Academic journal article Issues in Informing Science & Information Technology

Extended Object Languages for the Extolware Persistence Framework

Academic journal article Issues in Informing Science & Information Technology

Extended Object Languages for the Extolware Persistence Framework

Article excerpt


Structured Query Language or SEQUEL (later rename to SQL) has been evolving since early 1970 after Relational Data Model was first proposed by E.F. Codd (Date, 2000) and released by IBM as System R commercially to the market. The impact was great then with its ease of use and simple to understand concept. Since then, SQL2 was continuously enhanced and evolved with many new features such as new data types, new predicates, enhanced security and semantic, and active database. As such, the idea of having a query language must incorporate three requirements, that is simple to use, simple to understand and powerful enough to capture difficult and complex domain semantics. The SQL standardisation committees, ANSI (X3H2) and ISO (ISO/IEC JTC1/SC21/WG3), have been adding and enhancing the SQL standard so that new requirements requirements could be handled by SQL efficiently, nevertheless, one must also not forget these three design ingredients that make SQL the de factor standard database language. Many questions such as "Could we simplify SQL3?" by David Beech (2001) and "Do we really need SQL3?" by John E. Seytabla (2001) and other database language issues concerning language complexity and computational completeness are always discussed and raised in journals and articles, hence, designing database languages are no small task at all.

ODMG, on the other hand, proposes Object Definition Language and Object Query Language standard, to get most of the leading object database vendors to agree and endorse a set of guidelines in order to consolidate skill, expertise and technology so that applications developed on Object Database Management System (ODMS) can easily be migrated with minimum changes to another ODMS (Yugopuspito & Araki, 2000) environment. SQL standard was used by ODMG as a reference in the process of drafting ODL and OQL standard. The intension is not to produce a computationally complete database language but to create a standard, which is easy to migrate from SQL to OQL in very short period. This will help popularising ODMS (Yugopuspito & Araki, 2000) in a much faster pace. Even some aspects of Object Database technology are not quite as mature as Relational Database technology; the need of such technology is definitely undeniable. Hence, many debates and proposals are put forward to relational and object people such as integrating SQL and OQL and "merging" relational with object database technology (Pujianto Yugopuspito & Araki, 2000).

C. J. Date, M. Nelson, Francois Bancilhon and Richard Mark (1995) in "Objects and SQL: Strange Relations?" argue facts such as possibilities of bringing SQL and OQL as the standard of database language, keeping relational database technology unchanged and using object database technology on a specific domain. But the reality is the market demand should be the bottom line that drives and dictates what is required and what is not, not the technology.

The next three sections present an overview on Extended Object Language or EOL, SQL3 and ODL/OQL on their database constructs, operators and features. The fourth section summaries these languages' features from three aspects, i.e. ease of use, ease of understanding and powerful constructs and operators. Object-oriented features such as simple object, complex object, association, collection and inheritance are criteria used in conjunction with these languages' constructs for an overall languages' review and assessment.

Extended Object Language (EOL)

Extended Object Language or EOL is designed with three major features in mind; they must allow creation, deletion and modification of classes, manipulation of objects such as insert, delete and update of objects, and querying of objects from databases by selecting objects with filtering criteria and other querying features. Most of the language constructs designed and implemented in EOL languages are borrowed from ODL/OQL and SQL3. …

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