H. Balsters, R,. A. de By and R,. Zicari, "Typed sets as a basis for object-oriented database schemas," Proc. Seventh European Conference on Object-Oriented Programming, July 1993, Kaiserslautern, Germany, LNCS 707, Springer-Verlag, pp. 161-184.  Home/Search   Document Details and Download   Summary   Related Articles   Check

....object states. Both method overloading and method overriding are supported. Method inheritance is handled following class type hierarchies. Behavior inheritance is thus considered. DTL DTL ( Data Type Log) 9] has been designed as a query language for a database specified in the TM language. TM [10] is a high level specification language for object oriented database schemas, in corporating predicative sets as first class objects and static constraints in the context of multiple inheritance and full static typecheckability. In TM objects have an object identifier used for sharing and ....

H. Balsters, R. A. de By, and R. Zicari. Typed Sets as a Basis for Object-Oriented Database Schemas. In O. Nierstrasz, editor, Proc. Seventh European Conference on Object- Oriented Programming, Lecture Notes in Computer Science, 1993.

....0 ) 8a 0 : T 0 2 A[a 6= a 0 ]g. Note that redefined attributes override the corresponding attributes in the superclass. 2 Every class in a class hierarchy has an underlying type, which describes the structure of the class, i.e. the structure of the objects in its extensions (cf. TM FM [3, 4]) Informally, the underlying type of a class is an aggregation of its attributes, where recursive types [2] are used to cope with attributes that refer to classes. Definition 3. First, postulate a new type oid , whose extension is an enumerable set of object identifiers. Let H be a class ....

H. Balsters, R. de By, and R. Zicari. Typed sets as a basis for object-oriented database schemas. In Proc. Computing Science in the Netherlands, pages 62--77. Stichting Mathematisch Centrum, Amsterdam, The Netherlands, 1991.

.... TA , viz. atts(C) fname:string, address: house:integer, street:string, city:string, zip:integer g, are well typed. Hence, H is well defined. 2 5 Every class in a class hierarchy has an underlying type, i.e. a type that describes the structure of the objects in its extensions (cf. TM FM [4, 5]) Since a class can refer to other classes, its underlying type depends on the class hierarchy as a whole. The underlying type of a class is an aggregation of its attributes, where recursive types [3] are used to cope with attributes that refer to classes. Definition 4 (Underlying types) First, ....

H. Balsters, R. de By, and R. Zicari. Typed sets as a basis for object-oriented database schemas. In Proc. Computing Science in the Netherlands, pages 62--77. Stichting Mathematisch Centrum, Amsterdam, The Netherlands, 1991.

....and every method as a fixed function from the set of instances and the domains of the parameters to the corresponding codomain. An instance can be queried and manipulated by applying the formalised attributes, constraints, and methods. We have chosen another option, similar to the approach of [4], where the attributes of a class and a special identifier attribute are aggregated into a record type (the underlying type of the class) The set of possible instances of a class is the set of instances of its underlying type. Furthermore, every constraint is formalised as a logical formula, the ....

....powerset of the set of instances to the domain of the booleans, and every method is formalised as a lambda expression, the interpretation of which is a function from the set of instances and the domains of the parameters to the corresponding codomain. Our formalisation differs from the approach of [4] as follows. In [4] identifier attributes are used both to discriminate between different instances and to cope with recursive class definitions. In our formalisation, identifier attributes are used to discriminate between different instances and recursive types are used to cope with recursive ....

[Article contains additional citation context not shown here]

H. Balsters, R. de By, and R. Zicari. Typed sets as a basis for object-oriented database schemas. In Proc. Computing Science in the Netherlands, pages 62--77. Stichting Mathematisch Centrum, Amsterdam, The Netherlands, 1991.

....on integrity enforcement by triggers. A general overview of semantic integrity constraints in distributed and or federated databases is given in [55, 45, 69] The connection between integrity constraints and object objected database concepts such as subtyping and subclasses is discussed in [25, 4, 68]. The latter work particularly deals with the inheritance of integrity constraints and shows that there are integrity constraints that cannot be inherited to subclasses. Further interesting work on integrity constraints in object oriented databases can be found in [6, 43, 72] We have not ....

H. Balsters, R. A. de By, and R. Zicari. Typed Sets as a Basis for Object-Oriented Database Schemas. In O. Nierstrasz, editor, ECOOP'93 --- Object-Oriented Programming, Proc. 7th European Conf., Kaiserslautern, Germany, July 1993, Lecture Notes in Computer Science, Vol. 707, pages 161--184. Springer-Verlag, Berlin, 1993.

