Concepts Archives - Page 5 of 14

JSTL Core Library Actions

Apr

16

2013

source: Exam Guide : David Bridgewater There are 14 core library actions, divided into 4 groups 1. General Purpose : <c:out>, <c:set>,<c:remove> and <c:catch> 2. Conditional : <c:if>, <c:choose>, <c:when>, <c:otherwise> 3. Iteration : <c:forEach>, <c:forTokens> 4. URL Related : <c:import>, <c:url>, <c:redirect>,<c:param> S.No. Core Libary Action Attribute Name Run Time Expression Allowed Mandatory Default Value Type 1. <c:out> value Yes Yes NA Object ...

JSP standard actions

Apr

16

2013

JSP Standard action are predefined tags which perform some action based on information that is available at the time when the browser requested a jsp page. There are 11 jsp standard actions are available S.No. Standard Actions Descriptions 1. <jsp:useBean> to create or search an exisiting bean 2 <jsp:setProperty> to set the bean property ...

JSP include standard action and include directive

Apr

16

2013

S.No. include directive <%@ include file=”…” %> JSP include 1. Content of the file specified in the attribute “file” of the include directive will be pasted as it is at tranlation time , where include directive is used in the jsp At runtime, the includED file will be executed and the response will be included ...

Is Invalid Statement

Apr

16

2013

1. Using the method isUserInRole(), overrides any declarative authorization related to method in which it is invoked – isUserInRole() method itself doesn’t do any authorization. 2. <c:remove scope=”session”> name </c:remove> – value attribute is mandatory for <c:remove> 3. Benefits of the JSP precompilation is , it avoids initialization on the first request. ...

Why use Generics in Java?

Apr

15

2013

Generics add a way to specify concrete types to general purpose classes and methods that operated on Object before. Code that uses generics has many benefits over non-generic code: 1. Stronger type checks at compile time(Compile-time type safety). A Java compiler applies strong type checking to generic code and issues errors if the code violates ...

What is Tunneling protocol?

Apr

15

2013

A technology that enables one network to send its data via another network’s connections. Tunneling works by encapsulating a network protocol within packets carried by the second network. i.e. one network protocol (the delivery protocol) encapsulates a different payload protocol. By using tunneling one can carry a payload over an incompatible delivery-network, or provide a ...

What is Object-Relational mapping (ORM) framework? 1

Apr

15

2013

Object-relational mapping (ORM, O/RM or O/R mapping) in computer software is a programming technique for converting data between incompatible type systems in relational databases and object-oriented programming languages. This creates, in effect, a “virtual object database” that can be used from within the programming language. There are both free and commercial packages available that perform ...

What is Cloud Computing?

Apr

15

2013

Cloud computing is a type of computing that relies on sharing computing resources rather than having local servers or personal devices to handle applications. In cloud computing, the word cloud (also phrased as “the cloud”) is used as a metaphor for “the Internet,” so the phrase cloud computing means “a type of Internet-based computing,” ...

Web Server and Application Server

Apr

15

2013

A Web server exclusively handles HTTP/HTTPS requests. It serves content to the web using HTTP/HTTPS protocol. An Application server serves business logic to application programs through any number of protocols, possibly including HTTP. The application program can use this logic just as it would call a method on an object. In most cases, the server exposes this business ...

UnsupportedClassVersionError

Apr

15

2013

Description : java.lang.UnsupportedClassVersionError:Bad version number in .class file Cause: When code was compiled on a new version of Java and user is trying to run it on the older version of Java Possible Solution : Make sure that both the versions are same.