· publisher-Subscriber层:RTPS 上的简化抽象
· Writer-Reader层,对于RTPS端点的直接控制(更底层)
Publisher-Subscriber层为大多数开发者提供了一个方便的抽象。允许定义与topic关联的发布者和订阅者,以及传输topic数据的简单方法。
Writer-Reader层更接近于RTPS标准中定义的概念,并且可以进行更精准的控制,但是要求开发者直接与每个端点的历史记录缓存进行交互。
这篇文章是基于 Publisher-Subscriber层 进行记录的,如果文中的问题有道友知道解决方法,劳烦指出,谢谢。
首先安装就不说了,包括 fastrtpsgen 的安装,现在这个工具叫 fastddsgen,是一样的。看别的博客,也有人自己改用的 protobuf 做序列化,这个我还没研究,不太清除。
先编写好 msg.idl 文件,里面是定义的通讯格式,比如一个结构体,如下
struct MSG
{
unsigned long index;
string rbuf;
};
然后使用 fastddsgen 工具,使用命令fastddsgen msg.idl
就会生成四个文件 xxx.cxx、 xxx.h、xxxPubSubTypes.cxx、 xxxPubSubTypes.h
如果需要例程文件,也可以使用命令 fastrtpsgen -example CMake msg.idl
就会生成几个 .cxx .h 文件,不过这里的 publihser.cpp subscriber.cpp我是自己写的
然后再找个例程,把cmakelists.txt 拷贝一下,然后修改一下
我这里简单贴一下,省得找
# Copyright 2016 Proyectos y Sistemas de Mantenimiento SL (eProsima).
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
cmake_minimum_required(VERSION 2.8.12)
if(NOT CMAKE_VERSION VERSION_LESS 3.0)
cmake_policy(SET CMP0048 NEW)
endif()
project("DDSTCP")
# Find requirements
if(NOT fastcdr_FOUND)
find_package(fastcdr REQUIRED)
endif()
if(NOT foonathan_memory_FOUND)
find_package(foonathan_memory REQUIRED)
endif()
if(NOT fastrtps_FOUND)
find_package(fastrtps REQUIRED)
endif()
#Check C++11
include(CheckCXXCompilerFlag)
if(CMAKE_COMPILER_IS_GNUCXX OR CMAKE_COMPILER_IS_CLANG OR
CMAKE_CXX_COMPILER_ID MATCHES "Clang")
check_cxx_compiler_flag(-std=c++11 SUPPORTS_CXX11)
if(NOT SUPPORTS_CXX11)
message(FATAL_ERROR "Compiler doesn't support C++11")
endif()
endif()
message(STATUS "Configuring DDSTCP example...")
file(GLOB HELLOWORLD_EXAMPLE_SOURCES_CXX "*.cxx")
file(GLOB HELLOWORLD_EXAMPLE_SOURCES_CPP "*.cpp")
#file(GLOB XML_CONFIG_FILES "*.xml")
#message(STATUS "XML Files: " ${XML_CONFIG_FILES})
# configure_file("HelloWorldSubscriber.xml" "HelloWorldSubscriber.xml" COPYONLY)
# configure_file("HelloWorldPublisher.xml" "HelloWorldPublisher.xml" COPYONLY)
# configure_file("dh2048.pem" "dh2048.pem" COPYONLY)
# configure_file("server.pem" "server.pem" COPYONLY)
# configure_file("ca.pem" "ca.pem" COPYONLY)
add_executable(ddstcp ${HELLOWORLD_EXAMPLE_SOURCES_CXX} ${HELLOWORLD_EXAMPLE_SOURCES_CPP})
target_compile_definitions(ddstcp PRIVATE
$<$<AND:$<NOT:$<BOOL:${WIN32}>>,$<STREQUAL:"${CMAKE_BUILD_TYPE}","Debug">>:__DEBUG>
$<$<BOOL:${INTERNAL_DEBUG}>:__INTERNALDEBUG> # Internal debug activated.
)
target_link_libraries(ddstcp fastrtps fastcdr foonathan_memory fastdds::optionparser)
#install(TARGETS ddstcp
# RUNTIME DESTINATION examples/C++/ddstcp/${BIN_INSTALL_DIR})
现在说一下publisher里面
/**
* @file msgPublisher.h
*
*/
#ifndef MSGPUBLISHER_H_
#define MSGPUBLISHER_H_
#include
#include
#include
#include "messagePubSubTypes.h"
#include "message.h"
#include
class MsgPublisher
{
class PubListener : public eprosima::fastrtps::PublisherListener
{
public:
PubListener() : n_matched(0), firstConnected(false){};
~PubListener(){};
// 回调实现。每当发布者在网络上找到侦听同一主题的订阅者时,就会调用此函数
void onPublicationMatched(eprosima::fastrtps::Publisher *pub, eprosima::fastrtps::rtps::MatchingInfo &info);
// 回调函数,错过截止日期时调用的方法
void on_offered_deadline_missed(eprosima::fastrtps::Publisher *pub, const eprosima::fastrtps::OfferedDeadlineMissedStatus &status);
// 回调函数,当发布者的活力丧失时调用的方法
void on_liveliness_lost(eprosima::fastrtps::Publisher *pub, const eprosima::fastrtps::LivelinessLostStatus &status);
int n_matched;
bool firstConnected;
} listener_;
DDSTCP message_;
eprosima::fastrtps::Participant *participant_;
eprosima::fastrtps::Publisher *publisher_;
DDSTCPPubSubType type_;
void runThread(uint32_t number, long sleep_ms);
public:
MsgPublisher();
virtual ~MsgPublisher();
//! Initialize
bool init(const std::string &wan_ip, unsigned short port, std::string topicDataType, std::string topicName);
// fill publisher buff
bool getPublishMsg(char *p);
//! Publish a sample
bool publish(bool waitForListener = true);
//! Run for number samples
void run(uint32_t number, long sleep_ms);
};
#endif /* MSGPUBLISHER_H_ */
这里面的三个回调函数,都是基于父类里面找出来的,就只有 onPublicationMatched
这个函数,在找到订阅者的时候会调用一下,然后订阅者丢失,不会再次调用,就是这个坑。其他两个函数基本不会调用。
所以就会导致问题,n_matched 匹配的个数只会增长,不会下降。
void MsgPublisher::PubListener::onPublicationMatched(Publisher *, MatchingInfo &info)
{
printf("发现回调函数........\n ");
if (info.status == MATCHED_MATCHING)
{
n_matched++;
firstConnected = true;
// logError(HW, "Matched");
std::cout << "Publisher matched, online num = " << n_matched << std::endl;
}
else
{
n_matched--;
std::cout << "Publisher unmatched, online num = " << n_matched << std::endl;
}
}
就这样,记录完毕,下次记录 reader-writer层