....as follows from the predomains: 1. For a basic type fi, D(fi) D p (fi) 2. D(oe ) D(oe) D( 3. D(P) P(D( 4. If = hl 1 : 1 ; l n : n i, then D( S oe D p (oe) Methods are typed as well in the autonomous data model. This is done through function types, like in TM FM [6]. In this approach a method is a function mapping an object state and input parameters to a new object state and output parameters. In our model, however, the underlying type of an object a method is defined on is not fixed. This is caused by the evolution of an object through the addon ....

Herman Balsters, Rolf A. de By, and Roberto Zicari. Typed sets as a basis for objectoriented database schemas. In Proceedings of the 7th European Conference on ObjectOriented Programming, 1993.

....c fl UT 1994 Page 9 UT TR 0009 V2.0 WPIV October 7, 1994 Merge options for LOTOS and TM TransCoop EP 8012 2. 1 TM TM is an object oriented (and type theoretic) data model that is theoretically well founded, and capable of expressing many, if not all, features of data models currently in use [BBBB93, BaBZ93]. It is formally founded in a typed lambda calculus allowing for subtyping and multiple inheritance, based on the ideas of [Card88] We use it here for the description of the communicated data structures of the scenario, and for the description of the database schemata. Characteristic features of ....

H. Balsters, R. A. deBy& R. Zicari, "Typed sets as a basis for object-oriented database schemas," in Proceedings Seventh European Conference on Object-Oriented Programming, July 26--30, 1993, Kaiserslautern, Germany, LNCS #707 , O. M. Nierstrasz, ed., SpringerVerlag, New York--Heidelberg--Berlin, 1993, 161--184.

.... theoretical proposals and system implementations of object oriented data models are restricted to the possibility INRIA Design and Implementation of a Type System for a Knowledge Representation System 27 of defining only enumerated sets [BKKK87, LR89] However, the object oriented data model TM [BdBZ93] is the first that is formally capable of dealing with arbitrary set expressions and powertypes in the context of sub typing and multiple inheritance. For such a purpose, TM permits arbitrary set expressions (enumerated sets and predicative sets defined as fx : oejOE(x)g) as well typed ....

H. Balsters, R.A. de By, and R. Zicari. Typed sets as a basis for object-oriented database schemas. In O.M. Nierstrasz, editor, 7th European Conference on Object-Oriented Programming, volume 707 of Lecture Notes in Computer Science, pages 161--184, Kaiserslautern (Germany), July 1993. Springer-Verlag.

....Our current solution to at least an important subset of the interoperability problems is to combine two existing formal languages, one to describe the database schema, the other to describe the way the database systems interact. TM is an object oriented (and type theoretic) data model [BaBZ91,BaVr91], that is theoretically well founded, and capable of expressing many, if not all, features of data models currently in use. LOTOS is a specification language [BoBr87,ISO87,VSSB91] that was designed for the formal description of distributed, concurrent systems. LOTOS is an ISO standard (ISO 8807) ....

....object s is changed to reflect the number of seats A is willing to contribute. To this end, the FLIGHTS table is correspondingly changed to account for the fact that A now has less seats for the flight at its disposal. 6 Updates and Retrievals TM is formally founded in FM, a functional language [BaBZ91,BaVr91,ByBV92]. The advantages of FM as a functional language are clear: ffl FM has a simple set theoretic, and well defined denotational semantics. ffl FM has a theoretically well founded type system, allowing for subtyping and multiple inheritance. ffl FM is declarative and side effect free, which greatly ....

[Article contains additional citation context not shown here]

H. Balsters, R. A. de By & R. Zicari, "Typed sets as a basis for object-oriented database schemas," in Proceedings Computer Science in The Netherlands (CSN-SION), Utrecht, 7--8 November, 1991, 1991, 62--77.

.... persistent databases TM is an object oriented language with a high level data model that is based on the formal theory of the set based FM language [14] The language has been used to address the problems of database interoperability and advanced data modelling issues in objectoriented databases [5, 15]. To support interoperability, it uses LOTOS [20] together with TM to specify pairwise agreements about the nature of data and operations provided by the two systems. In the open environment envisioned by ODP systems, such pairwise agreements are unacceptable due to scaling problems. TM supports ....

