J2EE Interview Tips Part 7
301. 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.
302. What is transaction manager
Provides the services and management functions required to support transaction demarcation, transactional resource management, synchronization,
and transaction context propagation.
303. 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/.
304. 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.
305. 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.
306. What is unparsed entity
A general entity that contains something other than XML. By its nature, an unparsed entity contains binary data.
306. 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.
307. 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.
308. 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
309. 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.
310. 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.
311. What is user (security)
An individual (or application program) identity that has been authenticated. A user can have a set of roles associated with that identity, which entitles the user
to access all resources protected by those roles.
312. What is user (security)
A valid XML document, in addition to being well formed, conforms to all the constraints imposed by a DTD. It does not contain any tags that are not
permitted by the DTD, and the order of the tags conforms to the DTD's specifications.
313. What is validating parser
A parser that ensures that an XML document is valid in addition to being well formed. See also parser.
314. What is value-binding _expression
A JavaServer Faces EL _expression that refers to a property of a backing bean. A component tag uses this _expression to bind the associated component's value or
the component instance to the bean property. If the component tag refers to the property via its value attribute, then the component's value is bound to the
property. If the component tag refers to the property via its binding attribute then the component itself is bound to the property.
315. What is virtual host
Multiple hosts plus domain names mapped to a single IP address.
316. What is W3C
World Wide Web Consortium. The international body that governs Internet standards. Its Web site is http://www.w3.org/.
317. What is WAR file
Web application archive file. A JAR archive that contains a Web module.
318. What is warning
A SAX parser warning is generated when the document's DTD contains duplicate definitions and in similar situations that are not necessarily an error but which
the document author might like to know about, because they could be. See also fatal error, error.
319. What is Web application
An application written for the Internet, including those built with Java technologies such as JavaServer Pages and servlets, as well as those built with
non-Java technologies such as CGI and Perl.
320. What is Web application, distributable
A Web application that uses J2EE technology written so that it can be deployed in a Web container distributed across multiple Java virtual machines running on the
same host or different hosts. The deployment descriptor for such an application uses the distributable element.
321. What is Web component
A component that provides services in response to requests; either a servlet or a JSP page.
322. What is Web container
A container that implements the Web component contract of the J2EE architecture. This contract specifies a runtime environment for Web components that includes
security, concurrency, life-cycle management, transaction, deployment, and other services. A Web container provides the same services as a JSP
container as well as a federated view of the J2EE platform APIs. A Web container is provided by a Web or J2EE server.
323. What is Web container, distributed
A Web container that can run a Web application that is tagged as distributable and that executes across multiple Java virtual machines running on the same
host or on different hosts.
324. What is Web container provider
A vendor that supplies a Web container.
325. What is Web module
A deployable unit that consists of one or more Web components, other resources, and a Web application deployment descriptor contained in a hierarchy of directories and files in a standard Web application format.
326. What is Web resource
A static or dynamic object contained in a Web application that can be referenced by a URL.
327. What is Web resource collection
A list of URL patterns and HTTP methods that describe a set of Web resources to be protected.
328. What is Web server
Software that provides services to access the Internet, an intranet, or an extranet. A Web server hosts Web sites, provides support for HTTP and other
protocols, and executes server-side programs (such as CGI scripts or servlets) that perform certain functions. In the J2EE architecture, a Web server
provides services to a Web container. For example, a Web container typically relies on a Web server to provide HTTP message handling. The J2EE architecture
assumes that a Web container is hosted by a Web server from the same vendor, so it does not specify the contract between these two entities. A Web server can
host one or more Web containers.
329. What is Web server provider
A vendor that supplies a Web server.
330. What is Web service
An application that exists in a distributed environment, such as the Internet. A Web service accepts a request, performs its function based on the request, and returns a response. The request and the response can be part of the same operation, or they can occur separately, in which case the consumer does not need to wait for a response. Both the request and the response usually take the form of XML, a portable data-interchange format, and are delivered over a wire protocol, such as HTTP.
331. What is well-formed
An XML document that is syntactically correct. It does not have any angle brackets that are not part of tags, all tags have an ending tag or are themselves
self-ending, and all tags are fully nested. Knowing that a document is well formed makes it possible to process it. However, a well-formed document may not be
valid. To determine that, you need a validating parser and a DTD.
332. What is Xalan
An interpreting version of XSLT.
333. What is XHTML
An XML look-alike for HTML defined by one of several XHTML DTDs. To use XHTML for everything would of course defeat the purpose of XML, because the idea of XML is to identify information content, and not just to tell how to display it. You can reference it in a DTD, which allows you to say, for example, that the text in an element can contain < em > and < b > tags rather than being limited to plain text.
334. What is XLink
The part of the XLL specification that is concerned with specifying links between documents.
335. What is XLL
The XML Link Language specification, consisting of XLink and XPointer.
