Purdy, A. / Schuchardt, B. / Maier, D. "Integrating an Object Server with Other Worlds" From "Object-Oriented Databases with applications to CASE, Networks, and VLSI" Gupta, R. / Horowitz, E. (Editors) ISBN 0-13-629833-8; Prentice hall  Home/Search   Document Not in Database   Summary   Related Articles   Check

....pointers are always external identifiers, and consequently must always be looked up. We permit object pointers to be both real memory addresses and object identifiers, and our design demonstrates an alternative approach to persistence that does not require an explicit object table. GemStone [Purdy et al. 1987], is another effort to expand the Smalltalk heap to include objects 12 on disk. However, it extends Smalltalk to provide considerable database functionality, including queries and an execution model. Integration with Smalltalk systems is not totally seamless, since the virtual image is modified ....

Alan Purdy, Bruce Schuchardt, and David Maier. Integrating an object server with other worlds. ACM Transactions on Office Information Systems 5, 1 (January 1987), 27--47.

....designed for centralized rather than distributed use, and its large object identifiers and higher overhead interface make it less efficient as a platform for our persistent programming languages. 5. 2 Object Oriented Databases Some relevant object oriented database systems are Orion [25] GemStone [36], and VBase [3] These systems are oriented toward specific languages (Lisp, Smalltalk, and C C , respectively) Orion and GemStone do support (single) servers, but none of the systems have Mneme s orientation toward a large distributed space of objects. More importantly, Orion and GemStone are ....

PURDY, A., SCHUCHARDT, B., AND MAIER, D. Integrating an object server with other worlds. ACM Trans. Office Inf. Syst. 5, 1 (Jan. 1987), 27--47.

....implementing monitors and atomic objects for concurrency control, and linking models to views in Smalltalk s MVC interface framework. Encapsulators have been used to build proxy objects in several distributed Smalltalk systems [1, 8] the NeXTSTEP [9] environment, and object oriented databases [13]. Encapsulators have also been used for tracing and debugging Smalltalk programs [6] and providing general reflexive facilities [4] The Self system includes interceptor objects which are simple encapsulators [17] Figure 1 illustrates the basic design of an encapsulator. The target object is ....

A. Purdy, D. Maier, and B. Schuchardt. Integrating an object server with other worlds. ACM Transactions on Information Systems, 5(1), January 1987.

....will be in virtual memory. In the same way as the operating system uses physical RAM as a cache against the virtual memory backing store, the virtual memory is used by the execution environment as a cache against the persistent store on secondary storage. Examples of this approach are GemStone [Purdy87], PSalgol [Atkin87] Mneme [Moss88] Comandos [COMAN87] Avance [Bjorn88] and, in general, most of today s database systems. We call this the multilevel approach, because several levels of memory are explicitly managed by the execution environment. Note that no logical difference between these ....

A. Purdy, B. Schuchardt, and D. Maier, "Integrating an Object Server with Other Worlds," ACM Transactions on Office Information Systems, vol. 5, no. 1, pp. 27-47, Jan. 1987.

....to problem of managing objects. An object oriented database is therefore a system that provides database like support (i.e. for persistence, transactions, querying, etc. for objects, that is, encapsulated data and operations. Some examples are the GemStone system from Servio Logic [24][30], Orion from MCC [6] and Iris from Hewlett Packard Labs [12] 14] Although object oriented databases are being built and have clearly practical applications, there are several open problems in this area. First of all, there is no agreement as to a standard data model for object oriented ....

A. Purdy, B. Schuchardt and D. Maier, "Integrating an ObjectServer with Other Worlds," ACM TOOIS, vol. 5, no. 1, pp. 2747, Jan 1987.

....POSs and storage managers include the Exodus storage manager [23, 32] O 2 [29] and Mneme 4 [33, 34, 35] Mneme is the POS used for this study. There have also been a number of designs related to virtual memory such as [2, 3, 36, 37, 38] Object servers include ObServer [39] and Gemstone [40]. We know of no prior studies of swizzling performance, and hence can offer no comparison with directly related work. Published OODB benchmarks and performance studies include [41, 42, 43, 44, 45, 46] 1.2 Simplifying assumptions To study swizzling and obtain clear results, we focus on ....

