Abstract. Persistent programming systems are designed as an implementation technology for long lived, concurrently accessed and potentially large bodies of data and programs, known here as persistent application systems (PASs). Within a PAS the persistence concept is used to abstract over the physical properties of data such as where it is kept, how long it is kept and in what form it is kept. As such it is seen as having a number of benefits in simplifying the task of PAS programming. Here, we describe the integrated design of the Napier88 persistent programming system and how Napier88 may be used to develop PASs.

Persistent systems support mechanisms which allow programs to create and manipulate arbitrary data structures which outlive the execution of the program which created them. A persistent store supports mechanisms for the storage and retrieval of objects in a uniform manner regardless of their lifetime. Since all data of the system is in this repository it is important that it always be in a consistent state. This property is called integrity. The integrity of the persistent store depends in part on the store being resilient to failures. That is, when an error occurs the store can recover to a previously recorded consistent state. The mechanism for recording this state and performing recovery is called stability. This paper considers an implementation of a persistent store based on a large virtual memory and shows how stability is achieved.

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