M. P. Atkinson, K. J. Chisolm, and W. P. Cockshott. PS-Algol: an Algol with a persistent heap. SIGPLAN Notices, 17(7):24--31, July 1982.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....2.1.1 Orthogonal Persistence Orthogonal Persistence (OP) AM95] is a language independent model of persistence, defined by the 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. ....

M.P. Atkinson, K.J. Chisholm, and W.P. Cockshott. PS-Algol: an Algol with a Persistent Heap. ACM SIGPLAN Notices, 17(7):24--31, July 1982.

....Databases have always been capable of operating on data, generally through queries. More recently, programming languages have supported orthogonal persistence. This is the notion that all data types, whether stored persistently or temporarily, are treated equivalently in the language. PS algol [4] and Elle [1] were among the first programming languages to support orthogonal persistence. Napier88 [26] is a more recent example. Persistent object systems have been around nearly this long. Persistent object systems provide orthogonal persistence in object based environments. One of the ....

....the design must be re implemented for each language run time system. Language persistence is commonly integrated into the language run time system. This approach is the earliest in persistent systems. Persistent systems grew up around such early persistent programming languages as PS algol [4] and Elle [1] as well as the later Napier88 [26] in which persistence support existed as a part of the language run time system. The earliest persistent object system was POMS [16] more recent examples include Thor [54] and Mneme [58] Java has been a specific target of modifications to support ....

M. Atkinson, K. Chisholm, and P. Cockshott. PS-algol: an algol with a persistent heap. SIGPLAN Notices, 17(7):24--31, July 1982.

....systems track changes at the granularity of objects. This granularity has also been shown to reduce contention in distributed shared memory systems [20] This approach is the earliest in persistent systems. Persistent systems grew up around such early persistent programming languages as PS Algol [2] and Elle [1] as well as the later Napier88 [10] in which persistence support existed as a necessary part of the language run time system. The earliest persistent object system was POMS [7] more recent examples include Thor [23] and Mneme [26] Java has been a specific target of modifications ....

M. Atkinson, K. Chisholm, and P. Cockshott. PS-Algol: an Algol with a persistent heap. SIGPLAN Notices, 17(7):24--31, July 1982.

....designates an object a persistent root and provides applications with a built in function for locating it. Any object that is reachable from the persistent root, for instance by following pointers, is automatically made persistent. The first language to provide orthogonal persistence, PSAlgol [5], was conceived in order to add persistence to an existing language with minimal perturbation of its initial semantics and implementation. There are persistent versions of functional programming languages, such as Persistent Poly [6] and Poly ML [7] There has also been research done on adding ....

Atkinson, M. P.; Chisholm, K.; Cockshott, W.: "PS- Algol: An Algol with a Persistent Heap". ACM SIGPLAN Notices 17(7), pp. 24 -- 31, July 1981.

....system program ming tasks. By virtue of its polymorphic type system TL can also be utihzed as a data modehng language. In this respect, Tr resembles Lisp development systems [3] and commercial object oriented languages hke Smalltalk [9] From integrated database programming languages hke PS Algol [2], Napier88 (see Chapter 1.1.3) Amber [4] and P Quest, mentioned before, Tycoon inherits the orthogonahty of elementary kernel concepts for persistence abstraction, type complete data struc turing, and iteration abstraction [1, 24] Motivated by an analysis of the conceptual and technological ....

M.P. Atkinson, K.J. Chisholm, and W.P. Cockshott. PS-algol: An algol with a persistent heap. ACM SICPLAN Notices, 17(7), July 1981.

....to the clients. Instead, objects that the clients can access by dereferencing pointers starting from either root are considered live and will be preserved by the system. A garbage collector will identify unreachable objects and recycle their storage. Our interface provides orthogonal persistence [4]: objects that are reachable via the persistent root are guaranteed to survive system failures. In Figure 1, the stability of the persistent root and the stable heap to which it points are indicated by their gray background. In contrast, objects reachable only via the transitory root are not ....

