simple,exible, text-based markup language. XML data is marked using tags enclosed in angled
brackets.The tags contain the meaning of the data they mark. Such markup allows dierent
systemsto easily exchange data with each other.
ADocument Type Denition (DTD) or XML Schema Denition (XSD) describes the structure
ofan XML document. It has information on the tags the corresponding XML document can
have,the order of those tags, and so forth.
XSLT,which stands for eXtensible Stylesheet Language Transformation, is used for
transformingXML documents from one format to another.
WebServices Standards
SimpleObject Access Protocol (SOAP) provides a common messaging format for web services.
SOAPenables objects not known to one another to exchange messages. SOAP uses an
XML-baseddata encoding format and HTTP to transport messages. SOAP is independent of
boththe programming language and the operational platform, and it does not require any
specictechnology at its endpoints
UniversalDescription, Discovery, and Integration (UDDI) provides a standard way to register,
de-register,and look up web services. Similar to a telephone system's yellow pages, a UDDI
registry'senables providers to register their services and requestors to nd services. Once a
requestornds a service, the registry has no more role to play between the requestor and the
provider.
WebServices Description Language (WSDL) denes a standard way to specify the details of a
webservice. It is a general-purpose XML schema that can species details of web service
interfaces,bindings, and other deployment details. By having such a standard way to specify
detailsof a service, clients who have no prior knowledge of a web service can use it.
ebXML(Electronic Business using eXtensible Markup Language) is a set of specications that
enablesenterprises to conduct business over the Internet. OASIS (Organization for the
Advancementof Structured Information Standards) controls the ebXML specications.
JavaEE Web Service Standards
JavaAPIs for XML processing (JAXP) is a vendor-neutral set of lightweight APIs for parsing or
processingXML documents. JAXP enables a web service to “plug in” any conforming XML
parser.If no external parser is “plugged in,”then JAXP uses its own XML parser
implementation.
JavaAPI for XML-based remote procedure calls (JAX-RPC) uses an XML-based protocol for
client-serverremote procedure calls . JAX-RPC enables SOAP-basedinteroperable and portable
webservices. Developers use the JAX-RPC programming model to develop SOAP-basedweb
OverviewofWeb Services
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