2.1 AcuODBC Design

Open Database Connectivity (ODBC), developed by Microsoft, is the standard way to connect Windows applications to relational and non-relational databases. To submit a request to a database, ODBC-enabled applications use Structured Query Language (SQL).

There are three main ways to generate SQL commands from Windows applications:

• By invoking MS Query and navigating through menus to submit a request. MS Query then generates SQL commands transparently.

• By writing SQL directly (without menus) in Access. This interface is through the Microsoft Jet Database Engine.

• By writing application-specific programs. For instance, in Word for Windows, you can generate SQL commands by writing WordBasic programs. In Excel, you can use Excel/Visual Basic. This approach provides more flexibility, but requires programming expertise and is for advanced users only.

AcuODBC is designed to let Windows users read and write ACUCOBOL-GT's Vision files as well as relative files. Since none of these file formats is relational, AcuODBC's job is to receive ODBC calls from ODBC-enabled applications (like MS Word) and translate them into the appropriate I/O actions.

After AcuODBC translates the ODBC calls into Vision I/O, it processes these requests for data and returns results to the driver manager, which passes them along to the calling Windows application.

AcuODBC can operate in one of three scenarios:

• Local processing of local files

• Local processing with remote file access

• Remote processing

Each of these is described more fully in this chapter.