Publishing rest API changes based on subscriber's customized request

1. A method to automatically publish representational state transfer (REST) application program interface (API) changes in a cloud environment, the method comprising:

receiving, by a publish/subscribe server (PSS) from a subscriber operating in the cloud environment, a customized request specifying a registered REST API supported by a REST service provider (RSP) and registered with the PSS, wherein the registered REST API is invoke-able at the RSP by the subscriber;

receiving, by the PSS from the subscriber, a schedule that defines a time scheme to both monitor whether the registered REST API is changed and to provide a notification of the changed registered REST API, wherein the time scheme defined by the schedule specifies at least one of a time, date, or frequency to both monitor whether the registered REST API is changed and provide the notification of the changed registered REST API;

monitoring, by the PSS, the registered REST API for any changes associated with the registered REST API at the RSP based on the customized request and the schedule;

in response to a determination that the registered REST API is changed at the RSP, generating, by the PSS, a REST API change report indicating a change event occurred to the registered REST API at the RSP after being registered with the PSS; and

transmitting, by the PSS based on the schedule, the REST API change report to the subscriber as the notification of the changed registered REST API.

2. The method as recited in claim 1 , further comprising:

receiving, by the PSS from a publisher, a plurality of REST API specifications supported by the RSP; and

registering, by the PSS, the plurality of REST API specifications, wherein the registered REST API is associated with one of the plurality of REST API specifications.

3. The method as recited in claim 2 , wherein the determination that the registered REST API is changed at the RSP comprises:

receiving, from the RSP, a current REST API specification associated with the registered REST API;

retrieving, from the registered plurality of REST API specifications, a registered REST API specification associated with the registered REST API; and

comparing the current REST API specification with the registered REST API specification to determine whether the registered REST API is changed.

4. The method as recited in claim 3 , wherein:

the customized request includes a customization request tree indicating one or more monitoring-elements in the registered REST API specification for change-monitoring, and

the determination whether the registered REST API is changed is based on comparing the current REST API specification and the registered REST API specification for changes at the one or more monitoring-elements.

5. The method as recited in claim 1 , wherein the generating of the REST API change report is also based on the schedule, wherein the schedule is specified by the customized request, wherein the schedule further includes information related to a mechanism for delivery of the REST API change report to the subscriber as the notification of the changed registered REST API, and wherein the PSS maintains multiple different schedules each associated with a specific subscriber.

6. The method as recited in claim 1 , wherein the subscriber is configured to not invoke the registered REST API at the RSP based on the REST API change report.

7. A non-transitory computer-readable storage medium, containing a set of instructions which, in response to execution by a processor, cause the processor to perform a method to automatically publish representational state transfer (REST) application programming interface (API) changes in a cloud environment, wherein the method comprises:

prior to invoking a registered REST API at a REST service provider (RSP):

transmitting, to a publish/subscribe server (PSS) by a subscriber operating in the cloud environment, a customized request specifying the registered REST API for evaluating whether the registered REST API, which is registered by the PSS, is changed at the RSP; and

transmitting, to the PSS from the subscriber, a schedule that defines a time scheme to both monitor whether the registered REST API is changed and to provide a notification of the changed registered REST API, wherein the time scheme defined by the schedule specifies at least one of a time, date, or frequency to both monitor whether the registered REST API is changed and provide the notification of the changed registered REST API;

receiving, by the subscriber and based on the schedule, a REST API change report associated with the registered REST API from the PSS, wherein the REST API change report is generated as the notification by the PSS based on the customized request; and

in response to the REST API change report indicating that a change event occurred to the registered REST API at the RSP after the registered REST API is registered by the PSS, skipping, by the subscriber, the invoking of the registered REST API at the RSP.

8. The non-transitory computer-readable storage medium of claim 7 , wherein the PSS generates the REST API change report by:

receiving, by the PSS from a publisher, a plurality of REST API specifications supported by the RSP; and

registering, by the PSS, the plurality of REST API specifications, wherein the registered REST API is associated with one of the plurality of REST API specifications.