336. What is XML
Extensible Markup Language. A markup language that allows you to define the tags (markup) needed to identify the content, data, and text in XML documents.
It differs from HTML, the markup language most often used to present information on the Internet. HTML has fixed tags that deal mainly with style or presentation. An XML document must undergo a transformation into a language with style tags under the control of a style sheet before it can be presented by a browser or other presentation mechanism. Two types of style sheets used with XML are CSS and XSL. Typically, XML is transformed into HTML for presentation. Although tags can be defined as needed in the generation of an XML document, a document type definition (DTD) can be used to define the elements allowed in a particular type of document. A document can be compared by using the rules in the DTD to determine its validity and to locate particular elements in the document. A Web services application's J2EE deployment descriptors are expressed in XML with schemas defining allowed elements. Programs for processing XML documents use SAX or DOM APIs.
337. What is XML registry
An infrastructure that enables the building, deployment, and discovery of Web services. It is a neutral third party that facilitates dynamic and loosely coupled business-to-business (B2B) interactions.
338. What is XML Schema
The W3C specification for defining the structure, content, and semantics of XML documents.
339. What is XPath
An addressing mechanism for identifying the parts of an XML document.
340. What is XPointer
The part of the XLL specification that is concerned with identifying sections of documents so that they can be referenced in links or included in other documents.
341. What is XSL
Extensible Stylesheet Language. A standard that lets you do the following: Specify an addressing mechanism, so that you can identify the parts of an XML document
that a transformation applies to (XPath). Specify tag conversions, so that you can convert XML data into different formats (XSLT). Specify display characteristics, such page sizes, margins, and font heights and widths, as well as the flow objects on each page. Information fills in one area of a page and then automatically flows to the next object when that area fills up. That allows you to wrap text around
pictures, for example, or to continue a newsletter article on a different page (XSL-FO).
342. What is XSL-FO
A subcomponent of XSL used for describing font sizes, page layouts, and how information flows from one page to another.
343. What is XSLT
XSL Transformations. An XML document that controls the transformation of an XML document into another XML document or HTML. The target document often has
presentation-related tags dictating how it will be rendered by a browser or other presentation mechanism. XSLT was formerly a part of XSL, which also included a
tag language of style flow objects.
344. What is XSLTC
A compiling version of XSLT.
345. What is binary entity
A general entity that contains something other than XML. By its nature, an unparsed entity contains binary data.
346. What is component (JavaServer Faces technology)
A user interface control that outputs data to a client or allows a user to input data to a JavaServer Faces application.
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.
302. What is transaction manager
Provides the services and management functions required to support transaction demarcation, transactional resource management, synchronization,
and transaction context propagation.
303. 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/.
304. 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.
305. 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.
306. What is unparsed entity
A general entity that contains something other than XML. By its nature, an unparsed entity contains binary data.
306. 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.
307. 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.
308. 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
309. 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.
310. 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.
311. What is user (security)
An individual (or application program) identity that has been authenticated. A user can have a set of roles associated with that identity, which entitles the user
to access all resources protected by those roles.
312. What is user (security)
A valid XML document, in addition to being well formed, conforms to all the constraints imposed by a DTD. It does not contain any tags that are not
permitted by the DTD, and the order of the tags conforms to the DTD's specifications.
313. What is validating parser
A parser that ensures that an XML document is valid in addition to being well formed. See also parser.
314. What is value-binding _expression
A JavaServer Faces EL _expression that refers to a property of a backing bean. A component tag uses this _expression to bind the associated component's value or
the component instance to the bean property. If the component tag refers to the property via its value attribute, then the component's value is bound to the
property. If the component tag refers to the property via its binding attribute then the component itself is bound to the property.
315. What is virtual host
Multiple hosts plus domain names mapped to a single IP address.
316. What is W3C
World Wide Web Consortium. The international body that governs Internet standards. Its Web site is http://www.w3.org/.
317. What is WAR file
Web application archive file. A JAR archive that contains a Web module.
318. What is warning
A SAX parser warning is generated when the document's DTD contains duplicate definitions and in similar situations that are not necessarily an error but which
the document author might like to know about, because they could be. See also fatal error, error.
319. What is Web application
An application written for the Internet, including those built with Java technologies such as JavaServer Pages and servlets, as well as those built with
non-Java technologies such as CGI and Perl.
320. What is Web application, distributable
A Web application that uses J2EE technology written so that it can be deployed in a Web container distributed across multiple Java virtual machines running on the
same host or different hosts. The deployment descriptor for such an application uses the distributable element.
321. What is Web component
A component that provides services in response to requests; either a servlet or a JSP page.
322. What is Web container
A container that implements the Web component contract of the J2EE architecture. This contract specifies a runtime environment for Web components that includes
security, concurrency, life-cycle management, transaction, deployment, and other services. A Web container provides the same services as a JSP
container as well as a federated view of the J2EE platform APIs. A Web container is provided by a Web or J2EE server.
