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Class: event

June 19, 2024

Contributed by:

X X

Asynchronous event registration and handling

Fields for class: event

Field	Type	Qualifier	Description
`class`	`string`	RO/constructor	The name of the class of the object that changed
`id`	`int`	RO/constructor	An ID, monotonically increasing, and local to the current session
`obj_uuid`	`string`	RO/constructor	Deprecated. The uuid of the object that changed
`operation`	`event_operation`	RO/constructor	The operation that was performed
`ref`	`string`	RO/constructor	A reference to the object that changed
`timestamp`	`datetime`	RO/constructor	Deprecated. The time at which the event occurred
snapshot	object record	RO/runtime	The record of the database object that was added, changed or deleted

RPCs associated with class: event

RPC name: from

Overview:

Blocking call which returns a new token and a (possibly empty) batch of events. The returned token can be used in subsequent calls to this function.

Signature:

event batch from (session ref session_ref, string set classes, string token, float timeout)
<!--NeedCopy-->

Arguments:

Type	Name	Description
`session ref`	`session_ref`	Reference to a valid session
`string set`	`classes`	register for events for the indicated classes
`string`	`token`	A token representing the point from which to generate database events. The empty string represents the beginning.
`float`	`timeout`	Return after this many seconds if no events match

Minimum Role: read-only

Return Type: event batch

a structure consisting of a token (‘token’), a map of valid references per object type (‘valid_ref_counts’), and a set of event records (‘events’).

Possible Error Codes: SESSION_NOT_REGISTERED, EVENTS_LOST

RPC name: get_current_id

Overview:

Return the ID of the next event to be generated by the system

Signature:

int get_current_id (session ref session_ref)
<!--NeedCopy-->

Arguments:

Type	Name	Description
`session ref`	`session_ref`	Reference to a valid session

Minimum Role: read-only

Return Type: int

the event ID

RPC name: inject

Overview:

Injects an artificial event on the given object and returns the corresponding ID in the form of a token, which can be used as a point of reference for database events. For example, to check whether an object has reached the right state before attempting an operation, one can inject an artificial event on the object and wait until the token returned by consecutive event.from calls is lexicographically greater than the one returned by event.inject.

Signature:

string inject (session ref session_ref, string class, string ref)
<!--NeedCopy-->

Arguments:

Type	Name	Description
`session ref`	`session_ref`	Reference to a valid session
`string`	`class`	class of the object
`string`	`ref`	A reference to the object that will be changed.

Minimum Role: read-only

Return Type: string

the event ID in the form of a token

RPC name: next

This message is deprecated.

Overview:

Blocking call which returns a (possibly empty) batch of events. This method is only recommended for legacy use. New development should use event.from which supersedes this method.

Signature:

event record set next (session ref session_ref)
<!--NeedCopy-->

Arguments:

Type	Name	Description
`session ref`	`session_ref`	Reference to a valid session

Minimum Role: read-only

Return Type: event record set

A set of events

Possible Error Codes: SESSION_NOT_REGISTERED, EVENTS_LOST

RPC name: register

This message is deprecated.

Overview:

Registers this session with the event system for a set of given classes. This method is only recommended for legacy use in conjunction with event.next.

Signature:

void register (session ref session_ref, string set classes)
<!--NeedCopy-->

Arguments:

Type	Name	Description
`session ref`	`session_ref`	Reference to a valid session
`string set`	`classes`	the classes for which the session will register with the event system; specifying * as the desired class will register for all classes

Minimum Role: read-only

Return Type: void

RPC name: unregister

This message is deprecated.

Overview:

Removes this session’s registration with the event system for a set of given classes. This method is only recommended for legacy use in conjunction with event.next.

Signature:

void unregister (session ref session_ref, string set classes)
<!--NeedCopy-->

Arguments:

Type	Name	Description
`session ref`	`session_ref`	Reference to a valid session
`string set`	`classes`	the classes for which the session’s registration with the event system will be removed

Minimum Role: read-only

Return Type: void

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Class: event

June 19, 2024

Contributed by:

X X

June 19, 2024

Contributed by:

X X

Class: event

Fields for class: event

RPCs associated with class: event

RPC name: from

RPC name: get_current_id

RPC name: inject

RPC name: next

RPC name: register

RPC name: unregister

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