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Web ServicesWeb Services

Representation and Management of Data on the

Web

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"Web services are loosely coupled software components

delivered over Internet standard technologies."

"Web services are loosely coupled software components

delivered over Internet standard technologies."

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Example Scenario:Get Online Information

Stock Exchange

Stock Broker

Application

Get Stock Price

Get Stock Price

Return Stock

Price

Return Stock

Price

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Example Scenario – Online Trade

Book Store

The Hobbit (5)Price: 25.95

Copies in Stock: 1

The Hobbit (5)Price: 25.95

Copies in Stock: 0

Book Store

The Hobbit (5)Price: 20.95

Copies in Stock: 5

Buy The Hobbit (5)

Buy The Hobbit (5)

How Much?

20.95

Buy it

The Hobbit (5)Price: 20.95

Copies in Stock: 4

The Hobbit (5)Price: 25.95

Copies in Stock: 1

The Hobbit (5)Price: 25.95

Copies in Stock: 0

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Example Scenario:Grid Computation

Grid Computation

Using seamlesslythe combinedresources of many computersthat are connectedto the Internet

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What is a Web Service?

• Self-contained, modular Web application that can be published, located and invoked across the Web

• A Web service can perform functions of varying complexities

• Once deployed, other applications (and other Web services) can discover and invoke the deployed service

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Why is it Difficult to Use Ordinary Web Sites as Services?

• Consider an application that should return the price of the book “The Hobbit”– How can your application find suitable

online stores?– How can your application find the price of

the book in a Web page?– How can your application fill forms, if

needed?

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What is the price here?

How can we find this URL?

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Calling Remote FunctionsCould Help

• It would help if we could call functions, such as:– Amazon.getPrice(“The Hobbit")– Amazon.buyBook(“The Hobbit", myId)

getPrice(…)

The Internet

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Difficulties in UsingRemote Functions

• How can the calling application know in what language the functions are written?

• How can the application know what functions are available and what are their signatures?

• How can an application call a function that resides behind a firewall?

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The Solution

• Use an agreed interface and a syntax that all applications are familiar with (e.g., XML)– For example, SOAP

• Use HTTP to transfer data through port 80• Use a standard for publishing methods, their

signatures and their usage– For example, WSDL

• Use standard directory structures for publishing available services– For example, UDDI

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Web Services that areAlready Available

• Google search (http://www.google.com/apis)• Weather reports• Stock prices• Currency exchanges• Sending SMS messages, faxes• Prices of books in Barnes and Nobles• Dictionaries• etc.

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Implementing Web Services

• Programmers are given tools that spare the need to directly write SOAP or WSDL documents

• In Java:– JAX-RPC: part of SUN tools for publishing and

deploying Web Services

– AXIS: Apache’s tool for handling Web services in Java

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SOAPSimple Object-Access Protocol

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What is SOAP?• SOAP is a protocol for accessing Web

Services• SOAP is XML based

– Thus, SOAP provides interoperability

• In SOAP, applications exchange information over HTTP– Thus, SOAP is not restricted by firewalls

• SOAP allows to exchange structured and typed information on the Web– XSchema types are used to add types to XML

• SOAP specification: http://www.w3.org/2000/xp/Group/

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POST /soap HTTP/1.0SOAPAction: ""Content-Length: 520

<?xml version="1.0" encoding="UTF-8"?>

<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">

<soapenv:Body> <ns1:getRate soapenv:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/" xmlns:ns1="urn:xmethods-CurrencyExchange">

<country1 xsi:type="xsd:string">Euro</country1> <country2 xsi:type="xsd:string">Israel</country2> </ns1:getRate> </soapenv:Body></soapenv:Envelope>

A request to A request to http://services.xmethodshttp://services.xmethods

.net:80/soap.net:80/soap

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HTTP/1.0 200 OKDate: Sat, 07 May 2005 23:26:21 GMTContent-Length: 492Content-Type: text/xml

<?xml version='1.0' encoding='UTF-8'?>

<soap:Envelope xmlns:soap='http://schemas.xmlsoap.org/soap/envelope/' xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance' xmlns:xsd='http://www.w3.org/2001/XMLSchema' xmlns:soapenc='http://schemas.xmlsoap.org/soap/encoding/' soap:encodingStyle='http://schemas.xmlsoap.org/soap/encoding/'>

<soap:Body> <n:getRateResponse xmlns:n='urn:xmethods-CurrencyExchange'>

<Result xsi:type='xsd:float'>5.5825</Result> </n:getRateResponse> </soap:Body></soap:Envelope>

