
	Subscription Flags
	Subscription Options
	Subscription Events
	Message Reader
Entities/Objects
typedef struct EspSubscriberOptions	EspSubscriberOptions
typedef struct EspSubscriberEvent	EspSubscriberEvent
typedef struct EspSubscriber	EspSubscriber
typedef void(*	SUBSCRIBER_CALLBACK_T )(const EspSubscriberEvent event, void user_data)
typedef struct EspMessageReader	EspMessageReader
typedef struct EspRowReader	EspRowReader

Functions
ESPAPICALL EspSubscriber *	esp_subscriber_create (const EspUri uri, const EspCredentials credentials, const EspSubscriberOptions options, EspError error)
ESPAPICALL int32_t	esp_subscriber_free (EspSubscriber subscriber, EspError error)
ESPAPICALL EspProject *	esp_subscriber_get_project (EspSubscriber subscriber, EspError error)
ESPAPICALL int32_t	esp_subscriber_connect (EspSubscriber subscriber, EspError error)
ESPAPICALL int32_t	esp_subscriber_disconnect (EspSubscriber subscriber, EspError error)
ESPAPICALL int32_t	esp_subscriber_close (EspSubscriber subscriber, EspError error)
ESPAPICALL int32_t	esp_subscriber_subscribe (EspSubscriber subscriber, const EspStream stream, EspError *error)
ESPAPICALL int32_t	esp_subscriber_subscribe_streamname (EspSubscriber subscriber, const char stream_name, EspError *error)
ESPAPICALL int32_t	esp_subscriber_subscribe_sql (EspSubscriber subscriber, const char sql, EspError *error)
ESPAPICALL int32_t	esp_subscriber_get_subscribed_streams (EspSubscriber subscriber, EspList stream_list, EspError *error)
ESPAPICALL int32_t	esp_subscriber_set_callback (EspSubscriber subscriber, uint32_t events, SUBSCRIBER_CALLBACK_T callback, void user_data, EspError *error)
ESPAPICALL int32_t	esp_subscriber_select_with (EspSubscriber subscriber, EspSelector selector, uint32_t events, EspError *error)
ESPAPICALL EspSubscriberEvent *	esp_subscriber_get_next_event (EspSubscriber subscriber, EspError error)

Function Documentation

ESPAPICALL int32_t esp_subscriber_close	(	EspSubscriber *	subscriber,
		EspError *	error
	)

Closes this instance of EspSubscriber. In DIRECT access mode returns when the entity is closed. In CALLBACK/SELECT will generate an ESP_SUBSCRIBER_EVENT_CLOSED event.

Returns:: 0 on success.

Parameters:

subscriber EspSubscriber to close

ESPAPICALL int32_t esp_subscriber_connect	(	EspSubscriber *	subscriber,
		EspError *	error
	)

Connect to the backend project. In DIRECT access mode returns when connected. In CALLBACK/SELECT will generate an ESP_SUBSCRIBER_EVENT_CONNECTED event.

Returns:: 0 on success.

Parameters:

subscriber EspSubscriber to connect

ESPAPICALL EspSubscriber* esp_subscriber_create	(	const EspUri *	uri,
		const EspCredentials *	credentials,
		const EspSubscriberOptions *	options,
		EspError *	error
	)

Creates an EspSubscriber object. The created object must be freed using esp_subscriber_free().

Returns:: EspSubscriber, NULL on error.

Parameters:

uri	URI of the project to which subscription is to be established
credentials	EspCredentials object for authentication, NULL if no authentication is needed
options	Options to use for the EspSubscriber

ESPAPICALL int32_t esp_subscriber_disconnect	(	EspSubscriber *	subscriber,
		EspError *	error
	)

Disconnect from the project. In DIRECT access mode returns when disconnected. In CALLBACK/SELECT will generate an ESP_SUBSCRIBER_EVENT_DISCONNECTED event.

Returns:: 0 on success.

Parameters:

subscriber EspSubscriber to disconnect

ESPAPICALL int32_t esp_subscriber_free	(	EspSubscriber *	subscriber,
		EspError *	error
	)

Frees an EspSubscriber created using esp_subscriber_create().

Returns:: 0 on success.

Parameters:

subscriber EspSubscriber to free

ESPAPICALL EspSubscriberEvent* esp_subscriber_get_next_event	(	EspSubscriber *	subscriber,
		EspError *	error
	)

Determine the next event pending at the subscriber. This call should be made in DIRECT ACCESS mode only. In other access modes, the events are retrieved by the SDK and are either passed to the callback handler or returned from esp_selector_select() call.

The event retrieved by this call must be freed using esp_subscriber_event_free(). This is the only instance where an event needs to be explicitly freed by user code.

Returns:: EspSubscriberEvent, NULL on error. Error details on error

Parameters:

subscriber EspSubscriber to query

ESPAPICALL EspProject* esp_subscriber_get_project	(	EspSubscriber *	subscriber,
		EspError *	error
	)

Retrieve the parent EspProject.

Returns:: EspProject, NULL on error.

ESPAPICALL int32_t esp_subscriber_get_subscribed_streams	(	EspSubscriber *	subscriber,
		EspList *	stream_list,
		EspError *	error
	)

Retrieves a list of streams currently subscribed to. If this is an SQL subscription, the list will contain a single EspStream with the type SQL_QUERY and a schema that corresponds to the SQL statement that was used to subscribe.

Returns:: 0 on success.

Parameters:

subscriber	EspSubscriber to query
stream_list	Pointer to EspList in which to return the stream list

ESPAPICALL int32_t esp_subscriber_select_with	(	EspSubscriber *	subscriber,
		EspSelector *	selector,
		uint32_t	events,
		EspError *	error
	)

Use the specified esp_selector to monitor events for this EspSubscriber.

Returns:: 0 on success.

Parameters:

subscriber	EspSubscriber to monitor
selector	EspSelector with which to monitor
events	events to monitor for - bitwise OR'd values of ESP_SUBSCRIBER_EVENT_xxx values

ESPAPICALL int32_t esp_subscriber_set_callback	(	EspSubscriber *	subscriber,
		uint32_t	events,
		SUBSCRIBER_CALLBACK_T	callback,
		void *	user_data,
		EspError *	error
	)

Registers a callback handler.

Returns:: 0 on success.

Parameters:

subscriber	a valid EspSubscriber object
events	bitwise OR'd values of ESP_SUBSCRIBER_EVENT_xxx values
callback	callback pointer to the handler function
user_data	pointer to user data that will be passed back by the SDK

ESPAPICALL int32_t esp_subscriber_subscribe	(	EspSubscriber *	subscriber,
		const EspStream *	stream,
		EspError *	error
	)

Subscribe to the specified stream. This call must be made after the subscriber has connected.

Returns:: 0 on success.

Parameters:

subscriber	EspSubscriber to use for the subscription
stream	Stream to which to subscribe

ESPAPICALL int32_t esp_subscriber_subscribe_sql	(	EspSubscriber *	subscriber,
		const char *	sql,
		EspError *	error
	)

Subscribes using the provided SQL statement.

Returns:: 0 on success.

Parameters:

subscriber	EspSubscriber to use for the subscription
sql	SQL statement to use as a projection for the data

ESPAPICALL int32_t esp_subscriber_subscribe_streamname	(	EspSubscriber *	subscriber,
		const char *	stream_name,
		EspError *	error
	)

Not in R5. Subscriber to the stream named by stream_name.

Returns:: 0 on success

Parameters:

subscriber	EspSubscriber to use for the subscription
stream_name	Name of the stream to subscribe to

Entities/Objects

Functions

Function Documentation