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Creating NETCONF Java Toolkit Program Files

Creating and Executing a NETCONF Java Toolkit Program File

1. Create a Java program that includes code to connect to a device and to execute the desired operations or requests.
2. Compile the Java code and execute the program.

These steps are reviewed in detail in the following sections:

• Creating a NETCONF Java Toolkit Program File
• Compiling and Executing a NETCONF Java Toolkit Program File

Creating a NETCONF Java Toolkit Program File

1. Create a .java file.

   The filename should be identical to the class name, excluding the extension. For example, the ShowChassis class is saved in the file ShowChassis.java.

2. Create the general boilerplate, which includes the code for import statements, the class declaration, and the Java method, main().

   import java.io.IOException;
   import javax.xml.parsers.ParserConfigurationException;
   import net.juniper.netconf.Device;
   import net.juniper.netconf.NetconfException;
   import net.juniper.netconf.XML;
   import org.xml.sax.SAXException;
   
   public class ShowChassis {
       public static void main(String args[]) throws NetconfException, 
                 ParserConfigurationException, SAXException, IOException {
   
       }
   }

3. Within main(), create a Device object and call the connect() method.

   This also creates a default NETCONF session with the NETCONF server over SSHv2.

   Device device = new Device("hostname", "username", "password", null); 
   device.connect();

4. Execute operational and configuration requests by executing RPCs and performing NETCONF operations on the Device object.

   For example, to execute an operational request to retrieve chassis inventory information from the device, include the following line of code:

   XML reply = device.executeRPC(“get-chassis-inventory”);

5. Add code to print, parse, or take action on RPC replies received from the NETCONF server.

   The following line of code prints the RPC reply in XML format to standard output:

   System.out.println(reply.toString());

6. Close the device and release resources by calling the close() method on the Device object.

   device.close();
   

/* ShowChassis.java */
import java.io.IOException;
import javax.xml.parsers.ParserConfigurationException;
import net.juniper.netconf.Device;
import net.juniper.netconf.NetconfException;
import net.juniper.netconf.XML;
import org.xml.sax.SAXException;

public class ShowChassis {
    public static void main(String args[]) throws NetconfException, 
              ParserConfigurationException, SAXException, IOException {
        
        //Create the device object and establish a NETCONF session
        Device device = new Device("hostname", "username", "password", null);
        device.connect();
        
        //Send RPC and receive RPC reply as XML
        XML rpc_reply = device.executeRPC("get-chassis-inventory");

        //Print the RPC reply and close the device
        System.out.println(rpc_reply.toString());
        device.close();
    }
}

Compiling and Executing a NETCONF Java Toolkit Program File

1. Compile the Java source code to create a Java class file containing Java bytecode.

   For example, to compile the ShowChassis.java file using the javac compiler included in the Java Development Kit (JDK) from Oracle Corporation, you would issue the following command on the command line of the configuration management server:

   >javac ShowChassis.java

   This creates the ShowChassis.class file.

2. Execute the resulting program.
   >java ShowChassis

Example: Using the NETCONF Java Toolkit to Execute an Operational Request RPC

This NETCONF Java toolkit program executes an RPC to obtain operational information from a device, which is then printed to standard output. This example serves as an instructional example for creating and executing a basic NETCONF Java toolkit program.

• Requirements
• Overview
• Configuration
• Verification
• Troubleshooting

Requirements

• NETCONF Java toolkit is installed on the configuration management server.
• Client application can log in to the device where the NETCONF server resides.
• NETCONF service over SSH is enabled on the device where the NETCONF server resides.

Overview

You can use the NETCONF Java toolkit to request operational information from a remote device. The following example illustrates how to create a NETCONF Java toolkit program to execute an operational request from the Junos XML API on a device running Junos OS. The example also explains how to compile the code, execute the program, and verify the results.

Configuration

Creating the Java Program

Step-by-Step Procedure

1. Give the file a descriptive name.

   The filename must be the same as the class name. For this example, the file and class are named GetChassisInventory.

