Session I Part II: WS Standards

1. Session I Part II: WS Standards Umesh Bellur IIT Bombay umesh[at]it.iitb.ac.in

2. Session II: Contents • XML Basics • WS Core Standards: • WSDL • SOAP • UDDI

3. Basic SOAP Message Exchange WSDL describing service Exposing Program Service Provider Consuming Program Service Requestor SOAP message http transport SOAP message http transport discover services Service Registry UDDI WSDLs describing services

4. SOAP Message

5. Sample SOAP Message • <env:Envelope xmlns:env="http://www.w3.org/2003/05/soap-envelope"> • <env:Header> <n:alertcontrol xmlns:n="http://example.org/alertcontrol"> <n:priority>1</n:priority> <n:expires>2001-06-22T14:00:00-05:00</n:expires> </n:alertcontrol> </env:Header> • <env:Body> <m:alert xmlns:m="http://example.org/alert"> <m:msg>Pick up Mary at school at 2pm</m:msg> </m:alert></env:Body> • </env:Envelope>

6. Conversational Message Exchange seller buyer message broker RFQ seller QuoteResponse Award seller

7. Conversational SOAP Message Exchange: A Request <?xml version='1.0' ?> <env:Envelope xmlns:env="http://www.w3.org/2003/05/soap-envelope"> <env:Header> <r:RFQNum xmlns:r=“http://bigco.example.org/RFQ” env:mustUnderstand=“true”>101</r:RFQNum> <r:custNum env:mustUnderstand=“true”>17</r:custNum> </env:Header> <env:Body> <r:RFQ xmlns:r=“http://bigco.example.org/RFQ”> <r:manufacturer>SanDisk</r:<Manufacturer> <r:productname>SecureDigital memory</r:productname> <r:size>1GB</r:size> <r:substitutable/> <r:quantity>100</r:quantity> </r:RFQ> </env:Body> </env:Envelope>

8. Conversational Exchange: A Response <?xml version='1.0' ?> <env:Envelope xmlns:env="http://www.w3.org/2003/05/soap-envelope"> <env:Header> <r:RFQNum xmlns:r=“http://bigco.example.org/RFQ”> env:mustUnderstand=“true”>101</m:RFQNum> <r:vendorID env:mustUnderstand=“true”>2470</r:vendorID> <r:bidNum env:mustUnderstand=“true”>1</r:RFQNum> <r:custNum env:mustUnderstand=“true”>17<r:custNum> </env:Header> <env:Body> <r:quoteRespons xmlns:r=“http://bigco.example.org/RFQ”> <r:manufacturer>KingMax</r:<Manufacturer> <r:productName>SecureDigital memory</r:productname> <r:size>1GB</r:size> <r:speed>9000KB/s</r:speed> <r:VendorName URL=“http://memunlim.com”>Memories Unlimited</r:VendorName> <r:SKU>KM-SD1000</r:SKU> <r:quantity>100</r:quantity> </r:quoteResponse> </env:Body> </env:Envelope>

9. Conversational Exchange:Completion <?xml version='1.0' ?> <env:Envelope xmlns:env="http://www.w3.org/2003/05/soap-envelope"> <env:Header> <r:vendorID env:mustUnderstand=“true”>2470</r:vendorID> <r:bidNum env:mustUnderstand=“true”>1</r:bidNum> <r:custNum env:mustUnderstand=“true”>17<r:custNum> </env:Header> <env:Body> <r:Award xmlns:r=“http://bigco.example.org/RFQ”> <r:SKU>KM-SD1000</r:SKU> <r:quantity>50</r:quantity> </r:Award> </env:Body> </env:Envelope>

10. Remote Procedure Calls • To invoke RPC • Address of target SOAP node • Method name • Identities and values of arguments • Separation of arguments identifying target of RPC versus data • Plus values of properties for binding (e.g. GET, POST) • Optional header data

11. RPC Invocation <?xml version='1.0' ?> <env:Envelope xmlns:env="http://www.w3.org/2003/05/soap-envelope"><env:Header><t:transaction xmlns:t=“http://shippingservice.org/transaction” env:encodingStyle=“http://shippingservice.org/encoding” env:mustUnderstand=“true”>5</t:transaction> </env:Header>

12. Body <env:Body> <s:shipOrder xmlns:s=“http://shippingservice.org”> <s:origin env:encodingStyle="http://www.w3.org/2003/05/soap-encoding" > <r:vendorID xmlns:r=“http://bigco.example.org/RFQ”> 2470 </r:vendorID> </s:origin> <s:destination> <r:custNum env:mustUnderstand=“true”>17<r:custNum> </s:destination> <s:weight>500g</s:weight> </s:shipOrder> </env:Body> </env:Envelope>

