Java Web Services [3/5]: WSDL, WADL and UDDI

Topic 3

WSDL and WADL and UDDI

Assoc.Prof. Dr. Thanachart Numnonda
www.imcinstitute.com
August 2010

Agenda

 What is and Why WSDL?
 WSDL Elements
 WSDL Transmission Patterns
 WADL Basics and Elements
 UDDI Basics and Data Types

2

What is and why WSDL?

3

What is WSDL?
• XML language for describing web services
• Web service is described as
– A set of communication endpoints (ports)
• Endpoint is made of two parts
– Abstract definitions of operations and messages
– Concrete binding to networking protocol (and corresponding
endpoint address) and message encoding
• Why this separation?
– Enhance reusability (of the abstract part, for example)

4

WSDL Service Description
• WSDL is “the interface for Web Services” describing:
• What a service does - the operations (methods) the
service provides, and the data (arguments and returns)
needed to invoke them.
• How a service is accessed - details about data formats
and protocols necessary to access the service
operations.
• Where a service is located - details of the protocol-
specific network address, such as a URL.
5

Where is WSDL Used?
Web service Web service
W
requester provider
(4) Invoke web
e service
Servlets JAXR
b
Business partner
or other system
soap request

WSDL
Document

(3) Retrieve WSDL
definition

Soap request

(2) Search for web
service
(1) Register web
UDDI service
Soap request
UDDI
service Soap request
Registry

6

Why WSDL?

source: WSDL 1.2 primer 7

Why WSDL? (cont.)
• Enables automation of communication details
between communicating partners
– Machines can read WSDL
– Machines can invoke a service defined in WSDL
• Discoverable through registry
• Arbitration
– 3rd party can verify if communication conforms to
WSDL
8

WSDL Document Structure
<wsdl:definitions xmlns:wsdl="http://schemas.xmlsoap.org/wsdl"
targetNamespace="your namespace here"
xmlns:tns="your namespace here"
xmlns:soapbind="http://schemas.xmlsoap.org/wsdl/soap">
<wsdl:types>
<xs:schema targetNamespace="your namespace here (could be another) "
xmlns:xsd="http://www.w3.org/2001/XMLSchema"

</schema>
</wsdl:types>
<wsdl:message name="some operation input">

</wsdl:message>
<wsdl:message name="some operation output">

</wsdl:message>
<wsdl:portType name="your type name">

</wsdl:portType>
<wsdl:binding name="your binding name" type="tns:port type name above">

</wsdl:binding>
<wsdl:service>

</wsdl:service>
</wsdl:definitions>
9

WSDL Structure
 Abstract part
– Types
– Message
– Operation
– Port Type
 Concrete part
– Binding
– Port
– Service 11

WSDL Structure - Abstract
 port type - logical collection of
related operations
 operation - abstract description
of an action supported by the
service
 message - data exchanged in a
single logical transmission
 types - data structures that will
be exchanged as parts of
messages
12

WSDL Structure - Concrete
 interface bindings - message
encoding and protocol binding
for all operations and messages
defined in a given porttype
 ports - combine the interface
binding information with a
network address specified by a
URI
 services - are logical groupings
of ports
13

WSDL Information Model

14

WSDL : Example (cont.)

16

WSDL Elements : Definitions
 name attribute - corresponds to the name of the
web service. It is only for documentation and is
optional
 targetNamespace attribute - a URI for the entire
WSDL file
 default namespace - all elements without a
namespace prefix, such as message or portType,
are assumed to be part of the default WSDL
namespace: http://schemas.xmlsoap.org/wsdl/
 other XML namespace declarations 17

WSDL Elements : Type
 Data type definitions
 Used to describe exchanged messages
 Uses W3C XML Schema as canonical type system

18

WSDL Example: Types
<definitions name="StockQuote"
targetNamespace="http://example.com/stockquote.wsdl"
xmlns:tns="http://example.com/stockquote.wsdl"
xmlns:xsd1="http://example.com/stockquote.xsd"
xmlns:soap="http://schemas.xmlsoap.org/wsdl/soap/"
xmlns="http://schemas.xmlsoap.org/wsdl/”>
<types>
<schema targetNamespace="http://example.com/stockquote.xsd"
xmlns="http://www.w3.org/2000/10/XMLSchema">
<element name="TradePriceRequest">
<complexType>
<all>
<element name=”tickerSymbol" type="string"/>
</all>
</complexType>
</element>
<element name="TradePrice">
<complexType>
<all>
<element name="price" type="float"/>
</all>
</complexType>
</element>
</schema>
</types>
19

WSDL Elements : Message
 A message describes the abstract form of an input,
output or a fault message.
 A message describes the data being communicated.
 Each message has a unique name within the WSDL
document and contains a collection of parts.
 A message may have several parts.
 A part may belong to several messages.

