rmw.h File Reference

#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>
#include "rcutils/types.h"
#include "rosidl_generator_c/message_type_support_struct.h"
#include "rosidl_generator_c/service_type_support_struct.h"
#include "rmw/macros.h"
#include "rmw/qos_profiles.h"
#include "rmw/types.h"
#include "rmw/visibility_control.h"

Go to the source code of this file.

Functions
const char *	rmw_get_implementation_identifier (void)
rmw_ret_t	rmw_init (void)
rmw_node_t *	rmw_create_node (const char *name, const char *namespace_, size_t domain_id, const rmw_node_security_options_t *security_options)
rmw_ret_t	rmw_destroy_node (rmw_node_t *node)
const rmw_guard_condition_t *	rmw_node_get_graph_guard_condition (const rmw_node_t *node)
	Return a guard condition which is triggered when the ROS graph changes. More...
rmw_publisher_t *	rmw_create_publisher (const rmw_node_t *node, const rosidl_message_type_support_t *type_support, const char *topic_name, const rmw_qos_profile_t *qos_policies)
rmw_ret_t	rmw_destroy_publisher (rmw_node_t *node, rmw_publisher_t *publisher)
rmw_ret_t	rmw_publish (const rmw_publisher_t *publisher, const void *ros_message)
rmw_ret_t	rmw_publish_serialized_message (const rmw_publisher_t *publisher, const rmw_serialized_message_t *serialized_message)
	Publish an already serialized message. More...
rmw_ret_t	rmw_serialize (const void *ros_message, const rosidl_message_type_support_t *type_support, rmw_serialized_message_t *serialized_message)
	Serialize a ROS message into a rmw_serialized_message_t. More...
rmw_ret_t	rmw_deserialize (const rmw_serialized_message_t *serialized_message, const rosidl_message_type_support_t *type_support, void *ros_message)
	Deserialize a ROS message. More...
rmw_subscription_t *	rmw_create_subscription (const rmw_node_t *node, const rosidl_message_type_support_t *type_support, const char *topic_name, const rmw_qos_profile_t *qos_policies, bool ignore_local_publications)
rmw_ret_t	rmw_destroy_subscription (rmw_node_t *node, rmw_subscription_t *subscription)
rmw_ret_t	rmw_take (const rmw_subscription_t *subscription, void *ros_message, bool *taken)
rmw_ret_t	rmw_take_with_info (const rmw_subscription_t *subscription, void *ros_message, bool *taken, rmw_message_info_t *message_info)
rmw_ret_t	rmw_take_serialized_message (const rmw_subscription_t *subscription, rmw_serialized_message_t *serialized_message, bool *taken)
	Take a message without deserializing it. More...
rmw_ret_t	rmw_take_serialized_message_with_info (const rmw_subscription_t *subscription, rmw_serialized_message_t *serialized_message, bool *taken, rmw_message_info_t *message_info)
	Take a message without deserializing it and with its additional message information. More...
rmw_client_t *	rmw_create_client (const rmw_node_t *node, const rosidl_service_type_support_t *type_support, const char *service_name, const rmw_qos_profile_t *qos_policies)
rmw_ret_t	rmw_destroy_client (rmw_node_t *node, rmw_client_t *client)
rmw_ret_t	rmw_send_request (const rmw_client_t *client, const void *ros_request, int64_t *sequence_id)
rmw_ret_t	rmw_take_response (const rmw_client_t *client, rmw_request_id_t *request_header, void *ros_response, bool *taken)
rmw_service_t *	rmw_create_service (const rmw_node_t *node, const rosidl_service_type_support_t *type_support, const char *service_name, const rmw_qos_profile_t *qos_policies)
rmw_ret_t	rmw_destroy_service (rmw_node_t *node, rmw_service_t *service)
rmw_ret_t	rmw_take_request (const rmw_service_t *service, rmw_request_id_t *request_header, void *ros_request, bool *taken)
rmw_ret_t	rmw_send_response (const rmw_service_t *service, rmw_request_id_t *request_header, void *ros_response)
rmw_guard_condition_t *	rmw_create_guard_condition (void)
rmw_ret_t	rmw_destroy_guard_condition (rmw_guard_condition_t *guard_condition)
rmw_ret_t	rmw_trigger_guard_condition (const rmw_guard_condition_t *guard_condition)
rmw_wait_set_t *	rmw_create_wait_set (size_t max_conditions)
	Create a wait set to store conditions that the middleware will block on. More...
rmw_ret_t	rmw_destroy_wait_set (rmw_wait_set_t *wait_set)
rmw_ret_t	rmw_wait (rmw_subscriptions_t *subscriptions, rmw_guard_conditions_t *guard_conditions, rmw_services_t *services, rmw_clients_t *clients, rmw_wait_set_t *wait_set, const rmw_time_t *wait_timeout)
	Waits on sets of different waitable entities and returns when one is ready. More...
rmw_ret_t	rmw_get_node_names (const rmw_node_t *node, rcutils_string_array_t *node_names)
rmw_ret_t	rmw_count_publishers (const rmw_node_t *node, const char *topic_name, size_t *count)
rmw_ret_t	rmw_count_subscribers (const rmw_node_t *node, const char *topic_name, size_t *count)
rmw_ret_t	rmw_get_gid_for_publisher (const rmw_publisher_t *publisher, rmw_gid_t *gid)
rmw_ret_t	rmw_compare_gids_equal (const rmw_gid_t *gid1, const rmw_gid_t *gid2, bool *result)
rmw_ret_t	rmw_service_server_is_available (const rmw_node_t *node, const rmw_client_t *client, bool *is_available)
	Check if a service server is available for the given service client. More...
rmw_ret_t	rmw_set_log_severity (rmw_log_severity_t severity)

