};
+}

kafka/GraftcodePluginsInterfaces/_common.h

@@ -0,0 +1,9 @@
+#pragma once
+#ifndef byte
+typedef unsigned char byte;
+#endif
+#ifndef int32_t
+typedef int int32_t;
+#endif
+#include <string>
+#include <iostream>

kafka/KafkaPlugin/CMakeLists.txt

@@ -0,0 +1,56 @@
+# Graftcode Kafka plugin (request/reply via librdkafka C++ API).
+set(target_name KafkaPlugin)
+
+add_library(${target_name} SHARED
+    TransportKafka.cpp
+    KafkaClient.cpp
+    KafkaServer.cpp
+)
+
+target_include_directories(${target_name} PUBLIC
+    "${CMAKE_SOURCE_DIR}/GraftcodePluginsInterfaces"
+)
+
+include(FetchContent)
+
+FetchContent_Declare(
+    json
+    GIT_REPOSITORY https://github.com/nlohmann/json.git
+    GIT_TAG v3.12.0
+    GIT_SHALLOW TRUE
+)
+FetchContent_MakeAvailable(json)
+
+set(RDKAFKA_BUILD_STATIC ON CACHE BOOL "Build librdkafka as static library" FORCE)
+set(RDKAFKA_BUILD_EXAMPLES OFF CACHE BOOL "Skip librdkafka examples" FORCE)
+set(RDKAFKA_BUILD_TESTS OFF CACHE BOOL "Skip librdkafka tests" FORCE)
+
+FetchContent_Declare(
+    librdkafka
+    GIT_REPOSITORY https://github.com/confluentinc/librdkafka.git
+    GIT_TAG v2.8.0
+    GIT_SHALLOW TRUE
+)
+FetchContent_MakeAvailable(librdkafka)
+
+if(NOT TARGET rdkafka++)
+    message(FATAL_ERROR "librdkafka FetchContent succeeded but rdkafka++ target was not found")
+endif()
+
+target_link_libraries(${target_name} PUBLIC
+    nlohmann_json::nlohmann_json
+    rdkafka++
+)
+
+if(TARGET rdkafka)
+    target_link_libraries(${target_name} PUBLIC rdkafka)
+endif()
+
+if(WIN32 OR CMAKE_SYSTEM_NAME STREQUAL "Windows")
+    target_link_libraries(${target_name} PUBLIC ws2_32)
+endif()
+
+if(UNIX AND NOT APPLE)
+    find_package(Threads REQUIRED)
+    target_link_libraries(${target_name} PUBLIC Threads::Threads)
+endif()