13. RPC Result <?xml version='1.0' ?> <env:Envelope xmlns:env="http://www.w3.org/2003/05/soap-envelope" ><env:Header><t:transaction xmlns:t=“http://shippingservice.org/transaction” env:encodingStyle=“http://paymentservice.org/encoding” env:mustUnderstand=“true”>5</t:transaction> </env:Header> <env:Body> <s:shipOrderResponse env:encodingStyle=“http://www.w3.org/2003/05/soap-encoding” xmlns:rpc=“http://www.w3.org/2003/05/soap-rpc” xmlns:s=“http://shippingservice.org”> <rpc:result>s:status</rpc:result> <s:status>confirmed</s:status> <s:amount>$20.00</s:amount> </s:shipOrderResponse> </env:Body> </env:Envelope>

14. SOAP Faults • Place faults inside env:Body elements • In single env:Fault • env:Node identifies node which generated fault • Absence indicates “ultimate recipient” • env:Code • env:Value • env:Subcode • env:Reason • env:Text • env:Detail • Application specific

15. SOAP Fault Example <?xml version='1.0' ?> <env:Envelope xmlns:env="http://www.w3.org/2003/05/soap-envelope" xmlns:rpc='http://www.w3.org/2003/05/soap-rpc'> <env:Body> <env:Fault> <env:Code> <env:Value>env:Sender</env:Value> <env:Subcode> <env:Value>rpc:BadArguments</env:Value> </env:Subcode> </env:Code> <env:Reason> <env:Text xml:lang="en-US">Processing error</env:Text> <env:Text xml:lang="cs">Chyba zpracování</env:Text> </env:Reason> <env:Detail> <e:myFaultDetails xmlns:e="http://shippingservice.org/faults"> <e:message>Unknown destination</e:message> <e:errorcode>999</e:errorcode> </e:myFaultDetails> </env:Detail> </env:Fault> </env:Body> </env:Envelope>

16. SOAP Faults on MustUnderstand <?xml version='1.0' ?> <env:Envelope xmlns:env="http://www.w3.org/2003/05/soap-envelope> <env:Header> <env:NotUnderstood qname="t:transaction" xmlns:t="http://shippingservice.org/transaction"/> </env:Header> <env:Body> <env:Fault> <env:Code> <env:Value>env:MustUnderstand</env:Value> </env:Code> <env:Reason> <env:Text xml:lang="en-US">Header not understood</env:Text> <env:Text xml:lang="fr">En-tête non compris</env:Text> </env:Reason> </env:Fault> </env:Body> </env:Envelope>

17. SOAP Processing Model • SOAP messages are sent from one sender node passing through zero or more intermediaries • Three roles • next: each SOAP intermediary or end destination must act in this role • none: SOAP nodes must not act in this role • ultimateReceiver: destination acts in this role • Header blocks targeted to specific roles using Role attribute • If mustUnderstand=“true” SOAP receiver must understand or generate SOAP fault • Header blocks processed by intermediaries are generally removed before forwarding • Override with relay attribute • Allows targeting of headers to specific intermediaries (but mustUnderstand would then generally be turned off)

18. SOAP Extensibility in Practice <S:Envelope ...> <S:Header> <wsa:ReplyTo> <!-- WS-Addressing header block --> <wsa:Address>http://bigco.example.org/buyer</wsa:Address> </wsa:ReplyTo> <wssec:Security> <wssec:BinarySecurityToken ValueType=”wssec:X509v3” encodingType=”wssec:Base64Binary”> dhw6weiurU982ndya73jdVBGt2567...d79HID7ghd652ad2 </wssec:BinarySecurityToken> <wsrm:Sequence> <wsu:Identifier>http://f123.com/sq14<wsu:Identifier> <wsrm:MessageNumber>10</wsrm:MessageNumber> </wsrm:Sequence> </S:Header> <S:Body>...</S:Body> </S:Envelope>

19. SOAP Processing: Header Blocks, MustUnderstand and Relay <?xml version="1.0" ?> <env:Envelope xmlns:env="http://www.w3.org/2003/05/soap-envelope"> <env:Header> <p:oneBlock xmlns:p="http://example.com" env:role="http://example.com/Log" env:mustUnderstand="true"> ... </p:oneBlock> <q:anotherBlock xmlns:q="http://example.com" env:role="http://www.w3.org/2003/05/soap-envelope/role/next" env:relay="true"> ... ...</q:anotherBlock> <r:aThirdBlock xmlns:r="http://example.com"> ... ... </r:aThirdBlock> </env:Header> <env:Body > ... ... </env:Body> </env:Envelope>