The ResponseThe Response

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A SOAP Message

• A SOAP message is an ordinary XML document containing the following elements:– Envelope – identifies the XML document as a

SOAP message: required– Header – contains header information: optional – Body – contains call or response information:

required– Fault – provides information about errors that

occurred while processing the message: optional

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<?xml version="1.0"?><Hello>    <sayHelloTo>        <name>Lisa</name>    </sayHelloTo></Hello>

SOAP Simplification (1)

• Consider the Java interface:

• Suppose that a client wants to call the server's sayHelloTo method

• Could send an XML message:

Name of the Interface

Name of the Method

Name of the Parameter

public interface Hello {

public String sayHelloTo(String name);

}

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SOAP Simplification (2)

• The Server could respond with:<?xml version="1.0"?><Hello>    <sayHelloToResponse>       <message>Hello Lisa, How are you?</message>    </sayHelloToResponse></Hello>

Name of the Interface

Name of the Method + Response

Returned Value

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SOAP Intuition

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Skeleton SOAP Message<?xml version="1.0"?>

<soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/" soap:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/">

<soap:Header>

... ...

</soap:Header>

<soap:Body>

... ...

<soap:Fault>

... ...

</soap:Fault>

</soap:Body>

</soap:Envelope>

A SOAP envelope must be Associated with this name space

Envelope

Header

Body

Fault

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encodingStyle Attribute

• “The SOAP encodingStyle attribute indicates the encoding rules used to serialize parts of a SOAP message”– Needed when sending data structures

• This attribute may appear on any SOAP element, and it will apply to that element's content and all child elements

• A SOAP message has no default encoding– Unencoded data may be used in SOAP

messages• The SOAP default XMLSchema for SOAP encoding

and data types is:http://www.w3.org/2002/12/soap-encoding

– Other encoding rules may be used

25Envelope

Actual Soap Request

<SOAP-ENV:Envelope

xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/"

xmlns:xsi="http://www.w3.org/1999/XMLSchema-instance"

   xmlns:xsd="http://www.w3.org/1999/XMLSchema">    <SOAP-ENV:Header> </SOAP-ENV:Header>    <SOAP-ENV:Body>         <ns1:sayHelloTo  xmlns:ns1="Hello"

SOAP-ENV:encodingStyle="

http://schemas.xmlsoap.org/soap/encoding/">           <name xsi:type="xsd:string">Lisa</name>         </ns1:sayHelloTo>    </SOAP-ENV:Body>

</SOAP-ENV:Envelope>

26Name Spaces

Actual Soap Request

<SOAP-ENV:Envelope

xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/"

xmlns:xsi="http://www.w3.org/1999/XMLSchema-instance"

   xmlns:xsd="http://www.w3.org/1999/XMLSchema">    <SOAP-ENV:Header> </SOAP-ENV:Header>    <SOAP-ENV:Body>         <ns1:sayHelloTo  xmlns:ns1="Hello"

SOAP-ENV:encodingStyle="

http://schemas.xmlsoap.org/soap/encoding/">           <name xsi:type="xsd:string">Lisa</name>         </ns1:sayHelloTo>    </SOAP-ENV:Body>

</SOAP-ENV:Envelope>

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Actual Soap Request

HeaderBody

<SOAP-ENV:Envelope

xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/"

xmlns:xsi="http://www.w3.org/1999/XMLSchema-instance"

   xmlns:xsd="http://www.w3.org/1999/XMLSchema">    <SOAP-ENV:Header> </SOAP-ENV:Header>    <SOAP-ENV:Body>         <ns1:sayHelloTo  xmlns:ns1="Hello"

SOAP-ENV:encodingStyle="

http://schemas.xmlsoap.org/soap/encoding/">           <name xsi:type="xsd:string">Lisa</name>         </ns1:sayHelloTo>    </SOAP-ENV:Body>

</SOAP-ENV:Envelope>

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Actual Soap Request

<SOAP-ENV:Envelope

xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/"

xmlns:xsi="http://www.w3.org/1999/XMLSchema-instance"

   xmlns:xsd="http://www.w3.org/1999/XMLSchema">    <SOAP-ENV:Header> </SOAP-ENV:Header>    <SOAP-ENV:Body>         <ns1:sayHelloTo  xmlns:ns1="Hello"

