Explain what is happening internally once you upload a file in Amazon S3

This article will explain what is happening inside the S3 once you upload a file. 

1. The client sends an HTTP PUT request to create a bucket by giving its name(“s3_bucket-that-you-need-to-get”).
2. The request will be forwarded to the API service.
3. The API service communicates with Identity and Access Management (IAM) to ensure the client user has the authorization to WRITE.
4. The API service calls the metadata store and will create an entry with the bucket info in metadata database.
5. After the entry creation is done, its returns the client a success message.
6. Once the bucket is created, the client sends an HTTP PUT request to create an object that you give.
7. The API service verifies the user credentials and identity and ensures the user has WRITE permission on the bucket .
8. As soon as the validation is done with success the API service sends the object data in the HTTP PUT payload to the data store.
9. The data store persists the payload as an object and it will returns the UUID of the object.
10. The API service then will calls the metadata store to create a new entry in the metadata database.
11. The metadata database contains information such as the object_id (UUID), bucket_id , object_name, time it created , permission etc.