The database server houses a database engine and your PeopleSoft application database, which includes all the PeopleTools metadata, application definitions, system tables, application tables, and application data. The database server simultaneously handles the application server connections, development environment connections, and batch programs running against it.
The PeopleSoft database is the repository for all information managed by your PeopleSoft application. Both application data and PeopleSoft metadata are stored and maintained in the database. Application Designer, the main tool of the development environment, enables you to define, modify, and maintain this metadata, which the system uses to drive the runtime architecture. This collection of metada defines a PeopleSoft application.
With Application Designer you can create dozens of different types of application definitions, such as fields, records, and pages. When an application developer saves an application definition, the system saves this definition to the metadata repository in the PeopleSoft database. At runtime, the application server retrieves the most recent application object definitions from the metadata repository, compiles and caches the application definition into memory, and runs the business rules based on the most current definitions.