323. What is Web container, distributed
A Web container that can run a Web application that is tagged as distributable and that executes across multiple Java virtual machines running on the same
host or on different hosts.
324. What is Web container provider
A vendor that supplies a Web container.
325. What is Web module
A deployable unit that consists of one or more Web components, other resources, and a Web application deployment descriptor contained in a hierarchy of directories and files in a standard Web application format.
326. What is Web resource
A static or dynamic object contained in a Web application that can be referenced by a URL.
327. What is Web resource collection
A list of URL patterns and HTTP methods that describe a set of Web resources to be protected.
328. What is Web server
Software that provides services to access the Internet, an intranet, or an extranet. A Web server hosts Web sites, provides support for HTTP and other
protocols, and executes server-side programs (such as CGI scripts or servlets) that perform certain functions. In the J2EE architecture, a Web server
provides services to a Web container. For example, a Web container typically relies on a Web server to provide HTTP message handling. The J2EE architecture
assumes that a Web container is hosted by a Web server from the same vendor, so it does not specify the contract between these two entities. A Web server can
host one or more Web containers.
329. What is Web server provider
A vendor that supplies a Web server.
330. What is Web service
An application that exists in a distributed environment, such as the Internet. A Web service accepts a request, performs its function based on the request, and returns a response. The request and the response can be part of the same operation, or they can occur separately, in which case the consumer does not need to wait for a response. Both the request and the response usually take the form of XML, a portable data-interchange format, and are delivered over a wire protocol, such as HTTP.
331. What is well-formed
An XML document that is syntactically correct. It does not have any angle brackets that are not part of tags, all tags have an ending tag or are themselves
self-ending, and all tags are fully nested. Knowing that a document is well formed makes it possible to process it. However, a well-formed document may not be
valid. To determine that, you need a validating parser and a DTD.
332. What is Xalan
An interpreting version of XSLT.
333. What is XHTML
An XML look-alike for HTML defined by one of several XHTML DTDs. To use XHTML for everything would of course defeat the purpose of XML, because the idea of XML is to identify information content, and not just to tell how to display it. You can reference it in a DTD, which allows you to say, for example, that the text in an element can contain < em > and < b > tags rather than being limited to plain text.
334. What is XLink
The part of the XLL specification that is concerned with specifying links between documents.
335. What is XLL
The XML Link Language specification, consisting of XLink and XPointer.
336. What is XML
Extensible Markup Language. A markup language that allows you to define the tags (markup) needed to identify the content, data, and text in XML documents.
It differs from HTML, the markup language most often used to present information on the Internet. HTML has fixed tags that deal mainly with style or presentation. An XML document must undergo a transformation into a language with style tags under the control of a style sheet before it can be presented by a browser or other presentation mechanism. Two types of style sheets used with XML are CSS and XSL. Typically, XML is transformed into HTML for presentation. Although tags can be defined as needed in the generation of an XML document, a document type definition (DTD) can be used to define the elements allowed in a particular type of document. A document can be compared by using the rules in the DTD to determine its validity and to locate particular elements in the document. A Web services application's J2EE deployment descriptors are expressed in XML with schemas defining allowed elements. Programs for processing XML documents use SAX or DOM APIs.
337. What is XML registry
An infrastructure that enables the building, deployment, and discovery of Web services. It is a neutral third party that facilitates dynamic and loosely coupled business-to-business (B2B) interactions.
338. What is XML Schema
The W3C specification for defining the structure, content, and semantics of XML documents.
339. What is XPath
An addressing mechanism for identifying the parts of an XML document.
340. What is XPointer
The part of the XLL specification that is concerned with identifying sections of documents so that they can be referenced in links or included in other documents.
341. What is XSL
Extensible Stylesheet Language. A standard that lets you do the following: Specify an addressing mechanism, so that you can identify the parts of an XML document
that a transformation applies to (XPath). Specify tag conversions, so that you can convert XML data into different formats (XSLT). Specify display characteristics, such page sizes, margins, and font heights and widths, as well as the flow objects on each page. Information fills in one area of a page and then automatically flows to the next object when that area fills up. That allows you to wrap text around
pictures, for example, or to continue a newsletter article on a different page (XSL-FO).
342. What is XSL-FO
A subcomponent of XSL used for describing font sizes, page layouts, and how information flows from one page to another.
343. What is XSLT
XSL Transformations. An XML document that controls the transformation of an XML document into another XML document or HTML. The target document often has
presentation-related tags dictating how it will be rendered by a browser or other presentation mechanism. XSLT was formerly a part of XSL, which also included a
tag language of style flow objects.
344. What is XSLTC
A compiling version of XSLT.
345. What is binary entity
A general entity that contains something other than XML. By its nature, an unparsed entity contains binary data.
346. What is component (JavaServer Faces technology)
A user interface control that outputs data to a client or allows a user to input data to a JavaServer Faces application.
