Creating a ROS msg and srv

https://wiki.ros.org/ROS/Tutorials/CreatingMsgAndSrv

1、介绍

msg：msg 文件是描述 ROS 消息字段的简单文本文件。 它们用于生成不同语言的消息的源代码。

srv：srv 文件描述服务。 它由两部分组成：请求和响应。

msg文件存放在包的msg目录下，srv文件存放在srv目录下。

msgs 只是简单的文本文件，每行包含一个字段类型和字段名称。 您可以使用的字段类型有：

  • int8, int16, int32, int64 (plus uint*)
  • float32, float64
  • string
  • time, duration
  • other msg files
  • variable-length array[] and fixed-length array[C]

There is also a special type in ROS: Header, the header contains a timestamp and coordinate frame information that are commonly used in ROS. You will frequently see the first line in a msg file have Header header.

Here is an example of a msg that uses a Header, a string primitive, and two other msgs :