Java29 07/10/2008
 

What is UnicastRemoteObject?

All remote objects must extend UnicastRemoteObject, which provides functionality that is needed to make objects available from remote machines.

What is RMI?

Remote Method Invocation (RMI) allows java object that executes on one machine and to invoke the method of a Java object to execute on another machine.

What is connection pooling?

With servlets, opening a database connection is a major bottleneck because we are creating and tearing down a new connection for every page request and the time taken to create connection will be more. Creating a connection pool is an ideal approach for a complicated servlet. With a connection pool, we can duplicate only the resources we need to duplicate rather than the entire servlet. A connection pool can also intelligently manage the size of the pool and make sure each connection remains valid. A number of connection pool packages are currently available. Some like DbConnectionBroker are freely available from Java Exchange Works by creating an object that dispenses connections and connection Ids on request. The ConnectionPool class maintains a Hastable, using Connection objects as keys and Boolean values as stored values. The Boolean value indicates whether a connection is in use or not. A program calls getConnection() method of the ConnectionPool for getting Connection object it can use; it calls returnConnection() to give the connection back to the pool.

What are the types of statements in JDBC?

Statement: to be used createStatement() method for executing single SQL statement PreparedStatement — To be used preparedStatement() method for executing same SQL statement over and over.
CallableStatement — To be used prepareCall() method for multiple SQL statements over and over.

Are there any global variables in Java, which can be accessed by other part of your program?

No, it is not the main method in which you define variables. Global variables is not possible because concept of encapsulation is eliminated here

 


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