J2EE Interview Questions and Answers 18

What is servlet context ?
An object that contains a servlet's view of the Web application within which the servlet is running. Using the context, a servlet can log events, obtain URL references to resources, and set and store attributes that other servlets in the context can use.

What is servlet mapping ?
Defines an association between a URL pattern and a servlet. The mapping is used to map requests to servlets.

What is session ?
An object used by a servlet to track a user's interaction with a Web application across multiple HTTP requests.

What is session bean ?
An enterprise bean that is created by a client and that usually exists only for the duration of a single client-server session. A session bean performs operations, such as calculations or database access, for the client. Although a session bean can be transactional, it is not recoverable should a system crash occur. Session bean objects either can be stateless or can maintain conversational state across methods and transactions. If a session bean maintains state, then the EJB container manages this state if the object must be removed from memory. However, the session bean object itself must manage its own persistent data.

What is SGML ?
Standard Generalized Markup Language. The parent of both HTML and XML. Although HTML shares SGML's propensity for embedding presentation information in the markup, XML is a standard that allows information content to be totally separated from the mechanisms for rendering that content.

What is SOAP ?
Simple Object Access Protocol. A lightweight protocol intended for exchanging structured information in a decentralized, distributed environment. It defines, using XML technologies, an extensible messaging framework containing a message construct that can be exchanged over a variety of underlying protocols.

What is SOAP with Attachments API for Java (SAAJ) ?
The basic package for SOAP messaging, SAAJ contains the API for creating and populating a SOAP message.

What is SQL ?
Structured Query Language. The standardized relational database language for defining database objects and manipulating data.

What is SQL/J ?
A set of standards that includes specifications for embedding SQL statements in methods in the Java programming language and specifications for calling Java static methods as SQL stored procedures and user-defined functions. An SQL checker can detect errors in static SQL statements at program development time, rather than at execution time as with a JDBC driver.

What is SSL ?
Secure Socket Layer. A security protocol that provides privacy over the Internet. The protocol allows client-server applications to communicate in a way that cannot be eavesdropped upon or tampered with. Servers are always authenticated, and clients are optionally authenticated.

What is stateful session bean ?
A session bean with a conversational state.

What is stateless session bean ?
A session bean with no conversational state. All instances of a stateless session bean are identical.

What is system administrator ?
The person responsible for configuring and administering the enterprise's computers, networks, and software systems.

What is tag ?
In XML documents, a piece of text that describes a unit of data or an element. The tag is distinguishable as markup, as opposed to data, because it is surrounded by angle brackets (<>). To treat such markup syntax as data, you use an entity reference or a CDATA section.

What is template ?
A set of formatting instructions that apply to the nodes selected by an XPath expression.