【通信中间件】Fdbus HelloWorld实例

Fdbus实例教程

Fdbus简介

Fdbus 全称 Fast Distributed Bus（高速分布式总线），提供IPC+RPC功能。适用于多种OS：

Linux
QNX
AnroidOS
Window

Fdbus本质是Socket，IPC基于Unix domain socket，RPC基于TCP。使用Google Protobuf进行序列化和反序列化。

利用它，可以实现同域间的IPC通信，比如应用和OS间。也可以实现跨域、跨设备间通信，比如不同设备间数据传输，比如host/gust间的数据传输。
在这里插入图片描述

Fdbus的一些特点

支持多种通信模式，比如点对点、注册/发布、广播等等。
支持服务动态发现，自带心跳检测、重连，上线通知、离线检测等功能。
支持一定程度的安全策略配置，token、证书、访问鉴权等等。
支持Log调试，可以通过调试工具抓取在Fdbus上传输的内容。

其作者jeremy_cz（膜拜大神）对于FDBus的介绍非常详细。本文就不介绍了。关于FDBUS的内容，可以阅读作者的《Fast Distributed Bus - FDBus：高速分布式总线以及中间件开发框架》

Fdbus实例教程

基于Fdbus在一台Linux上，写一个C/S通信的Hellworld(例子）。
PC OS：Ubutun 20.04

编译Fdbus

编译protobuf

git clone https://github.com/protocolbuffers/protobuf.git
git submodule update --init --recursive
mkdir -p build
cd build
# 这里把/usr作为了安装目录 
cmake -DCMAKE_INSTALL_PREFIX=/usr -DBUILD_SHARED_LIBS=1 ../cmake
make -j4
make install

编译fdbus


git clone https://gitee.com/jeremyczhen/fdbus.git
cd fdbus
mkdir -p build/install
cd build
cmake -DCMAKE_INSTALL_PREFIX=install -Dfdbus_LOG_TO_STDOUT ../cmake
make -j4

编译成功后，会在build目录下生成大概以下文件，其中name_server是FDBUS用来管理服务名的进程，一会跑test需要运行它（具体请查看Fdbus作者jeremy_cz的博客）。编译生成内容大概如下

CMakeCache.txt
CMakeFiles
cmake_install.cmake
cmake_uninstall.cmake
fdbclienttest
fdbservertest
fdbxclient
fdbxserver
host_server
libfdbus-clib.so
libfdbus.so
logsvc
logviewer
lsclt
lsdp
lsevt
lshost
lssvc
Makefile
name_server
ntfcenter

HellWorld

这里直接在fdbus/example中新建了HelloWorld目录，目录结构（主要为了方便，直接借用fdbus源码的cmake。使用其他方式也可以，只要引用fdbus的lib和头文件即可。）

HelloWorld
-- HelloClient.cpp
-- HelloServer.cpp
-- HelloWorld.pb.h
-- HelloWorld.pb.cc
-- HelloWorld.proto

其中HelloWorld.pb.cc和HelloWorld.pb.h，是通过HelloWorld.proto生成的。生成命令

protoc --proto_path=. --cpp_out=. HelloWorld.proto

HelloWorld.proto

syntax = "proto2";message HelloWorld
{required string name = 1; 
}

HelloServer.cpp

#define FDB_LOG_TAG "HELLO_SERVER"
#include <fdbus/fdbus.h>
#include "HelloWorld.pb.h"
#include <fdbus/CFdbProtoMsgBuilder.h>
#include <fdbus/cJSON/cJSON.h>
#include <fdbus/CFdbCJsonMsgBuilder.h>using namespace ipc::fdbus;
// FDBUS提供的功能线程
static CBaseWorker main_worker;static const int METHOD_ID = 1;class HelloServer : public CBaseServer
{
public:HelloServer(const char*name, CBaseWorker* work = 0): CBaseServer(name, work){// Empty}protected:void onOnline(const CFdbOnlineInfo &info){std::cout << "connected to the client" << std::endl;}void onOffline(const CFdbOnlineInfo &info){std::cout << "disconnected from client" << std::endl;}/* called when client calls invoke() */void onInvoke(CBaseJob::Ptr &msg_ref){auto msg = castToMessage<CBaseMessage *>(msg_ref);static int32_t elapse_time = 0;switch (msg->code()){case METHOD_ID:{HelloWorld client;CFdbProtoMsgParser parser(client);if (!msg->deserialize(parser)){return;}std::cout << "Client name " << client.name() << std::endl;/* fill in protocol buffer and reply to client */HelloWorld server;server.set_name("Linduo");CFdbProtoMsgBuilder builder(server);msg->reply(msg_ref, builder);}break;default:break;}}
};int main(int argc, char*argv[])
{
/* start fdbus context thread */FDB_CONTEXT->start();fdbLogAppendLineEnd(true);FDB_CONTEXT->registerNsWatchdogListener([](const tNsWatchdogList &dropped_list){for (auto it = dropped_list.begin(); it != dropped_list.end(); ++it){printf("Error!!! Endpoint drops - name: %s, pid: %d\n",it->mClientName.c_str(), it->mPid);}});CBaseWorker *worker_ptr = &main_worker;/* start worker thread */worker_ptr->start();/* create servers and bind the address: svc://service_name */for (int i = 1; i < argc; ++i){std::string server_name = argv[i];std::string url(FDB_URL_SVC);url += server_name;server_name += "_server";auto server = new HelloServer(server_name.c_str(), worker_ptr);server->enableWatchdog(true);server->enableUDP(true);server->setExportableLevel(FDB_EXPORTABLE_SITE);server->bind(url.c_str());}// 将主线程变为WorkThreadCBaseWorker background_worker;background_worker.start(FDB_WORKER_EXE_IN_PLACE);
}

