M. Schrefl and G. Kappel, "Cooperation Contracts," in Proceedings of the 10th Int. Conf. on the Entity-Relationship Approach, ed. T.J.Teorey, pp. 285--307, 1991.  Home/Search   Document Details and Download   Summary   Related Articles   Check

....a contract between a the implementor of a class and the implementor of one of its subclasses. The guarantee required, is that and change to the superclass implementation should not invalidate the subclass implementation. In contrast to the above informal design oriented notions, Schrefl and Kappel[SK91] recently CHAPTER 3. CONTRACTS IN CONTEXT 23 cooperation contract PRICING between PRODUCT and CUSTOMER methods shippingCharge( returns Integer f return(50) g totalPrice( returns Integer f return( self(PRODUCT) netPrice( self(PRODUCT) salesTax( ....

....Figure 12: Cooperation Contract introduced a more concrete concept called Cooperation Contracts. The motivations and basic syntactic form of this concept are quite similar to the icontract concept but the model extension proposed is quite different. Figures 12 and 13 describe a brief example from [SK91] Schrefl and Kappel propose Cooperation Contracts for modeling certain object behaviors in the object oriented database domain which can not be conveniently expressed in terms of the basic object oriented model. Their primary concern is expressing functionality which depends on multiple ....

Maichael Schrefl and Gerti Kappel. Cooperation Contracts. In International Conference on the ER Approach. North-Holland, 1991.

....not completely happy with the adaptation. In cooperation with Dean Rosenzweig, he prepared a simpler evolving algebra description of full Prolog [BRo2] Georg Gottlob, Gerti Kappel, and Michael Schrefl used EAs to specify the semantics of characteristic features of object oriented database models [GKS, KS]. An EA based manual for a programming language could be precise and relatively easy to read. Q: Do you expect evolving algebras to be used for proving things about algorithms A: Yes. The possibility to tailor EAs to any given abstraction level is especially useful. I have already mentioned ....

Gerti Kappel and Michael Schrefl, "Cooperation Contracts", Proc. 10th International Conference on the Entity Relationship Approach (ed. T. J. Teorey), San Mateo, California, 1991, ER Institute, 285--307. The authors introduce the concept of cooperative message handling and use evolving algebras to give formal semantics.

....object oriented database management systems. Finally, Section 6 gives a summary and compares cooperation contracts with related work on collaborative behavior modeling. This paper revises and extends our paper presented at the 10th International Conference on the Entity Relationship Approach [40], where we have introduced cooperation contracts in a straw man data model as novice construct for behavior modeling and where we have presented a formal semantics of cooperative message passing by means of Evolving Algebras [18] This paper follows the same line of thoughts as its predecessor, ....

....is used with a different meaning in AI. There, cooperative refers to the feature that a system is willing to cooperate actively, whereas cooperation contract refers only to the feature that objects collaborate in giving passive responses. But to indicate the relationship to our previous work [40], we continue using the term cooperation contract for the concept to model collaborative behavior. 2 GemStone is a registered trademark of GemStone Systems, Inc. 3 2 A sample problem statement In this section, we give a sample problem statement of behavior modeling and introduce the object ....

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M. Schrefl and G. Kappel, "Cooperation Contracts," in Proceedings of the 10th Int. Conf. on the Entity-Relationship Approach, ed. T.J.Teorey, pp. 285--307, 1991.

....database management systems. Finally, Section 6 compares cooperation contracts with related work on cooperative behavior modeling and discusses future research topics. This paper revises and extends our paper presented at the 10 th International Conference on Entity Relationship Approach [42], where we have introduced cooperation contracts in a straw man data model as novice construct for behavior modeling and where we have presented a formal semantics of cooperative message passing by means of Evolving Algebras [19] This paper follows the same line of thoughts as its predecessor, ....

....PricingForeign reimplements the cooperative method totalPrice of cooperation contract Pricing. The new implementation takes into account that foreign customers are exempted from paying a sales tax. We describe now informally how cooperative messages are handled. A formal definition is given in [42]. An implementation based on this formal definition is presented in Section 5. A cooperative message m addressed to two objects o1 and o2 is handled as follows: 1. A most specific cooperation contract C to which o1 and o2 are subject and which implements m is determined. There may be several. How ....

M. Schrefl and G. Kappel, "Cooperation Contracts," in Proceedings of the 10th Int. Conf. on ER Approach, ed. T.J.Teorey, pp. 285-307, Oct. 1991.

....object oriented , those by the later behaviorally object oriented [8] Fully object oriented data models cover both aspects, which are equally relevant in object oriented design. We have addressed this topic in our previous research [12, 13] and have contributed to behavior modeling [27, 28] in particular. In this paper we continue our work by focusing on a specific aspect of structure modeling, local referential integrity. Local referential integrity extends the well known notion of referential integrity in the realm of composite objects. Referential integrity is satisfied if every ....

M. Schrefl and G. Kappel, "Cooperation Contracts," in Proceedings of the 10th Int. Conf. on ER Approach, pp. 285-307, Oct. 1991.

....message. An example of a cooperative message is the message withdrawalRate sent jointly to a user u and a service station s. Cooperative messages are defined with cooperation contracts which are established between several object classes. Cooperation contracts have been originally introduced in (Schrefl 1991) and extended in (Schrefl 1996) A cooperation contract fulfills a similar purpose in behaviour modelling as the symmetric, undirected relationship does in data modelling. Symmetric, undirected relationships are used in data modelling to express relations between several objects. They make a ....

Schrefl, M. and Kappel, G. (1991) Cooperation Contracts, in Proceedings of the 10th International Conference on the Entity/Relationship Approach (ed. T.J. Teorey), 285--307.

....message. An example of a cooperative message is the message withdrawalRate sent jointly to a user u and a service station s. Cooperative messages are defined with cooperation contracts which are established between several object classes. Cooperation contracts have been originally introduced in (Schrefl 1991) and extended in (Schrefl 1996) A cooperation contract fulfills a similar purpose in behaviour modelling as the symmetric, undirected relationship does in data modelling. Symmetric, undirected relationships are used in data modelling to express relations between several objects. They make a ....

Schrefl, M. and Kappel, G. (1991) Cooperation Contracts, in Proceedings of the 10th International Conference on the Entity/Relationship Approach (ed. T.J. Teorey), 285-- 307.

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M. Schrefl and G. Kappel, "Cooperation Contracts" in Proceedings of the 10th International Conference on Entity Relationship Approach, San Mateo (CA), October 1991.

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