Observe Subscription

Internal API for handling CoAP Observe Subscriptions (RFC7641) More...

Collaboration diagram for Observe Subscription:

Data Structures
struct	coap_subscription_t
	Number of notifications that may be sent non-confirmable before a confirmable message is sent to detect if observers are alive. More...

Functions
void	coap_subscription_init (coap_subscription_t *)
void	coap_handle_failed_notify (coap_context_t *context, coap_session_t *session, const coap_bin_const_t *token)
	Handles a failed observe notify.
coap_subscription_t *	coap_add_observer (coap_resource_t *resource, coap_session_t *session, const coap_bin_const_t *token, const coap_pdu_t *pdu)
	Adds the specified peer as observer for resource.
coap_subscription_t *	coap_find_observer (coap_resource_t *resource, coap_session_t *session, const coap_bin_const_t *token)
	Returns a subscription object for given peer.
void	coap_touch_observer (coap_context_t *context, coap_session_t *session, const coap_bin_const_t *token)
	Flags that data is ready to be sent to observers.
int	coap_delete_observer (coap_resource_t *resource, coap_session_t *session, const coap_bin_const_t *token)
	Removes any subscription for session observer from resource and releases the allocated storage.
int	coap_delete_observer_request (coap_resource_t *resource, coap_session_t *session, const coap_bin_const_t *token, coap_pdu_t *request)
	Removes any subscription for session observer from resource and releases the allocated storage.
void	coap_delete_observers (coap_context_t *context, coap_session_t *session)
	Removes any subscription for session and releases the allocated storage.
int	coap_resource_notify_observers_lkd (coap_resource_t *resource, const coap_string_t *query)
	Initiate the sending of an Observe packet for all observers of resource, optionally matching query if not NULL.
void	coap_check_notify_lkd (coap_context_t *context)
	Checks all known resources to see if they are dirty and then notifies subscribed observers.
void	coap_persist_cleanup (coap_context_t *context)
	Close down persist tracking, releasing any memory used.
coap_subscription_t *	coap_persist_observe_add_lkd (coap_context_t *context, coap_proto_t e_proto, const coap_address_t *e_listen_addr, const coap_addr_tuple_t *s_addr_info, const coap_bin_const_t *raw_packet, const coap_bin_const_t *oscore_info)
	Set up an active subscription for an observe that was previously active over a coap-server inadvertant restart.
int	coap_persist_startup_lkd (coap_context_t *context, const char *dyn_resource_save_file, const char *observe_save_file, const char *obs_cnt_save_file, uint32_t save_freq)
	Start up persist tracking using the libcoap module.
void	coap_persist_stop_lkd (coap_context_t *context)
	Stop tracking persist information, leaving the current persist information in the files defined in coap_persist_startup().
int	coap_cancel_observe_lkd (coap_session_t *session, coap_binary_t *token, coap_pdu_type_t message_type)
	Cancel an observe that is being tracked by the client large receive logic.

Detailed Description

Internal API for handling CoAP Observe Subscriptions (RFC7641)

Function Documentation

coap_add_observer()

coap_subscription_t * coap_add_observer	(	coap_resource_t *	resource,
		coap_session_t *	session,
		const coap_bin_const_t *	token,
		const coap_pdu_t *	pdu
	)

Adds the specified peer as observer for resource.

The subscription is identified by the given token. This function returns the registered subscription information if the observer has been added, or NULL on error.

Parameters

resource	The observed resource.
session	The observer's session
token	The token that identifies this subscription.
pdu	The requesting pdu.

Returns

A pointer to the added/updated subscription information or NULL on error.

coap_cancel_observe_lkd()

int coap_cancel_observe_lkd	(	coap_session_t *	session,
		coap_binary_t *	token,
		coap_pdu_type_t	message_type
	)

Cancel an observe that is being tracked by the client large receive logic.

(coap_context_set_block_mode() has to be called) This will trigger the sending of an observe cancel pdu to the server.

Note: This function must be called in the locked state.

Parameters

session	The session that is being used for the observe.
token	The original token used to initiate the observation.
message_type	The COAP_MESSAGE_ type (NON or CON) to send the observe cancel pdu as.

Returns

1 if observe cancel transmission initiation is successful, else 0.

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coap_check_notify_lkd()

void coap_check_notify_lkd

(

coap_context_t *

context

)

Checks all known resources to see if they are dirty and then notifies subscribed observers.

Note: This function must be called in the locked state.

Parameters

context

The context to check for dirty resources.

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coap_delete_observer()

int coap_delete_observer	(	coap_resource_t *	resource,
		coap_session_t *	session,
		const coap_bin_const_t *	token
	)

Removes any subscription for session observer from resource and releases the allocated storage.

The result is 1 if an observation relationship with session observer and token existed, 0 otherwise.

Parameters

resource	The observed resource.
session	The observer's session.
token	The token that identifies this subscription or NULL for the first subscription.

Returns

1 if the observer has been deleted, 0 otherwise.

