J2EE Interview questions and answers

291. What is transaction isolation level

What is transaction isolation level The degree to
which the intermediate state of the data being
modified by a transaction is visible to other
concurrent transactions and data being modified by
other transactions is visible to it.

292. What is transaction manager

Provides the services and management functions
required to support transaction demarcation,
transactional resource management, synchronization,
and transaction context propagation.



293. What is Unicode

A standard defined by the Unicode Consortium that uses
a 16-bit code page that maps digits to characters in
languages around the world. Because 16 bits covers
32,768 codes, Unicode is large enough to include all
the world's languages, with the exception of
ideographic languages that have a different character
for every concept, such as Chinese. For more
information, see http://www.unicode.org/.

294. What is Universal Description, Discovery and
Integration (UDDI) project

An industry initiative to create a
platform-independent, open framework for describing
services, discovering businesses, and integrating
business services using the Internet, as well as a
registry. It is being developed by a vendor
consortium.

295. What is Universal Standard Products and Services
Classification (UNSPSC)

A schema that classifies and identifies commodities.
It is used in sell-side and buy-side catalogs and as a
standardized account code in analyzing expenditure.



296. What is unparsed entity

A general entity that contains something other than
XML. By its nature, an unparsed entity contains binary
data.

296. What is URI

Uniform resource identifier. A globally unique
identifier for an abstract or physical resource. A URL
is a kind of URI that specifies the retrieval protocol
(http or https for Web applications) and physical
location of a resource (host name and host-relative
path). A URN is another type of URI.

297. What is URL

Uniform resource locator. A standard for writing a
textual reference to an arbitrary piece of data in the
World Wide Web. A URL looks like this:
protocol://host/localinfo where protocol specifies a
protocol for fetching the object (such as http or
ftp), host specifies the Internet name of the targeted
host, and localinfo is a string (often a file name)
passed to the protocol handler on the remote host.



298. What is URL path

The part of a URL passed by an HTTP request to invoke
a servlet. A URL path consists of the context path +
servlet path + path info, where Context path is the
path prefix associated with a servlet context of which
the servlet is a part. If this context is the default
context rooted at the base of the Web server's URL
namespace, the path prefix will be an empty string.
Otherwise, the path prefix starts with a / character
but does not end with a / character. Servlet path is
the path section that directly corresponds to the
mapping that activated this request. This path starts
with a / character. Path info is the part of the
request path that is not part of the context path or
the servlet path

299. What is URN

Uniform resource name. A unique identifier that
identifies an entity but doesn't tell where it is
located. A system can use a URN to look up an entity
locally before trying to find it on the Web. It also
allows the Web location to change, while still
allowing the entity to be found.

300. What is user data constraint

Indicates how data between a client and a Web
container should be protected. The protection can be
the prevention of tampering with the data or
prevention of eavesdropping on the data.