Connect to the NETCONF Server in Perl Client Applications

The NETCONF server supports several access protocols. For each connection to the NETCONF server on a device running Junos OS, the application must specify the protocol it is using. Perl client applications can communicate with the NETCONF server via SSH only.

Before your application can run, you must satisfy the prerequisites for SSH. This involves enabling NETCONF on the device by configuring the set system services netconf ssh statement.

Establishing a connection to the NETCONF server on a device running Junos OS is one of the more time-intensive and resource-intensive functions performed by an application. If the application sends multiple requests to a device, it makes sense to send all of them within the context of one connection. If your application sends the same requests to multiple devices, you can structure the script to iterate through either the set of devices or the set of requests. Keep in mind, however, that your application can effectively send only one request to one NETCONF server at a time. This is because the NET::Netconf::Manager object does not return control to the application until it receives the closing </rpc-reply> tag that represents the end of the NETCONF server's response to the current request.

The NET::Netconf::Manager object takes the following required parameters, specified as keys in a Perl hash:

• access—The access protocol to use when communicating with the NETCONF server. Before the application runs, satisfy the SSH prerequisites.

• hostname—The name of the device to which to connect. For best results, specify either a fully-qualified hostname or an IP address.

• login—The username under which to establish the connection to the NETCONF server and issue requests. The username must already exist on the specified device and have the permission bits necessary for making the requests invoked by the application.

• password—The password corresponding to the username.

The sample scripts in the NETCONF Perl distribution record the parameters in a Perl hash called %deviceinfo, declared as follows:

my %deviceinfo = (
        'access' => $access,
        'login' => $login,
        'password' => $password,
        'hostname' => $hostname,
);

The sample scripts included in the NETCONF Perl client distribution obtain the parameters from options entered on the command line by a user. For more information about collecting parameter values interactively, see Collect Parameters Interactively in NETCONF Perl Client Applications. Your application can also obtain values for the parameters from a file or database, or you can hardcode one or more of the parameters into the application code if they are constant.

In addition to the parameters required by the NET::Netconf::Manager object, applications might need to define other parameters, such as the name of the file to which to write the data returned by the NETCONF server in response to a request.

As with the parameters required by the NET::Netconf::Manager object, the client application can hardcode the values in the application code, obtain them from a file, or obtain them interactively. The sample scripts obtain values for these parameters from command-line options in the same manner as they obtain the parameters required by the NET::Netconf::Manager object. Several examples follow.

The following line enables a debugging trace if the user includes the -d command-line option:

my $debug_level = $opt{'d'};

The following line sets the $outputfile variable to the value specified by the -o command-line option. It names the local file to which the NETCONF server's response is written. If the -o option is not provided, the variable is set to the empty string.

my $outputfile = $opt{'o'} || "";

After obtaining values for the parameters required for the NET::Netconf::Manager object, each sample script records them in the %deviceinfo hash.

my %deviceinfo = ( 
      'access' => $access,
      'login' => $login,
      'password' => $password,
      'hostname' => $hostname,
);

The script then invokes the NETCONF-specific new subroutine to create a NET::Netconf::Manager object and establish a connection to the specified routing, switching, or security platform. If the connection attempt fails (as tested by the ref operator), the script exits.

my $jnx = new Net::Netconf::Manager(%deviceinfo);
unless (ref $jnx) {
    croak "ERROR: $deviceinfo{hostname}: failed to connect.\n";
}