SOAP-ENV:encodingStyle="

http://schemas.xmlsoap.org/soap/encoding/">           <name xsi:type="xsd:string">Lisa</name>         </ns1:sayHelloTo>    </SOAP-ENV:Body>

</SOAP-ENV:Envelope>

InterfaceInterface MethodMethod ParameterParameter

29Envelope

Actual Soap Response<SOAP-ENV:Envelope

xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/"

   xmlns:xsi="http://www.w3.org/1999/XMLSchema-instance"

xmlns:xsd="http://www.w3.org/1999/XMLSchema">    <SOAP-ENV:Body>          <ns1:sayHelloToResponse xmlns:ns1="Hello"                SOAP-ENV:encodingStyle="

http://schemas.xmlsoap.org/soap/encoding/">                 <return xsi:type="xsd:string">

Hello Lisa, How are you doing?

</return>          </ns1:sayHelloToResponse>    </SOAP-ENV:Body>

</SOAP-ENV:Envelope>

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Actual Soap Response

Body

<SOAP-ENV:Envelope

xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/"

   xmlns:xsi="http://www.w3.org/1999/XMLSchema-instance"

xmlns:xsd="http://www.w3.org/1999/XMLSchema">    <SOAP-ENV:Body>          <ns1:sayHelloToResponse xmlns:ns1="Hello"                SOAP-ENV:encodingStyle="

http://schemas.xmlsoap.org/soap/encoding/">                 <return xsi:type="xsd:string">

Hello Lisa, How are you doing?

</return>          </ns1:sayHelloToResponse>    </SOAP-ENV:Body>

</SOAP-ENV:Envelope>

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Actual Soap Response<SOAP-ENV:Envelope

xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/"

   xmlns:xsi="http://www.w3.org/1999/XMLSchema-instance"

xmlns:xsd="http://www.w3.org/1999/XMLSchema">    <SOAP-ENV:Body>          <ns1:sayHelloToResponse xmlns:ns1="Hello"                SOAP-ENV:encodingStyle="

http://schemas.xmlsoap.org/soap/encoding/">                 <return xsi:type="xsd:string">

Hello Lisa, How are you doing?

</return>          </ns1:sayHelloToResponse>    </SOAP-ENV:Body>

</SOAP-ENV:Envelope>

MethodMethod InterfaceInterface Returned ValueReturned Value

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SOAP Header Element• The SOAP Header element is optional• It contains application specific information (like

authentication, payment, etc) about the SOAP message

• If the Header element is present, it must be the first child element of the Envelope element

• Attributes that the namespace defines:– Actor – used to address the Header element to a

particular server (e.g., proxy) on the message path through the Internet

– mustUnderstand – used to indicate whether a header entry is mandatory or optional for the recipient to process

– encodingStyle – as explained before

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SOAP Header Element• Example:

<SOAP-ENV:Header>     <t:Transaction xmlns:t="some-URI"

SOAP-ENV:mustUnderstand="1">5</t:Transaction>

</SOAP-ENV:Header>• 5 is the transaction ID of which this method is a part• In the above example, the SOAP-envelope attribute

mustUnderstand is set to 1, which means that the server must either understand and honor the transaction request or must fail to process the message

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SOAP Response on Error

• There can be many errors in processing a SOAP request

• Error in Running Methods: For example, suppose that the "Hello Server" does not allow anyone to say hello on Tuesday

• Error in Processing SOAP Headers: For example, a problem running the method as part of a transaction

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The Fault Element May Include the Following Sub-Elements

• <faultcode> : A code for identifying the fault• <faultstring> : A human readable

explanation of the fault• <faultactor> : Information about who

caused the fault • <detail> : Holds application-specific error

information related to the Body element of the SOAP request

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SOAP Fault Codes

• VersionMismatch: Found an invalid namespace for the SOAP Envelope element

• MustUnderstand: An immediate child element of the Header element, with the mustUnderstand attribute set to 1, was not understood

• Client: The message was incorrectly formed or contained incorrect information

• Server: There was a problem with the server so the message could not proceed

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SOAP Error Response for Method Error

<SOAP-ENV:Envelope xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/">   <SOAP-ENV:Body>       <SOAP-ENV:Fault>           <faultcode>SOAP-ENV:Server</faultcode>           <faultstring>Server Error</faultstring>           <detail>               <e:myfaultdetails xmlns:e="Hello">                 <message>                   Sorry, I cannot say hello on Tuesday.                 </message>                 <errorcode>1001</errorcode>               </e:myfaultdetails>           </detail>       </SOAP-ENV:Fault>   </SOAP-ENV:Body></SOAP-ENV:Envelope>

