Presentation 7 part 2: SOAP & WSDL. Ingeniørhøjskolen i Århus Slide 2 Outline Building blocks in Web Services SOA SOAP WSDL (UDDI)

Presentation 7 part 2:

SOAP & WSDL

Ingeniørhøjskolen i ÅrhusSlide 2

Outline

• Building blocks in Web Services SOA• SOAP• WSDL• (UDDI)


Service-Oriented Architecture (SOA)

ClientClientServerServer

RegistryRegistryAbstract Architecture- Web service stackAbstract Architecture- Web service stack

Legacycode onserver

Legacycode onserver

11 22

33

Opening up for doing business (the sharing of objects) on the Internet


Technologies for Implementing SOA

SOAP for communicationSOAP for communication WSDL for contract & bindingWSDL for contract & binding

UDDI & WSDL for registration & discoveryUDDI & WSDL for registration & discovery


What is SOAP?

• Simple Object Access Protocol• Wire protocol similar to

– IIOP for CORBA– JRMP for RMI

• XML is used for data encoding – “text” based protocol vs. “binary” protocol

• Supports XML-based RPC


What is Not SOAP?

• Not a component model– So it will not replace objects and components, i.e. EJB,

JavaBeans and .NET

• Not a programming language– So it will not replace Java, C# og C++

• Not a solution for all– So it will not replace other distributed computing

technologies such as RMI and CORBA


Where is SOAP?

• W3C XML Protocol working group– SOAP 1.2 current version:

http://www.w3.org/TR/soap12/

• Microsoft, SUN, Oracle, HP, IBM all support the W3C recommendation– but there are still differences to be overcome– security issues, transactions etc.


What does SOAP define?

• Message Envelope• Encoding Rules• RPC Convention• Binding with underlying protocols

– HTTP (which we will use in this course)– SMTP– FTP and others


SOAP Message Format

Possible to Attach binaries (images, cryptographic material) to attachmentsPossible to Attach binaries (images, cryptographic material) to attachments


SOAP Message Envelope

• Encoding information• Header

– Optional– Could contain context knowledge

• Security• Transaction

• Body– RPC methods and parameters– Contains application data


Two types of communication


SOAP RPC Request Example

<SOAP-ENV:Envelope

xmlns:SOAP-ENV="…"

SOAP-ENV:encodingStyle="…">

<SOAP-ENV:Header>



</SOAP-ENV:Header>

<SOAP-ENV:Body>

<m:GetLastTradePrice xmlns:m=“some_URI">

<tickerSymbol>SUNW</tickerSymbol>

</m:GetLastTradePrice>

</SOAP-ENV:Body>

</SOAP-ENV:Envelope>


SOAP RPC Response Example

<SOAP-ENV:Envelopexmlns:SOAP-ENV="…"SOAP-ENV:encodingStyle="…"><SOAP-ENV:Header>

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

<m:GetLastTradePriceResponse xmlns:m=“some_URI"><price>30.5</price>

</m:GetLastTradePriceResponse></SOAP-ENV:Body>

</SOAP-ENV:Envelope>


SOAP RPC composition I

• Information needed for a method call:1. The URI of the target object (marked with red)

• <SOAP-ENV:Body><m:GetLastTradePrice xmlns:m=“http://stocks.com/StockQuotes">



</SOAP-ENV:Body>


SOAP RPC composition II

• Information needed for a method call:1. The URI of the target object

2. The Method Name

<SOAP-ENV:Body>

<m:GetLastTradePrice xmlns:m=“http://stocks.com/StockQuotes">



</SOAP-ENV:Body>


SOAP RPC composition III

• Information needed for a method call:1. The URI of the target object

2. The Method Name

3. Parameters

4. Binding protocol (next slide)

<SOAP-ENV:Body>

<m:GetLastTradePrice xmlns:m=“http://stocks.com/StockQuotes">



</SOAP-ENV:Body>

Name is not important

Name is not important


SOAP RPC composition IV: complete SOAP RPC Request

POST /StockQuote HTTP/1.1Host: www.stockquoteserver.comContent-Type: text/xml; charset="utf-8"Content-Length: nnnnSOAPAction: "Some-URI"

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

<SOAP-ENV:Body><m:GetLastTradePrice xmlns:m=" http://stocks.com/StockQuotes">

<tickerSymbol>SUNW</tickerSymbol></m:GetLastTradePrice>

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

HTTPHTTP

EncodingEncoding

Name-spaceName-space

STEP 4: BINDING TO PROTOCOLSTEP 4: BINDING TO PROTOCOL


Request to HelloWorld.jws

Input parameters type stringInput parameters type string

HTTP Post CallHTTP Post Call

HTTP Host TargetHTTP Host Target

Method nameMethod name


… and the HTTP Response from Server

HTTP ResponseHTTP Response

Method ResponseMethod Response

Parameter valueParameter valueParameter nameParameter name

Apache Tomcat Server RespondingApache Tomcat Server Responding


Issues with SOAP

• Issues with SOAP– Lack of business semantics– Insufficient functionality for business operations– Security– Reliability– Under development

• Low performance


WSDL

• WSDL is used for describing WebServices


What is WSDL?

• XML language for describing web services• Web service is described as

– A set of communication endpoints (ports)

• Endpoint is made of– Abstract definitions of operations and messages– Concrete binding to networking protocol and message

format


Why WSDL?

• Enables automation of communication details between communicating partners– Machines can read WSDL– Machines can invoke a service defined in WSDL

• Note that WSDL defines only low-level aspects of Web services, however other technologies might follow …– Security– Transactions– Persistency


WSDL Document Example

• Simple service providing stock quotes• A single operation called GetLastTradePrice• Deployed using SOAP 1.1 over HTTP• Request takes a ticker symbol of type string• Response returns price as a float


WSDL Elements

• Types– Data type definitions– Used to describe exchanged messages– Uses W3C XML Schema as canonical type system


WSDL Elements

• Messages– Abstract, typed definitions of data being exchanged

• Operations– Abstract description of an action– Refers to input and output messages

• Port type– Collection of operations – Resembles a Class in OOPL


WSDL Elements

• Binding– Concrete protocol and data format for a particular Port

type– Example: SOAP 1.1, HTTP, MIME

• Port– Defines a single communication endpoint– Address for binding– URL for HTTP, email address for SMTP

• Service– Aggregate set of related ports


HelloWorld.jws?wsdl


Tools

• Generate WSDL document from– existing Java classes or EJB components– AXIS: Java2WSDL

• Generate SOAP messages from– WSDL document (via client stub and server skeleton)

• JAX-RPC– Part of J2EE from Sun (needs AS)

• IDE Tools:– NetBeans, Eclipse, Forte for Java, JBuilder, JDeveloper

• Microsoft:– IIS for services and Visual Studio for IDE


UDDI

• UDDI for publishing & discovery – the SOA


UDDI

• Universel Descrition, Discovery & Integration• UDDI defines a scheme to publish and discover

information about Webservices• Programmatic registration and discovery business

entities and their Webservices• Based on SOAP, HTTP, XML• Registry data

– Business registrations– Service type definitions


Registration

• “ 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


What uses UDDI?

• Tool building client (Service Consumer)– Browse or search registry– Create a service proxy

• Tool publishing the service– Generates WSDL– Construct UDDI entries

• Application that needs dynamic binding– Directly access UDDI– Query can be pre-generated

Documents

Presentation 7 part 2: SOAP & WSDL. Ingeniørhøjskolen i Århus Slide 2 Outline Building blocks in Web Services SOA SOAP WSDL (UDDI)