RK-J

Scheme:

Create a cache named "BOOKID_BOOKSOURCE_CACHE" where key is documentProcessingId and value is BookSource
(Here, bookId means documentProcessingId)
If the documentProcessingId is present in map
- get the BookSource from the map.
- log this message "getting book source-url from the Cache for the bookId : " and give the documentProcessingId
Else
- get the ourl from datastore and store it in BookSource
- log this message "getting book source-url from the Datastore for the bookId : " and give the documentProcessingId
- update the value in map.

Handle the bookIdAndBookSourceMap during overwrite/Delete:
For these scenarios, delete the entry for the documentProcessingId in bookIdAndBookSourceMap.