Servlet and Database

Servlet Lifecycle Init(config) Service(request, response) Destroy()

Servlet Communication RequestDispatcher interface SendRedirect() method

JSP JSP is a servlet that calls RequestDispatcher Interface

JSP Lifecycle Init() -> service() -> destroy()

Cookie VS HTTP session Cookie is a user state storing in client side whereas HTTP session is on server side.

Different Scopes Page Request Session Application

EL in JSP Expression language used to provide the object and values.

Hibernate has thread safe session factory

Hibernate get() vs load() Returns real object – proxy object returned here. Null pointer handled – cannot point to null object

Hibernate update() vs merge() In session – out of session

Hibernate object states Transient – not associated with session, just values. Persistent – in session with database. Detached – session closed / disconnected.

Hibernate first level cache VS second level cache Session – session factory Enabled – not enabled by default

SQL cursor Temporary work area in system memorywhere SQL is executed