Function Documentation

rmw_get_implementation_identifier()

const char* rmw_get_implementation_identifier

(

void

)

rmw_init()

rmw_ret_t rmw_init

(

void

)

rmw_create_node()

rmw_node_t* rmw_create_node	(	const char *	name,
		const char *	namespace_,
		size_t	domain_id,
		const rmw_node_security_options_t *	security_options
	)

rmw_destroy_node()

rmw_ret_t rmw_destroy_node

(

rmw_node_t *

node

)

rmw_node_get_graph_guard_condition()

const rmw_guard_condition_t* rmw_node_get_graph_guard_condition

(

const rmw_node_t *

node

)

Return a guard condition which is triggered when the ROS graph changes.

The handle returned is a pointer to an internally held rmw guard condition. This function can fail, and therefore return NULL, if:

• node is NULL
• node is invalid

The returned handle is made invalid if the node is destroyed or if rmw_shutdown() is called.

The guard condition will be triggered anytime a change to the ROS graph occurs. A ROS graph change includes things like (but not limited to) a new publisher advertises, a new subscription is created, a new service becomes available, a subscription is canceled, etc.

---

Attribute	Adherence —
Allocates Memory	No
Thread-Safe	Yes
Uses Atomics	No
Lock-Free	Yes

Parameters

[in]

node

pointer to the rmw node

Returns

rmw guard condition handle if successful, otherwise NULL

rmw_create_publisher()

rmw_publisher_t* rmw_create_publisher	(	const rmw_node_t *	node,
		const rosidl_message_type_support_t *	type_support,
		const char *	topic_name,
		const rmw_qos_profile_t *	qos_policies
	)

rmw_destroy_publisher()

rmw_ret_t rmw_destroy_publisher	(	rmw_node_t *	node,
		rmw_publisher_t *	publisher
	)

rmw_publish()

rmw_ret_t rmw_publish	(	const rmw_publisher_t *	publisher,
		const void *	ros_message
	)

rmw_publish_serialized_message()

rmw_ret_t rmw_publish_serialized_message	(	const rmw_publisher_t *	publisher,
		const rmw_serialized_message_t *	serialized_message
	)

Publish an already serialized message.

The publisher must already be registered with the correct message type support so that it can send serialized data corresponding to that type. This function sends the serialized byte stream directly over the wire without having to serialize the message first. A ROS message can be serialized manually using the rmw_serialize() function.

Parameters

publisher	the publisher object registered to send the message
serialized_message	the serialized message holding the byte stream

Returns

RMW_RET_OK if successful, or

RMW_RET_ERROR if an unexpected error occurs.

rmw_serialize()

rmw_ret_t rmw_serialize	(	const void *	ros_message,
		const rosidl_message_type_support_t *	type_support,
		rmw_serialized_message_t *	serialized_message
	)

Serialize a ROS message into a rmw_serialized_message_t.

The ROS message is serialized into a byte stream contained within the rmw_serialized_message_t structure. The serialization format depends on the underlying middleware.

Parameters

ros_message	the typed ROS message
type_support	the typesupport for the ROS message
serialized_message	the destination for the serialize ROS message

Returns

RMW_RET_OK if successful, or

RMW_RET_BAD_ALLOC if memory allocation failed, or

RMW_RET_ERROR if an unexpected error occurs.

rmw_deserialize()

rmw_ret_t rmw_deserialize	(	const rmw_serialized_message_t *	serialized_message,
		const rosidl_message_type_support_t *	type_support,
		void *	ros_message
	)

Deserialize a ROS message.

