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Here enters Visual Basic 4.0

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Visual Basic 4.0 was released last year and provides a great update for the best RAD tool available. The primary areas we want to look at, though, are the data access components.

Data Access Components

In VB 4.0 Microsoft has provided us (with the exclusion of direct API access) three distinct ways of getting to SQL data. These are the Data Access Objects (DAO), the Remote Data Objects (RDO), and the very cool Remote Automation Objects (RAO).

DAO

DAO is the next stage in the evolution of the VB/Jet pairing. On the top it provides the objects to VB 4 that allow a developer to perform high level database access, at the bottom it provides the Jet 3.x engine the information it needs to perform efficiently.

RDO

RDO is a set of data objects that expose a similar (but not identical) set of methods and properties, as does the DAO set. However, RDO talks directly to ODBC, totally bypassing JET which does not even need to be loaded. The whole point of the RDO is to provide a programmer interface similar to DAO, but with native ODBC access speed, avoiding the need to deal with the ODBC API in application code.

RAO

RAO is an implementation of Remote OLE (it really gives a good indication of what we can expect from Distributed OLE). Objects can run on any 32 Bit Windows platform remotely, and provide a base for interesting implementations of three-tier technology. The underlying mechanism is a predefined OLE interface routed through RPC, to an OLE surrogate on the object host machine. As far as the local object is concerned, they are receiving a 'local' activation of their remote OLE object.

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