I wanted to know the concept behind the file-upload cancel. How the api call is being made to cancel the upload.
To upload a small file via the Dropbox API, an app would use the /2/files/upload endpoint. The upload is sent via an HTTPS connection to that endpoint, sending the file data in the request body. To cancel an upload, the app would suspend the HTTPS request while in progress. If the app is using an SDK or library, the SDK/library may abstract this away and offer the app a cancel method that would do this.
For larger files, an app would use the /2/files/upload_session/* endpoints. For those, any ongoing request could be suspended; it would also be sufficient to just not perform the final step of "committing" the file using /2/files/upload_session/finish*.
