Transmitting large data between two spring boot app

Problem is describe on stackoverflow page Question # 65262031

Project Structure

• There is a client project which receives Multipart File
• The client project uses the HttpClient & RequestEntity to push data in chunk directly to OutputStream
• There is a server project which works with HttpServletRequest/Response (each having it own stream)
• server project has to kind of opertion op1 and op2

For running any of the op1 or op2 operation use the postman configuration given in postman.json

op1

• Injects a 16bytes of random data into the response stream
• Reads data in chunk and count the size (even though it is the same - in actual project it will change after some business operation is perform - it is skipped to avoid complexity)
• Put the count of size in the response stream
• Put the chunk data in the response stream

On the client size the response received is then written into a temp-folder.

op2

• The file generated in the temp-folder is sent to the client which sends it over in chunk to server
• server is now reversing the process done by op1 -- Stripes the initial 16bytes -- Reads the next 6 bytes to find out the length of next bytes to be read -- Reads the bytes as identified in the previous step.

Problem Facing Currently

1. Unable to understand if Spring WebFlux can solve this problem?
2. For smaller file op1 works, but for large files it get stuck op2 - somehow something is wrong with streams internally, but can't pinpoint it. See below images
3. op2 doesn't work for any of the scenarios (smaller file or larger files)

This one works

This one doesn't (get stuck)