Mick Jordan and Malcolm Atkinson. Orthogonal persistence for java - a mid-term report. In Advances in Persistent Object Systems: Proceedings of POS-8 and PJAVA3, pages 335352. Morgan Kaufmann, 1998.  Home/Search   Document Details and Download   Summary   Related Articles   Check

....following three principles: 1. Type Orthogonality 2. Persistence by Reachability 3. Persistence Independence These were first introduced by Atkinson et al. Atk78, ACC82, ABC 83] summarised by Atkinson and Morrison [AM95] and their applicability to Java analysed by Atkinson and Jordan [JA98, AJ99, AJ00] Below we explain the above three principles in more detail. 2.1.1.1 Type Orthogonality Persistence is available for all data, irrespective of type. Many systems claim that they provide orthogonal (sometimes also referred to as transparent) persistence. However, deeper ....

....be re initialised and their values could become inconsistent with the state of the persistent instances of that class. If some initialisation (e.g. a native library loading) must be performed every time a class is loaded from the store, this can be done by Action Handlers that PJama supports [JA98] We have already mentioned that classes that are required to define the format of reachable instances, and that are referenced directly from persistent objects, are considered reachable. However, one other way for classes to become reachable exists: it is the reachability that is implicit in ....

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M.J. Jordan and M.P. Atkinson. Orthogonal Persistence for Java --- A Mid-term Report. In M.P. Atkinson, M.J. Jordan, and R. Morrison, editors, Proceedings of the 3rd International Workshop on Persistence and Java, pages 335--352. Morgan Kaufmann, 1998.

....of program state and process state, and extends it further. Various systems have used object persistence for saving state of data objects. They include the CMUDome project [1] object persistence features of Microsoft s COM and MFC, and the Forest project for orthogonal persistence in Java [11]. The current Java environment provides Object Serialization protocol, which is used for saving and transferring state of objects. As stated earlier, checkpointing of MT programs has not received much attention. In a previous work [12] we have demonstrated use and suitability of compile time ....

Mick Jordan and Malcolm Atkinson. Orthogonal persistence for java - a mid-term report. In Third International Workshop on Persistence and Java, Tiburon, CA, Sep 1-3, 1998.

.... originally implemented in General Magic s Telescript language [27] While it is possible to achieve some measure of transparent persistence by techniques such as having a special class loader insert read and write barriers into the source code before execution, such an approach poses many problems [13]. First, the transformed bytecodes could not be reused outside of a particular persistence framework, defeating the Java platform goal of code portability. Second, such an approach would not be applicable to the core classes, which cannot be loaded by this mechanism. Third, the code ....

Jordan, M., & Atkinson, M. (1998). Orthogonal persistence for Java A mid-term report. Sun Microsystems Laboratories.

.... of a disk database, can be used to store all persistent data [ABC 83, AM95] The PJama project, a collaboration between Sun Microsystems Laboratories and the University of Glasgow, is a development of a platform for the Java programming language that provides orthogonal persistence [JA98, AJ99, AJ00] One important aspect of handling orthogonally persistent data in PJama is that if an instance of some class is made persistent, the class itself is made persistent (by transitive closure) AJ99] This means that if the store is reopened for a later execution and an instance is ....

....oldC) method: 4.7 Copying and Conversion of Static Variables PJama supports the persistence of static variables unless they are marked transient. This sets PJama apart from most of the other known persistence solutions for the Java platform, which treat static variables as implicitly transient [JA98] Therefore the evolution system has to provide support for the conversion of static variables. When the new version of class C is loaded, its static fields are initialised with their initialisers as usual. After the change validation phase of evolution is complete, for each class that will ....

M.J. Jordan and M.P. Atkinson. Orthogonal Persistence for Java --- A Mid-term Report. In M.P. Atkinson, M.J. Jordan, and R. Morrison, editors, Proceedings of the 3rd International Workshop on Persistence and Java, pages 335--352. Morgan Kaufmann Publishers, Inc., 1998.

....from non persistent. To make some object and all objects reachable from it persistent, this object is declared a persistent root simply by passing it, together with an arbitrary text string, to the setPRoot(String, Object) method of 1 There are some limitations in the current implementation see [10] 1 org.opj.PJStore class. The string serves as a label of this persistent root. When the program terminates, all persistent objects are saved atomically to the persistent store. Later, this or different program can retrieve the same persistent root by calling the PJStore. getPRoot(String) ....

....are copied from one class to another. This happens for all fields except the final ones (in both or just one version of a class) they will always have the value defined in the last version of the class. Note that PJama arranges that the static initializers of a class are run exactly once (see [10]) and for a substitute class this happens when it is loaded, i.e. before the fields are copied from the old class. Thus if the programmer needs to re initialize some non final field, he she has to write a static data conversion method. The substituter itself removes old versions of classes from ....

Mick Jordan and Malcolm Atkinson. Orthogonal Persistence for Java - A Mid-term Report. To appear in proceedings of the Third International Workshop on Persistence and Java (PJW3), 1998.

