Using CA AppLogic® › Appliance Developer Guide › Appliance Kit › Appliance Boundary › Exterior Boundary › Network Configuration

Network Configuration

An appliance uses its last network interface (the one appearing last in a network device discovery scan) as the service interface, used to configure itself and to communicate with the CA AppLogic® grid. This interface is referred to in CA AppLogic® documentation as the default interface.

Upon startup, an appliance configures itself as follows:

• Set up the default interface and request DHCP configuration for it.
• The DHCP response will contain the network parameters for the interface, plus a file name (in the filename DHCP option).
• Retrieve the following files using HTTP requests to port 8080 sent to the address of the server that responded to the DHCP request ($filename is the name received in the DHCP response):
  $filename.net
  $filename.desc
  $filename.ext
• Use the data contained in the retrieved files to configure itself and begin normal operation. Note that except for the DHCP-configured default interface and the local loopback interface, the appliance's network is set up entirely according to data provided in the $filename.net configuration file (and not using any OS-specific network configuration data stored on the appliance itself).

The format of the configuration files that the appliance receives from the CA AppLogic® grid is described in the Appendix. Note that in most cases the appliance designer need not be concerned with the format of these files, as the APK initialization scripts take care to interpret them and configure the appliance accordingly. For appliances that have configurable properties, the APK provides their values in various easy to use cooked formats which can be read by the appliance-specific code. Also, in many cases it is possible to instruct the APK to modify appliance-specific configuration files on startup and insert the values of the appliance's properties into them at the right places. See the Interior Boundary section.