.... to reconstruct the committed contents of the stable heap from its stable log, 6 Related Work The basic literature on uniprocessor garbage collection techniques is surveyed by Wilson [21] Discussions of persistent heaps and language support for transactions appear in work on Persistent Algol [4] and Argus [15] Garbage collection algorithms based on replication appear in work by Nettles and O Toole [16, 17, 19] and an instance of the basic technique is also described by Huelsbergen and Larus [13] We are aware of only one other implementation of a concurrent collector for a persistent ....

M. P. Atkinson, K. J. Chisolm, and W. P. Cockshott. PS-Algol: an Algol with a persistent heap. SIGPLAN Notices, 17(7):24--31, July 1982.

....objects reside is retained. However, this address space is partitioned into semi independent regions. Each of these regions contains a logically related set of data and the model is optimised on the assumption that there will be few inter region references. Such an approach was used for PS algol [5] and is the basis of the Monads architecture [34] Providing that control can be retained over the interregion references it is possible to garbage collect and checkpoint regions (or at least limited sets of regions) independently, alleviating problems (i) and (iii) above [6, 33] In addition, the ....

Atkinson, M.P., Chisholm, K. J. and Cockshott, W. P. "PS-algol: An Algol with a Persistent Heap", ACM SIGPLAN Notices, vol 17, 7, pp.24-31, 1981.

....has been introduced [4] The idea was to add persistence to programming languages in a way that persistent data are seamlessly managed with respect to transient data. Persistence is integrated into the programming language with high level of transparency. Representative projects include PS Algol [5, 4], Napier88 [28] and PJama [6] In the early 80 s, Stonebraker pointed out the poor operating systems support for database management systems requirements [58] Representative projects having taken into account such requirements include the work on Mach s external mapers [64] single address ....

M.P. Atkinson, K.J. Chisholm, and P.W. Cockshott. PS-Algol: an Algol with a persistent heap. ACM SIGPLAN Notices, 17(7):24-31, 1982.

....an object as a persistent root and provides applications with a built in function for locating it. Any object that is reachable from the persistent root, for instance by following pointers, is automatically made persistent. The first language providing orthogonal persistence, PS Algol [3], was conceived in order to add persistence to an existing language with minimal perturbation to its initial semantics and implementation. There are persistent versions of functional programming languages such as Persistent Poly and Poly ML [4] There has also been work on adding orthogonal ....

Atkinson, M.P.; Chisholm, K.; Cockshott, W.: "PS-Algol: An Algol with a Persistent Heap". ACM SIGPLAN Notices 17(7), pp.24--31, July 1981.

....library search. 4 Pun intended. 16 Third, programming language and database ideas are merging, as witnessed by programming language design influencing query languagedesign(and vice versa) and more recently, the incorporation of persistence and atomic transactions in programming languages [9, 4, 1, 11]. We show a deeper connection between the two areas by identifying their different ideas of satisfaction: a program satisfies a specification and a database object satisfies a query are instances of the same general idea. Here, we use unification to do satisfaction checking, i.e. to do ....

M. P. Atkinson, K. J. Chisolm, and W. P. Cockshott. PS-Algol: an Algol with a persistent heap. SIGPLAN Notices, 17(7):24--31, July 1982.

....to extend its functionality. The persistence support, based on typed memory, has been specifically designed for use in a heterogeneous environment, and requires no changes to existing language compilers. The literature discusses many other approaches for obtaining object persistence. In PS Algol [2, 8], SOS [12] and GemStone [4] existing programming languages are extended, thus allowing an almost seemless addition of persistence. An alternative approach is taken in Arjuna [13] and Choices [5] where persistence is provided at the programmer level in a semi transparent way, by using the ....

Malcolm Atkinson, Ken Chisholm, and Paul Cockshott, "PS-algol: an Algol with a Persistent Heap" ACM Sigplan Notices, Vol.17 (7) , pp. 24-31 (July, 1982).

