Policy Framework - Customizing the Policy Object UI Example

Customizing the PolicyObjectUI - Example

Feature Overview
Example Overview
Integration with Web NMS
Sample Output

Feature Overview

The word 'policy', in general, refers to a plan of action. Here, in Web NMS context, it refers to executing a task or set of tasks at a specified time based on a set of specified conditions. Policies are tasks that are executed by Web NMS at a system level, at a specified point of time. In Network Management, policies are used to control a variety of network activities like automated backups, routing & prioritization of network traffic, bandwidth allocation, cleaning up database tables, deleting failed nodes, etc.

This policy framework enables scalable administration of the Web NMS server and the network elements managed by it. The primary goal of the policy engine is to enable administration of complex functions easily. In Web NMS, policies can be used to customize the behaviour of the NMS and to provide a framework for adding policies for different network elements.

Web NMS policies can be broadly classified into two categories :

Periodic Policies - Policies are triggered periodically by the server at the specified time interval. By default, the periodic policies are configured to be executed in the interval of 10 seconds.
Non-periodic Policies - Policies are executed at the specified time. In this case, there is no fixed time interval. You need to specify the time at which the policy has to be executed. No default value is assigned for non-periodic policies.

For more details, refer to the following section of our documentation : Developer Guide --> Policy Framework

Example Overview

Example name : Customizing the PolicyObject UI
Related files : ExamplePolicyCustomizer.java and ExamplePolicy.java
Location : <Web NMS Home>/examples/policy

By default a UI has been provided for viewing the PolicyObject properties. If you want to have your own UI, you can plugin your own UI forms. This example explains how this can be done using the PolicyObjectCustomizer.

How to plugin your own property form ?

Follow the steps detailed below to define your own property form :

Write a class extending com.adventnet.nms.ui.PolicyObjectCustomizer. You need to override the following three methods :

public abstract void init(Properties p);
public abstract Window getCustomizer();
public abstract Properties getProperties()

The method init(Properties p) will be called first, before instantiating the customizer to pass the required PolicyObject properties.

Construct a GUI and return it as "Window" Object so that Web NMS takes care of making it visible.
Instantiate your customizer class. Upon doing this, a Property change listener will be added to your class.
After finishing all your modifications make your component invisible and fire the property changed event by calling the method firePropertyChange(). This is to initimate that all the modifications have been completed.
After listening to the Property changed event, Web NMS will get back the modified properties by calling the method getProperties(). At this point, you need to return the modified properties through the getProperties() method.
Web NMS finally updates the Policy with modified properties.

You need to write two java files, one to define your own customizer class and the other to invoke the customizer class. Here, in this example, the ExamplePolicyCustomizer.java file is used to construct a GUI and pass it as a Window Object to the Policy Client. The ExamplePolicy.java is for invoking the customizer class.

Code Snippet

The following code snippets would help you in defining your own property forms :

The init (Properties p ) method will be called first, before instantiating the customizer to pass the required PolicyObject properties.

public void init(Properties p)
{
this.prop = p;
}

The getCustomizer() method actually returns a window to be displayed for the PolicyObject. You can construct a GUI as per your requirement and can pass your GUI as a Window Object to the PolicyClient. Then PolicyClient will take care of displaying the Window for the corresponding PolicyObject.

public Window getCustomizer()
{
return getGUI();
}

Once you complete all the modifications in the property form, it is required to fire the PropertyChanged Event in addition to disposing the customizer Window, to intimate the PolicyClient that all modification has been done. If you do not want to save the changes, simply dispose the window.

public void actionPerformed(ActionEvent ae)
{
if(ae.getActionCommand().equals("Sumbit"))
{
   prop.put("message",textarea.getText());
   dialog.dispose();
   this.firePropertyChange();
}

Once the PolicyClient listens to the PropertyChanged Event, it get backs the modified properties by the method getProperties()

public Properties getProperties()
{
return this.prop;
}

User written customizer class can be mentioned in the method getPolicyObjectCustomizer() of the corresponding PolicyObject. This method is defined in the ExamplePolicy.java file, which is used to invoke the ExamplePolicyCustomizer class.

public String getPolicyObjectCustomizer()
{
return test.policy.policyui.ExamplePolicyCustomizer;
}

Using the Example

The steps given below will help you in integrating this example with Web NMS. If any of the steps given below are not followed properly, then the example might not function in a desired manner.

The user defined file is compiled and the class files are placed under the directories <Web NMS Home>/ classes/test/policy/policies and <Web NMS Home>/classes/test/policy/policyui. Then the customizer class file is bundled into the NmsClientClasses.jar file. The ExamplePolicy class name should be entered into the Policy.conf file, to invoke the user defined policy.

The following steps are to be followed to use the user defined Policy from the policies of Web NMS Client.

Classpath Settings
Set the class path as set classpath= <Web NMS Home >/classes, <Web NMS Home>/classes/NmsClientClasses.jar for compiling the ExamplePolicyCustomizer.java file and ExamplePolicy.java file.
Compiling and Bundling with Web NMS

Compile the java files from <Web NMS Home>/examples/policy directory using the following command

javac -d ../../classes ExamplePolicyCustomizer.java and
javac -d ../../classes ExamplePolicy.java

The ExamplePolicyCustomizer class file will be created under <Web NMS Home >/ classes/test/policy/policyui directory and the ExamplePolicy class file will be created under <Web NMS Home >/ classes/test/policy/policies directory.

You have to bundle the ExamplePolicyCustomizer.class file into the NmsClientClasses.jar file using the following command from <Web NMS Home>/classes directory

jar -uvf NmsClientClasses.jar/test/policy/policyui/ExamplePolicyCustomizer.class
The above command will include the class required to invoke the ExamplePolicyCustomizer.java file.

Invoking the Example

The following entry should be made in Policy.conf file under <Web NMS Home>/conf directory.

<POLICY_CONF>

<POLICY_LIST>

----------------------------

<POLICY

classname="test.policy.policies.ExamplePolicy"

display_name="ExamplePolicy" />

</POLICY_LIST>

</POLICY_CONF>

Make an entry for this policy in relationalclasses.conffile as shown below.

test.policy.policies.ExamplePolicy policydb RelationalPolicyObject PolicyObject

Start the Web NMS Server
Start the client.
To view the change on the Web NMS Client, select the policies and right click it.
From the pop-up menu select the "AddPolicy" menu item.
The AdventNet Add Policy details form gets displayed. In that form, the ExamplePolicy gets included in the policy list (along with other policies), as specified in the policy.conf file.
Choose the ExamplePolicy and click on add.
The ExamplePolicyCustomizer form gets displayed instead of the default screen.
After entering the values for the GroupName and Message in the customizer click on submit thereby adding the new policy.

Sample Output

The image shown below, is the user-defined event details form invoked from the events panel of Web NMS Client.