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SOAP Error Response for Header Error

<SOAP-ENV:Envelope xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/">   <SOAP-ENV:Body>       <SOAP-ENV:Fault>           <faultcode>SOAP-ENV:MustUnderstand</faultcode>           <faultstring>SOAP Must Understand Error</faultstring>       </SOAP-ENV:Fault>   </SOAP-ENV:Body></SOAP-ENV:Envelope>

No detail element may appear when there is an error in processing the Headers of a SOAP request

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Sending a Request

• The SOAP request does not contain the address to which it should be sent

• Q: Where do we put the URL of the Web Service?

• A: It depends on the Protocol used to send the request (usually HTTP, but could also be another protocol, e.g., SMTP)

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SOAP Request via HTTPPOST http://www.Hello.com/HelloApplication HTTP/1.0

Content-Type: text/xml; charset=UTF-8 Content-Length: 587

SOAPAction: urn:helloApp

<SOAP-ENV:Envelope …

Note: There are 2 addresses(1) URL of a SOAP Server (2) URI of an application to run (this needn't

correspond to an actual Internet address)

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SOAPAction Header

• Used to indicate the intent of the SOAP HTTP request

• The presence and content of the SOAPAction header field can be used by servers, such as firewalls, to appropriately filter SOAP request messages in HTTP

• The header-field value of an empty string ("") means that the intent of the SOAP message is provided by the URL of the HTTP Request

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SOAP Response via HTTPHTTP/1.0 200 OK

Content-Type: text/xml; charset=UTF-8 Content-Length: 615

<SOAP-ENV:Envelope …

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Example: Currency Rate

• There are many available Web services that you can use

• See http://www.xmethods.com/ for a list• Look, in particular, at those marked "RPC"

(Remote Procedure Call)• To get Currency exchange, for example, you

can do "telnet wwwproxy.cs.huji.ac.il 8080" and then send the following request…

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POST http://services.xmethods.net:80/soap HTTP/1.0

Content-Type: text/xml

Content-Length: 485

SOAPAction: ""

<SOAP-ENV:Envelope xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/" xmlns:xsi="http://www.w3.org/1999/XMLSchema-instance" xmlns:xsd="http://www.w3.org/1999/XMLSchema">

<SOAP-ENV:Body>

<ns1:getRate xmlns:ns1="urn:xmethods-CurrencyExchange" SOAP-ENV:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/">

<country1 xsi:type="xsd:string">United States</country1>

<country2 xsi:type="xsd:string">Israel</country2>

</ns1:getRate>

</SOAP-ENV:Body></SOAP-ENV:Envelope>

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HTTP/1.0 200 OK

Content-Type: text/xml

<?xml version='1.0' encoding='UTF-8'?>

<soap:Envelope xmlns:soap='http://schemas.xmlsoap.org/soap/envelope/' xmlns:xsi='http://www.w3.org/1999/XMLSchema-instance' xmlns:xsd='http://www.w3.org/1999/XMLSchema' xmlns:soapenc='http://schemas.xmlsoap.org/soap/encoding/' soap:encodingStyle='http://schemas.xmlsoap.org/soap/encoding/'>

<soap:Body><n:getRateResponse

xmlns:n='urn:xmethods-CurrencyExchange'>

<Result xsi:type='xsd:float'>4.521</Result>

</n:getRateResponse>

</soap:Body></soap:Envelope>

And Here is the Response

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Example - Calling Google Spelling<?xml version="1.0" encoding="UTF-8" ?>

<SOAP-ENV:Envelope xmlns:SOAP

ENV=“http://schemas.xmlsoap.org/soap/envelope/”

xmlns:xsi=“http://www.w3.org/1999/XMLSchema-instance”

xmlns:xsd=“http://www.w3.org/1999/XMLSchema”>

<SOAP-ENV:Body>

<ns1:doSpellingSuggestion xmlns:ns1=“urn:GoogleSearch” SOAP- ENV:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/"> 

<key xsi:type="xsd:string">00000000000000000000000000</key>  

<phrase xsi:type="xsd:string">britney speers</phrase>  

</ns1:doSpellingSuggestion> 

</SOAP-ENV:Body> 

</SOAP-ENV:Envelope>

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Example - Google Spelling Response<?xml version="1.0" encoding="UTF-8" ?>

