Abstract
Stateful Compute Server
- Remembers client data like Session-Cookie Authentication (state) from one request to the next
- From the above diagram, user A’s session data and profile image are stored in Server 1
- To authenticate User A, HTTP requests must be routed to Server 1
- If a request is sent to other servers like Server 2, authentication would fail because Server 2 does not contain User A’s session data
- Similarly, all HTTP requests from User B must be routed to Server 2; all requests from User C must be sent to Server 3
Limitations
- Every request from the same client must be routed to the same server. This can be done with Sticky Session with an overhead
- Adding and removing servers is much difficult with this approach, challenging to handle server failures
- Thus, less Scalability and Fault Tolerance (容错性)
Stateless Compute Server
