When the user connects to more than one database, there are two basic configurations:
Federated— All databases are local. The following figure illustrates federated database
connections.
Figure 1. Federated database configuration
Distributed — One or more of the databases reside on one or more remote machines in the
network, and OpenEdge sessions connect to the database using a single networking protocol.
The following figure illustrates distributed database connections.
Figure 2. Distributed database configuration
A multi-tier configuration is more complex than the basic
federated and distributed models. A multi-tier configuration consists of a database tier that
supports self-service clients, an application tier that supports remote clients, and a
thin-client tier. Multi-tier configurations might improve system performance for a large
installation. The following figure illustrates a three-tier configuration. Figure 3. Sample multi-tier configuration
The OpenEdge RDBMS architecture provides multiple simultaneous paths to a database. Each
self-service client can access the database and service its own requests. Each network server
queues and runs requests for one or more network clients. The database broker initializes
shared memory and starts a new server for each additional client or set of clients that access
the database. By removing the server as a bottleneck, the OpenEdge architecture increases
overall performance.
