What are direct-connect drivers?
Direct-connect drivers are built as libraries that are installed with and execute in the process space of the client application. They allow you to connect from a client application to an ArcSDE geodatabase using the database's connection methods instead of an ArcSDE service.
The direct-connect drivers are built from the same software code that is used to build an ArcSDE service. The difference is the direct-connect drivers run as libraries on the client, whereas the ArcSDE service is built as an executable program that runs on the server machine.
Since the direct-connect drivers are built from the same software code as ArcSDE services, the database must have the same configuration as when setting up a database to use with an ArcSDE service. The same administrator user and geodatabase repository must exist for direct connection configurations. In addition, for some database management systems, a database client is required on the connecting client computer. You (or your database administrator) must set these up prior to any ArcSDE connection requests.
For each release of the product, direct-connect drivers for that release are installed in ArcGIS (the whole product suite), ArcIMS, and ArcInfo Workstation. For example, if you installed ArcGIS 9.2, the direct-connect drivers to connect to an ArcSDE 9.2 geodatabase are automatically present.
Beginning with ArcGIS 9.3, you can connect directly from a client application to an older ArcSDE geodatabase. To do so for ArcGIS 9.3, you must separately install the drivers for the previous release. These drivers are provided on the client installation media.
If you are connecting from an ArcGIS 10 client to an older, supported ArcSDE geodatabase, the backward-compatible direct-connect drivers are automatically present.