Receiving data from topics.

Functions
TOPIC_HANDLER_T	subscribe (SESSION_T *session, const SUBSCRIPTION_PARAMS_T params)
	Subscribe to topics.
void	notify_subscription_register (SESSION_T *session, const NOTIFY_SUBSCRIPTION_PARAMS_T params)
	Register to receive subscription notifications.
void	unsubscribe (SESSION_T *session, const UNSUBSCRIPTION_PARAMS_T params)
	Unsubscribe from one or more topics.
void	notify_unsubscription_register (SESSION_T *session, const NOTIFY_UNSUBSCRIPTION_PARAMS_T params)
	Register to receive unsubscription notifications.
DIFFUSION_FETCH_REQUEST_T *	diffusion_fetch_request_init (SESSION_T *session)
	Creates an unconfigured fetch request.
DIFFUSION_FETCH_REQUEST_T *	diffusion_fetch_request_dup (const DIFFUSION_FETCH_REQUEST_T *fetch_request)
	Create a duplicate (copy) of an existing DIFFUSION_FETCH_REQUEST_T.
void	diffusion_fetch_request_free (DIFFUSION_FETCH_REQUEST_T *fetch_request)
	Free a memory allocated DIFFUSION_FETCH_REQUEST_T

Detailed Description

Function Documentation

diffusion_fetch_request_dup()

DIFFUSION_FETCH_REQUEST_T * diffusion_fetch_request_dup

(

const DIFFUSION_FETCH_REQUEST_T *

fetch_request

)

Create a duplicate (copy) of an existing DIFFUSION_FETCH_REQUEST_T.

diffusion_fetch_request_free should be called on this pointer when no longer needed.

Parameters

fetch_request

fetch request to be duplicated

Returns

a copy of the provided fetch request. NULL, if the fetch request is NULL.

diffusion_fetch_request_free()

void diffusion_fetch_request_free

(

DIFFUSION_FETCH_REQUEST_T *

fetch_request

)

Free a memory allocated DIFFUSION_FETCH_REQUEST_T

Parameters

fetch_request

The fetch request to be freed

diffusion_fetch_request_init()

DIFFUSION_FETCH_REQUEST_T * diffusion_fetch_request_init

(

SESSION_T *

session

)

Creates an unconfigured fetch request.

Parameters

session

The session handle. If NULL, the function returns NULL.

Returns

a new unconfigured fetch request

notify_subscription_register()

void notify_subscription_register	(	SESSION_T *	session,
		const NOTIFY_SUBSCRIPTION_PARAMS_T	params
	)

Register to receive subscription notifications.

This function should be called by the application to register to receive notifications that it has been subscribed to a topic.

Parameters

session	The current session. If NULL, this function returns immediately.
params	Callbacks and other parameters. on_notify_subscription should be set to receive notifications.

notify_unsubscription_register()

void notify_unsubscription_register	(	SESSION_T *	session,
		const NOTIFY_UNSUBSCRIPTION_PARAMS_T	params
	)

Register to receive unsubscription notifications.

This function should be called by the application to receive notifications that it has been unsubscribed to a topic.

Parameters

session	The current session. If NULL, this function returns immediately.
params	Callbacks and other parameters. on_notify_unsubscription should be set to receive notifications.

subscribe()

TOPIC_HANDLER_T subscribe	(	SESSION_T *	session,
		const SUBSCRIPTION_PARAMS_T	params
	)

Subscribe to topics.

This function has the roles of subscribing to the topics specified by the selector and installing handlers for received TOPIC_MESSAGE_T messages which match that selector and also any other service messages related to subscription.

If a topic handler was already registered for the supplied selector, it is replaced and the old handlers are returned.

The session will become subscribed to each existing topic matching the selector unless the session is already subscribed to the topic, or the session does not have READ_TOPIC permission for the topic path. For each topic to which the session becomes subscribed, a subscription notification and initial value (if any) will be delivered to registered value streams before the completion handler is called.

The subscription request is also retained at the server and the session will be automatically subscribed to newly created topics that match the selector (unless a subsequent unsubscription cancels the request).

Parameters

session	The session handle. If NULL, the function returns immediately.
params	Parameters describing the subscription request and callbacks handlers which may be invoked in response.

Returns

Previous topic handler if replacing, else NULL.

unsubscribe()

void unsubscribe	(	SESSION_T *	session,
		const UNSUBSCRIPTION_PARAMS_T	params
	)

Unsubscribe from one or more topics.

This function has the roles of subscribing to the topics specified by the selector and installing handlers for received TOPIC_MESSAGE_T messages which match that selector and also any other service messages related to unsubscription.

Parameters

session	The session handle. If NULL, this function returns immediately.
params	Parameters describing the unsubscription request and callback handlers which may be invoked in response.