20. SOAP Bindings • specify how SOAP messages may be passed from one SOAP node to another using an underlying protocol • provides a serialized representation of the message • provides a mechanism to support features needed by SOAP applications (security, reliability, etc...) • describes the features it provides

21. SOAP HTTP Binding Example • POST /Reservations HTTP/1.1 • Host: marketplace.example.org • Content-Type: application/soap+xml; charset="utf-8" • Content-Length: nnnn • <?xml version='1.0' ?> • <env:Envelope xmlns:env=”...”> • <env:Body> • <r:RFQ>

22. SOAP SMTP Binding Example From: buyer@bigco.example.org To: rfqs@marketplace.example.org Subject: RFQ: Memory purchase Date: Thursday, September 9 2004 Message-Id: <17-101@bigco.example.org> Content-Type: application/soap+xml <?xml version='1.0' ?> <env:Envelope xmlns:env=”...”> <env:Body>

23. SOAP Remoting Architecture application level Client application code Server object implementation Server skeleton Client stub XML marshaller XML unmarshaller remoting architecture level envelope header header body http protocol http server http server wire protocol level TCP/IP socket

24. So what’s different? • Open format usable from any platform • Easy to understand and debug • Stable supported interfaces • Standards enable “expose service once” and have multiple consumers • versus typical point to point integration efforts • Easy for intermediaries to process messages and add value • Routing and delivery • security • management and monitoring • schema and service design • acceleration • Easy to extend with additional semantics

25. CORBA Client application code Server object implementation application level Client stub Server skeleton Implementation repository Implementation repository Corba runtime Corba runtime ORB ORB TCP/IP socket

26. CORBA Dynamic Invocation application level Client application code Server object implementation binding method Client stub Implementation repository Server skeleton Implementation repository Corba runtime Corba runtime Remoting architecture level ORB ORB TCP/IP socket Wire protocol level

27. CORBA • Scalability • Stateful programming model - • Shared activation + • Performance • CORBA is only intermediary until object obtained (allowing direct client-server interaction) + • Binary transport + • Activation • Sophisticated four policy activation methods + • State Management • Provides state management with a connection-oriented protocol + • Garbage Collection • Implemented on per ORB vendor basis • No concept of distributed memory management • Security • Just uses SSL -

28. DCOM and DCE RPC application level Client application- code Server object implementation binding method Client proxy Server stub COM runtime COM runtime Remoting architecture level SCM SCM registry registry RPC channel Wire protocol level OXID Resolver Ping client/server

29. DCOM Object Creation application level Client application- code Server object implementation binding method Client proxy Server stub COM runtime COM runtime Remoting architecture level SCM SCM registry registry RPC channel Wire protocol level OXID Resolver Ping client/server

30. DCOM Object Invocation application level Client application- code Server object implementation binding method Client proxy Server stub COM runtime COM runtime Remoting architecture level SCM SCM registry registry RPC channel Wire protocol level OXID Resolver Ping client/server

31. DCOM Comparison • Scalability • Not scalable due to garbage collection and connection overhead • All clients involved in call required to send pings to servers at two minute intervals • Performance • Many roundtrips to activate and use remote object • Activation • Client obtains reference to remote object’s class object through local SCM from remote SCM • Client creates instances of remote objects through its proxy • State Management • DCOM goal: location transparency • Makes it very difficult to have a stateless model • User interface IFaces • Iteration IFaces • Garbage Collection • After three ping fails, server cleans up resources for objects owned by remote client • Security • Provides authentication, authorization and identity • Many authentication methods

32. Java RMI application level Client application- code Server object implementation binding method Client stub Server skeleton RMI Registry Remote Reference Layer Remote Reference Layer remoting architecture level Transport Layer Transport Layer TCP/IP Socket wire protocol level

33. JRMP signature (JRMI) version SingleOpProtocol StreamProtocol MultiplexProtocol protocol Message (serialized arguments based On Java’s Object Serialization Protocol)

34. RMI Comparison • Scalabilitiy • Good overall • Registry could be bottleneck • Performance • Fairly high • Use from Java applets in browser cause conversion to http –expensive • Activation • Stub can be download over the network • Lazy activation and selection of specific server instances • Allows automatic instantiation of objects based on methods faulting and the fault resolution process instantiating the remote object • State Management • Provides both connection-oriented and connectionless protocols (good!) • Garbage Collection • Distributed reference counting (like CORBA, DCOM) • Reference to remote objects is considered lease on object, which must be periodically renewed • Security • Strong security • Must have security credentials to perform dynamic class loading

