Application tier

The application tier includes the application objects and the LN application virtual machine and the database driver. Together, the application objects and the application virtual machine provide much of the functionality of LN. The database driver provides connectivity to the database server for storing and retrieving application data.

The application objects include the compiled LN applications and the data dictionary. The LN applications provide the functionality that is required to implement the LN Enterprise Resource Planning (ERP) system.

These applications are written in Baan 3GL or Baan 4GL, which are programming languages, supported by the Infor Enterprise Server package. These programming languages are compiled into an intermediate code that is interpreted at runtime by the virtual machine (VM).

The data dictionary defines the data models that are used by the applications. The data dictionary includes information about the domains, schemas, and referential integrity rules that are used by LN.

The LN application VM performs these tasks:

  • Schedules and runs the application objects.
  • Sends and receives information to and from the display server.
  • Initiates an instance of the database driver as necessary for communication with the database server.

A running database driver can support multiple connections to a single RDBMS instance. If an LN installation stores data tables in multiple RDBMS products or instances, the application virtual machine must start one instance of the database driver for each RDBMS product or RDBMS instance with which it must communicate.

The LN application virtual machine has traditionally been called the LN shell, or more often the bshell.

Throughout the remainder of this document, it is referred to as the LN application virtual machine or the application virtual machine.

The LN database driver is also typically a part of the application tier. The database driver provides a common interface between the LN application virtual machine and the database server. Communication between the application virtual machine and the database driver is the same, no matter which RDBMS product is used as the database server. There is one database driver for each of the RDBMS products that LN supports.