L. Liu, "A Recursive Object Algebra Based on Aggregation Abstraction for Complex Objects," J. Data and Knowledge Eng., vol. 11, no. 1, pp. 21-60, 1993.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....such that objects of the container interface may access the objects of component interfaces directly. As a result, the operations defined in the component interfaces can be invoked via the container s interface. The aggregation mechanism is a useful facility for implementing behavioral composition [29, 30] and ad hoc polymorphism [11] based on coercion of operations. Another benefit of using interface aggregation abstraction is to minimize the impact of component schema changes over the application programs working with the existing interoperation interfaces. Interface Composition Mechanism: ....

L. Liu. A recursive object algebra based on aggregation abstraction for complex objects. Journal of Data and Knowledge Engineering, 11(1):21--60, 1993.

....of an aggregation relationship, i.e. has a relationship, rather than those of an is a 4 relationship. In fact, we say that a parent process is defined via a sequenced aggregation of its child activities whereas conventionally has a relationships have the semantics of being unordered [Kim89] Liu93] In Figure 1, note that the Wafer cleaning process can be executed in two ways, either as a sequence of the steps Organic clean and Water rinsing or the sequence of steps Inorganic clean and Water rinsing. To handle such cases, we need to allow specification of processes in terms of alternative ....

....rules will converge. Proof: Given in Appendix A. Thus PSOM design guidelines lead to the definition of active rules whose termination behavior is easy to analyze. 5 Related Work An extended object oriented model for exploring semantics in aggregation relationships is presented in [Liu92] Liu93] Composite objects are used as a mechanism of object queries, allowing users to remain within the framework of composite objects when querying the database. Aggregation relationships are also used as a means of encapsulation by allowing the aggregate object to freely use the methods defined on ....

L. Liu, "A Recursive Object Algebra Based on Aggregation Abstraction for Manipulating Complex Objects," Data and Knowledge Engineering, 11, 1993, 21-60.

....of objectoriented databases and their query optimizers. We propose the stack based approach to query languages as an adequate framework aiming at the same goals. 1 Introduction Object algebras are proposed as tools to formalise object oriented databases and their query languages (QLs) see [AbFi95, AlAr93, BaWi94, CDV88, Clue89, ClDe92, ClDe94, DGG94, GZC89, HFLP89, KeMa94, LMSVVZ93, Liu93, PoSm94, ShZd89a, ShZd89b, ShZd90, StOz90, SZLV93, SLVZ95, VaDe91], and many others. They are claimed to be well suited to solve query optimisation problems. In this paper we carry out a critical analysis of this research activity. There are two principal reasons motivating our work. First, we see in these algebras severe flaws, which cause doubts concerning ....

L. Liu. A Recursive Object Algebra Based on Aggregation Abstraction for Manipulating Complex Objects. Data & Knowledge Engineering Vol. 11, No. 1, 1993, pp.21-60

....here. For the output of the transformation process we focus on the conventional logical data modelling techniques, such as the relational model, the hierarchical model and the network model. We also use the nested relational model, which is similar to so called complex object models (see e.g. [13]) We give emphasis to describing a mechanism for examining trade offs. As a consequence, transformation of integrity constraints has a relatively low priority. We do however indicate where constraints play a role and how this can be dealt with. For example, constraint enforce ment will in ....

L. Liu. A recursive object algebra based on aggregation abstraction for manipulating complex objects. Data & Knowledge Engineering, 11:21--60, 1993.

....degree of formality, performance, and how well database issues are handled. The algebra described does well when evaluated with these criteria. Several object oriented algebras have been created. Bertino at al. Bertino92] create a calculus based on first order logic and recursion. Liu [Liu93] develops an algebra based on recursion and aggregation. Su, Guo, and Lam [Su93] Gou91] develop an algebra based on associations. In contrast to these other algebras, the one presented in this work strives for similarity to the relational algebra, so as to achieve ease of learning and ....

, Ling Liu, A Recursive Object Algebra Based on Aggregation Abstraction for Manipulating Complex Objects, Data & Knowledge Engineering, North-Holland, 11:21-60, 1993.

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L. Liu, "A Recursive Object Algebra Based on Aggregation Abstraction for Complex Objects," J. Data and Knowledge Eng., vol. 11, no. 1, pp. 21-60, 1993.