2. Include the appropriate import statements, and the code for the class declaration and the Java method, main().

   import java.io.IOException;
   import javax.xml.parsers.ParserConfigurationException;
   import net.juniper.netconf.Device;
   import net.juniper.netconf.NetconfException;
   import net.juniper.netconf.XML;
   import org.xml.sax.SAXException;
   
   public class GetChassisInventory {
       public static void main(String args[]) throws NetconfException, 
                 ParserConfigurationException, SAXException, IOException {
       }
   }

3. Within main(), create a Device object and call the connect() method.

   This creates a default NETCONF session over SSHv2 with the NETCONF server. You must update the code with the appropriate arguments for connection to and authentication on your specific device.

   Device device = new Device("10.10.1.1", "admin", "PaSsWoRd", null);
   device.connect();
   

   Having established a Device object, you can perform NETCONF operations on the device. For a complete list of available methods corresponding to NETCONF operations, refer to the NETCONF Java toolkit Javadocs.

4. Call the executeRPC() method with the operational request RPC command as the argument.

   This example uses the Junos XML API get-chassis-inventory RPC. The reply, which is returned in XML, is stored in the rpc_reply variable.

   XML rpc_reply = device.executeRPC(“get-chassis-inventory”);
   

5. Add code to take action on the RPC reply.

   The following code converts the NETCONF server’s reply to a string and prints it to the screen:

   System.out.println(rpc_reply.toString());

6. Close the device and release resources by calling the close() method on the device object.

   device.close();

Results

/*GetChassisInventory*/
import java.io.IOException;
import javax.xml.parsers.ParserConfigurationException;
import net.juniper.netconf.Device;
import net.juniper.netconf.NetconfException;
import net.juniper.netconf.XML;
import org.xml.sax.SAXException;

public class GetChassisInventory {
    public static void main(String args[]) throws NetconfException, 
              ParserConfigurationException, SAXException, IOException {
        
        Device device = new Device("10.10.1.1","admin","PaSsWoRd",null);
        device.connect();
        XML rpc_reply = device.executeRPC("get-chassis-inventory");
        System.out.println(rpc_reply.toString());
        device.close();
    }
}

Compiling and Running the Java Program

Step-by-Step Procedure

1. Compile the GetChassisInventory.java file.
   >javac GetChassisInventory.java
2. Execute the resulting GetChassisInventory program.
   >java GetChassisInventory

Verification

Verifying Program Execution

Purpose

Verify that the GetChassisInventory program runs correctly.

Action

If the program executes successfully, it establishes a connection and a creates a NETCONF session with the specified device. The program sends the get-chassis-inventory RPC to the NETCONF server, and the server responds with the requested operational information enclosed in the <rpc-reply> tag element. The program prints the reply to standard out. Following is a sample RPC reply with some output omitted for brevity.

<rpc-reply xmlns="urn:ietf:params:xml:ns:netconf:base:1.0" 
     xmlns:junos="http://xml.juniper.net/junos/11.2R1/junos">
<chassis-inventory xmlns="http://xml.juniper.net/junos/11.2R1/junos-chassis">
<chassis junos:style="inventory">
<name>Chassis</name>
<serial-number>12345</serial-number>
<description>M7i</description>
<chassis-module>
 
...output omitted...
 
</chassis>
</chassis-inventory>
</rpc-reply>

Troubleshooting

• Troubleshooting NETCONF Exceptions

Troubleshooting NETCONF Exceptions

Problem

A NETCONF exception occurs, and you see the following error message:

Exception in thread "main" net.juniper.netconf.NetconfException: There was a problem while connecting to 10.10.1.1:830
        at net.juniper.netconf.Device.createNetconfSession(Device.java:344)
        at net.juniper.netconf.Device.connect(Device.java:225)
        at GetChassisInventory.main(GetChassisInventory.java:14)

NETCONF over SSH might not be enabled on the device where the NETCONF server resides, or it might be enabled on a different port.

Solution

Ensure that you have enabled NETCONF over SSH on the device where the NETCONF server resides. Since the example program does not specify a specific port number in the Device arguments, the NETCONF session is established on the default NETCONF-over-SSH port, 830. To verify whether NETCONF over SSH is enabled on the default port for a device running Junos OS, enter the following operational mode command on the remote device:

ftp;
netconf {
    ssh;
}

If the netconf configuration hierarchy is absent, issue the following statements in configuration mode to enable NETCONF over SSH on the default port:

netconf {
    ssh {
        port 12345;
    }
}

Device device = new Device("10.10.1.1", "admin", "PaSsWoRd", null, 12345);