H. Balsters, R. A. de By, and R. Zicari. Typed Sets as a Basis for Object-Oriented Database Schemas.

....of control in the organisational view. In this report, the semantics of COCOA is explained by showing how the two views can be mapped to LOTOS TM [EvFB95] a formal specification language based on the processalgebraic language LOTOS [BoBr87,ISO87,VSSB91] and the database specification language TM [BBBB95,BaBZ93,BaFo91]. We assume that the reader is familiar with LOTOS, TM, and LOTOS TM. 1 In the organisational view, activities comprise all kinds of operations that the users can perform. See Section 2.5 for an overview of these. 2 By consistency, we mean consistency as defined by database constraints in the ....

H. Balsters, R. A. deBy& R. Zicari, "Typed sets as a basis for object-oriented database schemas," in Proceedings Seventh European Conference on Object-Oriented Programming, July 26--30, 1993, Kaiserslautern, Germany, LNCS #707 , O. M. Nierstrasz, ed., SpringerVerlag, New York--Heidelberg--Berlin, 1993, 161--184.

....precise function typing. Napier88 v.2.2.1 [MBC 96] is an imperative database programming language with very powerful type system and certain reflexive capabilities. It is not object oriented and its parametric types though powerful can not be used until fully instantiated. The language TM [BBZ93] BBB 93] is partially reflexive and separates interface from implementation. However, it does not allow method redefinitions, does not have multiple dispatch, does not support userdefinable parametric types, and its subtyping does not imply substitutability. TL [MMS94] is a database ....

Herman Balsters, Rolf A. De By, and Roberto Zicari, Typed sets as a basis for object-oriented database schemas, Proceedings ECOOP'93 (Kaiserslautern, Germany) (O. Nierstrasz, ed.), Springer-Verlag, July 1993, pp. 161--184.

....embedded in the reference architecture for federated database system by Sheth and Larson [18] Our approach implies the use of the object oriented data model as the global data model, enabling the specification of methods and constraints on the integrated data structure. TM We use the TM [2,9] object oriented database specification language, because of its high level of abstraction and its expressiveness. TM allows the specification of data structures in terms of Classes and Sorts (abstract data types without object identity) the definition of constraints on this structure using ....

H. Balsters, R. A. de By & R. Zicari, "Typed sets as a basis for object-oriented database schemas," in Proceedings Seventh European Conference on ObjectOriented Programming, July 26--30, 1993, Kaiserslautern, Germany, LNCS #707 , O. M. Nierstrasz, ed., Springer--Verlag, New York--Heidelberg--Berlin, 1993, 161-- 184.

....as objects, classes and inheritance .computationally complete expression language for specification of constraints and methods, enabling SQL like query formulation .high abstraction level (incl. non constructive expressions) TM is based on a strict typing theory and has a complete formal semantics [6]. C. The IMPRESS Database Design Toolset System (or rather database) design is performed by the creation (using stepwise refinement) of TM specifications of the database schema, together with its constraints and methods, and validation of these specifications, possibly leading to iterative ....

H. Balsters, R. A. de By & R. Zicari, "Typed sets as a basis for object-oriented database schemas", in Proceedings Seventh European Conference on Object-Oriented Programming (ECOOP), July 26-30, 1993, Kaiserslautern, Germany, 1993.

....= 0 is applied. 3 Nested TM Queries 3.1 General Description of TM In this section we describe the features of TM that are important for the purpose of this paper support for complex objects and the SELECT FROM WHERE construct. For a more comprehensive description of TM we refer the reader to [1, 2, 3]. TM is a high level, object oriented database specification language. It is formally founded in the language FM, a typed lambda calculus allowing for subtyping and multiple inheritance. Characteristic features of TM are the distinction between types, classes, and sorts, support for object ....

Balsters, H., de By, R.A., and Zicari, R.: Typed Sets as a Basis for Object-Oriented Database Schemas. Proceedings ECOOP, Kaiserslautern (1993)

....regarding the scenarios. Our goal is to arrive at a well founded and complete specification language. With this goal in mind, we explore the orthogonal integration of two very different, but already existing, formal specification languages: TM, an object oriented database specification language [10, 11, 12], and LOTOS, a processalgebraic specification language for distributed systems [13, 14, 15] Both languages have been in satisfactory use in their respective application areas for a number of years. Features provided by the proposed LOTOS TM language combination specific to supporting cooperation ....