20

WSDL Elements : Part
 Parts provide a flexible mechanism for describing
the logical content of messages.
 A part element has two properties:
– name : represented by the name attribute,
which must be unique among all the part
elements of the message element
– kind : defined as either a type or an element
attribute:
• element - the payload of the message on the
wire is precisely the XML element
• type - any element conforming to the type 21

WSDL Elements : PortType
 portType is a collection of one or more related operations
describing the interface of a web service.
 portType definition is a collection of operation elements.
 Generally, WSDL documents contain only one portType
element, because different web service interface
definitions are written with different documents.
 portType has a single name attribute.
 The name of portType together with the namespace of the
WSDL document define a unique name for the portType.

22

WSDL Elements : Operation
 operation defines a method of a web service, including the
name of the method, input parameters, and the output or
return type of the method.
 All operations in a portType must have different names.
 Each operation may define:
– input message
– output message
– fault message
 An operation in WSDL is the equivalent of a method
signature in Java.
23

Abstract Elements : Example

<message name="GetLastTradePriceInput">
<part name="body" element="xsd1:TradePriceRequest"/>
</message>

<message name="GetLastTradePriceOutput">
<part name="body" element="xsd1:TradePrice"/>
</message>

<portType name="StockQuotePortType">
<operation name="GetLastTradePrice">
<input message="tns:GetLastTradePriceInput"/>
<output message="tns:GetLastTradePriceOutput"/>
</operation>

</portType>
24

WSDL Elements : Binding
 The binding element specifies how to format messages in a
protocol specific manner:
– message encoding
– protocol binding
 Each portType can have several binding elements
associated with it.
 Each binding specifies how to invoke operations using
particular transport protocols. For instance: SOAP over
HTTP, SOAP over SMTP, etc.

25

WSDL Elements : Binding (cont.)
 The binding element has two attributes:
– name : must be unique among all binding elements
defined in the WSDL document
– type : identifies which portType the binding
describes

26

WSDL Elements : Binding (cont.)
 Defines protocol details and message format for
operations and messages defined by a particular
portType
 Specify one protocol out of
 SOAP (SOAP over HTTP, SOAP over SMTP)
 HTTP GET/POST

 Provides extensibility mechanism
 Can includes binding extensibility elements
 Binding extensibility elements are used to specify the
concrete grammar
27

RPC and Document-style
RPC Document-style

 Procedure call  Business documents
 Method signature  Schema
 Marshaling  Parsing & Validating
 Tightly-coupled  Loosely coupled
 Point to point  End to end
 Synchronous  Asynchronous
 Typically within  Typically over
Intranet internet

28

RPC and Document-style (cont.)
RPC Document-style
 Within Enterprise  Between enterprise
and enterprise
 Simple, point-to-  Complex, end to end
point with intermediaries
 Short running  Long running
business process business process
 Reliable and high  Unpredictable
bandwidth bandwidth
 Trusted  Blind trust
environment

29

Binding Protocol Encoding Rules
 The binding also specifies the encoding rules used in
serializing parts of a message into XML:
– literal encoding: takes the WSDL types defined in
XML Schemaand “literally” uses those definitions to
represent the XML content of messages. Abstract
WSDL types becomes concrete types
– SOAP encoding : considers the XML Schema
definitions as abstract entities and translates them into
XML using SOAP encoding rules
 Literal encoding is used for document style interactions.
 SOAP encoding is used for RPC style interactions. 30

WSDL Elements : Port
 Port specifies the network address of the end-point
hosting the web service.
 port is a single end-point defined as a combination of a
binding and a network address.
 There can be many ports for a binding, just like many
implementations for the same interface.
 The soap:address element is used to give a port an
address.

