The Objectivity/SQL++ ODBC Driver (Objectivity/ODBC) enables ODBC-compliant applications to connect to an Objectivity/SQL++ ODBC server, which in turn connects to an Objectivity/DB federated database. You can use Objectivity/ODBC with client applications such as Microsoft Access, which conform to the Microsoft ODBC interface.
Note: Objectivity/ODBC supports ODBC 3.0 and must be used with an Objectivity/SQL++ ODBC server that implements ODBC 3.0.
About Objectivity/DB Databases
In an Objectivity/DB system, data for a particular application is normally stored in one or more individual databases that are unified in a single federated database. A federated database provides a consistent logical view of the data, even when the component databases are physically distributed among multiple hosts on a network of computers. Physically, a federated database is represented by two files:
- A system-database file, which contains the first (or only) database in the federation
- A boot file, which contains information about the federated database, including its location
Objectivity/DB applications and tools locate and open a federated database by specifying its boot file.
About ODBC Connections
You can access the data in an Objectivity/DB federated database through your ODBC-compliant application. To do so, you must enable your application to make an ODBC connection to the federated database. An ODBC connection is made through the following components:
- An Objectivity/SQL++ ODBC server (ODBC server)—an executable that accepts the ODBC connection (possibly over a network), parses the SQL statements it receives, and translates these statements into Objectivity/DB operations.
- An Objectivity/SQL++ ODBC Driver (Objectivity/ODBC)—a DLL or shared library that forwards SQL statements from the application to the correct ODBC server.
- An ODBC driver-manager—a utility used by the application to load (and unload) the correct ODBC driver. (This component is provided transparently on Windows; it is separately installed third-party software on UNIX.)
The connection can be made when you add an Objectivity/SQL++ data source that describes, among other things, where to find the federated database’s boot file and where to find the ODBC server that will access it.
When an ODBC-compliant application submits a SQL request to access an Objectivity/SQL++ data source, the application consults the ODBC driver-manager to determine which ODBC driver to use—in this case, Objectivity/ODBC. The ODBC driver then inspects the data source to determine which ODBC server to use, and forwards the SQL request to that server. The ODBC driver also forwards the name and location of the federated database’s boot file.
Upon receiving a request, the ODBC server uses its Objectivity/SQL++ engine to parse the SQL statements and translate them into Objectivity/DB operations. These operations are then performed by the Objectivity/DB kernel, which actually opens the specified federated database and obtains the requested data.
You install Objectivity/ODBC and add data sources on the same host (machine) as your ODBC-compliant application. However, the ODBC server may be running on the same or a different host from the driver, and the federated database’s files may be on the same or a different host from the ODBC server. Multiple ODBC servers running on different machines may access the same Objectivity/DB federated database; you can define different data sources for connecting to the same federated database through different ODBC servers.
Servers, drivers, and federated databases must all be on a network that uses the TCP/IP network protocol (a service that allows machines and processes on a network to communicate with each other). Objectivity/DB uses this protocol.
Summary of Steps for Using Objectivity/ODBC
To use Objectivity/ODBC, you or your system administrator must perform the following steps:
- Confirm that the Objectivity/SQL++ ODBC server is properly
configured and running. See the Windows or UNIX Objectivity/SQL++
Warning: If the Objectivity/SQL++ ODBC server is not properly configured and running, your ODBC-compliant application will be unable to find the federated database.
- Install the Objectivity/SQL++ ODBC Driver on the same host where you plan to use the ODBC-compliant application.
- Create a data source corresponding to the federated database you need to access; see Adding Objectivity/DB Data Sources in the Windows or UNIX ODBC Driver Configuration topic.
- Use the ODBC-compliant application:
- Start the application.
- Connect to the data source that you have just configured.
- Submit your queries.