rmw: ROS Middleware Abstraction Interface

rmw defines an interface of middleware primitives that are used by the higher level ROS API's. It consists of these main components:

• Initialization and Shutdown:
  • rmw/init.h
• Nodes
  • rmw/rmw.h
• Publisher
  • rmw/rmw.h
• Subscription
  • rmw/rmw.h
• Service Client
  • rmw/rmw.h
• Service Server
  • rmw/rmw.h

There are some common utility functions in combination with "Topics" or "Services":

• A function to validate a fully qualified topic or service name
  • rmw_validate_full_topic_name()
  • rmw/validate_full_topic_name.h
• A function to validate a node's namespace
  • rmw_validate_namespace()
  • rmw/validate_namespace.h
• A function to validate a node's name
  • rmw_validate_node_name()
  • rmw/validate_node_name.h

It also has some machinery that is necessary to wait on and act on these concepts:

• Initialization and shutdown management (global for now)
  • rmw/rmw.h
• Wait sets for waiting on messages and service requests / responses to be ready
  • rmw/rmw.h
• Guard conditions for waking up wait sets asynchronously
  • rmw/rmw.h
• Introspection of the ROS graph
  • rmw_names_and_types_t
  • rmw_get_topic_names_and_types()
  • rmw_get_service_names_and_types()
  • rmw/names_and_types.h
  • rmw/get_topic_names_and_types.h
  • rmw/get_service_names_and_types.h

Further still there are some useful abstractions and utilities:

• Allocator functions for various types
  • rmw/allocators.h
• Error handling functionality (C style)
  • rmw/error_handling.h
• Macros
  • rmw/macros.h
• Return code types and other utility types
  • rmw/types.h
• Sanity checks for some of the types
  • rmw/sanity_checks.h
• Macros for controlling symbol visibility on the library
  • rmw/visibility_control.h
• Utility function to demangle a type to a human readable string (C++ specific):
  • rmw/impl/cpp/demangle.hpp