For ten years researchers have been attempting to construct programming language systems that support orthogonal persistence above conventional operating systems.

Scoping, naming and binding are central concepts in the definition and understanding of programming languages. With the introduction of sophisticated data models, these issues become important for query languages as well. Additionally, the goal of integrating query and programming languages requires a common basis for their operational semantics. We offer here an approach to the definition of the operational semantics of query languages based on an abstract machine, in which names, their bindings, and scopes defined by query and data structure are central. The machine has its own simple data model for a store, in addiction to a stack for dealing with scopes. We argue for the generality of the approach and illustrate this by defining the semantics of many query language primitives. Finally, we consider briefly how assignments and procedures can be neatly added. 1 Introduction A major theme of database research in the last decade is the relationship between declarative, high level query...

The principal tenet of the persistence model is that it abstracts over all the physical properties of data such as how long it is stored, where it is stored, how it is stored, what form it is kept in and who is using it. Experience with programming systems which support orthogonal persistence has shown that the simpler semantics and reduced complexity can often lead to a significant reduction in software production costs. Persistent systems are relatively new and it is not yet clear which of the many models of concurrency and distribution best suit the persistence paradigm. Previous work in this area has tended to build one chosen model into the system which may then only be applicable to a particular set of problems. This thesis challenges the orthodoxy by designing a persistent framework in which all models of concurrency and distribution can be integrated in an add-on fashion. The provision of such a framework is complicated by a tension between the conceptual ideas of persistence...

In this paper, operating system support for persistent systems that execute on conventional hardware architectures is examined. The focus of the paper is to examine the inadequacies of traditional operating systems as vehicles for the construction of persistent systems. We concentrate on four major areas, namely: addressing, stability and resilience, process management and protection. We examine the consequences of making the operating system kernel itself persistent. We conclude by outlining the requirements which must be met by future operating systems designed to support orthogonal persistence.

This paper presents the design of a new store layer for PJama. PJama is a platform that provides orthogonal persistence for Java. Based on experience with a prototype, PJama0, a new architecture has been devised to permit incremental store management and to allow a number of object management regimes to co-exist in one store. It uses a plug-in model for composing a Java Virtual Machine (JVM) with the persistent store and a descriptor abstraction to limit the impact of changes in JVMs on store management. Its anticipated advantages over the current scheme include flexibility, adaptability, scalability, and maintainability.

In an orthogonally persistent programming system the longevity of data is independent of its other attributes. The advantages of persistence may be seen primarily in the areas of data modelling and protection resulting from simpler semantics and reduced complexity. These have been verified by the first implementations of persistent languages, typically consisting of a persistent store, a run-time system and a compiler that produces programs that may access and manipulate the persistent environment. This thesis demonstrates that persistence can deliver many further benefits to the programming process when applied to software construction and execution. To support the thesis, a persistent environment has been extended with all the components necessary to support program construction and execution entirely within the persistent environment. This is the first known example of a strongly-typed integrated persistent programming environment. The keystone of this work is the construction of ...

Distributed persistent object systems provide a convenient environment for applications that need to manage complex long-lived data. Since Java has no persistence model built into it, the tremendous growth in the popularity of Java has generated a lot of interest in systems that add persistence to Java. This thesis presents the design, implementation and performance evaluation of a Java Persistent Store called JPS. JPS is an efficient distributed persistent Java system built on top of the Thor object-oriented database. JPS provides

Persistent stores have been implemented using a variety of storage technologies including shadow paging, log-based and log-structured approaches. Here we compare these approaches and advocate the use of log-structuring. The advantages of such a technique include efficient support for large (64 bit) address spaces, scalability and fast snapshot processing. We describe the architecture of a new log-structured persistent store and how it has been used to support resilient persistent processes in the context of the Grasshopper operating system. This store is based on the use of a log server which provides clients with private logical logs. Keywords persistent stores, log-structured stores, recoverable virtual memory. 1 Introduction The concept of persistence may be defined as the attribute of data which specifies its period of existence. Stemming from this simple definition, a wide range of systems supporting various forms of persistence have emerged. In systems that support orthogonal ...

Persistent languages and systems provide the ability to create and manipulate all data in a uniform manner regardless of how long it persists. Such systems are usually implemented above a stable persistent store which supports reliable long-term storage of persistent data. In this paper we consider the issue of distribution of the persistent store across nodes. A number of existing persistent languages with support for distribution are described in terms of a taxonomy of distributed stores. It is shown that there are considerable difficulties with these systems, particularly in terms of scalability. A new mechanism based on the exportation and remote execution of procedures is then described. A key feature of this mechanism is that an exported procedure may dynamically bind to data in the remote store. It is shown that the mechanism alleviates most of the problems of existing systems and provides considerable flexibility. The paper concludes with some examples of practical use...

In recent years a range of single programming language systems have been developed that are supported by a persistent store. Examples of such systems include Argus, Galileo, PS-algol and Smalltalk. Although each of these systems is based on a subtly different concept of persistence a common approach is to utilise a layered architecture. This paper presents the design of one such layered architecture that can be used to support a persistent object store where the protection is enforced by a high level type system. The architecture has been used to construct the persistent programming system for Napier88 and is powerful enough to support languages with similar type systems. 2 1 Introduction In recent years a range of single programming language systems have been developed that are supported by a persistent store[atk82,atk83b,ros83,bro85,that86,bro89]. Examples of such systems include Argus[lis84], Galileo[alb85a], PS-algol[psa88] and Smalltalk[gol83]. Although each of these s...