31

WSDL Elements : Service
 A service is a collection of ports.
 Although a WSDL document can contain a collection
of service elements, by convention a WSDL document
contains a single service.
 Usage: group the ports that are related to the same
service interface (portType) but expressed by different
protocols (binding).

32

Concrete Elements : Example
<binding name="StockQuoteSoapBinding" type="tns:StockQuotePortType">
<soap:binding style="document"
transport="http://schemas.xmlsoap.org/soap/http"/>
<operation name="GetLastTradePrice">
<soap:operation
soapAction="http://example.com/GetLastTradePrice"/>
<input> <soap:body use="literal" />
</input>
<output> <soap:body use="literal" />
</output>
</operation>
</binding>

<service name="StockQuoteService">
<documentation>My first service</documentation>
<port name="StockQuotePort" binding="tns:StockQuoteSoapBinding">
<soap:address location="http://example.com/stockquote"/>
</port>
</service>

33

WSDL Transmission Patterns

34

Transmission Patterns in WSDL
 One-way
 The endpoint receives a message
 Request/response
 The endpoint receives a message, and sends a correlated
message
 Notification
 The endpoint sends a message
 Solicit/response
 The endpoint sends a message, and receives a correlated
message
35

Transmission Patterns in WSDL

36

One-way Operation : Example
<operation name=”submitPurchase”>
<input message=”purchase”/>
</operation>

37

Request/Response Operation : Example
<output message=”confirmation”/>
</operation>

<output message=”confirmation”/>
<fault message=”faultMessage”/>
</operation>
38

Notification Operation : Example
<operation name=”deliveryStatus”>
<output message=”trackingInformation”/>
</operation>

39

Solicit/Response Operation : Example
<operation name=”clientQuery”>
<output message=”bandwidthRequest”/>
<input message=”bandwidthInfo”/>
<fault message=”faultMessage”/>
</operation>

40

WADL Basic and Elements

41

WADL

 Web Application Description Language
 An XML-based file format
 A machine-readable description of HTTP-
based REST web Services
 Development language+platform neutral

42

WADL Elements
• Grammars
− Currently specify use of W3C XML Schema or RelaxNG
• Resources
– Identified by a URI template
– Specify which methods are supported
• Method
– Specify details of request and response contents
– Often refer to representations
• Representation
– Describe the format of a HTTP entity
– Can refer to grammars
43

WADL Document Structure
<application>
<doc/>*
<grammars/>?
<resources base='anyURI'>?
<doc/>*
<resource path='template' type='anyURI+'?>+
<doc/>*
<param/>*
( <method/> | <resource/> )+
</resource>
</resources>
( <method/> | <representation/> | <fault/> |
<resource_type/>)*
</application>
* => 0 or more
? => 0 or 1
+ => 1 or more
44

WADL Method Structure
<method name='NMTOKEN'? id='ID'? href='anyURI'?>
<doc/>*
<request>?
<param>*
<representation/>*
</request>
<response>?
( <representation/> | <fault/> )*
</response>
</method>

45

Yahoo News Search
• http://api.search.yahoo.com/NewsSearchService/
V1/newsSearch
• Query parameters
– appid: get this from Yahoo by registering
– query: space separated list of keywords
– many others including language, sort, result count
etc.
• Get back results as XML, JSON or PHP
– XML schema available for normal and error
responses
46

Yahoo News Search in WADL
<application xmlns:...>

<grammars>
<include href=".../NewsSearchResponse.xsd"/>
<include href=".../NewsSearchError.xsd"/>
</grammars>

<resources
base="http://api.search.yahoo.com/NewsSearchService/V1/">
<resource path="newsSearch">
<param name="appid" type="xsd:string"
required="true" style="query"/>
<method href="#search"/>
</resource>
</resources>

47

Yahoo News Search in WADL (cont.)
<method name="GET" id="search">
<request>
<param name="query" type="xsd:string"
required="true" style="query"/>
<param name="type" type="xsd:string"
default="all" style="query">
<option value="all"/>
<option value="any"/>
<option value="phrase"/>
</param>
...
</request>
<response>
<representation href="#resultSet"/>
<fault href="#searchError"/>
</response>
</method>
48

Yahoo News Search in WADL (cont.)
<representation id="resultSet"
mediaType="application/xml"
element="yn:ResultSet">
<doc xml:lang="en"
title="A matching list of news items"/>
</representation>

