[KAFKA-2440] Use `NetworkClient` instead of `SimpleConsumer` to fetch data from replica

• Type: Sub-task
• Status: Resolved
• Priority: Blocker
• Resolution: Fixed
• Fix Version/s: 0.9.0.0
• Component/s: security
• Assignee: Ismael Juma
• Reporter: Ismael Juma
• Reviewer: Jun Rao
• Created: 17/Aug/15 17:10
• Updated: 11/Sep/15 23:08
• Resolved: 11/Sep/15 23:08

Description

This is necessary for SSL/TLS support for inter-broker communication as `SimpleConsumer` will not be updated to support SSL/TLS.

As explained by junrao in KAFKA-2411: we need to be a bit careful since the follower fetcher thread doesn't need to refresh metadata itself. Instead, the information about the leader is propagated from the controller.

This work was originally described in KAFKA-2411, which was then updated to be more narrowly focused on replacing `BlockingChannel` with `Selector`.