....to multiple databases. The TM language is introduced in Section 2.1; Sections 2.2 and 2.3 describe LOTOS. 2.1. TM TM is an object oriented (and type theoretic) data model that is theoretically well founded, and capable of expressing many, if not all, features of data models currently in use [10, 11, 12]. It is formally founded in a typed lambda calculus allowing for subtyping and multiple inheritance, based on the ideas of [17] Charac teristic features of TM are the distinction between types, classes, and sorts; support for object identity and complex objects; and multiple inheritance of data ....

H. Balsters, R,. A. de By and R,. Zicari, "Typed sets as a basis for object-oriented database schemas," Proc. Seventh European Conference on Object-Oriented Programming, July 1993, Kaiserslautern, Germany, LNCS 707, Springer-Verlag, pp. 161-184.

....regarding the scenarios. Our goal is to arrive at a well founded and complete specification language. With this goal in mind, we explore the orthogonal integration of two very different, but already existing, formal specification languages: TM, an object oriented database specification language [10, 11, 12], and LOTOS, a processalgebraic specification language for distributed systems [13, 14, 15] Both languages have been in satisfactory use in their respective application areas for a number of years. Features provided by the proposed LOTOS TM language combination specific to supporting cooperation ....

....to multiple databases. The TM language is introduced in Section 2.1; Sections 2.2 and 2.3 describe LOTOS. 2.1. TM TM is an object oriented (and type theoretic) data model that is theoretically well founded, and capable of expressing many, if not all, features of data models currently in use [10, 11, 12]. It is formally founded in a typed lambda calculus allowing for subtyping and multiple inheritance, based on the ideas of [17] Characteristic features of TM are the distinction between types, classes, and sorts; support for object identity and complex objects; and multiple inheritance of data ....

H. Balsters, R. A. de By and R. Zicari, "Typed sets as a basis for object-oriented database schemas," Proc. Seventh European Conference on Object-Oriented Programming , July 1993, Kaiserslautern, Germany, LNCS #707, Springer-Verlag, pp. 161--184.

....of a company database. A TM specification roughly is a description of classes, defining 3.2. AN INTRODUCTION TO TM 25 ffl data structures, ffl static constraints, and ffl operations (or methods) that pertain to those structures TM uses a three level methodology for its database representation [BaBZ93]. The three levels are the object level (level 0) the class extension (level 1) and the database level (level 2) where one may easily recognize their relational peers. For instance, the object and class level describe the tuple and relation structure respectively. 3.2.1 Data structure Let us ....

....TM specification means to characterize the allowed database states and the allowed operations on such states using FM. The database representation that is described is based on the three level methology, as introduced in [Broc84] which gives a set theoretic foundation for relational databases. In [BaBZ93] this methodology is adapted for an object oriented environment in terms of classes; this section provides an overview. Most of TM s higher order concepts translate to FM in a fairly straightforward manner. We discuss the mapping of the Class concept to a predicative set, characterizing the set of ....

H. Balsters, R. A. de By & R. Zicari, "Typed sets as a basis for object-oriented database schemas," in ECOOP 1993 Kaiserslautern, 1993.

....operations, to allow the users in the cooperative activity to work in parallel. Both the specification language C oC oA [5] and the transaction model CoAct were designed during the ESPRIT TransCoop project. C oC oA is based on the object oriented, functional database specification language TM [2]. The semantics of the language has been defined by mappings to the language LOTOS TM [4] which is based on the process algebraic language LOTOS [3] and TM, both of which have well defined semantics. A tool set for C oC oA has been implemented within the TransCoop project; it includes a ....

H. Balsters, A. de By R. and R. Zicari. Typed sets as a basis for object-oriented database schemas. In Oscar M. Nierstrasz, editor, Proceedings of the Seventh European Conference on Object-Oriented Programming, LNCS #707, pages 161--184, Kaiserslautern, Germany, 1993. Springer.

....that relabeling of all action names is explicit in each instantiation of a process, instead of introducing a separate operator for this purpose. 1. 3 TM specifying monolithic information systems The TM language has been developed for describing conceptual schemas of object oriented databases ([BaBZ 1991]) Its strength stems from its richness as a specification language and its formal, type theoretic background. The TM language incorporates state of the art features of object oriented data models, such as complex objects and multiple inheritance, but it also extends known models to general set ....