35. SOAP Comparison • Scalability • Very scaleable especially over http if request/response model is maintained • Performance • Degraded by XML overhead • But if you’re interoping between architectures anyway that overhead isn’t unreasonable • Activation • Beyond SOAP’s scope • State Management • Stateless if over http • Garbage Collection • Beyond scope

36. Soap Comparison (2) • Security • https/SSL - not ideal for routability of course • WS-Security • Other Disadvantages • No true standard serialization method • Multiple copies of objects transported • Other Advantages • Encouragement of loose coupling (both physical and interface) • Protection of apps from changes in standards • Truly vendor-agnostic

37. Web Services Description Language (WSDL)

38. Web Services Description Language • Provides a model and an XML format for the “contract” of a web service • Separates abstract service description from both concrete network protocol and message format • Describes data types used in messages • Messages are defined as aggregation of typed parts • Operations are message exchange patterns supported by the web service • PortTypes are named collections of operations

39. WSDL Components • Types– a container for data type definitions using some type system (such as XSD). • 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 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 related endpoints.

40. WSDL Specification types message message message porttype operation operation operation binding service port

41. An Example - WSDL Types <?xml version="1.0"?> <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://schems.xmlsoap.org/wsdl/soap/" xmlns="http://schemas.xmlsoap.org/wsdl/">

42. <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>

43. WSDL Operations <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>

44. WSDL Bindings, Services, Ports <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>

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

46. Import for Types <?xml version="1.0"?> <definitions name="StockQuote" targetNamespace="http://example.com/stockquote/definitions" xmlns:tns="http://example.com/stockquote/definitions" xmlns:xsd1="http://example.com/stockquote/schemas" xmlns:soap="http://schemas.xmlsoap.org/wsdl/soap/" xmlns="http://schemas.xmlsoap.org/wsdl/"> <import namespace="http://example.com/stockquote/schemas" location="http://example.com/stockquote/stockquote.xsd"/> <message name="GetLastTradePriceInput"> <part name="body" element="xsd1:TradePriceRequest"/></message>

47. WSDL Binding • maps the abstract service functionality to a specific network protocol and message format • defines: • the communication protocol to use • how service interactions are accomplished using this protocol • the address to communicate with • Three bindings are defined in the WSDL spec: • SOAP binding – HTTP binding • SMTP binding

48. WSDL Binding Example:One-way Over SMTP <message name="SubscribeToQuotes"> <part name="body" element="xsd1:SubscribeToQuotes"/> <part name="subscribeheader" element="xsd1:SubscriptionHeader"/> </message> <portType name="StockQuotePortType"> <operation name="SubscribeToQuotes"> <input message="tns:SubscribeToQuotes"/> </operation> </portType> <binding name="StockQuoteSoap" type="tns:StockQuotePortType"> <soap:binding style="document" transport="http://example.com/smtp"/> <operation name="SubscribeToQuotes"> <input message="tns:SubscribeToQuotes"> <soap:body parts="body" use="literal"/> <soap:header message="tns:SubscribeToQuotes" part="subscribeheader" use="literal"/> </input> </operation> </binding> <service name="StockQuoteService"> <port name="StockQuotePort" binding="tns:StockQuoteSoap"> <soap:address location="mailto:subscribe@example.com"/> </port> </service>

49. Request-Response RPC Over HTTP <binding name="StockQuoteSoapBinding" type="tns:StockQuotePortType"> • <soap:binding style="rpc" transport="http://schemas.xmlsoap.org/soap/http"/> • <operation name="GetTradePrice"> • <soap:operation soapAction="http://example.com/GetTradePrice"/> • <input> <soap:body use="encoded" namespace="http://example.com/stockquote" encodingStyle="http://schemas.xmlsoap.org/soap/encoding/"/> • </input> • <output> <soap:body use="encoded" namespace="http://example.com/stockquote" encodingStyle="http://schemas.xmlsoap.org/soap/encoding/"/> • </output> • </operation>> </binding> <service name="StockQuoteService"> <documentation>My first service</documentation> <port name="StockQuotePort" binding="tns:StockQuoteBinding"> <soap:address location="http://example.com/stockquote"/> </port> </service>

50. Web Services Survey • Public APIs • Google • Amazon • Business APIs • SalesForce • Siebel CRM OnDemand