1. Web Services (NSWI145)
Lecture 04: Web Services Description Language
Martin Nečaský, Ph.D.
Faculty of Mathematics and Physics
Charles University in Prague, Czech Republic
Winter 2011

2. WSDL Foundations
 Web Services Description Language
 language for describing web service interfaces
in machine-readable notation
 XML format
 current version: 2.0
 http://www.w3.org/TR/wsdl20
 currently mostly supported version: 1.1
 http://www.w3.org/TR/wsdl

3. WSDL Foundations
Interface
Port 1
Location: URL_1
Client
Transport: SOAP/HTTP
A
Implementation
Port 2
Location: URL_2
Client
Transport: SOAP/JMS
B
Port 3
Location: URL_3
Client
Transport: XML/HTTP
C
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4. WSDL Document
 types
 XML schema describing XML elements and attributes
 messages
 representation of data exchanged between clients and service
 based on types
 operations
 service capabilities offered to clients
 input and output messages
 port types
 collection of operations
 bindings
 specification of concrete protocol for exchanging messages between service
and clients which call operations from particular port type
 ports
 single endpoint combining particular binding and network address
 services
 collection of related ports
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5. WSDL Document
Service Description
Types
Abstract Messages
Description =
Operations
Port Types
Bindings
Concrete
= Ports
Description
Service