A. Purdy, B. Schuchardt, and D. Maier, "Integrating an object server with other worlds," ACM Trans. Office Information Systems, vol. 5, pp. 27--47, Jan. 1987.

....to objects. 5 Objectivity, Inc. 800 El Camino Real, 4th Floor, Menlo Park, CA 94025. 6 Versant Object Technology Corporation, 4500 Bohannon Drive, Menlo Park, CA 94025. 7 Ontologic, Inc. Three Burlington Woods, Burlington, MA 01803. 2.2.2. 1 GemStone GemStone [Copeland and Maier, 1984; Purdy et al. 1987; Bretl et al. 1989] is a commercial database system incorporating the data model of Smalltalk (consisting of objects, messages, and classes) and the programming language OPAL, 8 with syntax much like that of Smalltalk, for data definition and manipulation. To support sharing, the database is ....

Purdy, A., Schuchardt, B., and Maier, D. (1987). Integrating an object server with other worlds. ACM Transactions on Office Information Systems, 5(1):27--47.

....approach to LOOM in its implementation of a persistent Smalltalk system, using an object table to translate between object pointers and memory addresses. Alltalk performs no swizzling: object pointers are always external identifiers that must be translated whenever they are dereferenced. GemStone [17], is another effort to expand the Smalltalk heap to include objects on disk. However, it extends Smalltalk to provide considerable database functionality, including queries and a query execution model. Gemstone s integration with Smalltalk systems is not totally seamless, since the virtual image ....

A. Purdy, B. Schuchardt, and D. Maier. Integrating an object server with other worlds. ACM Trans. Office Inf. Syst., 5(1):27--47, Jan. 1987.

....necessary, however, because it models a dependence in the application domain. For this reason, the Remote Place pattern is very commonly used together with Single Place (3) Known Uses: The proxy objects used in distributed operating systems (such as NextStep [11] and databases (such as Gemstone [19]) are Remote Places which provide access to the Single Place in other address spaces where objects are really stored [8] Just as relational database normalisation ensures each data item is stored in a Single Place (3) a database foreign key is a Remote Place by which one table can refer to ....

Alan Purdy, Bruce Schuchardt, and David Maier. Integrating an object server with other worlds. ACM Transactions on Information Systems, 5(1), January 1987.

....the narrow issue of distributed relational systems that, as pointed out before, seem less than perfect for the engineering world. Lately, stimulated by CAD applications, full distribution has been reduced to the server client paradigm where distribution control appears more manageable, see, e.g. [10]. What, now, is the basic premise untouched by all these efforts We claim that ubiquity is this premise, i.e. the assumption that each item in the database must potentially be accessible in an equitable fashion by any user from any site at any time. By necessity, this entails a large degree ....

A. Purdy, B. Schuchardt, and D. Maier. Integrating an object server with other worlds. ACM Trans. Office Information Syst., 5(1):27--47, Jan 1987.

....preference specifications are used to resolve constraints violated in the target by preferring facts from one of the sources over the others. 1 Introduction One of the features touted by persistent object base researchers is the lack of need for object identification in POBs[FBC 87, PSM87, Gro87, DCBM89] In essence, persistent objects have persistent Identifiers (IDs) which make them distinct from all other objects simply by the way they are created. In fact, this feature is shared with the programming language freedom to create arrays, vectors, records and other structures, ....

Alan Purdy, Bruce Schuchardt, and David Maier. Integrating an object server with other worlds. ACM Transactions on Office Information Systems, 5(1):27--47, January 1987.

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Purdy, A. / Schuchardt, B. / Maier, D. "Integrating an Object Server with Other Worlds" From "Object-Oriented Databases with applications to CASE, Networks, and VLSI" Gupta, R. / Horowitz, E. (Editors) ISBN 0-13-629833-8; Prentice hall

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