Failure semantics

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In distributed computing, failure semantics is used to describe and classify errors that distributed systems can experience.[1][2]

Types of errors[edit]

A list of types of errors that can occur:

  • An omission error is when one or more responses fails.
  • A crash error is when nothing happens. A crash is a special case of omission when all responses fail.
  • A Timing error is when one or more responses arrive outside the time interval specified. Timing errors can be early or late. An omission error is a timing error when a response has infinite timing error.
  • An arbitrary error is any error, (i.e. a wrong value or a timing error).
  • When a client uses a server it can cope with different type errors from the server.
    • If it can manage a crash at the server it is said to assume the server to have crash failure semantics.
    • If it can manage a service omission it is said to assume the server to have omission failure semantics.
      • Failure semantics are the type of errors that are expected to appear.
  • Should another type of error appear it will lead to a service failure because it cannot be managed.


  1. ^ Flaviu Christian, Understanding Fault-Tolerant Distributed Systems
  2. ^ Arno Puder; Kay Romer; Frank Pilhofer (2005). Distributed Systems Architecture. Morgan Kaufmann. ISBN 1558606483., pp 14–16.