6. WSDL Document Structure
<?xml version="1.0" encoding="utf-8" ?>
<definitions xmlns:wsdl="http://schemas.xmlsoap.org/wsdl/">
<documentation> ... </documentation>
<!-- types (0,1) -->
<types> ... </types>
<!-- messages (0,*) -->
<message> ... </message>
<!-- port types (0,*) -->
<portType> ... </portType>
<!-- bindings (0,*) -->
<binding> ... </binding>
<!-- services (0,*) -->
<service> ... </service>
</definitions>
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7. Types Definitions
<?xml version="1.0" encoding="utf-8" ?>
<definitions xmlns="http://schemas.xmlsoap.org/wsdl/">
<documentation> ... </documentation>
<!-- types (0,1) -->
<types> ... </types>
<!-- messages (0,*) -->
<message> ... </message>
<!-- port types (0,*) -->
<portType> ... </portType>
<!-- bindings (0,*) -->
<binding> ... </binding>
<!-- services (0,*) -->
<service> ... </service>
</definitions>
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8. Types Definition
 describes building blocks of XML messages
exchanged with service
 any XML schema language with XML syntax
can be applied inside
 XML Schema (XSD), Relax NG, Schematron, etc.
 XSD preferred and used in practice
 non-XML type system can be applied as well
? Do you know XSD ?
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9. Message Definition
<?xml version="1.0" encoding="utf-8" ?>
<definitions xmlns="http://schemas.xmlsoap.org/wsdl/">
<documentation> ... </documentation>
<!-- types (0,1) -->
<types> ... </types>
<!-- messages (0,*) -->
<message> ... </message>
<!-- port types (0,*) -->
<portType> ... </portType>
<!-- bindings (0,*) -->
<binding> ... </binding>
<!-- services (0,*) -->
<service> ... </service>
</definitions>
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10. Message Definition
 zero or more message definitions
 element message
 defines single message type which can be
exchanged with the service
 has unique name among all message types
• attribute name
<message name="[name]">
</message>
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11. Message Definition
 message consists of one or more logical units called
message parts
 element part
 defines single message part
 has unique name among all parts of the same message
• attribute name
 is associated with element from the types definition ...
• attribute element
 ... or with simple or complex type from the types definition
• attribute type
<message name="[name]">
<!-- message part (1,*) -->
<part name="[part-name]" element="[element-ref]" type="[type-ref]" />
</message>
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12. Port Type Definition
<?xml version="1.0" encoding="utf-8" ?>
<definitions xmlns="http://schemas.xmlsoap.org/wsdl/">
<documentation> ... </documentation>
<!-- types (0,1) -->
<types> ... </types>
<!-- messages (0,*) -->
<message> ... </message>
<!-- port types (0,*) -->
<portType> ... </portType>
<!-- bindings (0,*) -->
<binding> ... </binding>
<!-- services (0,*) -->
<service> ... </service>
</definitions>
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13. Port Type Definition
 zero or more port type definitions
 port type encapsulates one or more
operations
 element portType
 defines single port type
 has unique name among all port types types
• attribute name
<portType name="[name]">
</portType>
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14. Port Type Definition
 element operation
 defines single operation
 has unique name among all operations in the port type
• attribute name
 operation consumes input message and produces output
message, four supported message exchange patterns:
 one-way (in)
 request-response (in-out)
 solicit-response (out-in)
 notification (out)
<portType name="[name]">
<!-- operation (1,*) -->
<operation name="[operation-name]" />
</portType>
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15. Port Type Definition
 element input (output, fault)
 specifies input (output, fault) message type
 has unique name among all inputs, outputs and faults within the
operation (attribute name )
 reference to message type definition (attribute message)
one-way notification
<operation name="[operation-name]"> <operation name="[operation-name]">
<input name="[param-name]" <output name="[param-name]"
message="[message-ref]" /> message="[message-ref]" />
</operation> </operation>
request-response solicit-response
<operation name="[operation-name]"> <operation name="[operation-name]">
<input name="[param-name]" <output name="[param-name]"
message="[message-ref]" /> message="[message-ref]" />
<output name="[param-name]" <input name="[param-name]"
message="[message-ref]" /> message="[message-ref]" />
<fault name="[param-name]" <fault name="[param-name]"
message="[message-ref]" /> message="[message-ref]" />
</operation> </operation>
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16. Binding Definition
<?xml version="1.0" encoding="utf-8" ?>
<definitions xmlns="http://schemas.xmlsoap.org/wsdl/">
<documentation> ... </documentation>
<!-- types (0,1) -->
<types> ... </types>
<!-- messages (0,*) -->
<message> ... </message>
<!-- port types (0,*) -->
<portType> ... </portType>
<!-- bindings (0,*) -->
<binding> ... </binding>
<!-- services (0,*) -->
<service> ... </service>
</definitions>
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17. Binding Definition
 zero or more binding definitions
 defines message format and protocol details for
operations and messages in particular port type
 element binding
 defines single binding
 has unique name among all bindings
• attribute name
 refers to particular port type
• attribute type
<binding name="[name]" type="[portType-ref]">
</binding>
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18. Binding Definition
 specifies binding for each operation defined in port type
 input and output messages, faults
 element operation
 binding of particular operation
• referred by attribute name
 element input (output, fault)
 binding of particular input (output, fault) message type
<binding name="[name]" type="[portType-ref]">
<!-- protocol specific binding information -->
<operation name="[operation-ref]">
<!-- protocol specific binding information -->
<input><!-- protocol specific binding information --></input>
<output><!-- protocol specific binding information --></output>
<fault><!-- protocol specific binding information --></fault>
</operation>
</binding>
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19. Service Definition
<?xml version="1.0" encoding="utf-8" ?>
<definitions xmlns="http://www.w3.org/ns/wsdl">
<documentation> ... </documentation>
<!-- types (0,1) -->
<types> ... </types>
<!-- messages (0,*) -->
<message> ... </message>
<!-- port types (0,*) -->
<portType> ... </portType>
<!-- bindings (0,*) -->
<binding> ... </binding>
<!-- services (0,*) -->
<service> ... </service>
</definitions>
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20. Service Definition
 zero or more service definitions
 i.e. one WSDL document can eventually define more
interfaces to one or more services
 element service
 defines single service interface + binding to particular
protocol and physical address
 has unique name among all services
• attribute name
<service name="[name]">
</service>
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21. Service Definition
 service consists of ports
 element port
 defines service port
 has unique name among all ports of the service
• attribute name
 refers to particular port type which defines port
operations and their input and output messages
• attribute binding
<service name="[name]">
<port name="[name]" binding="[binding-ref]">
<!-- protocol specific information -->
</port>
</service>
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22. Service Definition
Message of defined by
Message Types
Binding
input fault output input fault output
Operation of
Service Operation
Binding
comprises comprises comprises
has of
Port Binding PortType
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23. More on Bindings
 HTTP
 SOAP 1.1 over HTTP
 SOAP 1.2 over HTTP
 SOAP 1.1 over Java Messaging Service (JMS)
 SOAP 1.2 over Java Messaging Service (JMS)
 SOAP 1.1 over SMTP
 ...
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24. SOAP 1.2 Binding
 namespace with SOAP 1.2 specific binding
extensions
 http://schemas.xmlsoap.org/wsdl/soap12/
 we will use prefix wsoap12
 binding to SOAP 1.2 must start with element
wsoap12:binding
<binding name="[name]">
<wsoap12:binding />
</binding>
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25. SOAP 1.2 Binding
 optional default operation style
 specifies default style of each operation (RPC-oriented or document-
oriented operations)
 attribute style
• values rpc or document, respectively
• document is default
 mandatory transport protocol
 URI of particular protocol
 HTTP has http://schemas.xmlsoap.org/soap/http
 attribute transport
<binding name="[name]">
<wsoap12:binding style="[style]" transport="[protocol-URI]"/>
</binding>
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26. SOAP 1.2 Binding
 RPC-oriented operations
 SOAP body contains only one part – element
whose name is the name of remote procedure to
be called
• contains element for each procedure parameter
 document-oriented operations
 SOAP body contains one or more child elements
called parts
 part can be anything
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27. SOAP 1.2 Binding
 each operation is further specified by wsoap:operation
element
 may optionally have own style (rpc or document)
• attribute style
 if the operation is not determined by its request message we can
determine it by SOAPAction HTTP header
• the value of the SOAPAction HTTP header for the operation can be specified in
attribute soapAction
• if you want SOAPAction HTTP header to be mandatory for this operation, use
attribute soapActionRequired
<binding name="[name]">
<operation name="[operation-ref]">
<wsoap12:operation style="[style]" soapAction="[action-URI]“
soapActionRequired="[boolean]" />
</operation>
</binding>
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28. SOAP 1.2 Binding
 for each operation input/output we map one or more
message parts to SOAP body
 element wsoap12:body
 message parts specified by attribute parts
 attribute use indicates whether parts specify schema for messages or
some other encoding of data to messages is used
• values literal or encoded, respectively
<binding name="[name]">
<operation name="[operation-ref]">
<input>
<wsoap12:body parts="[part-refs-list]" use="[use]" />
</input>
</operation>
</binding>
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29. SOAP 1.2 Binding
 for each operation input/output we can map particular
message part to SOAP header
 element wsoap12:header
 mandatory attribute message
 message part specified by attribute part
 attribute use indicates whether part specifies schema for messages or
some other encoding of data to messages is used
• values literal or encoded, respectively
<binding name="[name]">
<operation name="[operation-ref]">
<input>
<wsoap12:header message="[message-ref]" part="[part-ref]"
use="[use]" />
</input>
</operation>
</binding>
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30. SOAP 1.2 Binding
 for each operation input/output we can map
particular faults to SOAP fault
 element wsoap12:fault
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31. SOAP 1.2 Binding
 port is extended with physical location of
SOAP 1.2 endpoint
 element wsoap12:address
• attribute location
<service name="[name]">
<port name="[operation-ref]">
<wsoap12:address location="[URI]" />
</port>
</binding>
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32. Examples
 PublicContractWS.wsdl
 TripleStoreWS.wsdl
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