Building an integrated persistent application

Abstract

The major motivation for database programming language (DBPL) research is to facilitate the construction and maintenance of large data-intensive applications. To fully benefit from DBPLs, supporting methodologies and tools are needed. This paper describes the construction of a multi-author, multi-level thesaurus application (TA). Some tools and methodologies were used in the TA construction, and requirements for other tools and methodologies are identified as the result of our experiences. Although built in a specific language (Napier88), the principles discovered apply to other DBPLs. The TA comprises several loosely-integrated components constructed by different programmers. The components were themselves implemented using general purpose sub-components, including libraries. A principle result is that a realistic application could be constructed quickly in a DBPL. Rapid construction was facilitated by the use of libraries, code reuse and an incremental construction methodology supported by the persistent store. Language features such as a polymorphic type system and structural type equivalence were important. Nevertheless, some problems were encountered with code reuse, with integrating independently constructed components, with the lack of concurrency and with build management such as installation and recompilation. Our experiences lead us to suggest several improvements, including models, methodologies and supporting tools for persistent application construction and maintenance.