....with the general programming language design principle of data type completeness, all data values, whatever their type, should be allowed the full range of persistence. Languages that achieve both of the principles are called persistent programming languages. Some examples are PS algol [ACC81, ABC 83] Napier [AM88] and Galileo [ACO85] PS algol adds persistence to S algol [CM82] In PS algol a database exists as a persistent heap external to the program, and there is a persistent object management system which makes the database appear transparently as part of the standard ....

M. P. Atkinson, K. J. Chisholm, and W. P. Cockshott. Ps-algol: An algol with a persistent heap. SIGPLAN Notices, 17(7):24--31, July 1981.

....application in future Internet applications. An important design choice in persistent programming languages is deciding how objects will become persistent. Although many systems rely on explicit programmer actions to make particular objects persistent, we believe that orthogonal persistence [1] is the more desirable choice for reasons of safety and convenience. We have built a system that provides orthogonal persistence and in this paper we present an optimization to its implementation. In a system with orthogonal persistence, an object is persistent if it is reachable from the ....

M. P. Atkinson, K. J. Chisolm, and W. P. Cockshott. PS-Algol: an Algol with a persistent heap. SIGPLAN Notices, 17(7):24--31, July 1982.

....programming environment to arrive at an object oriented DBMS [Maier 84, Agrawal89] The prime issues to be addressed are support for persistency, concurrency control, recovery, and declarative query formulations. Although many recent DBPL papers [Dearle89, Agrawal89, LeCluse, Matthes 89, Atkinson81] aim at these potential markets, few have taken the requirements imposed by them as a driving force 4 for language design. To partially alleviate this situation, we believe that the application domain characteristics sketched in this paper have a significant impact on the syntax and semantics of ....

....The extensibility aspects, such as abstract data types and external libraries, are introduced in Section 11. We conclude with a project status and future work plan. 2 Data Types The core of Goblin consists of a type system common among database programming languages, such as PS Algol [Atkinson81] Napier88 [Dearle89] and DBPL [Matthes 89] These languages have their roots in the class of imperative programming languages and we assume a background in their predominant language concepts. The rationale for choosing an imperative programming language is one of historical stubbornness and ....

M.P. Atkinson et.al. `PS-Algol: An Algol with a Persistent Heap', ACM SIGPLAN Notices, 17(7):24-31, 1981

....name in a relationship no longer refers to an entity due to mutation of the name or removal of the entity. The above three points appear to be fundamental to all CMLs, and were advocated in the database context in the pioneering work of 2 For further details, consult the work of Atkinson (e.g. Atkinson et al. 82] who has considered in depth the problem of data persistence. 3 See [Date 81] for a review. 4 Abrial and Chen. Three special semantic relations: attribute, type, subtype As observed by McLeod and Smith in [Brodie Zilles 81] many CMs single out three binary semantic relations for ....

....allows TAXIS to take advantage of the considerable work on optimization in DBMS, but at the cost of not being able to fine tune this for an object oriented database. A similar philosophy was adopted by Kulkarni [Kulkarni 83] who implemented an extension of the DAPLEX language in PS Algol ( Atkinson et al. 82] Atkinson et al. 83] a language which allows for the storage of persistent data. In conclusion, none of the languages considered above appears to be clearly superior to the others; in fact there is room for a language which would capture the best of the ideas present in each language, such as ....

Atkinson, M.P., K.J.Chisholm & W.P.Cockshott. PS-Algol: an Algol with a persistent heap. ACM SIGPLAN Notices 17(7), July, 1982.

....used in these systems. 1. Introduction Lumberjack is a new log structured persistent object store intended for use with conventional operating systems such as Unix. The design of Lumberjack draws together facets of previous work, in particular, the CPOMS object store [3] used to support PS algol [1], and the page based log structured store [7] used in the Grasshopper persistent operating system [13] We believe that Lumberjack exhibits a novel store design that provides a number of benefits. Firstly, the use of log structured storage techniques allows I O operations to be optimised by ....