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coap_delete_observer_request()

int coap_delete_observer_request	(	coap_resource_t *	resource,
		coap_session_t *	session,
		const coap_bin_const_t *	token,
		coap_pdu_t *	request
	)

Removes any subscription for session observer from resource and releases the allocated storage.

The result is 1 if an observation relationship with session observer and token existed, or cache-key derived from request matches, 0 otherwise.

Parameters

resource	The observed resource.
session	The observer's session.
token	The token that identifies this subscription or NULL for the first subscription.
request	The requesting PDU.

Returns

1 if the observer has been deleted, 0 otherwise.

coap_delete_observers()

void coap_delete_observers	(	coap_context_t *	context,
		coap_session_t *	session
	)

Removes any subscription for session and releases the allocated storage.

Parameters

context	The CoAP context to use.
session	The observer's session.

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coap_find_observer()

coap_subscription_t * coap_find_observer	(	coap_resource_t *	resource,
		coap_session_t *	session,
		const coap_bin_const_t *	token
	)

Returns a subscription object for given peer.

Parameters

resource	The observed resource.
session	The observer's session
token	The token that identifies this subscription or NULL for the first subscription.

Returns

A valid subscription if exists or NULL otherwise.

coap_handle_failed_notify()

void coap_handle_failed_notify	(	coap_context_t *	context,
		coap_session_t *	session,
		const coap_bin_const_t *	token
	)

Handles a failed observe notify.

Parameters

context	The context holding the resource.
session	The session that the observe notify failed on.
token	The token used when the observe notify failed.

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coap_persist_cleanup()

void coap_persist_cleanup

(

coap_context_t *

context

)

Close down persist tracking, releasing any memory used.

Parameters

context

The current CoAP context.

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coap_persist_observe_add_lkd()

coap_subscription_t * coap_persist_observe_add_lkd	(	coap_context_t *	context,
		coap_proto_t	e_proto,
		const coap_address_t *	e_listen_addr,
		const coap_addr_tuple_t *	s_addr_info,
		const coap_bin_const_t *	raw_packet,
		const coap_bin_const_t *	oscore_info
	)

Set up an active subscription for an observe that was previously active over a coap-server inadvertant restart.

Only UDP sessions currently supported.

Note: This function must be called in the locked state.

Parameters

context	The context that the session is to be associated with.
e_proto	The CoAP protocol in use for the session / endpoint.
e_listen_addr	The IP/port that the endpoint is listening on.
s_addr_info	Local / Remote IP addresses. ports etc. of previous session.
raw_packet	L7 packet as seen on the wire (could be concatenated if Block1 FETCH is being used).
oscore_info	Has OSCORE information if OSCORE is protecting the session or NULL if OSCORE is not in use.

Returns

ptr to subscription if success else NULL.

coap_persist_startup_lkd()

int coap_persist_startup_lkd	(	coap_context_t *	context,
		const char *	dyn_resource_save_file,
		const char *	observe_save_file,
		const char *	obs_cnt_save_file,
		uint32_t	save_freq
	)

Start up persist tracking using the libcoap module.

If the files already exist with saved data, then this information is used in building back up the persist information.

Note: This function must be called in the locked state.

Parameters

context	The current CoAP context.
dyn_resource_save_file	File where dynamically created resource information is stored or NULL if not required.
observe_save_file	File where observe information is stored or NULL if not required.
obs_cnt_save_file	File where resource observe counter information is stored or NULL if not required.
save_freq	Frequency of change of observe value for calling the save observe counter logic.

Returns

1 if success else 0.

coap_persist_stop_lkd()

void coap_persist_stop_lkd

(

coap_context_t *

context

)

Stop tracking persist information, leaving the current persist information in the files defined in coap_persist_startup().

It is then safe to call coap_free_context() to close the application down cleanly.

Note: This function must be called in the locked state.

Alternatively, if coap_persist_track_funcs() was called, then this will disable all the callbacks, as well as making sure that no 4.04 is sent out for any active observe subscriptions when the resource is deleted after subsequently calling coap_free_context().

Parameters

context

The context that tracking information is to be stopped on.

coap_resource_notify_observers_lkd()

int coap_resource_notify_observers_lkd	(	coap_resource_t *	resource,
		const coap_string_t *	query
	)

Initiate the sending of an Observe packet for all observers of resource, optionally matching query if not NULL.

Note: This function must be called in the locked state.

Parameters

resource	The CoAP resource to use.
query	The Query to match against or NULL

Returns

1 if the Observe has been triggered, 0 otherwise.

coap_subscription_init()

void coap_subscription_init

(

coap_subscription_t *

)

coap_touch_observer()

void coap_touch_observer	(	coap_context_t *	context,
		coap_session_t *	session,
		const coap_bin_const_t *	token
	)

Flags that data is ready to be sent to observers.

Parameters

context	The CoAP context to use.
session	The observer's session
token	The corresponding token that has been used for the subscription.

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