ros自定义srv记录

自定义srv

ros 版本：kinetic
自定义test包的文件结构如下

|-- test
|   |-- CMakeLists.txt
|   |-- srv
|   |   `-- WordCount.srv
|   |-- package.xml
|   |-- scripts
|   |   `-- sevice_server.py

srv和msg非常相似，有关自定义msg见链接。

1. 定义srv文件

WordCount.srv #通常大写字母开头；---上方表输入，下方表输出。

string words
---
uint32 count

2. 修改 package.xml

向其中添加如下信息，首先是<build_depend>message_generation</build_depend>和<exec_depend>message_runtime</exec_depend>；其次，需要使用那些包就添加进去，例如 std_msgs，roscpp。

  <buildtool_depend>catkin</buildtool_depend>
  <build_depend>rospy</build_depend>
  <build_export_depend>rospy</build_export_depend>
  <build_depend>message_generation</build_depend>
  <build_depend>std_msgs</build_depend>
  <build_depend>roscpp</build_depend>
  <exec_depend>roscpp</exec_depend>
  <exec_depend>rospy</exec_depend>
  <exec_depend>message_runtime</exec_depend>
  <exec_depend>std_msgs</exec_depend>

3. 修改 CMakeLists.txt

find_package(catkin REQUIRED COMPONENTS
  rospy
  roscpp
  std_msgs
  message_generation #放在末尾
)

添加自定义的srv文件

add_service_files(
  FILES
  WordCount.srv
)

## Generate added messages and services with any dependencies listed here
generate_messages(
  DEPENDENCIES
  std_msgs  # Or other packages containing msgs
)

catkin_package(
#   INCLUDE_DIRS include
#   LIBRARIES test
   CATKIN_DEPENDS rospy message_runtime std_msgs roscpp
#   DEPENDS system_lib
)

## Mark executable scripts (Python etc.) for installation
## in contrast to setup.py, you can choose the destination
catkin_install_python(PROGRAMS
  scripts/sevice_server.py
  DESTINATION ${CATKIN_PACKAGE_BIN_DESTINATION}
)

4. sevice_server.py

#!/usr/bin/env python

import rospy
from test.srv import WordCount, WordCountRequest, WordCountResponse

def count_words(request):
    return WordCountResponse(len(request.words.split()))

rospy.init_node("service_server")
service = rospy.Service("word_count", WordCount, count_words)

rospy.spin()

5. 运行 catkin build

创建service会生成三个类。本例会同时创建：WordCount, WordCountRequest, WordCountResponse 三个类。

测试

roscore

rosrun test sevice_server.py

rosservice info word_count

顺利的话，会出现如下结果。

使用 (rosservice 命令)

rosservice call word_count 'one two three four'

返回： 4