9. The non-transitory computer-readable storage medium of claim 8 , wherein the PSS further generates the REST API change report by:

receiving, from the RSP, a current REST API specification associated with the registered REST API;

retrieving, from the registered plurality of REST API specifications, a registered REST API specification associated with the registered REST API; and

determining whether the registered REST API is changed by comparing the current REST API specification with the registered REST API specification.

10. The non-transitory computer-readable storage medium of claim 9 , wherein:

the customized request includes a customization request tree indicating one or more monitoring-elements in the registered REST API specification for change-monitoring, and

the determining whether the registered REST API is changed is based on comparing the current REST API specification and the registered REST API specification for changes at the one or more monitoring-elements.

11. The non-transitory computer-readable storage medium of claim 7 , wherein the PSS monitors the registered REST API for any changes at the RSP based on the schedule, wherein the schedule is specified by the customized request, wherein the schedule further includes information related to a mechanism for delivery of the REST API change report to the subscriber as the notification of the changed registered REST API, and wherein the PSS maintains multiple different schedules each associated with a specific subscriber.

12. The non-transitory computer-readable storage medium of claim 11 , wherein the PSS further generates the REST API change report based on the schedule.

13. The non-transitory computer-readable storage medium of claim 7 , wherein:

when the REST API change report indicates that no change event occurred to the registered REST API at the RSP after the registered REST API is registered by the PSS, invoking, by the subscriber, the registered REST API at the RSP.

14. A system for to automatically publish representational state transfer (REST) application programming interface (API) changes in a cloud environment, the system comprising:

a publish/subscribe server (PSS) supported by a first cloud in the cloud environment for registering a REST API;

a REST service provider (RSP) supported by a second cloud in the cloud environment for supporting the registered REST API; and

a subscriber operating in the cloud environment and coupled with the RSP and the PSS, wherein prior to invoking the registered REST API at the RSP through the second cloud, the subscriber is configured to:

transmit, to the PSS through the first cloud, a customized request specifying the registered REST API for evaluating whether the registered REST API is changed at the RSP:

transmit, to the PSS, a schedule that defines a time scheme to both monitor whether the registered REST API is changed and to provide a notification of the changed registered REST API, wherein the time scheme defined by the schedule specifies at least one of a time, date, or frequency to both monitor whether the registered REST API is changed and provide the notification of the changed registered REST API;

receive, based on the schedule, a REST API change report associated with the registered REST API from the PSS, wherein the REST API change report is generated as the notification by the PSS based on the customized request; and

in response to that the REST API change report indicates that a change event occurred to the registered REST API at the RSP after being registered, skip the invoking of the registered REST API at the RSP.

15. The system of claim 14 , further comprising:

a publisher coupled with the PSS, wherein the publisher is configured to transmit to the PSS a plurality of REST API specifications supported by the RSP, and the PSS registers the REST API by associating the registered REST API with one of the plurality of REST API specifications.

16. The system of claim 14 , wherein the RSP is configured to transmit to the PSS a plurality of REST API specifications supported by the RSP, and the PSS registers the REST API by associating the registered REST API with one of the plurality of REST API specifications.

17. The system of claim 14 , wherein to generate the REST API change report, the PSS is configured to:

receive, from the RSP, a current REST API specification associated with the registered REST API;

retrieve, from the registered plurality of REST API specifications, a registered REST API specification associated with the registered REST API; and

determine whether the registered REST API is changed by comparing the current REST API specification with the registered REST API specification.

18. The system of claim 17 , wherein:

the customized request includes a customization request tree indicating one or more monitoring-elements in the registered REST API specification for change-monitoring, and

the PSS determines whether the registered REST API is changed by comparing the current REST API specification and the registered REST API specification for changes at the one or more monitoring-elements.

19. The system of claim 14 , wherein the PSS monitors the registered REST API for any changes associated with the registered REST API at the RSP based on the schedule, wherein the schedule is specified by the customized request, wherein the schedule further includes information related to a mechanism for delivery of the REST API change report to the subscriber as the notification of the changed registered REST API, and wherein the PSS maintains multiple different schedules each associated with a specific subscriber.

20. The system of claim 19 , wherein the PSS further generates the REST API change report based on the schedule.