Web Services Using SOAP, WSDL, and UDDI
SOAP Services in Mule Esb
What are Web Services?IBM A Web service is an interface that
describes a collection of operations that are network accessible
through standardized XML messagingMicrosoft: XML Web Services..
expose useful functionality to Web users through a standard Web
protocol.. provide a way to describe their interfaces in enough
detail to allow a user to build a client application to talk to
them.. are registered so that potential users can find them
easily
Why Web Services?From business standpointIntegrationWithin an
organizationBetween companiesAllows time/cost efficienciesPurchase
ordersAnswering inquiriesProcessing shipment requestsDo this
without locking in to a single partner
Web Service ArchitectureService-Oriented Architecture
Service Registry
Service Requestor
Service Provider
FindPublishBind
Architecture IIAll the technologies are XML based
Registry(UDDI)
Service Requestor
Service Provider
FindPublishBind(SOAP)(SOAP)(WSDL)
XML Leveraging FeaturesXML NamespacesCollisionCommon XML element
namesApplication specific or embedded in message?Allows composition
of multiple XML documentsIdentifies elements belonging to the same
document type
XML Leveraging Features IIXML SchemasAlternative to DTDs for
describing document structureWritten in XMLSimple typesComplex
typesReusableIntended to be used with namespaces
SOAPSimple Object Access ProtocolWeb service messaging and
invocation2nd Generation XML ProtocolTakes advantage ofXML
NamespacesXML Schema
First Generation XML ProtocolBased on XML 1.0Example:
XML-RPCIntroduced by Userland in 1998Uses HTTP as underlying
transport
twenty-eight
CallResponse
NumberToText 28
First Gen. XML Protocol IssuesExtensibilityAll protocol
architects had to agree for changesAvoid with
namespacesDatatypingSingle DTDsLimited in use of XML
elementsDescriptive nature of XML sacrificedXML schema is a better
solution
SOAP History
1998 Term SOAP coined at Microsoft1999
Microsoft works with BizTalk to release SOAP 0.9 Submitted to
IETF SOAP 1.0 released in December
2000
SOAP 1.1 submitted to W3C with IBM IBM releases a Java SOAP
implementation Sun starts work on Web services in J2EE
2001
SOAP 1.2 released by XML Protocol working group at W3CCurrently,
about 80+ SOAP implementations available including Apple
SOAP Messaging Layers
App API
SOAP, XML Processing
App API
SOAP, XML Processing
SOAP Message
SOAP Message
HTTP
HTTPDeveloperSOAP Service ProviderHTTP
ClientProviderView
SOAP Message
SOAP EnvelopeRoot elementMandatoryDoes not expose any protocol
versionsProtocol version is the URI of SOAP envelope
namespaceencodingStyle attribute for complex types
SOAP HeaderOptionalAllows packaging of information orthogonal to
messageTransactionsAuthentication informationAccount
informationSOAP-ENV:mustUnderstand
SOAP-ENV:mustUnderstandAttribute for Header elementValue 0 skip
this element if it doesnt make senseValue 1 must fail if it doesnt
make senseEnsures recipients be aware of important protocol
extensions
[email protected]
SOAP BodyCan contain arbitrary XMLConventions
forRPCsFaultsFaultcode lookup stringFaultstring human readable
stringFaultactor where in the message pathDetail optionalData
encoding
Data encoding in SOAPSOAP provides default encoding schemaWhy
reinvent the wheel?Simple data typesUse xsi:typeString, floats
etcComplex data typesSOAP arraysStructs: compound typesData
referencingHref and id attributes
Data encoding in SOAPBinary dataBase64 encoding
Can roll your own schemaencodingStyleInteroperability issues
SOAP Protocol Binding: HTTP
POST /ServiceLoc HTTP/1.1Host: www.foo.comContent-Type:
text/xml; charset=utf-8Content-Length: nnnnSOAPAction:
Directory/Service
Out-of-message context
In-message contextSample RPC Call
Other SOAP Protocol BindingsHTTPSSimilar to HTTPUse POSTReturn
200 for success500 for failure + SOAP faultSOAPAction HTTP header
for hintMIME media type: text/htmlSMTPSOAP messages with
Attachments
SOAP RPC Example: getQuoteimport SOAPserver =
SOAP.SOAPProxy("http://services.xmethods.com:80/soap", namespace =
'urn:xmethods-delayed-quotes')
print "IBM>>", server.getQuote(symbol = 'IBM')
RPC Invocation Message
IBM
RPC Reply Message
107.89
Roadmap
Registry(UDDI)
Service Requestor
Service Provider
FindPublishBind(SOAP)(SOAP)(WSDL)