<fault id="searchError"
status="400"
mediaType="application/xml"
element="ya:Error"/>

49

wadl2java
• Open source project
– http://wadl.dev.java.net
• Generates client-side stubs
• Command line or Apache Ant task
− java -jar wadl2java.jar
• Uses JAXB for XML processing
• file.wadl

50

Yahoo News Search Stub
public class NewsSearch {
public NewsSearch() {...}
public ResultSet getAsResultSet(
String appid, String query) {...}
public DataSource getAsApplicationXml(
public DataSource getAsApplicationJson(
public DataSource getAsApplicationPhp(
...
}
51

Mapping WADL to Java

}

52

Mapping WADL to Java (cont.)
}

<param name="appid" style="query"/>
<method name="GET">
...
</method>
</resource>
53

}

<method name="GET">
...
</method>
</resource>
54

}

<method name="GET">
...
</method>
</resource>
55

}

<method name="GET">
<request>
<param name="query" style="query"/>
</request>
<response>
<representation element="y:ResultSet"/>
</response>
</method> 56
56

}

<method name="GET">
<request>
<param name="query" style="query"/>
</request>
<response>
<representation element="y:ResultSet"/>
</response>
57
</method> 57

Client Code

NewsSearch s = new NewsSearch();
ResultSet rs = s.getAsResultSet("some_app_id","java");
for (Result r: rs.getResultList()) {
System.out.printf("%s (%s)n",
r.getTitle(),
r.getClickUrl());
}

58

UDDI Basic and Data Types

59

Service Architecture
Service
Provider

Publish Bind

Service Service
Registry Consumer

Discover

UDDI defines a scheme to publish and discover
information about Web services. 60

UDDI Runs “Over” SOAP

UDDI Registry
User Node
UDDI
SOAP Request HTTP SOAP
Server Processor
UDDI
SOAP Response UDDI
Registry Service

Create, View, B2B Directory
Update, and Delete
registrations Platform-neutral

62

What is UDDI?
 Programmatic registration and discovery of
business entities and their Web services
 Public UDDI registries
IBM, Microsoft, and SAP have shut down their public
UDDI registries on January 12, 2006 after first
announcement in 2000.

 Private UDDI registries within an intranet
(where we are today)
63

Business Registration Data
 “White pages”
– address, contact, and known identifiers
 “Yellow pages”
– industrial categorizations
 Industry: NAICS (Industry codes - US Govt.)
 Product/Services: UN/SPSC (ECMA)

 Location: Geographical taxonomy

• “Green pages”
– technical information about services 64

Registry Data
Created by standard
organizations, industry
Created by businesses consortium

Service Type
Business Definitions
Registrations (Meta information on
WSDL documents)

businessEntity's
tModel's
businessService's
bindingTemplate's
65

UDDI Data Types

Business Entity BusinessEntity
White Pages information

Business Services BusinessService
Yellow Pages information

Binding Templates BindingTemplate
Green Pages information
Contains references to BindingTemplate
tModels

tModels Tmodel
Service Type Definitions
Contains references to
WSDL documents Tmodel
66

tModel Example
<tModel authorizedName="..." operator="..." tModelKey="...">
<name>StockQuote Service</name>
<description xml:lang="en">
WSDL description of a standard stock quote service interface
</description>
<overviewDoc>
<description xml:lang="en"> WSDL source document. </description>
<overviewURL> http://stockquote-definitions/stq.wsdl </overviewURL>
</overviewDoc>
<categoryBag>
<keyedReference tModelKey="UUID:..."
keyName="uddi-org:types"
keyValue="wsdlSpec"/>
</categoryBag>
</tModel>

67

Resources

 Some contents are borrowed from the presentation
slides of Sang Shin, Java™ Technology Evangelist,
Sun Microsystems, Inc.
 Some contents are borrowed from the presentation
slides of Marc Hadley and Ayub Khan
 Web Services and Java, Elsa Estevez, Tomasz
Janowski and Gabriel Oteniya, UNU-IIST, Macau

68

Thank you

thananum@gmail.com
www.facebook.com/imcinstitute
www.imcinstitute.com

69

Java Web Services [3/5]: WSDL, WADL and UDDI

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