Subscription(POST) Call Flow
The Subscription service operation allows to:
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Create a subscription such that the SMF can request notification (depending on certain filters) in the following scenarios:
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When there is a registration or deregistration in the NRF.
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When there is a modification to a profile.
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Create a subscription to a specific NF instance such that the SMF can request notification in the following scenarios:
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When there is a modification to an NF instance.
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When there is a deregistration of an NF instance.
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Important | Currently, SMF only supports subscription of NF instances that the NF receives as its discovery response. |

Implementing the subscription to notifications on NF instances creates a new individual resource under the collection resource "subscriptions." Issuing a POST request starts the operation on the Uniform Resource Identifier (URI) representing the "subscriptions" resource.
Step | Description |
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1 |
The NF Service Consumer sends a POST request to the resource URI representing the "subscriptions" collection resource. The request body includes data that indicates the type of notifications that the SMF has subscribed to receive. It also contains a callback URI, where the SMF prepares to receive the actual notification from the NRF. The notification contains the SMF suggested validity time, which represents the time span during which the subscription remains active. The subscription request may also include more parameters indicating the list of attributes in the NF Profile to monitor (or to exclude from monitoring). This request determines if the NRF must send a notification, when there is a change in any of the attributes of the profile. |
2a |
When a subscription is successful, the NRF sends a "201 Created" response. This response contains newly created subscription data that includes the NRF-determined validity time beyond which, the subscription is invalid. When the subscription expires, the SMF creates a new subscription in the NRF to continue receiving status notifications. |
2b |
The NRF returns a "400 Bad Request" status code with the problem details if the subscription fails due to errors in the subscription data. The NRF returns a "500 Internal Server Error" with the problem details if the subscription fails due to internal errors in the NRF. |