Failure semantics

Failure Semantics is a concept used in Distributed computing to describe and classify errors that distributed systems can experience.

Example (service):

• A crash error is when nothing happens.
• An omission error is when is when one or more responses fails. A crash is a special case of omission when all responses fails.
• A timing error is when 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 an service omission it is said to assume the server to have omission failure semantics
• Failure Semantics are the type of errors that we expect to appear.
• Should another type of error appear it will lead to a service failure since we can not manage it.