The given rmw_serialized_message_t's internal byte stream buffer is deserialized into the given ROS message. The ROS message must already be allocated and initialized, and must match the given typesupport structure. The serialization format expected in the rmw_serialized_message_t depends on the underlying middleware.

Parameters

serialized_message	the serialized message holding the byte stream
type_support	the typesupport for the typed ros message
ros_message	destination for the deserialized ROS message

Returns

RMW_RET_OK if successful, or

RMW_RET_BAD_ALLOC if memory allocation failed, or

RMW_RET_ERROR if an unexpected error occurs.

rmw_create_subscription()

rmw_subscription_t* rmw_create_subscription	(	const rmw_node_t *	node,
		const rosidl_message_type_support_t *	type_support,
		const char *	topic_name,
		const rmw_qos_profile_t *	qos_policies,
		bool	ignore_local_publications
	)

rmw_destroy_subscription()

rmw_ret_t rmw_destroy_subscription	(	rmw_node_t *	node,
		rmw_subscription_t *	subscription
	)

rmw_take()

rmw_ret_t rmw_take	(	const rmw_subscription_t *	subscription,
		void *	ros_message,
		bool *	taken
	)

rmw_take_with_info()

rmw_ret_t rmw_take_with_info	(	const rmw_subscription_t *	subscription,
		void *	ros_message,
		bool *	taken,
		rmw_message_info_t *	message_info
	)

rmw_take_serialized_message()

rmw_ret_t rmw_take_serialized_message	(	const rmw_subscription_t *	subscription,
		rmw_serialized_message_t *	serialized_message,
		bool *	taken
	)

Take a message without deserializing it.

The message is taken in its serialized form. In contrast to rmw_take, the message is not deserialized in its ROS type but rather returned as a byte stream. The subscriber has to be registered for a specific type. But instead of receiving the message as its corresponding message type, it is taken as a byte stream. If needed, this byte stream can then be deserialized in a ROS message with a call to rmw_deserialize.

Parameters

subscription	subscription object to take from
serialized_message	the destination in which to store the serialized message
taken	boolean flag indicating if a message was taken or not

Returns

RMW_RET_OK if successful, or

RMW_RET_BAD_ALLOC if memory allocation failed, or

RMW_RET_ERROR if an unexpected error occurs.

rmw_take_serialized_message_with_info()

rmw_ret_t rmw_take_serialized_message_with_info	(	const rmw_subscription_t *	subscription,
		rmw_serialized_message_t *	serialized_message,
		bool *	taken,
		rmw_message_info_t *	message_info
	)

Take a message without deserializing it and with its additional message information.

The same as rmw_take_serialized_message(), except it also includes the rmw_message_info_t.

Parameters

subscription	subscription object to take from
serialized_message	the destination in which to store the serialized message
taken	boolean flag indicating if a message was taken or not

Returns

RMW_RET_OK if successful, or

RMW_RET_BAD_ALLOC if memory allocation failed, or

RMW_RET_ERROR if an unexpected error occurs.

rmw_create_client()

rmw_client_t* rmw_create_client	(	const rmw_node_t *	node,
		const rosidl_service_type_support_t *	type_support,
		const char *	service_name,
		const rmw_qos_profile_t *	qos_policies
	)

rmw_destroy_client()

rmw_ret_t rmw_destroy_client	(	rmw_node_t *	node,
		rmw_client_t *	client
	)

rmw_send_request()

rmw_ret_t rmw_send_request	(	const rmw_client_t *	client,
		const void *	ros_request,
		int64_t *	sequence_id
	)

rmw_take_response()

rmw_ret_t rmw_take_response	(	const rmw_client_t *	client,
		rmw_request_id_t *	request_header,
		void *	ros_response,
		bool *	taken
	)

rmw_create_service()

rmw_service_t* rmw_create_service	(	const rmw_node_t *	node,
		const rosidl_service_type_support_t *	type_support,
		const char *	service_name,
		const rmw_qos_profile_t *	qos_policies
	)

rmw_destroy_service()

rmw_ret_t rmw_destroy_service	(	rmw_node_t *	node,
		rmw_service_t *	service
	)

rmw_take_request()

rmw_ret_t rmw_take_request	(	const rmw_service_t *	service,
		rmw_request_id_t *	request_header,
		void *	ros_request,
		bool *	taken
	)

rmw_send_response()

rmw_ret_t rmw_send_response	(	const rmw_service_t *	service,
		rmw_request_id_t *	request_header,
		void *	ros_response
	)

rmw_create_guard_condition()

rmw_guard_condition_t* rmw_create_guard_condition

(

void

)

rmw_destroy_guard_condition()

rmw_ret_t rmw_destroy_guard_condition

(

rmw_guard_condition_t *

guard_condition

)

rmw_trigger_guard_condition()

rmw_ret_t rmw_trigger_guard_condition

(

const rmw_guard_condition_t *

guard_condition

)

rmw_create_wait_set()

rmw_wait_set_t* rmw_create_wait_set

(

size_t

max_conditions

)