HelloClient.cpp

#define FDB_LOG_TAG "HELLO_SERVER"
#include <fdbus/fdbus.h>
#include "HelloWorld.pb.h"
#include <fdbus/CFdbProtoMsgBuilder.h>
#include <fdbus/cJSON/cJSON.h>
#include <fdbus/CFdbCJsonMsgBuilder.h>using namespace ipc::fdbus;
// FDBUS提供的功能线程
static CBaseWorker main_worker;static const int METHOD_ID = 1;class HelloServer : public CBaseServer
{
public:HelloServer(const char*name, CBaseWorker* work = 0): CBaseServer(name, work){// Empty}protected:void onOnline(const CFdbOnlineInfo &info){std::cout << "connected to the client" << std::endl;}void onOffline(const CFdbOnlineInfo &info){std::cout << "disconnected from client" << std::endl;}/* called when client calls invoke() */void onInvoke(CBaseJob::Ptr &msg_ref){auto msg = castToMessage<CBaseMessage *>(msg_ref);static int32_t elapse_time = 0;switch (msg->code()){case METHOD_ID:{HelloWorld client;CFdbProtoMsgParser parser(client);if (!msg->deserialize(parser)){return;}std::cout << "Client name " << client.name() << std::endl;/* fill in protocol buffer and reply to client */HelloWorld server;server.set_name("Linduo");CFdbProtoMsgBuilder builder(server);msg->reply(msg_ref, builder);}break;default:break;}}
};int main(int argc, char*argv[])
{/* start fdbus context thread */FDB_CONTEXT->start();fdbLogAppendLineEnd(true);FDB_CONTEXT->registerNsWatchdogListener([](const tNsWatchdogList &dropped_list){for (auto it = dropped_list.begin(); it != dropped_list.end(); ++it){printf("Error!!! Endpoint drops - name: %s, pid: %d\n",it->mClientName.c_str(), it->mPid);}});CBaseWorker *worker_ptr = &main_worker;/* start worker thread */worker_ptr->start();/* create servers and bind the address: svc://service_name */for (int i = 1; i < argc; ++i){std::string server_name = argv[i];std::string url(FDB_URL_SVC);url += server_name;server_name += "_server";auto server = new HelloServer(server_name.c_str(), worker_ptr);server->enableWatchdog(true);server->enableUDP(true);server->setExportableLevel(FDB_EXPORTABLE_SITE);server->bind(url.c_str());}// 将主线程变为WorkThreadCBaseWorker background_worker;background_worker.start(FDB_WORKER_EXE_IN_PLACE);
}

编译部分：加到了dbus/cmake/pb-example/example.cmake中，在cmake中编译上面的cpp

add_executable(helloworldclient${PACKAGE_SOURCE_ROOT}/example/HelloWorld/HelloClient.cpp${PACKAGE_SOURCE_ROOT}/example/HelloWorld/HelloWorld.pb.cc${PACKAGE_SOURCE_ROOT}/example/HelloWorld/HelloWorld.pb.h
)add_executable(helloworldserver${PACKAGE_SOURCE_ROOT}/example/HelloWorld/HelloServer.cpp${PACKAGE_SOURCE_ROOT}/example/HelloWorld/HelloWorld.pb.cc${PACKAGE_SOURCE_ROOT}/example/HelloWorld/HelloWorld.pb.h
)

在fdbus/cmake/CMakeLists.txt中引入了这个cmake，并且加入了C++14的Flag。

if (MSVC)add_definitions("-D__WIN32__")
elseif(fdbus_ANDROID)add_definitions("-D__LINUX__")
else()if(CMAKE_COMPILER_IS_GNUCXX)set(CMAKE_CXX_FLAGS "-std=gnu++14 -Wall -Wl,--copy-dt-needed-entries ${CMAKE_CXX_FLAGS}")endif()#add_compile_options(-g -O0)add_definitions("-D__LINUX__")
endif()include(pb-example/example.cmake)

重新运行cmake，然后make。编译出helloworldclient和helloworldserver两个文件。

cmake -DCMAKE_INSTALL_PREFIX=install -Dfdbus_LOG_TO_STDOUT ../cmake
make -j4

运行HelloWorld

开三个终端，分别运行，无先后顺序。Server/Client运行无需先后顺序，这点也是Fdbus的有点。大概原理是，通过服务动态绑定，当网络中的Server上线时，Client会自动连接该Service。

# 开3个终端，分别运行。其中name_server(用来实现服务动态绑定)
./name_server
./helloworldserver my
./helloworldclient my

执行成功后：
helloworldserver会输出从客户端收到的内容。

connected to the client
Client name Adver

helloworldclient会输出从服务端收到的内容。

connected to the server
Server name Linduo

PS：name_server在服务端和客户端连接时，不是必须得。如果两端指定了IPC端口，可以不使用name_server连接。但是不使用name_server时，就需要控制好连接时序。所以一般来讲，应用时都是启动一个name_server。