....that constitutes Lumberjack. Finally, section 5 describes the future directions for Lumberjack before concluding. 2. Object Addressing in the CPOMS The CPOMS [3] is a persistent object management system written in C that provides a stable storage layer for the PS algol abstract machine [1]. The architecture of the abstract machine and the CPOMS is shown in Figure 1, which depicts two heaps: a local heap that is managed by the abstract machine, and an external heap that is managed by the CPOMS. Objects held within the external heap are stable and are addressed by special pointers ....

M.P. Atkinson, K. Chisholm, and W. Cockshott, "PS-algol: An Algol with a Persistent Heap", ACM SIGPLAN Notices, 17(7), pp. 24-31, 1981.

....applications (e.g. simulations) would prefer it if these were automatically restarted from the point at which the crash occurred. Since the operating system does not include such services, they are added to each application on an ad hoc basis as discussed in the next section. In 1981, Atkinson [1, 2] proposed that all data in a system should be able to survive for as long as that data is required; he called the attribute of longevity persistence. He also proposed that all data should be treated in a uniform manner regardless of the length of time for which it persists. That is, the ....

....systems provide a uniform abstraction over all data storage. Furthermore, since the state of a process is just data, processes themselves may be made persistent [15] and may outlive a single invocation of a system. Although persistence can be implemented by a programming language runtime system [2] it is our contention that the provision of support for persistence at the operating system level ensures the overall integrity of the data without restricting the system to a single language, and that such a persistent operating system provides a solution to the problems outlined above. Although ....

Atkinson, M. P., Chisholm, K. J. and Cockshott, W. P. "PS-algol: An Algol with a Persistent Heap", ACM SIGPLAN Notices, 17(7), pp. 24-31, 1981.

....uniformly, contravening the first principle. The technique used to identify persistent data must be independent of the type system. One such method would be to employ persistence by reachability. The system automatically identifies persistent data by following pointers from some persistent root [2]. 5.1 The Grasshopper Operat ing System Grasshopper is an example of a persistent operating system. In this section we describe the three basic abstractions provided by Grasshopper. The abstraction over storage is the container and the abstraction over execution is the locus (plural loci) The ....

M.P. Atkinson, K.J. Chisholm, and W.P. Cockshott, "PS-algol: An Algol with a Persistent Heap", ACM SIGPLAN Notices, 17(7), pp. 24-31, 1981.

....the need for multivalued dependencies to be handled as a special case of dependency. The codomain (range) of a functional dependency can be typed as single or multiplevalued enabling fourth normal form (4NF) to be forgotten. Work through the 1980s on persistent data systems by Atkinson et al. [Atkinson, Chisholm Cockshott 1981] highlighted another weakness in the conventional database approach: that variables defined in a host language accessing the database were from a different world to those within the database. Moreover, the type systems within, say, a relational database system of the 1980s were very limited being ....

Atkinson, Chisholm & Cockshott 1981, Atkinson, M P, Chisholm, K J, & Cockshott, W P, (July 1981), PS-Algol: an Algol with a persistent heap, ACM SIGPLAN Notices 17(7).

....8 OID: 11 value: 8 (0) OID: 12 value: 3 (1) OID: 13 value: 5 (0) OID: 14 value: 1 (1) OID: 15 value: 7 (0) OID: 16 value: 0 (1) Figure 2. A simple persistent store organized as a binary tree. erroneous. Our persistence model uses the mechanism of persistence by reachability [8]. The event set root indicates the (super) root of the reachability analysis. It is important to understand that PTF does not enforce any notion of access consistency. Nor does it require any particular storage reclamation scheme, namely manual versus automatic storage reclamation. Clearly, the ....

Atkinson MP, Chisholm KJ, Cockshott WP. PS-Algol: An Algol with a persistent heap. ACM SIGPLAN Notices 1982; 17(7):24--31.

