Oauth setup for third party application

[amu]

As per the product document OAuth external client scenario  : if third-party clients to pull data from the instance and OAuth provider scenario is instance pulls data from a third-party provider.

If ServiceNow is receiving data where third part vendor push the data to service now using service now  build in rest APIs  for eg : 

POST https://xyz.service-now.com/api/sn_sc/servicecatalog/items/{sys_id}/order_now

which type of  OAuth scenario should be used in the above situation.

[amu]

I did some research and I have found if third party is pulling or pushing data to ServiceNow Instances then we can use  OAuth external client . Please correct me in case my understanding is incorrect.

[amu]

I did some research and I have found if third party is pulling or pushing data to ServiceNow Instances then we can  OAuth external client. Please correct me in case my understanding is incorrect.