Object Design. ObjectStore User Guide, March 1991. Release 1.1.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....of a database object means changing its internal structure and its value. Changing the object internal format is the task of the database system and it is done automatically without the need for s Other object database systems using a similar approach are GemStone [5] and ObjectStore [10]. 4Lazy updates are also called deferred updates. Changing the object value is mainly an application dependent task. The solution for the schema designer or application builder is to write a conversion function which tells the database systems how to change the value of the affected objects, and ....

Object Design Inc. Objectstore User Guide, chapter 9. Object Design Inc., 1993.

....the database, besides providing object versions. The designer has to write a program which reads the necessary objects in the old format and assigns the values to the corresponding objects in the new format. The program can be written to transform the database both eagerly and lazily. ObjectStore [9] makes use of immediate database conversion. Transformation functions, which override the default conversion, can be associated with each modified class. A new instance, which conforms to the new definition of a corresponding class, is created for each old instance. The transformation function ....

Object Design Inc. ObjectStore User Guide, Release 3.0. Chapter 10, December 1993.

....temperature will be executed automatically every time this field is updated in either representation. On the other hand, the majority of the existing commercially available systems do not use versioning for updating the database. Instances are converted either immediately or lazily. ObjectStore [13] makes use of immediate database transformations. Transformation functions, which override the default transformation, can be associated with each modified class. As in PJama, instances are not restructured, but a new instance which conforms to the new definition of a corresponding class, is ....

Object Design Inc. ObjectStore User Guide, Release 3.0. Chapter 10, December 1993.

....technique described in [Wilso90] allows programs to access persistent objects by dereferencing standard virtual memory pointers, eliminating the need for software residency checks. The basic ideas presented in [Wilso90] were, at the same time, independently used by the designers of ObjectStore [Objec90, Lamb91], a commercial OODBMS product from Object Design, Inc. The implementation of ObjectStore, outlined briefly in [Objec90] differs in some interesting ways from the scheme described in [Wilso90] most notably in the way that pointer swizzling is implemented, and in how pointers are represented on ....

....eliminating the need for software residency checks. The basic ideas presented in [Wilso90] were, at the same time, independently used by the designers of ObjectStore [Objec90, Lamb91] a commercial OODBMS product from Object Design, Inc. The implementation of ObjectStore, outlined briefly in [Objec90], differs in some interesting ways from the scheme described in [Wilso90] most notably in the way that pointer swizzling is implemented, and in how pointers are represented on disk. Under the approach outlined in [Objec90] pointers between persistent objects are stored on disk as virtual memory ....

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Object Design, Inc., "ObjectStore User Guide", Release 1.0, October 1990.

....is used. 2 On the other hand majority of the existing commercial systems do not use versioning for updating the database. Applications can run on top of the schema as defined after the last update. Instances of a class, in this case are converted either immediately or lazily. Objectstore [5] makes use of immediate database transformation. Objects are not physically restructured but a new object is made instead. The transformation function reads the value in the oldobject and assigns it (after having made some modification to it) to the new object. Deferred transformation of objects ....

Object Design Inc. Object Store User Guide, Release 3.0, chapter 10, December 1993

....possibility to add conversion methods to a class. In both these systems versioning is used. One the other hand majority of the existing commercial systems do not use versioning for updating the database. Instances of a class, in this case are converted either immediately or lazily. Objectstore [5] makes use of immediate database transformation. Deferred transformation of objects is provided in systems like Itasca [4] and Versant [9] Both these systems do not provide the user with flexible conversion functions like the one presented in O2 [1] O2 object database system offers an automatic ....

Object Design Inc. Object Store User Guide, Release 3.0, chapter 10, December 1993

....of a database object means changing its internal structure and its value. Changing the object internal format is the task of the database system and it is done automatically without the need for 3 Other object database systems using a similar approach are GemStone [5] and ObjectStore [10]. 4 Lazy updates are also called deferred updates. manual assistance by the schema designer. Changing the object value is mainly an application dependent task. The solution for the schema designer or application builder is to write a conversion function which tells the database systems how to ....

Object Design Inc. Objectstore User Guide, chapter 9. Object Design Inc., 1993.

....[9, 19, 21] but nested relations do not alone support object oriented programming. The second problem is the difficulty of sharing data among applications with heterogeneous object schemata even when using a common database. Some object oriented database management systems are available currently [14, 15, 23], but they permit us to define only one conceptual schema for each database and do not support the view concept. This means all the applications which access the same database are forced to use the same structure of the object classes. As the result, application development is quite limited and ....

Object Design, Inc. ObjectStore User Guide. 1991.