....approach. We focus exclusively on advanced languages that support object oriented data models, and do not discuss database programming languages (e.g. Pascal R, RIGEL, etc. that extend relational programming techniques because the former are more relevant to our research. PS algol PS algol [ACC82, ABC 83a, ABC 83b] was the first truly persistent programming language, and has contributed much to the study and development of efficient persistent systems. The notion of orthogonal persistence was pioneered in the implementation of PS algol, which supports full reachability based ....

Malcolm P. Atkinson, Ken J. Chisholm, and W. Paul Cockshott. PS-Algol: An Algol with a Persistent Heap. ACM SIGPLAN Notices, 17(7):24--31, July 1982.

....important. They also demonstrate that software write detection mechanisms can signi#cantly outperform approaches that rely solely on the hardware and operating system. Categories and Subject Descriptors: ##: General Terms: Additional Key Words and Phrases: 1. INTRODUCTION A persistent system #Atkinson et al. 1982; Atkinson et al. 1983; Atkinson et al. 1983; Atkinson and Buneman 1987# maintains data independently of the transitory programs that create and manipulate that data data may outlive their creators, and be manipulated by yet other programs. To achieve this, persistent systems provide an ....

Atkinson, M., Chisolm, K., and Cockshott, P. 1982. PS-Algol: an Algol with a persistent heap. ACM SIGPLAN Notices 17, 7 #July#, 24#31.

....programs may create data structures which outlive their execution and there is no need to write code to flatten data structures in order to store them in files. A number of persistent systems have been constructed, most of which have been built above conventional operating systems, usually Unix [1,4,25,26,32]. Although these systems have been successful in terms of demonstrating the feasibility of persistence as a programming paradigm, efficiency has been a major problem. This is not surprising since they are being constructed above operating systems with a model that is fundamentally different from ....

Atkinson, M. P., Chisholm, K. J. and Cockshott, W. P. "PS-algol: An Algol with a Persistent Heap ", ACM SIGPLAN Notices, 17(7), pp. 24-31, 1981.

.... semantics and compile time program analysis and optimization [67, 43, 42, 64, 38, 39, 48, 66, 65, 18, 17] 3 Related 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 ....

ATKINSON,M.,CHISOLM,K.,AND COCKSHOTT, P. PS-Algol: an Algol with a persistent heap. ACM SIGPLAN Notices 17,7(July 1982), 24--31.

.... of the basic technique is described in by Huelsbergen and Larus[11] Related work on concurrent collection appears in [6] The basic literature on uniprocessor garbage collection techniques is surveyed in [18] and discussions of persistent heaps and language support for transactions appears in [4, 13]. There are two earlier designs of concurrent garbage collectors for persistent heaps. Both of these designs are based on the concurrent garbage collection algorithm of Ellis, Li, and Appel. Detlefs[9] described how to apply this algorithm in a C environment which included transactions. ....

M. P. Atkinson, K. J. Chisolm, and W. P. Cockshott. PS-Algol: an Algol with a persistent heap. SIGPLAN Notices, 17(7):24--31, July 1982.

....to be as easily extended as Mneme is through its pool strategies, forwarding protocols, etc. Also, these other systems are all attempts at complete database management systems, and end up being heavy weight compared with Mneme. 5. 3 Persistent and Database Programming Languages PS Algol [4, 5] is representative of the persistent programming languages, and E (already mentioned) O 2 [27, 6] O [1, 2] and Opal (the language in the Gemstone system) of recent database programming languages. These systems are all oriented toward particular programming languages and or data models, ....

ATKINSON, M., CHISOLM, K., AND COCKSHOTT, P. PS-algol: an Algol with a persistent heap. ACM SIGPLAN Notices 17, 7 (July 1982), 24--31.

....the system, makes it more difficult to understand and means that 3 applications which do not fit into the relational model cannot be implemented without resorting to an external file system. In many persistent systems persistence is determined by reachability from some form of persistent root [13, 15, 19]. Thus all persistent objects can be found by computing the transitive closure of that root. Other systems have taken the approach of associating persistence with type [40, 50] in violation of the third principle (and the second as a consequence) This can result in dangling references, or at best ....

