Web Service Description Language WSDL

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Web Service Description Language (WSDL)

• John Schneider
• Chief Technologist
• john.schneider_at_agiledelta.com

2
Overview

• What is WSDL?
• WSDL Concepts
• What things does WSDL describe?
• WSDL Syntax
• How does WSDL describe these things?
• WSDL Use Cases
• How might you use WSDL?

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What is WSDL?

• An XML format for describing web services
• To the Consumer How to use the service(e.g.,
  To use my shopping cart, send these SOAP
  messages over HTTP to http//myservice.net/cart)
• To the Server How to configure the
  service(e.g., Make my shopping cart available
  using SOAP over HTTP at http//myservice.net/cart
  )
• To the Registry How to find the service(e.g.,
  Find me all the shopping carts I can talk to.)

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WSDL Concepts by Example
Shopping Cart
Add
Remove
List
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WSDL Concepts by Example
WSDL Terms
Port Type
Operation
Shopping Cart
Add
Remove
List
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WSDL Concepts by Example
WSDL Terms
Shopping Cart Service
Port Type
Operation
AddItemInput
Shopping Cart
Binding
Port
Add
HTTP SOAP
Remove
Service
HTTP XML
List
Message
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What does WSDL Describe?

• Abstract Concepts
• Port Types (e.g., shopping basket)
• Operations (e.g., add, remove, list)
• Messages (i.e., inputs, outputs and faults)
• Data types (i.e., schemas)
• Concrete Bindings
• Data encoding styles (e.g., SOAP encoding)
• Transport protocols (e.g., HTTP, SMTP)
• Network addresses (e.g., http//myservice.net/cart
  )

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How does WSDL Describe Things?

• ltdefinitions nameShoppingCartDefinitions
• xmlnshttp//schemas/xmlsoap.org/wsdl
  targetNamespace gt
• lttypesgt lt/typesgt
• ltmessage nameAddItemInputgt lt/messagegt
• ltmessage nameAddItemOutputgt lt/messagegt
• ltportType nameShoppingCartgt lt/portTypegt
• ltbinding nameCartHTTPXMLBinding
  typetnsShoppingCartgt
• ltbinding nameCartSOAPBinding
  typetnsShoppingCartgt
• ltservice nameShoppingCartServicegt
• ltport nameHTTPXMLCart bindingtnsCartHTTPXM
  LBindinggt
• ltport nameSOAPCart bindingtnsCartSOAPBindi
  nggt
• lt/servicegt
• ltimport namespace locationgt
• lt/definitionsgt

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How WSDL Describes Port Types

• A named collection of related operations
• ltportType nameShoppingCartgt
• ltoperation nameAddItemgt lt/operationgt
• ltoperation nameRemoveItemgt lt/operationgt
• ltoperation nameListItemsgt lt/operationgt
• lt/portTypegt

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How WSDL Describes Operations

• A signature (input, output and fault messages)
• Operations can be one-way, request-response,
  notifications or solicit-response
• ltoperation nameAddItemgt
• ltinput messagetnsAddItemInput/gt
• ltoutput messagetnsACK/gt
• ltfault nameBadCartID messagetnsBadCartID/
  gt
• ltfault nameServiceDown messagetnsServiceDo
  wn/gt
• lt/operationgt

Add
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How WSDL Describes Messages

• A named collection of message parts
• Each part has a name and a type
• ltmessage nameAddItemInputgt
• ltpart namecart-id typexsdstring/gt
• ltpart nameitem typecarttypesitem/gt
• ltpart nameimage typexsdbase64Binary/gt
• lt/messagegt

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How WSDL Describes Data Types

• Using the XML Schema language (however, other
  type systems are permitted)
• lttypesgt
• ltschema targetNamespacehttp//myservice.net/car
  t/types
• xmlnshttp//www.w3.org/2000/10/XMLSchemagt
• ltcomplexType nameitemgtltallgt
• ltelement namedescription typexsdstring/gt
  
• ltelement namequantity typexsdinteger/gt
• ltelement nameprice typexsdfloat/gt lt/all
  gtlt/complexTypegt
• lt/schemagt
• lt/typesgt

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How WSDL Describes Bindings

• A named association of protocol details with a
  port type, its operations and its messages
• ltbinding nameCartHTTPXMLBinding
  typetnsShoppingCartgt
• lthttpbinding verbPOST/gt
• ltoperation nameAddItemgt
• lthttpoperation location/AddItem/gt
• ltinputgt ltmimemimeXML/gt lt/inputgt
• ltoutputgt ltmimemimeXML/gt lt/outputgt
• ltfault nameBadCartIDgt ltmimemimeXML/gt
  lt/faultgt
• ltfault nameServiceDowngt ltmimemimeXML/gt
  lt/faultgt lt/operationgt
• lt/bindinggt

HTTP XML
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How WSDL Describes Bindings