.... veld get value(char mark, lnt scheme preferred) if (Students 1 (self) mark(self) gradetescere(grade(self) mark(self) pelnttescere(pelnt(self) mark(self) scere(self) print errer message ; Figure 8: An example of user defined conversion functions in IDL behavioral composition [14, 15] and ad hoc polymorphism [5] based on coercion of operations. Recall the Claim Folder example given earlier. We have so far presented two alternative approaches that generate the ClaimFolder objects through linking the claims with the relevant images and the corresponding doctors report. The ....

L. Liu. A recursive object algebra based on aggregation abstraction for complex objects. Joural of Data ad ,Uowledge Egmeermg, 11:21 60, 1993.

....of the container interface may access the objects of component interfaces directly. As a result, the operations defined in the component interfaces can be invoked via the container s interface. The aggregation abstraction mechanism is a useful facility for implementing behavioral composition [18, 19] and ad hoc polymorphism [6] based on coercion of operations. Recall the Claim Folder example given earlier. Assume that each claim may contain more than one X ray image but involve only one doctor s diagnosis report. In order to build links that connect the claims with the relevant images and ....

L. Liu. A recursive object algebra based on aggregation abstraction for complex objects. Joural of Data ad I(owledge Egieerig, 11(1):21 60, 1993.

....of the container interface may access the objects of component interfaces directly. As a result, the operations defined in the component interfaces can be invoked via the container s interface. The aggregation abstraction mechanism is a useful facility for implementing behavioral composition [18, 19] and ad hoc polymorphism [6] based on coercion of operations. Recall the Claim Folder example given earlier. Assume that each claim may contain more than one X ray image but involve only one doctor s diagnosis report. In order to build links that connect the claims with the relevant images and the ....

L. Liu. A recursive object algebra based on aggregation abstraction for complex objects. Journal of Data and Knowledge Engineering, 11(1):21--60, 1993.

....that objects of the container interface may access the objects of component interfaces directly. As a result, the operations defined in the component interfaces can be invoked via the container s interface. The aggregation mechanism is a useful facility for implementing behavioral composition [18, 19] and ad hoc polymorphism [5] based on coercion of operations. Recall the Claim Folder example given earlier. Assume that each claim may contain more than one X ray image but involve only one doctor s diagnosis report. In order to build links that connect the claims with the relevant images and the ....

....source. These subqueries will be then passed to the corresponding wrappers for subquery processing. The DIOM mediator will collect the subquery results returned from the wrappers, and perform some filtering and assembly jobs to package the final 3 Aggregation based join refers to an object join [18] which follows the aggregation path specified by object identities. AAAA AAAA AAAA AAAA AAAA AAAA AAAA AAAA AAAA AAAA AAAA AAAA AA AA AA AA A AA AA AA AA AA AA AAA AAA AAA AA AA AA A AAAA AAAA AAAA AAAA AAAA AAAA AAAA AAAA AAAA AAAA AAAA AAAA AAAA AAAA AAAA A A A A A Project X Select ....

L. Liu. A recursive object algebra based on aggregation abstraction for complex objects. Journal of Data and Knowledge Engineering, 11(1):21--60, 1993.

....ClaimFolder by an aggregation based join, namely D AggregationJoin, over the three interfaces Claim, Image, and DiagnosisRep. An aggregation based join refers to an object join which maintains the nested aggregation structure while traversing through the objects following the aggregation path [8]. Then we replace each generalization interface by the corresponding base interfaces. In our example, Claims is replaced by S4:Claim, Insur Agreement is replaced by S4:Agreements, Image is replaced by S3:Images, and DiagnosisRep is replaced by S5:DiagReport. Thus the query is reformulated into ....

L. Liu. A recursive object algebra based on aggregation abstraction for complex objects. Journal of Data and Knowledge Engineering, 11(1):21--60, 1993.

....query: CREATE INTERFACE QueryResult Q1 ( extent resultQ1objects ) AGGREGATION OF Book, Supplier; ATTRIBUTES Book title, Book price, Book medium, Supplier name; If this query is installed as a continual query [15] its result type is persistent. We use the basic techniques described in [12] for automatic generation of query result type for an IQL query expression. 4 Query Mediation Process 4.1 The Framework The main task of DIOM distributed query mediation manager is to coordinate the communication and the distribution of the processing of information consumer s query requests ....

L. Liu. A recursive object algebra based on aggregation abstraction for complex objects. Journal of Data and Knowledge Engineering, 11(1):21--60, 1993.

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