Atkinson, M. P., Chisholm, K. J. and Cockshott, W. P. "PS-algol: An Algol with a Persistent Heap", ACM SIGPLAN Notices, 17(7), pp. 24-31, 1981.

.... first identified as being orthogonal to its other attributes by Atkinson in [Atk78] After some attempts to provide persistence in other languages, S algol [Mor82] was identified as a suitable candidate and the first implementation of PS algol, the first persistent language, was completed in 1980 [ACC81]. Napier, a language based on PS algol but with a much richer type system, was first described in general terms in [AM85a] and the Napier88 system [MBC89] was released in 1988. A plethora of other persistent languages has also appeared since 1985 [MS89, Eve85, RC89, ACO85, Mat85, DM90, Car85, ....

M.P. Atkinson, K.J. Chisholm and W.P. Cockshott "PS-algol: an Algol with a Persistent Heap" ACM SIGPLAN Notices 17, 7 ( July 1981 ) pp 24 - 31

....memory. With shadowing, there is no log; updates are made to a shadow database that is swapped with the current database in a single atomic operation. When the version of persistent data stored in durable memory is consistent, it is called a checkpoint. 4.4. 1 Shadowing GemStone [15] and PS Algol [7, 25] are two persistent storage systems that use shadowing to provide recoverability. The system maintains multiple mappings of the database: an old mapping for the checkpoint and a new mapping for modified pages. Pages in memory are mapped copy on write [23] from the checkpoint. The system is ....

....and logging can be used to simplify concurrent compacting garbage collection [84] Compacting garbage collection offers many benefits to a persistent store. It can be used to support implicit object deletion, to reduce fragmentation, to recluster objects, and to implement implicit persistence [7]. Concurrency is important for the obvious reason that most applications will not tolerate long pause times that would otherwise occur while objects are being copied. Compacting collectors work by copying objects from the active copy of the database, called from space, into to space [65, 3, 104] ....

Malcolm Atkinson, Ken Chisholm, and Paul Cockshott. PS-Algol: an Algol with a persistent heap. SIGPLAN Notices, 17(7):24--31, July 1982.

....Procedural: Execution in a non object oriented procedural language proceeds through the invocation of statically determined procedures. Ignoring possibilities for optimization of residency checks based on local global data flow analysis, every dereference requires a residency check. 1 [ACC82, BC86, KK83, Kae86, CM84, RMS88, SMR89, BBB 88, Ric89, RC90, Ric90, SCD90, WD92, HMB90, Hos91, HM93a, LLOW91, SKW92, WK92] Static OO: Object oriented programs execute through the invocation of methods on objects. A method typically accesses the encapsulated state of its target object. Thus, ....

Malcolm Atkinson, Ken Chisolm, and Paul Cockshott. PS-Algol: an Algol with a persistent heap. ACM SIGPLAN Notices, 17(7):24--31, July 1982.

....to be supported by a common framework. It should be high performance in that it should be possible to optimise the storage system to suit specific classes of applications, in particular OODB applications. 1. 1 Persistent Programming Languages A persistent programming language, such as PS Algol [3], is a language which treats persistent or long lived date in the same way as volatile data. Persistent data is data which would traditionally be stored in data files. Persistent programming languages were originally devised to remove the impedance mismatch which arises when an application ....

....stores objects and supports their identity and structure. Applications can control clustering, prefetch, caching, concurrency control, recovery and versioning policies. POMS The Persistent Object Management System [32] POMS) implements persistence for the PS algol persistent programming language [3] . ObServer ObServer [33] is a type less object storage system which can support multiple data models. It uses the client server model. The following systems are included only because of their approaches to solving some particular design and implementation issues. MFS The Multi structured File ....