.... work The notion of orthogonal persistence has a long history [7] traced through the development of prototype orthogonal persistent programming languages such as PS Algol [5, 8, 6] and Napier88 [61, 28] and extensions to existing languages such as Smalltalk [55, 54, 77, 44, 40, 38] and Java [10, 52, 9, 53]. It is important to note that all of these prototypes rely on support for persistence from an underlying virtual machine, implemented as an interpreter of abstract machine instructions. While dynamic translation (i.e. JIT compilation) can improve performance in these systems, neither ....

....of an abstract execution model is that persistence of code and active execution states (i.e. threads) can be supported more easily. Napier88, Tycoon [60] and Smalltalk support both, while the PJama implementation of orthogonal persistence for Java supports persistent code but not threads (yet) [10, 52, 9, 53]. Performance conscious persistent programming languages have historically been based almost exclusively upon C , which at its outset was hostile to ideas of automatic storage management on the grounds that it compromised performance. Hence, C based persistence extensions have adopted models ....

JORDAN,M.,AND ATKINSON, M. Orthogonal persistence for Java -- a mid-term report. In Morrison et al. [62].

.... originally implemented in General Magic s Telescript language [27] While it is possible to achieve some measure of transparent persistence by techniques such as having a special class loader insert read and write barriers into the source code before execution, such an approach poses many problems [12]. First, the transformed bytecodes could not be reused outside of a particular persistence framework, defeating the Java platform goal of code portability. Second, such an approach would not be applicable to the core classes, which cannot be loaded by this mechanism. Third, the code ....

Jordan, M., & Atkinson, M. (1998). Orthogonal persistence for Java---A mid-term report. Sun Microsystems Laboratories,

....definition) The latter principle gives a simple idea of how to distinguish persistent data from non persistent. To make some object and all objects reachable from it persistent, this object is declared a persistent root simply by 1 There are some limitations in the current implementation see [10] passing it, together with an arbitrary text string, to the setPRoot(String, Object) method of org.opj.PJStore class. The string serves as a label of this persistent root. When the program terminates, all persistent objects are saved atomically to the persistent store. Later, this or different ....

....which are present both in C and in C 0 are copied from one to another. This happens for all fields except the final ones the latter will always have the value defined in the last version of the class. Note that PJama arranges that the static initializers of a class are run exactly once (see [10]) and for a substitute class this happens when it is loaded, i.e. before the fields are copied from the old class. Thus if the programmer needs to re initialize some non final field, he she has to write a static data conversion method. The substituter itself removes old versions of classes from ....

Mick Jordan and Malcolm Atkinson. Orthogonal Persistence for Java - A Mid-term Report. To appear in proceedings of the Third International Workshop on Persistence and Java (PJW3), 1998.

....system, it may be crucial that its evolution subsystem can guarantee that any reasonable modification of persistent classes (schema) and, consequently, persistent objects, can be performed with minimum effort and without the necessity of rebuilding the whole database from scratch. PJama [1, 2, 10, 13] is an experimental persistent programming system for the Java programming language. It has much in common with object oriented database systems used together with Java. PJama is being developed as a collaborative project between Glasgow University and Sun Microsystems. For PJama, mechanisms are ....

....or individual bytecodes. At present PJama writes both persistent objects and their classes to a persistent store (an equivalent of a single database) Furthermore, it preserves all classes reachable from classes of persistent objects. The reasons for adoption of such a policy are explained in [10]. For many applications this results in the number of persistent classes becoming large, often much larger than one intuitively expects. Once a class becomes persistent, it is saved inside the store and therefore can not be replaced by simply modifying its source code and running the Java ....

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Mick Jordan and Malcolm Atkinson. Orthogonal Persistence for Java - A Mid-term Report. In Advances in Persistent Object System. Proceedings of The 8th International Workshop on Persistent Object Systems (POS-8) and The 3rd International Workshop on Persistence and Java (PJAVA-3), Morgan Kaufmann, 1999, pp 335-352.

.... Requirement B Persistence Independence Independence, which is critical for convenient code re use, is assured if we achieve exact compliance with the (JLS [91] In the first three versions of PJama the initialization of classes was over eager and therefore there was not exact compliance [120]. This has been remedied. There are some places where the definition 7 They assume their initializer is run every time that a JVM execution loads them. 14 of Java platform is not explicit about the semantics of resumption in the context of a continuous execution model. This requires ....

....This has been remedied. There are some places where the definition 7 They assume their initializer is run every time that a JVM execution loads them. 14 of Java platform is not explicit about the semantics of resumption in the context of a continuous execution model. This requires clarification [120, 121]. Otherwise, we can be reasonably confident that there are no unsolved problems with persistence independence. 4.2.3 Requirement C Durability Any persistent platform must provide application developers with confidence in its reliability. That is, they must be assured that their software ....

[Article contains additional citation context not shown here]

M.J. Jordan and M.P. Atkinson. Orthogonal Persistence for Java --- A Mid-term Report. In Morrison et al. [161], pages 335--352.

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Mick Jordan and Malcolm Atkinson. Orthogonal persistence for java - a mid-term report. In Advances in Persistent Object Systems: Proceedings of POS-8 and PJAVA3, pages 335352. Morgan Kaufmann, 1998.

No context found.

M. Jordan and M. Atkinson, Orthogonal Persistence for Java---A Mid-Term Report, Sun Microsystems Labs, 1998.

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