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Communication from and to WebServices is performed in XML. Also the data transfer can (but need not to) be managed using XML.
It is sometimes useful to divide up XML elements into groups or so called namespaces.
Sometimes you have an element that can have a different meaning in different contexts. A simple biology example could be a sequence element which
describes
a nucleotide sequence or protein sequence depending on context. Namespaces are used to avoid problems using the sequence element in both
ways in one document. |
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XML is often described by an XML Schema document. XML Schema Definition (short: XSD) is a language recommended by W3C to
describe structures of XML documents. Using such a grammar makes it easy to combine different WebServices.
The output of one WebService can simply be pushed to another one, without performing any conversion.
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WSDL stands for Web Service Description Language. WSDL is a XML grammar for describing a
WebService in a standardized way. The actual specification is available online
at http://www.w3.org/TR/wsdl. A WSDL document describes important
information about a WebService a client would basically need:
- the name of the service
- its location
- the available methods
- their supported input/output parameter for each method
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<definitions>
<import>*
<types>
<schema></schema>*
</types>
<message>*
<part></part>
</message>
<PortType>*
<operation>*
<input></input>
<output></output>
<fault></fault>
</operation>
</PortType>
<binding>*
<operation>*
<input></input>
<output></output>
<operation>
</binding>
<service>*
<port></port>
<service>
</definitions>
* indicates possible mutable occurance
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