M.P. Atkinson, K.J. Chisolm, and W.P. Cockshott. PS-algol: An Algol with a persistent heap. ACM SIGPLAN, 17(7):24--31, July 1982.

....of any other property. In particular whether an object could persist was not associated with its type. The programmer could then choose a representation for the data purely on the basis of the algorithm and not in order to satisfy the requirements of a database system. The language PS Algol[2] was designed to test these ideas. A PS Algol program can open and operate on data in a database, modify it and add new data to it. There are functions to open and close the database and to commit , or write back changes. These same operations would be present in any database system. The ....

Atkinson M.P., Chisholm K.J. and Cockshott W.P. "PS-Algol: An Algol with a Persistent Heap." Technical Report CSR-94-81, Computer Science Dept., University of Edinburgh.

....of any other property. In particular whether an object could persist was not associated with its type. The programmer could then choose a representation for the data purely on the basis of the algorithm and not in order to satisfy the requirements of a database system. The language PS Algol[Atk81] was designed to test these ideas. A PS Algol program can open and operate on data in a database, modify it and add new data to it. There are functions to open and close the database and to commit , or write back changes. These same operations would be present in any database system. The ....

Atkinson M.P., Chisholm K.J. and Cockshott W.P. "PS-Algol: An Algol with a Persistent Heap." Technical Report CSR-94-81, Computer Science Dept., University of Edinburgh.

....kind of support for persistence that PerDiS needs. However, they all lack a fundamental property: support for fault tolerance, i.e. none offers transactional or checkpointing mechanisms. On the other hand, systems supporting orthogonal persistence and persistence by reachability (e.g. PS algol[3]) have never been broadly used for several reasons. However, the current effort in PJava [5] seems to be most promising given that, among other aspects, Java is becoming a widely used language. PJava complements the Java environment with persistence by reachability and some basic fault tolerance ....

M. Atkinson, K. Chisholm, and W. Cockshott. Ps-algol: An algol with a persistent heap. ACM SIGPLAN Notices, 17(7):24--31, 1982.

....in orthogonally persistent systems. The essence of the paper is to demonstrate how these basic facilities may be provided in Java with the same attendant benefits. 2 The Joys of Persistence 2. 1 PS algol (Mk 1) The first successful attempt to provide orthogonal persistence was PS algol (Mk 1) [ACC82]. This took the language S algol [Mor79] and added a persistent store. The language had a small number of base types int, real, bool, string and picture as well as two constructor types vector and structure. Thus, the universe of discourse was infinite since the constructors could contain any ....

Atkinson, M.P., Chisholm, K.J. & Cockshott, W.P. "PS-algol: An Algol with a Persistent Heap". ACM SIGPLAN Notices 17, 7 (1982) pp 24-31.

....implementation outlined. Many more persistent programming languages exist and new ones are being developed currently, for example the PJava project at the University of Glasgow 1 Of persistent types. 1. 1 PS algol Orthogonal Persistence, Object Faulting, and Swizzling The PS algol language [6, 5] was developed in a joint project between the Universities of Edinburgh and St. Andrews. PS algol is a persistent extension of S algol, a member of the Algol family of languages, which was developed at St. Andrews. Thus, although not strictly an object oriented language, PS algol is included here ....

Malcolm Atkinson, Ken Chisholm, and Paul Cockshot. PS-algol: An Algol with a persistent heap. ACM SIGPLAN Notices, 17(7):24--31, 1982.

....and extending the Tycoon persistent programming environment. This STYLE workbench provides integrated graphical and textual modeling tools, generation support and data model animation. 1 Introduction and Overview One of the remarkable features of persistent programming languages like PS algol [ACC81] Napier88 [MBC 94] and Tycoon [Mat95] is their rich set of data structuring facilities. Languages with orthogonal persistence and a sophisticated type system greatly simplify the task of implementing information systems that have to work with complex, long lived bulk data structures [MS95] ....

M.P. Atkinson, K.J. Chisholm, and W.P. Cockshott. PS-algol: An Algol with a Persistent Heap. ACM SIGPLAN Notices, 17(7), July 1981.