....Updates When the schema of an object database system is modified, the database needs to be changed in such a way that the schema and the database remain consistent with each other. Several object database systems offer mechanisms to update the database: in few systems like O 2 [3] ObjectStore [10], and OTGen[7] the designer has the possibility to program so called user defined conversion functions which are associated to modified classes in the schema and define how objects have to be restructured. If no conversion functions are provided by the designer, the system provides default ....

Object Design Inc. ObjectStore User Guide, Release 3.0, chapter 10, December 1993.

.... normally using special primitives, see for example [9] and [10] while the database is modified using user defined conversion functions which take as input parameters the old and new schema class definitions and when executed transform the objects of the database to conform to the new schema [6]. The body of a conversion function defines the desired database transformation, and it is normally defined using the data manipulation language offered by the ODB, e.g. C [6] 7] The designer has to define for each modified class in the new schema a conversion function. System default ....

.... old and new schema class definitions and when executed transform the objects of the database to conform to the new schema [6] The body of a conversion function defines the desired database transformation, and it is normally defined using the data manipulation language offered by the ODB, e.g. C [6], 7] The designer has to define for each modified class in the new schema a conversion function. System default transformations are applied in case no explicit conversion functions are given by the designer [4] 6] 8] What is important for the application designer is that after execution of ....

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Object Design Inc. Objectstore User Guide, chapter 9, 1993.

....evaluate the effectiveness of the design of EPVM 2.0 this paper presents the results of a number of performance experiments that were conducted using the OO1 benchmark [Catte91] The experiments compare EPVM 2.0 with three alternative software architectures. The first of these is ObjectStore V1.2 [Objec90], a commercially available object oriented DBMS. ObjectStore uses a memory mapped approach to support pointer swizzling and fault objects into main memory. The second architecture is represented by EPVM 1.0 which supports only a limited form of pointer swizzling. The third architecture does not ....

....unswizzles any swizzled pointers that it contains. This ensures that there are no dangling references to objects that are no longer resident in memory. A pointer swizzling scheme based on virtual memory techniques is described in [Wilso90] A similar approach is used in Object Design s ObjectStore [Objec90, Lamb91]. The basic idea presented in [Wilso90] is to allocate virtual memory addresses for pages containing persistent data one step ahead of a program s actual usage of the pages. When a program first attempts to access a page, a virtual memory page fault occurs. This fault is intercepted by the ....

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Object Design, Inc., ObjectStore User Guide, Release 1.0, October 1990.

....temperature will be executed automatically every time this field is updated in either representation. On the other hand, the majority of the existing commercially available systems do not use versioning for updating the database. Instances are converted either immediately or lazily. ObjectStore [13] makes use of immediate database transformations. Transformation functions, which override the default transformation, can be associated with each modified class. As in PJama, instances are not restructured, but a new instance which conforms to the new definition of a corresponding class, is ....

Object Design Inc. ObjectStore User Guide, Release 3.0. Chapter 10, December 1993.

.... using special primitives, see for example [Zic89] and [Zic92] while the database is modified using user defined conversion functions which take as input parameters the old and new schema class definitions and when executed transform the objects of the database to conform to the new schema [Obj93a] The body of a conversion function defines the desired database transformation, and it is normally defined using the data manipulation language offered by the OODBMS, e.g. C [Obj93a] Obj93b] The SDE builder has to define for each modified class in the new schema a conversion function. ....

.... schema class definitions and when executed transform the objects of the database to conform to the new schema [Obj93a] The body of a conversion function defines the desired database transformation, and it is normally defined using the data manipulation language offered by the OODBMS, e.g. C [Obj93a] Obj93b] The SDE builder has to define for each modified class in the new schema a conversion function. System default transformations are applied in case no explicit conversion functions are given by the builder [Ita91] Obj93a] Ver92] What is important for the SDE builder is that after ....

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Object Design Inc. Objectstore User Guide, chapter 9, 1993.

....reprotects the page, and arranges for the load instruction that caused the fault to be restarted with a direct pointer to the resident object. The fault and indirect block pages are then reprotected before resuming execution of the program. Other approaches use page protections in a different way [14, 19, 21, 27]. When a given persistent object is to be assigned a virtual address, a page of virtual memory is reserved (although not necessarily allocated) for the page in the persistent store that contains the object. The offset of the object in the persistent page is known, allowing the virtual address of ....

Object Design, Inc. ObjectStore User Guide, Oct. 1990. Release 1.0.

....conversion functions as a lazy database transformation. The main problem encountered in implementing a lazy database transformation has been to ensure the equivalence of results with respect to the corresponding immediate database transformation [10, 9] 2 The ODBSs GemStone [6] and ObjectStore [7] use a similar approach. Object migration refers to the possibility for an object to change its class during its lifetime. This kind of migration is particularly useful when new classes are added to the schema which are more appropriate classes for existing objects. Migration of objects is also ....

