anchor.diff:  - messages are grouped by *topics* A topic can contain any number of *sub-topics* which are logically stored together in that topic.
   - an *appender* is the source of messages.
   - a *tailer* is a receiver of messages.
  -- *Chronicle Queue* in brokerless by default. You can use *Chronicle Engine* to act as a broker for remote access.
  +- *Chronicle Queue* in broker-less by default. You can use *Chronicle Engine* to act as a broker for remote access.
   
   NOTE: We deliberately avoid the term *consumer* as messages are not consumed/destroyed by reading.
   
  
positive.code: 
  === Efficiency
  
  We put significant effort into worring about latency you can't see.  Unlike products which focus on support of the web, we care about latency which are a fraction of the time you can see. For web application less than 40 ms is fine for web applications as it's faster than you can see (the frame rate of cinema is 24 Hz or about 40 ms)  However we attempt to be under 40 microsecond 99% to 99.99% of the time.  Using queue without replication we support applications with latencies below 40 microseconds end to end across multiple services.  Often the 99% latency of queue is entirely dependant on the chose of OS and disk subsystem.
  
  === Compression
  
  
negative.code: - you have a record of the order of the inputs you processed.
  - you have a record of all the decisions your new system is commited to, even if the new code would have made different decisions.
  
  === Guarantees
  
  Chronicle Queue provides the following guarantees
  
  - for each appender, messages are written in the order the appnder wrote them. Messages by different appenders are interleaved.
  - for each tailer, it will see every message for a topic in the same order as every other tailer.
  - when replicated, every replica has a copy of every message.
  
  Replication has three levels of gaurantees
  
  - replication happens soon but eventually (< 1ms in as much as 99.9% of cases)
  - or, a tailer will only see messages which have been replicated.
  