<SOAP-ENV:Envelope xmlns:SOAP ENV="http://schemas.xmlsoap.org/soap/envelope/"

xmlns:xsi="http://www.w3.org/1999/XMLSchema-instance"

xmlns:xsd="http://www.w3.org/1999/XMLSchema">

<SOAP-ENV:Body>

<ns1:doSpellingSuggestionResponse xmlns:ns1="urn:GoogleSearch“

SOAP-ENV:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/"> 

<return xsi:type="xsd:string">britney spears</return>  

</ns1:doSpellingSuggestionResponse> 

</SOAP-ENV:Body> 

</SOAP-ENV:Envelope>

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An alternative to SOAP: XML-RPC

• XML-RPC is similar to SOAP but simpler

• You just have to specify what is the method and what are the parameters

• See http://www.xmlrpc.com for further details

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XML-RPC Request ExamplePOST /MyRPC HTTP/1.0

Host: www.cs.huji.ac.il

Content-Type: text/xml

Content-length: 181

<?xml version="1.0"?>

<methodCall> <methodName>Hello.sayHelloTo</methodName>

<params>

<param>

<value><string>Lisa</string></value> </param>

</params>

</methodCall>

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XML-RPC Response ExampleHTTP/1.1 200 OK

Connection: close

Content-Length: 158

Content-Type: text/xml

Date: Sun, 6 Jun 2004 10:33:08 GMT

<?xml version="1.0"?>

<methodResponse>

<params>

<param>

<value><string>Hello Lisa</string></value> </param>

</params>

</methodResponse>

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Example 1: MD5 Transform

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Example 2: Baghdad Weather

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Example 2: Baghdad Weather

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Example 3: World Cities

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Example 3: World Cities

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WSDL – Web Services Description Language

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Describing a Web Service• Need a standard way to describe a Web

Service:– the methods available– their parameters– etc.

• WSDL is a standard for describing Web services using XML, i.e., it is a language for the green pages of UDDI

• WSDL specification can be found at http://www.w3.org/TR/wsdl

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WSDL Can Describe

• What a Web service can do• Where it resides• How to invoke it

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<?xml version="1.0"?>

<definitions name="CurrencyExchangeService" targetNamespace="http://www.xmethods.net/sd/CurrencyExchangeService.wsdl" xmlns:tns="http://www.xmethods.net/sd/CurrencyExchangeService.wsdl" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:soap="http://schemas.xmlsoap.org/wsdl/soap/" xmlns="http://schemas.xmlsoap.org/wsdl/">

<message name="getRateRequest"> <part name="country1" type="xsd:string"/> <part name="country2" type="xsd:string"/> </message>

<message name="getRateResponse"> <part name="Result" type="xsd:float"/> </message>

<portType name="CurrencyExchangePortType"> <operation name="getRate"> <input message="tns:getRateRequest" name="getRate"/> <output message="tns:getRateResponse" name="getRateResponse"/> </operation></portType>

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<binding name="CurrencyExchangeBinding" type="tns:CurrencyExchangePortType">

<soap:binding style="rpc" transport="http://schemas.xmlsoap.org/soap/http"/>

<operation name="getRate"> <soap:operation soapAction=""/>

<input name="getRate"> <soap:body use="encoded" namespace="urn:xmethods-CurrencyExchange" encodingStyle="http://schemas.xmlsoap.org/soap/encoding/"/> </input>

<output name="getRateResponse"> <soap:body use="encoded" namespace="urn:xmethods-CurrencyExchange" encodingStyle="http://schemas.xmlsoap.org/soap/encoding/"/> </output> </operation></binding>

<service name="CurrencyExchangeService"> <documentation>Returns the exchange rate between the two currencies</documentation> <port name="CurrencyExchangePort" binding="tns:CurrencyExchangeBinding"> <soap:address location="http://services.xmethods.net:80/soap"/> </port></service></definitions>

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The Two Layers of WSDL

• The service definition layer describes abstract properties: – data types– message types– operations– services

• The binding layer describes concrete properties (using SOAP, HTTP, MIME):– protocols– data formats

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More on the Binding Layer

• WSDL defines services as collections of network endpoints or ports

• Endpoints are defined by binding a concrete network protocol and a concrete message format to abstract operations and messages

• In theory, WSDL can describe any endpoint regardless of the underlying network protocol or message format– In practice, WSDL is used with SOAP/HTTP/MIME

