EXPRESS is an experimental prototype data translation system which can access a wide variety of data and restructure it for new uses. The system is driven by two very high level nonprocedural languages: DEFINE for data description and CONVERT for data restructuring. Program generation and cooperating process techniques are used to achieve efficient operation.This paper describes the design and implementation of EXPRESS. DEFINE and CONVERT are summarized and the implementation architecture presented.The DEFINE description is compiled into a customized PL/l program for accessing source data. The restructuring specified in CONVERT is compiled into a set of customized PL/l procedures to derive multiple target files from multiple input files. Job steps and job control statements are generated automatically. During execution, the generated procedures run under control of a process supervisor, which coordinates buffer management and handles file allocation, deallocation, and all input/output requests.The architecture of EXPRESS allows efficiency in execution by avoiding unnecessary secondary storage references while at the same time allowing the individual procedures to be independent of each other. Its modular structure permits the system to be extended or transferred to another environment easily.
the resulting set of assertions would have been the same but the subset of assertions added by a particular query might have been different. Figure 16 contains a data structure diagram for the design that was created by the system. The DOCTOR-PATIENT confiuency is detected from ABOVE assertions made in the second and third queries, and the base for the confluent hierarchy, the TREATMENT record, is discovered from assertions made in the first and second queries. The ABOVE assertions from queries five and six are erased because of redundancy. Only five ABOVE assertions remain, resulting in five of the sets (excluding SYM13 and SYM15) of Figure 16.The INORABOVE assertions are reduced to eleven, with one assertion for each item except for DOCNAME.
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