Developing Router Initialization Scripts
When the SAE establishes a connection with a router, it can run a router initialization script to customize the setup of the connection. Router initialization scripts are run when the connection between a router and the SAE is established and again when the connection is dropped.
We provide the IorPublisher script in the /opt/UMC/sae/lib folder. The IorPublisher script publishes the IOR of the SAE in the directory so that a NIC can associate a router with an SAE.
Interface Object Fields
Router initialization scripts interact with the SAE through an interface object called Ssp. The SAE exports a number of fields through the interface object to the script and expects the script to provide the entry point to the SAE.
Table 9 describes the fields that the SAE exports.
The router initialization script must set the field Ssp.routerInit to a factory function that instantiates a router initialization object:
- <VRName>—Name of the virtual router in which the COPS client has been configured, format: virtualRouterName@RouterName
- <virtualIp>—Virtual IP address of the SAE (string, dotted decimal; for example: 192.168.254.1)
- <realIp>—Real IP address of the SAE (string, dotted decimal; for example, 192.168.1.20)
- <VRIp>—IP address of the virtual router (string, dotted decimal)
- <transportVR>—Name of the virtual router used for routing the COPS connection, or None, if the COPS client is directly connected
The factory function must implement the following interface:
Ssp.routerInit(VRName,virtualIp,realIp,VRIp,transportVR)The factory function returns an interface object that is used to set up and tear down a connection for a given COPS server. A common case of a factory function is the constructor of a class.
The factory function is called directly after a COPS server connection is established. In case of problems, an exception should be raised that leads to the termination of the COPS connection.
Required Methods
Instances of the interface object must implement the following methods:
- setup()—Is called when the COPS server connection is established and is operational. In case of problems, an exception should be raised that leads to the termination of the COPS connection.
- shutdown()—Is called when the COPS server connection is terminated to the virtual router. This method should not raise any exceptions in case of problems.
Example: Router Initialization Script
The following script defines a router initialization class named SillyRouterInit. The interface class does not implement any useful functionality; it just writes messages to the infoLog when the router connection is created or terminated.
class SillyRouterInit:def __init__(self, vrName, virtualIp, realIp, vrIp, transportVr):""" initialize router initialization object """self.vrName = vrNameSsp.infoLog.printin("SillyRouterInit created")def setup(self):""" initialize connection to router """Ssp.infoLog.printin("Setup connection to VR %(vrName)s" %vars(self))def shutdown(self):""" shutdown connection to router """Ssp.infoLog.printin("Shutdown connection to VR %(vrName)s" %vars(self))## publish interface object to Ssp core#Ssp.routerInit = SillyRouterInit