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The Elements of WSDL Documents• Types – containing XML Schema element and type

definitions• Message – an abstract typed definition of the data

being communicated• Operation – an abstract description of an action

supported by the service• Port Type – an abstract set of operations supported

by one or more endpoints• Binding – a concrete communication protocol and

data format specification for a particular port type• Port – a single endpoint defined as a combination of a

binding and a network address• Service – a collection of named ports, each

associated with a binding and a network address

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The Structure of a WSDL Document

<definition><types> definition of types….</types><messages> definition of a message</message><port type> definition of a port</port type><binding> definition of a binding</binding></definition>

<definition>

<types>

<messages>

<portType>

<binding>

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Example

<?xml version="1.0" encoding="UTF-8"?>

<definitions name="HelloService"

targetNamespace="http://www.hello.com/wsdl/HelloService.wsdl"

xmlns="http://schemas.xmlsoap.org/wsdl/"

xmlns:soap="http://schemas.xmlsoap.org/wsdl/soap/"

xmlns:tns="http://www.hello.com/wsdl/HelloService.wsdl"

xmlns:xsd="http://www.w3.org/2001/XMLSchema">

General and specific namespacesGeneral and specific namespaces

66

Types

• The <types> element defines the data types that are used by the Web service

• For maximum interoperability, WSDL uses XML Schema syntax to define data types

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Messages

• The <message> element defines the data elements of an operation

• Each message can consist of one or more parts

• These parts are analogous to the parameters of a function call in Java

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Example

<message name="SayHelloRequest">

<part name="firstName" type="xsd:string"/>

</message>

<message name="SayHelloResponse">

<part name="greeting" type="xsd:string"/>

</message>

String sayHello(String firstName)

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Port Types

• The <portType> element is the most important WSDL element

• The <portType> element is similar to a class in Java

• It defines the Web service, the operations that can be performed, and the messages that are involved

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Example

<portType name="Hello_PortType">

<operation name="sayHello">

<input message="tns:SayHelloRequest"/>

<output message="tns:SayHelloResponse"/>

</operation>

</portType>

public interface HelloService {

public String sayHello(String firstName);

}

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Operation Types

• We divide operations to four types:– One-way – the operation can receive a message

but will not return a response (the operation includes only input)

– Request-response – the operation can receive a request and will return a response (the operation includes input and output)

– Solicit-response – the operation can send a request and will wait for a response (the operation includes output and input)

– Notification – the operation can send a message but will not wait for a response (the operation includes only output)

72

Binding Using SOAP

• The SOAP <binding> element defines the details of the message format and protocol for each port

• The transport attribute defines the SOAP protocol to use (e.g., HTTP, FTP, SMTP)

• The style attribute of the binding can be either RPC (Remote Procedure Call) or document (document is the default)

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RPC vs. Document

• RPC style indicates that the messages contain parameters and return values

• Document style indicates that the messages contain document(s)

• Differently from document style:– In RPC, we need to clearly separate the

arguments from each other

– In RPC, the order of parameters is important

74

The SOAP Binding in WSDL

• Selects document or rpc style• Selects HTTP/SMTP/… protocol• Selects encoding (typically, the

SOAP encoding)• Places messages parts in header

or body parts of the envelope

75

<binding name="Hello_Binding" type="tns:Hello_PortType">

<soap:binding style="rpc“ transport="http://schemas.xmlsoap.org/soap/http"/>

<operation name="sayHello">

<soap:operation soapAction="sayHello"/>

<input>

<soap:body encodingStyle="http://schemas.xmlsoap.org/soap/encoding/"

namespace="urn:examples:helloservice" use="encoded"/>

</input>

<output>

<soap:body encodingStyle="http://schemas.xmlsoap.org/soap/encoding/"

namespace="urn:examples:helloservice" use="encoded"/>

</output>

</operation>

</binding>

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A Service Description in WSDL(defining an endpoint)

<service name="Hello_Service">

<documentation>WSDL File for HelloService</documentation>

<port binding="tns:Hello_Binding" name="Hello_Port">

<soap:address location="http://pita:8080/soap/servlet/myService"/>

</port>

</service>

</definitions>

The location attribute associates the binding with a URL

The location attribute associates the binding with a URL

77

Recall Currency Exchange Example

POST http://services.xmethods.net:80/soap HTTP/1.0

Content-Type: text/xml

Content-Length: 485

SOAPAction: ""

