JMS provide for two messaging models, publish-and-subscribe and point-to-point queuing.

Using System.exit(1); in try block will not allow finally code to execute.

You can use a client-side Refresh or Server Push.

Yes , of course you can use the constructor instead of init(). There’s nothing to stop you. But you shouldn’t. The original reason for init() was that ancient versions of Java couldn’t dynamically invoke constructors with arguments, so there was no way to give the constructur a ServletConfig. That no longer applies, but servlet containers still will only call your no-arg constructor. So you won’t have access to a ServletConfig or ServletContext.

YES. JSP technology is extensible through the development of custom actions, or tags, which are encapsulated in tag libraries.

Because it is not practical to have such model. Whether you set isThreadSafe to true or false, you should take care of concurrent client requests to the JSP page by synchronizing access to any shared objects defined at the page level.

There are three scripting language elements: declarations, scriptlets, expressions.

SQLWarning objects are a subclass of SQLException that deal with database access warnings. Warnings do not stop the execution of an application, as exceptions do; they simply alert the user that something did not happen as planned. A warning can be reported on a Connection object, a Statement object (including PreparedStatement and CallableStatement objects), or a ResultSet object. Each of these classes has a getWarnings method, which you must invoke in order to see the first warning reported on the calling object

SQLWarning warning = stmt.getWarnings();
if (warning != null)
{
while (warning != null)
{
System.out.println(“Message: ” + warning.getMessage());
System.out.println(“SQLState: ” + warning.getSQLState());
System.out.print(“Vendor error code: “);
System.out.println(warning.getErrorCode());
warning = warning.getNextWarning();
}
}

It is used to create an instance of a driver and register it with the DriverManager. When you have loaded a driver, it is available for making a connection with a DBMS.

Define a Class HttpSessionNotifier which implements HttpSessionBindingListener and implement the functionality what you need in valueUnbound() method.
Create an instance of that class and put that instance in HttpSession.