....we demonstrate how the mechanisms provided by Grasshopper may be used to implement a persistent version of the language Java. 1. Introduction Over the last ten to fifteen years we have seen a number of persistent language systems. Some of these were designed to be persistent from the outset [3, 19], others are persistent versions of ordinary programming languages e.g. 21] What these language systems have in common is that they have been implemented as separate language systems above a non persistent operating system. It is our belief that, although persistence can be implemented by a ....

Atkinson, M. P., Chisholm, K. J. and Cockshott, W. P. "PS-algol: An Algol with a Persistent Heap", ACM SIGPLAN Notices, vol 17, 7, pp. 24-31, 1981.

....to write persistent data to a flat binary file (e.g. a Unix file system file) or to a database management system (DBMS) The work involved in reading and writing this data is left to the programmer. Such languages are not presented here and are mentioned only to give a fuller picture. PS algol [ACC82] is a persistent programming language which provides persistence for any object reachable from a persistent root. PS algol provides basic support for persistent data and allows a programmer to access persistent objects without having to write persistent data to binary files. PS algol uses lazy ....

M.P. Atkinson, K.J. Chisolm, and W.P. Cockshott. PS-algol: An Algol with a persistent heap. ACM SIGPLAN, 17(7):24--31, July 1982.

....to be left unchanged, when new facilities are added to it, and makes third party library additions and experimentation easier. Examples of this trend are the C platform [15] and the still expanding Java platform [14, 33] In contrast, early orthogonally persistent languages, like PS algol [2] and Napier88 [21] were designed as closed systems. This allowed their implementers to achieve complete type orthogonality, since the state of all the data that needed to persist was known to the system. This approach proved the feasability of orthogonal persistence. However, it was very ....

M. P. Atkinson, K. J. Chisholm, and W. P. Cockshott. PS-Algol: an Algol with a Persistent Heap. ACM SIGPLAN Notices, 17(7):24--31, July 1982.

No context found.

M. P. Atkinson, K. J. Chisolm, and W. P. Cockshott. PS-Algol: an Algol with a persistent heap. SIGPLAN Notices, 17(7):24--31, July 1982.

No context found.

M. P. Atkinson, K. J. Chisholm, and W. P. Cockshott. PS-Algol: an Algol with a persistent heap. ACM SIGPLAN Notices, 17(7):24--31, 1981.

No context found.

M. P. Atkinson, K. J. Chisholm, and W. P. Cockshott. PS-Algol: an Algol with a persistent heap. ACM SIGPLAN Notices, 17(7):24--31, 1981.

No context found.

M. P. Atkinson, K. J. Chisholm, and W. P. Cockshott. PS-Algol: an Algol with a persistent heap. ACM SIGPLAN Notices, 17(7):24--31, 1981.

No context found.

Malcolm Atkinson. PS-Algol: An Algolwith Persistent Heap. Sigplan Notices, pages 24--30, July 1982.

No context found.

Malcom Atkinson et al. PS-Algol: an Algol with a persistent heap. Sigplan Notices, 24--30, July 1982.

No context found.

Malcom Atkinson et al. PS-Algol: an Algol with a persistent heap. Sigplan Notices, 24--30, July 1982.

No context found.

Atkinson MP, Chisholm KJ, Cockshott WP. PS-algol: An Algol with a Persistent Heap. ACM SIGPLAN Notices 1982; 17,7:24-31

No context found.

Atk82A Atkinson, M. P. & Chisholm, K. J. & Cockshott, W. P.: PS-algol: An algol with a persistent heap, ACM SIGPLAN Notices Vol. 17 No. 7 pp 24-31, ACM, 1982.

No context found.

M. P. Atkinson, K. J. Chisholm, and W. P. Cockshott. PS-Algol: An Algol with a Persistent Heap. ACM SIGPLAN Notices. 17(7):24-31, July 1982.

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