<SOAP-ENV:Envelope xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/" xmlns:xsi="http://www.w3.org/1999/XMLSchema-instance" xmlns:xsd="http://www.w3.org/1999/XMLSchema">

<SOAP-ENV:Body>

<ns1:getRate xmlns:ns1="urn:xmethods-CurrencyExchange" SOAP-ENV:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/">

<country1 xsi:type="xsd:string">United States</country1>

<country2 xsi:type="xsd:string">Israel</country2>

</ns1:getRate></SOAP-ENV:Body></SOAP-ENV:Envelope>

78

CurrencyExchange's WSDL

• Next is the WSDL for this service• Note that it has to describe:

– URL– URI– Method Name– Method Namespace– Parameter Names– Parameter Types– Encoding of Parameters

79

<?xml version="1.0"?>

<definitions name="CurrencyExchangeService" targetNamespace="http://www.xmethods.net/sd/CurrencyExchangeService.wsdl" xmlns:tns="http://www.xmethods.net/sd/CurrencyExchangeService.wsdl"

xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:soap="http://schemas.xmlsoap.org/wsdl/soap/" xmlns="http://schemas.xmlsoap.org/wsdl/">

<message name="getRateRequest">

<part name="country1" type="xsd:string"/>

<part name="country2" type="xsd:string"/>

</message>

<message name="getRateResponse">

<part name="Result" type="xsd:float"/>

</message>

80

<portType name="CurrencyExchangePortType">

<operation name="getRate">

<input message="tns:getRateRequest" />

<output message="tns:getRateResponse" />

</operation>

</portType>

<binding name="CurrencyExchangeBinding"

type="tns:CurrencyExchangePortType">

<soap:binding style="rpc"

transport="http://schemas.xmlsoap.org/soap/http"/>

<operation name="getRate">

<soap:operation soapAction=""/>

<input > <soap:body use="encoded"

namespace="urn:xmethods-CurrencyExchange"

encodingStyle="http://schemas.xmlsoap.org/soap/encoding/"/>

</input>

81

<output >

<soap:body use="encoded"

namespace="urn:xmethods-CurrencyExchange"

encodingStyle="http://schemas.xmlsoap.org/soap/encoding/"/>

</output>

</operation>

</binding>

<service name="CurrencyExchangeService">

<documentation>Returns the exchange rate </documentation>

<port name="CurrencyExchangePort"

binding="tns:CurrencyExchangeBinding">

<soap:address

location="http://services.xmethods.net:80/soap"/>

</port>

</service></definitions>

82

UDDI – Universal Description, Discovery and Integration

83

A Telephone Book

• How can you find a Web service?

• How can you register your Web service so that others will find it?

• UDDI is a standard for publishing and finding Web services

• Think of UDDI as a telephone book

84

How Does UDDI Work?

UDDI Business Registry

Service TypeRegistrations

BusinessRegistrations

UDDI assigns a universally unique identifier (UUID) to each registry record

Businesses populate the registry withdescriptions of the services they support

Businesses use this data to facilitate easier integration with each other over the Web

Marketplaces, search engines and business apps query the registry to discover services at other companies

Software companies, standards bodies and programmers populate the registry with descriptions of different service specifications

85

"Types" of Pages

• White Pages:White Pages: – Basic contact information, business name, address, etc. – Allow others to find you based on your identification

• Yellow Pages:Yellow Pages:– Describe Web services by category– Allow others to find you by category (e.g., car sales)

• Green Pages:Green Pages:– Technical information about supported methods of Web

services

86

UDDI Data Model

businessKey BA744ED0 . . . 5229C64 name XMethodsdescription Web services resource site contacts Lisa SimpsonbusinessServicesidentifierBagcategoryBag

businessEntity

tModelKey 8609C8 … D01823keyName D-U-N-SkeyValue 08-146-6849

keyedReference

tModelKey 8609C8 … D01823Name dnb-com:D-U-N-SDescription Dun&Bradstreet D-U-N-S NumberoverviewDoc www.uddi.org/taxonomies/ UDDI_Taxonomy_tModels.htm#D-U-N-ScategoryBag

tModel

serviceKey D59211 … 229C64name XMethods Delayed Stock Quotesdescription 20-minute delayed stock quotesbindingTemplatescategoryBag

businessService

bindingTemplate

bindingKey D594A … 229C64description SOAP binding for delayed stock quotes serviceaccessPoint http://services.xmethods.net:80/soaptModelInstanceDetails

tModelKey 0E727D … 229C64Name Xmethods Simple Stock Quotedescription Simple stock quote interfaceoverviewDoc xmethods.net/SimpleStockQuote.wsdlcategoryBag

tModel

87

UDDI Structure

• businessEntity - The top-level XML element (includes support for "yellow pages" taxonomies)

