Read the docs: https://flightstats.github.io/hub/

The hub is a distributed linked list.
The hub is a messaging system.
The hub is a long term data store.

• Stores each item at a unique key (url) (http://hub/channel/whatIs/2016/12/31/23/59/59/bhJ23I)
• Items are available for an arbitrarily long time
• Fault tolerant, easy to cluster
• Requires a quorum for a successful write

• Most KV stores allow mutations. The hub does not.
• The hub imposes that all item keys always move forward in time
• The hub offers ordering guarantees to provide consistent answers to time based queries

• Items are immutable
• Item keys always increase

• Most messaging systems do not let you access arbitrarily old items
• Many messaging systems are difficult to cluster
• Many messaging system require custom clients