O. Design Inc. Objectstore User Guide, chapter 9. Object Design Inc., 1993.

....commercial ODBSs on the market al..low both updating the schema and the database. A schema can be changed normally using special primitives, see for example [17] and [18] In few systems, as a consequence of a schema change, the database is also modified using userdefined conversion functions [4] [10] which take as input parameters the old and new schema class definitions and when executed transform the objects of the database to conform to the new schema. The body of a conversion function defines the desired database transformation, and it is normally defined using the data manipulation ....

....and new schema class definitions and when executed transform the objects of the database to conform to the new schema. The body of a conversion function defines the desired database transformation, and it is normally defined using the data manipulation language offered by the ODBS, e.g. C [4] [10]. The designer has to define a conversion function for each modified class in the new schema. System default transformations are applied in case no explicit conversion functions are given by the designer [4] 7] 10] 16] What is important for the application designer is that after definition ....

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Object Design Inc. ObjectStore User Guide, chapter 9, 1993.

....of the OODBS ObjectStore. The results are taken from the results of our functional benchmark implementation. The functional benchmark contains example applications for the requirements (R1 to R11) described above. Firstly, we will describe the general structure of the query language of ObjectStore [Obje 91a]. We will then describe the results by referring to the corresponding requirement. ObjectStore provides three interfaces to the database: the C library interface . the C library interface . the extended C interface (ObjectStore DML) In order to use the C library interface, every C compiler ....

Object Design, Inc: "ObjectStore User Guide", March 1991;

....languages, by evaluating the performance of a number of mechanisms for object faulting. White and DeWitt [26] have compared the overall performance of a number of architectures and systems that perform object faulting and pointer swizzling. The systems considered in that study include ObjectStore [13, 16], a commercially available object oriented DBMS, and a number of software architectures based on the EXODUS Storage Manager (ESM) 2, 20] Several of the architectures based on ESM require the program to manipulate objects through a call interface, with modifications being performed in the client ....

Object Design, Inc. ObjectStore User Guide, Oct. 1990. Release 1.0.

....Related work This work is loosely related to the performance study by White and DeWitt [22] which compares the overall performance of various object faulting and pointer swizzling schemes for persistent programming languages. The systems considered in that study include version 1. 2 of ObjectStore [11, 15], a commercially available object oriented DBMS, and a number of software architectures based on the EXODUS Storage Manager (ESM) 2, 16] Several of the architectures based on ESM require object updates to be carried out via a call interface, which modifies the object in the client buffer pool ....

Object Design, Inc. ObjectStore User Guide, Oct. 1990. Release 1.0.

....with two facilities: conversion functions 3 (c.f. and migration functions (m.f. 12, 11, 10] Henceforth, the notion of schema change means atomic schema update. All the O 2 LLPs are atomic. 3 Other object database systems using a similar approach are GemStone [8] and ObjectStore [7]. Default conversion function capabilities exist in the current O 2 release. The c.f. refers to the possibility for an object to conform to its new type consecutively to a structural class update. It takes as input parameters the old and new schema class definitions and when executed transform ....

Object Design Inc. ObjectStore User Guide, chapter 9. Object Design Inc., 1993.

....Dictionary for alternative access structures) O 2 requires the OOHDB implementer to develop these sort of support classes themselves. 5.3 ObjectStore ObjectStore, from Object Design, Inc. 3 , is a commercial object oriented database management system based on the C programming language [Obj92, OHMS92, LLOW91] 3 Object Design, Inc. Twenty Five Mall Road, Burlington, MA 86 ObjectStore uses a client server architecture where client applications request database pages from the server in response to page faults generated by the application. ObjectStore uses a Directory Manager that ....

Object Design, Inc., Burlington, MA. ObjectStore User Guide, October 1992.

....applications (e.g. Exodus [11] On the other hand, BeSS offers direct access to objects and utilizes the standard virtual memory facilities provided by hardware to detect access protection violations. BeSS also uses the underlying hardware to automatically detect writes, as in ObjectStore [19, 24] and QuickStore [34] Objects often contain references to other objects. Usually, the on disk representation of an object differs from the in memory representation of the object because of the way the storage manager treats interobject references. Some systems use object identifiers (OIDs) for ....

Object Design Inc., Burlington, Massachusetts. ObjectStore User Guide, Release 1.1, March 1991.

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Object Design. ObjectStore User Guide, March 1991. Release 1.1.

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Object Design, Inc., ObjectStore User Guide, Release 2.0, October 1992.

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