• businessService - contains descriptive business service information about a group of related technical services, including – the group name

– a brief description

– technical service-description information

– service properties

– service leasing details

– category information

88

UDDI Structure

• bindingTemplate - contains data relevant for applications that need to invoke or bind to a specific Web Service

• tModel - Descriptions of specifications (protocols, formats, etc.) for Web services or taxonomies– its role is to represent the technical specification of

the Web service, making it easier for Web-service consumers to find Web services that are compatible with a particular technical specification

89

Key Entities Description

businessEntitybusinessEntity

Information about the entity whooffers a service

businessServicebusinessService

Descriptive information about a particular family of technicalofferings

bindingTemplatebindingTemplate

Technical information about aservice entry point

tModeltModel

Description of specifications forservices

0..n

0..n

0..n

Bindings contain references to tModels. These references declare the interface specifications for a service.

90

Key Entities Example

businessEntitybusinessEntity

Name: Acme CorpDesc: Purveyors of Fine ProductsURL: www.acme.comContact: Joseph Cohen

businessServicebusinessService

Name: getPriceDesc: Accepts ACME product ID as a string. Returns product priceas a double.

bindingTemplatebindingTemplate

Access Point: http://soap.acme.com/getPriceDesc: SOAP endpoint for the getPrice service.

publisherAssertionpublisherAssertion

From Key: Acme Corp.To Key: Nadir Corp.

tModeltModel

Name: getPriceDesc: WSDL for the getPrice serviceOverview Doc:http://soap.acme.com/getPrice/wsdl

categorycategory

wsdlSpec

identifieridentifier

E1-AA-09-F3

91

Categorizing EntitiesbusinessEntitybusinessEntity

Name: Acme CorpDesc: Purveyors of Fine ProductsURL: www.acme.comContact: Joseph Cohen

businessServicebusinessService

Name: getPriceDesc: Accepts ACME product ID as a string. Returns product priceas a double.

bindingTemplatebindingTemplate

Access Point: http://soap.acme.com/getPriceDesc: SOAP endpoint for the getPrice service.

tModeltModel

Name: getPriceDesc: WSDL for the getPrice serviceOverview Doc:http://soap.acme.com/getPrice/wsdl

categorycategory

Retail

identifieridentifier

DUNS: 123456

categorycategory

Pricing

categorycategory

wsdlSpec

categorycategory

V 1.1

identifieridentifier

E1-AA-09-F3

publisherAssertionpublisherAssertion

From Key: Acme Corp.To Key: Nadir Corp.

92

UDDI Business Registry (UBR), Public Cloud

• Nodes contain all UDDI information

• Nodes are synchronized, so they retain the same data

• You can query any node

• You can add UDDI information to a node, and it will be replicated to all others

93

Registry Nodes Operation• Peer-operator nodes• A business can

register with any node• Registrations

replicated on a daily basis

• Operates like DNS: logically centralized, physically distributed

IBM

Microsoft

HPother

other

queries

UDDI Cloud Service

client

Registry Node

94

Interacting with the UDDI

• UDDI is itself a Web service!!!• Interaction is via SOAP messages• The JAXR package defines a standard way to

interact with registries (can work with other types of registries too, e.g., ebXML)

• Two types of interaction:– Inquiry: Does not need authentification – Publish: Needs authentification

• Here is a Web interface for a UBR node

95

JAXR

• Java API used to access registries that conform to standards, such as UDDI

• Part of Java WSDP

Taken from http://developer.java.sun.com/developer/technicalArticles/WebServices/WSPack/

96

UDDI API

• Inquiry API • Publishing API

• delete_business• delete_service• delete_binding• delete_tmodel

• delete_business• delete_service• delete_binding• delete_tmodel

• find_business• find_service• find_binding• find_tmodel

• find_business• find_service• find_binding• find_tmodel

• get_businessDetail

• get_serviceDetail• get_bindingDetail• get_tmodelDetail

• get_businessDetail

• get_serviceDetail• get_bindingDetail• get_tmodelDetail

• save_business• save_service• save_binding• save_tmodel

• save_business• save_service• save_binding• save_tmodel

• get_authtoken• discard_authtoke

n

• get_authtoken• discard_authtoke

n