Balsters, H., de By, R. A., Zicari, R., Typed sets as a basis for object-oriented database schemas, in: Proceedings Computer Science in the Netherlands (CSN-SION), November 7--8, 1991, Utrecht, The Netherlands.

....TM should be understood as a (rather heavily) syntactically sugared as not to say syruped version of FM, that gives a database modeller the full dictionary of object oriented data models. First ideas on this language originated in discussions during our visit to Milano in September 1990 [BaBZ91]. This is why the language is called TM: it stands for Twente Milano. Most of the present syntactical constructs of the language were developed in the early weeks of 1991. A redesign of the language took place in the first half of 1993. 1.2 Differences with prior versions TM is, like many other ....

....formal counterpart, the language FM. The FM language consists of a typed lambda calculus employing a notion of subtyping and is based on the well known ideas of Cardelli Wegner [CaWe85] type theory. The typing rules as defined in FM [BaFo91,BaVr91] could be used to type check a TM specification [BaBZ91,BaBV92]. However, this would be a rather rough test, because apart from the types we also have a user defined ISA hierarchy in TM. In this ISA hierarchy it is for instance defined which methods are defined for a certain class or sort, hence instead of using the FM types, classes and sorts should be ....

H. Balsters, R. A. de By & R. Zicari, "Typed sets as a basis for object-oriented database schemas," in Proceedings Computer Science in The Netherlands (CSN-SION), Utrecht, 7--8 November, 1991, 1991, 62--77.

.... Class , and Module level, described by a full first order typed logic) ffl Composition links (Direct references to other objects as values of attributes) ffl Static type checkability (The language has a complete formal basis) We note that the TM language is has a complete formal semantics ([BaBZ93]) and it is this property of having a formal semantics that actually creates the possibility of having an integrated tool set, as TM does. Having a formal semantics entails that all expressions in the language have a precise and unique meaning; without such a non ambiguous meaning for all ....

....as we will see to characterize valid parallel updates we will for each used class in C in the database record type augment that database type with an attribute C ext of type PC, to which the end user or specifier has no direct access. This is closely akin to the explicit extensions as used in [BaBZ93]. The C ext attributes can be seen as a formal implementation of object sharing, because in effect it will be these added database attributes that hold the actual object data, whereas the original database attributes will only hold object references in the form of oid values, besides other values. ....

[Article contains additional citation context not shown here]

H. Balsters, R. A. de By & R. Zicari, "Typed sets as a basis for object-oriented database schemas," in Proceedings Seventh European Conference on Object-Oriented Programming, July 2630, 1993, Kaiserslautern, Germany, 1993, ??--??.

....predicates that could not be proved safe at compile time. Our work extends the work of [2] Rather than a relational model, it uses a powerful specification and verification environment for object oriented databases with transactions and integrity constraints. The specification framework uses TM [6,7], a typed formal specification language based on the well known ideas of Cardelli [8] extended with logic formalism and sets [9] The declarative flavour of this language permits compile time transaction verification using a theorem prover, while retaining ODMG compliancy [10] The verification ....

H. Balsters, R. A. de By & R. Zicari, "Typed sets as a basis for object-oriented database schemas," in ECOOP 1993 Kaiserslautern, 1993.

....importance. The work presented here is meant to serve as the basis for the implementation of OSQL. Specific object oriented features can be handled as an addition or an extension. For example, the presence of object identity allows to speed up join algorithms [16] We remark that, in our framework [1], methods are written using OSQL instead of some general purpose programming language. Hence, method calls in a query can be textually substituted by their OSQL definition, allowing for additional optimization. We study the transformation of nested OSQL queries. In [17] we showed that in ....

Balsters, H., R.A. de By, and R. Zicari, "Typed Sets as a Basis for Object-Oriented Database Schemas," Proceedings ECOOP, Kaiserslautern, 1993.

....type constructors (record, variant, set and list) object identity, object sharing, structural and behavioural (multiple) inheritance, static type checkability, and a weak notion of encapsulation. We have reported on several matters relating to the theory [5] 6] and the use of the language [4], 14] in the past. A class (or sort) definition is constructed from three optional definition sections: a structure section in which, for instance, attributes can be defined, a constraint section in which constraints that restrict the possible structural values are defined, and a method section ....

H. Balsters, R. A. de By & R. Zicari, "Typed sets as a basis for object-oriented database schemas", in Proc. Seventh European Conf. on Object-Oriented Programming (ECOOP), July 26-30, 1993, Kaiserslautern, Germany, 1993.

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