• A named association of protocol details with a
  port type, its operations and its messages
• ltbinding nameCartHTTPXMLBinding
  typetnsShoppingCartgt
• lthttpbinding verbPOST/gt
• ltoperation nameAddItemgt
• lthttpoperation location/AddItem/gt
• ltinputgt ltmimemimeXML/gt lt/inputgt
• ltoutputgt ltmimemimeXML/gt lt/outputgt
• ltfault nameBadCartIDgt ltmimemimeXML/gt
  lt/faultgt
• ltfault nameServiceDowngt ltmimemimeXML/gt
  lt/faultgt lt/operationgt
• lt/bindinggt

HTTP XML
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How WSDL Describes Bindings

• A named association of protocol details with a
  port type, its operations and its messages
• ltbinding nameCartHTTPXMLBinding
  typetnsShoppingCartgt
• lthttpbinding verbPOST/gt
• ltoperation nameAddItemgt
• lthttpoperation location/AddItem/gt
• ltinputgt ltmimemimeXML/gt lt/inputgt
• ltoutputgt ltmimemimeXML/gt lt/outputgt
• ltfault nameBadCartIDgt ltmimemimeXML/gt
  lt/faultgt
• ltfault nameServiceDowngt ltmimemimeXML/gt
  lt/faultgt lt/operationgt
• lt/bindinggt

HTTP XML
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How WSDL Describes Bindings

• A named association of protocol details with a
  port type, its operations and its messages
• ltbinding nameCartHTTPXMLBinding
  typetnsShoppingCartgt
• lthttpbinding verbPOST/gt
• ltoperation nameAddItemgt
• lthttpoperation location/AddItem/gt
• ltinputgt ltmimemimeXML/gt lt/inputgt
• ltoutputgt ltmimemimeXML/gt lt/outputgt
• ltfault nameBadCartIDgt ltmimemimeXML/gt
  lt/faultgt
• ltfault nameServiceDowngt ltmimemimeXML/gt
  lt/faultgt lt/operationgt
• lt/bindinggt

HTTP XML
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How WSDL Describes Bindings

• A more complex example
• ltbinding nameCartHTTPSOAPBinding
  typetnsShoppingCartgt
• ltsoapbinding styleRPC transporthttp//schem
  as.xmlsoap.org/soap/http/gt
• ltoperation nameAddItemgt
• ltsoapoperation soapActionhttp//myservice.net
  /cart/AddItem/gt
• ltinputgt
• ltsoapbody useencoded namespacehttp//myse
  rvice.net/cart
• encodingStylehttp//schemas.xmlsoap.org/soap
  /encoding/gt
• lt/inputgt
• ltoutputgt
• ltsoapbody useencoded namespacehttp//myse
  rvice.net/cart
• encodingStylehttp//schemas.xmlsoap.org/soap
  /encoding/gt
• lt/outputgt
• ltfault nameBadCartIDgt ltsoapbody
  useencoded namespace /gt lt/faultgt
• ltfault nameServiceDowngt ltsoapbody use /gt
  lt/faultgtlt/operationgt
• lt/bindinggt

SOAP XML
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How WSDL Describes Ports

• A named association of a protocol binding with a
  network address
• ltport nameSOAPCart bindingtnsSOAPCartBindin
  ggt
• ltsoapaddress locationhttp//myservice.net/soa
  p/cart/gt
• lt/portgt
• ltport nameHTTPXMLCart bindingtnsHTTPXMLCart
  Bindinggt
• lthttpaddress locationhttp//myservice.net/car
  t/gt
• lt/portgt

HTTP SOAP
http//myservice.net/soap/cart
HTTP XML
http//myservice.net/cart
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How WSDL Describes Services

• A related collection of ports
• ltservice nameShoppingCartServicegt
• ltdocumentationgtA Shopping Cart for the
  Weblt/documentationgt
• ltport nameHTTPXMLCart bindingtnsHTTPXMLCart
  Bindinggt
• lthttpaddress locationhttp//myservice.net/car
  t/gt
• lt/portgt
• ltport nameSOAPCart bindingtnsSOAPCartBindin
  ggt
• ltsoapaddress locationhttp//myservice.net/soa
  p/cart/gt
• lt/portgt
• lt/servicegt

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How WSDL Describes Reuse

• ltimport namespacehttp//webservices.org/cart/car
  t-type locationhttp//services.org/cart/cart-t
  ype.wsdl/gt
• ltbinding xmlnswshttp//webservices.org/cart/car
  t-type nameCartHTTPXMLBinding
  typewsShoppingCartgt

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How might you use WSDL?

• Use an application to automatically generate Web
  Service stubs from WSDL
• Assists in developing standard web services
• Service provider fills in implementation details

WSDL
Web Service
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How might you use WSDL?

• Use an application to automatically generate WSDL
  descriptions of Web Services
• Describe web services to consumers
• Associate technical details with UDDI entries

Web Service
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How might you use WSDL?

• Use as a declarative way to configure services

WSDL
Web Service
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How might you use WSDL?

• Use to configure remote service proxy objects
• Insulate consumers from invocation details
• Support fail-over to other addresses and
  protocols
• Insulate consumers from changes (e.g., location)

WSDL
Web Service
Remote Service
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Review and Questions