CRDSS_Task1_05-8_LowLevelDatabaseAccessRoutines

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CRDSS TASK MEMORANDUM 1.05-8 Study of System Integration Issues DMI - Low-level Database Access Routines 1.0 ISSUE The CRDSS INFORMIX database contains model-independent data that can be accessed by different applications through the use of a data management interface (DMI). Applications which access the database do so by calling routines that use Embedded Standard Query Language (ESQL). A library of low-level routines has been developed using the C programming language to promote code reuse, and to help ease maintenance demands. Hereafter, this library is referred to as the low-level DMI library. Higher level DMI utilities (or DMIs) which handle model-specific formatting and data editing are discussed in Task Memorandum 1.05-9. This memorandum discusses the structure of the routines in the low-level DMI library. 2.0 DISCUSSION/ANALYSIS Model to Database Linkage DMIs are implemented as utilities that read from the database and create model input or other data products as flat files. The diagram in Task 1.05 of the scope of work describing DMI implementation is repeated below along with the advantages and disadvantages for the two main DMI options to move information from the database to model applications. After discussion with State and RTi team members, it has been decided that option (2), the flat file option, is the most appropriate for the CRDSS. DMI Routines Library (Using Embedded SQL) CRDSS Database GetTimeSeries (...) PutTimeSeries (...) GetRatingCurve (...) etc. Database- Database & Model-Dependent Option 1 Dependent DMI Utility Using Model Using Low-level DMI Low-level DMI Routine Option 2 Routine Calls Calls Model Model flat Input files Output Database-Independent Model (2) (1) (Possibly in Native Form) 1 A275 01.08.95 1.05-8 Malers