Recovery guarantees for software components

A method of providing recovery in a computer system, comprising:

• a) designating one or more software components that execute on a computer in the computer system as persistent components;
• and
• b) designating one or more software components that execute on a computer in the computer system as transactional components;
• c) making it possible to recreate the state of a persistent component by implementing a contract between any two communicating persistent or transactional components that logs data concerning at least one of the communicating components to a stable log so that a state of the communicating components can be recreated in the event of a failure in the computer system;
• and
• d) designating one or more software components that execute on the computer system as a related component which interacts with at least one persistent component so that interactions between the related component and a persistent component do not require logging to ensure that the state of an ensemble of related and persistent components can be reconstructed in the event of a computer system failure.

In a computer system, a process for failure recovery that specifies a joint behavior of two interacting components of the computer system comprising:

• a) storing data relating to a set of at least two software components communicating with each other on a survivable media to make the data available subsequent to an anticipated failure in the computer system;
• b) periodically removing saved data from the survivable media if two communicating components agree persistance of one or both of said components no longer requires said data to be stored on the survivable media;
• c) exchanging messages between other related software components and one or more software components of the set of software components;
• and p1 d) in the event of an occurrence of an anticipated failure, accessing data from the survivable media to restore a status of one or more software components of the set affected by said failure and re-executing communications between one or more software components of the set of components and said other related components for related components that are affected by said failure.

A computer readable storage medium having computer-executable instructions for performing the steps comprising:

• a) maintaining one or more software components that execute on a computer in the computer system as persistent components;
• and b) maintaining one or more software components that execute on a computer in the computer system as transactional components;
• c) implementing a contract between any two communicating persistent or transactional components that logs data concerning at least one of the communicating persistent or transactional components to a stable log so that a state of the communicating components can be re-instantiated in the event of a failure in the computer system;
• and d) maintaining one or more software components that execute on the computer system as a related component which interacts with at least one persistent component so that interactions between the related component and a persistent component do not require logging of a state of the related component on the stable log to allow the related components to be re-instantiated in the event of a computer system failure.