Prevention of circular event publication in publish/subscribe model using path vector
Techniques to prevent circular event publication are disclosed. In various embodiments, a change in an entity's own value is detected. A change event is published based at least in part on the detected change, including by associating with the change event an event path vector that includes an identifier associated with the entity.
1. A method to prevent circular event publication, comprising:
detecting a change in an entity's own value;
determining whether the detected change is from an another entity, wherein the entity and the another entity are page components of an application user interface page;
in the event the detected change is not from the another entity, publishing a change event based at least in part on the detected change and including in the change event an event path vector that includes an identifier associated with the entity; and
in the event the detected change is from the another entity, publishing the change event without including the identifier associated with the entity in the event path vector, wherein the change is associated with evaluation of a function used to determine the entity's own value, wherein the function is evaluated in response to a received event, wherein the received event indicates a change in the another entity's value, wherein the another entity's value is an argument of the function.
2. The method of claim 1 , wherein the received event includes a corresponding event path vector, and associating with the change event an event path vector that includes an identifier associated with the entity includes adding the identifier associated with the entity to a set of one or more identifiers included in the corresponding event path vector as received.
3. The method of claim 1 , wherein the change in the value associated with the another entity is received via a received change event and the detected change in the entity's own value is made in response to the received change event.
4. The method of claim 1 , wherein a subscribing entity is configured to receive the published change event.
5. The method of claim 4 , wherein the subscribing entity is configured to check the event path vector to determine whether an identifier associated with the subscribing entity is included in the event path vector.
6. The method of claim 5 , wherein the subscribing entity is configured to drop the event based at least in part on a determination that the identifier associated with the subscribing entity is included in the event path vector.
7. The method of claim 5 , wherein the subscribing entity is configured to act on the event based at least in part on a determination that the identifier associated with the subscribing entity is not included in the event path vector.
8. The method of claim 5 , wherein the subscribing entity is configured to act on the event based at least in part on a determination that the identifier associated with the subscribing entity is not included in the event path vector more than a prescribed number of times.
9. The method of claim 1 , wherein detecting a change in an entity's own value is detected by an application user interface or other page component.
10. The method of claim 1 , wherein the entity is configured to subscribe to a change event associated with the another entity.
11. A system to prevent circular event publication, comprising:
a memory; and
a processor coupled to the memory and configured to:
detect a change in an entity's own value as stored in the memory;
determine whether the changes is from an another entity, wherein the entity and the another entity are page components of an application user interface page;
in the event the detected change is not from an another entity, publish a change event based at least in part on the detected change and include in the change event an event path vector that includes an identifier associated with the entity; and
in the event the detected change is from the another entity, publish the change event without including the identifier associated with the entity in the event path vector, wherein the change is associated with evaluation of a function used to determine the entity's own value, wherein the function is evaluated in response to a received event, wherein the received event indicates a change in the another entity's value, wherein the another entity's value is an argument of the function.
12. A computer program product to prevent circular event publication, the computer program product being embodied in a non-transitory computer readable storage medium and comprising computer instructions for:
detecting a change in an entity's own value;
determining whether the change is from an another entity, wherein the entity and the another entity are page components of an application user interface page;
in the event the detected change is not from the another entity, publishing a change event based at least in part on the detected change and including in the change event an event path vector that includes an identifier associated with the entity; and
in the event the detected change is from the another entity, publishing the change event without including an identifier associated with the entity in the event path vector, wherein the change is associated with evaluation of a function used to determine the entity's own value, wherein the function is evaluated in response to a received event, wherein the received event indicates a change in the another entity's value, wherein the another entity's value is an argument of the function.