Create a wait set to store conditions that the middleware will block on.

If max_conditions is 0, the wait set can store an unbounded number of conditions to wait on. If max_conditions is greater than 0, the number of conditions that can be attached to the wait set is bounded at max_conditions.

Parameters

[in]

max_conditions

The maximum number of conditions that can be attached to the wait set.

Returns

A pointer to the created wait set, NULL if an error occurred.

rmw_destroy_wait_set()

rmw_ret_t rmw_destroy_wait_set

(

rmw_wait_set_t *

wait_set

)

rmw_wait()

rmw_ret_t rmw_wait	(	rmw_subscriptions_t *	subscriptions,
		rmw_guard_conditions_t *	guard_conditions,
		rmw_services_t *	services,
		rmw_clients_t *	clients,
		rmw_wait_set_t *	wait_set,
		const rmw_time_t *	wait_timeout
	)

Waits on sets of different waitable entities and returns when one is ready.

Add conditions to the wait set and wait until a response comes in, or until the timeout is reached. The arrays contain type-erased representations of waitable entities. This function casts the pointers to middleware-specific conditions and adds them to the wait set.

The count variables in the arrays represents the number of valid pointers in the array. NULL pointers are in the array considered invalid. If they are encountered, an error is returned.

The array structs are allocated and deallocated outside of this function. They do not have any information about how much memory is allocated for the arrays.

After the wait wakes up, the entries in each array that correspond to conditions that were not triggered are set to NULL.

Parameters

subscriptions	Array of subscriptions to wait on
guard_conditions	Array of guard conditions to wait on
services	Array of services to wait on
clients	Array of clients to wait on
wait_set	Storage for the wait set
wait_timeout	If NULL, block until a condition is ready. If zero, check only for immediately available conditions and don't block. Else, this represents the maximum time to wait for a response from the wait set.

Returns

RMW_RET_OK if success, or

RMW_RET_ERROR if error, or

RMW_RET_TIMEOUT if wait timed out.

rmw_get_node_names()

rmw_ret_t rmw_get_node_names	(	const rmw_node_t *	node,
		rcutils_string_array_t *	node_names
	)

rmw_count_publishers()

rmw_ret_t rmw_count_publishers	(	const rmw_node_t *	node,
		const char *	topic_name,
		size_t *	count
	)

rmw_count_subscribers()

rmw_ret_t rmw_count_subscribers	(	const rmw_node_t *	node,
		const char *	topic_name,
		size_t *	count
	)

rmw_get_gid_for_publisher()

rmw_ret_t rmw_get_gid_for_publisher	(	const rmw_publisher_t *	publisher,
		rmw_gid_t *	gid
	)

rmw_compare_gids_equal()

rmw_ret_t rmw_compare_gids_equal	(	const rmw_gid_t *	gid1,
		const rmw_gid_t *	gid2,
		bool *	result
	)

rmw_service_server_is_available()

rmw_ret_t rmw_service_server_is_available	(	const rmw_node_t *	node,
		const rmw_client_t *	client,
		bool *	is_available
	)

Check if a service server is available for the given service client.

This function will return true for is_available if there is a service server available for the given client.

The node parameter must not be NULL, and must point to a valid node.

The client parameter must not be NULL, and must point to a valid client.

The given client and node must match, i.e. the client must have been created using the given node.

The is_available parameter must not be NULL, and must point to a bool variable. The result of the check will be stored in the is_available parameter.

This function does manipulate heap memory. This function is not thread-safe. This function is lock-free.

Parameters

[in]	node	the handle to the node being used to query the ROS graph
[in]	client	the handle to the service client being queried
[out]	is_available	set to true if there is a service server available, else false

Returns

RMW_RET_OK if node the check was made successfully, or

RMW_RET_ERROR if an unspecified error occurs.

rmw_set_log_severity()

rmw_ret_t rmw_set_log_severity

(

rmw_log_severity_t

severity

)