exploring the purpose of inactive chain in `orderer/consensus`

[shivdeep-singh-ibm]

In fabric/orderer the consensus directory holds various pluggable consensus implementations. Currently the consensus implementations in the orderer/consensus/ directory are {etcdraft, kafka, solo, inactive}. This issue is created to understand the purpose of inactive chain.

Seeks to address questions like:

• whether it is required only in the case of channel participation apis / system channel?
• whether it can be removed or refactored?

[yacovm]

This issue is created to understand the purpose of inactive chain.

You can look at git blame and see the commit in which it was introduced.

The purpose of the inactive chain is to support a use case where an orderer is not part of a channel, but you don't want to return "this channel does not exist" to a client, so you have a dummy channel instance that returns a different message.