Revert "Remove ack"

This reverts commit fb254da94c0f66851d1a59ecadbbbe3a700846ab.
Revert "Ack messages"

This reverts commit 2e90cb66b24ea5b3e777f6edeca20b9b2a61f2ce.
Revert "Make Hash consistent"

This reverts commit 5716c6766198cb907ef0978f02a21b15c279302e.
Revert "Make messages persistent"

This reverts commit 729cafe066716c2518163b6d67ab2267f132d84a.