ECE450H1S Software Engineering II 2005University of TorontoTutorial IWeb Services1. What is a Web Service?2. An example Web Service3. OmniEditor: Wrapping a text editor into a WS4. OmniGraphEditor: supporting a graphic editor ReferencesGustavo Alonso, Fabio Casati, Karumi Kuno, Vijay Machiraju. Web Services, Concepts, Architectures and Applications. Springer-Verlag, 2004.OmniEditor is a result of the course project for CSC408H.ECE450H1S Software Engineering II 2005University of TorontoWhat is Web Service• Historic perspectives– Centralized versus Distributed Programming Models: Client/Server, Master/Slave, SPMD, etc…– Middleware architecture 2-tier, 3-tier, n-tier– Technical evolution• IPC (inter process call): RPC, Java RMI, CORBA, DCOM• Shared Memory, Distributed Shared Memory and Message Passing• Interoperability, interoperability, interoperabilityECE450H1S Software Engineering II 2005University of TorontoWhat is a Web Service? • Web Services Standards (XML-based)– SOAP (Simple Object Access Protocol)– WSDL (Web Service Description Language)– UDDI (Universal Description, Discovery, Integration)– WS-I (integration), WS-Policy, WS-Security, etc.• Chances and Challenges– Application Wrappers to WS– Web Services Compositions– Holy Grail: large reusable library of WS with interoperability: 1,000 public WS ~ 1 Million private WS– ROI (Return of Investments): > 10x ?– Issues: Privacy, Security, PerformanceECE450H1S Software Engineering II 2005University of TorontoAn example web servicexmethods provides a web services to get the stock price• Example SOAP messages• Structure of WSDL descriptions• A program that invokes the web serviceECE450H1S Software Engineering II 2005University of TorontoSOAP architectureService requestorapplication object(OpenOME)SOAP-based middlewareService providerapplication object(OmniGraphEditor)SOAP-based middlewarerequestresponseECE450H1S Software Engineering II 2005University of TorontoExampleSOAP message: request<?xml version="1.0" encoding="UTF-8"?><SOAP-ENV:Envelopexmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/"xmlns:SOAP-ENC="http://schemas.xmlsoap.org/soap/encoding/"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xmlns:xsd="http://www.w3.org/2001/XMLSchema"xmlns:ns="urn:xmethods-delayed-quotes"><SOAP-ENV:Body SOAP-ENV:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/"><ns:getQuote><symbol>IBM</symbol></ns:getQuote></SOAP-ENV:Body></SOAP-ENV:Envelope>ECE450H1S Software Engineering II 2005University of TorontoExampleSOAP message: response<?xml version="1.0" encoding="UTF-8"?><SOAP-ENV:Envelopexmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/"xmlns:SOAP-ENC="http://schemas.xmlsoap.org/soap/encoding/"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xmlns:xsd="http://www.w3.org/2001/XMLSchema"xmlns:ns="urn:xmethods-delayed-quotes"><SOAP-ENV:Body SOAP-ENV:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/"><ns:getQuoteResponse><Result>86.05</Result></ns:getQuoteResponse></SOAP-ENV:Body></SOAP-ENV:Envelope>ECE450H1S Software Engineering II 2005University of TorontoWSDL architectureService requestorstubSOAP-based middlewareService providerstubSOAP-based middlewarerequestresponseWSDL compiler(client)WSDL compiler (server side)WSDL (url)ECE450H1S Software Engineering II 2005University of TorontoExample WSDL structure: message<?xml version="1.0" encoding="UTF-8"?><definitions name="quote“xmlns:tns="urn:xmethods-delayed-quotes"… name spaces …>… types …<message name="getQuoteRequest"><part name="symbol" type="xsd:string"/></message><message name="getQuoteResponse"><part name="Result" type="xsd:float"/></message>… portType, binding, service …</definitions>ECE450H1S Software Engineering II 2005University of TorontoExample WSDL structure: portType<?xml version="1.0" encoding="UTF-8"?><definitions name="quote"… name spaces …>… types, messages, …<portType name="quotePortType"><operation name="getQuote"><input message="tns:getQuoteRequest"/><output message="tns:getQuoteResponse"/></operation></portType>… binding, service …</definitions>ECE450H1S Software Engineering II 2005University of TorontoExample WSDL structure: binding<?xml version="1.0" encoding="UTF-8"?><definitions name="quote"… name spaces …>… types, messages, portType …<binding name="quote" type="tns:quotePortType"><SOAP:binding style="rpc" transport="http://schemas.xmlsoap.org/soap/http"/><operation name="getQuote"><SOAP:operation soapAction=""/><input><SOAP:body use="encoded" namespace="urn:xmethods-delayed-quotes" encodingStyle="http://schemas.xmlsoap.org/soap/encoding/"/></input><output><SOAP:body use="encoded" namespace="urn:xmethods-delayed-quotes" encodingStyle="http://schemas.xmlsoap.org/soap/encoding/"/></output></operation></binding>… service …</definitions>ECE450H1S Software Engineering II 2005University of TorontoExample WSDL structure: service<?xml version="1.0" encoding="UTF-8"?><definitions name="quote"… name spaces …>… types, messages, portType, binding …<service name="quote"><port name="quote" binding="tns:quote"><SOAP:address location="http://services.xmethods.net/soap"/></port></service></definitions>ECE450H1S Software Engineering II 2005University of TorontoWeb Services InvocationXmethodsWSDLgetQuoteClientProgram<ns:getQuote><symbol>IBM</symbol></ns:getQuote><ns:getQuoteResponse><Result>86.05</Result></ns:getQuoteResponse>ECE450H1S Software Engineering II 2005University of TorontoInvoking the web servicegsoap/soapcpp2/samples/quote//gsoap ns service name: quote//gsoap ns service style: rpc//gsoap ns service encoding: encoded//gsoap ns service namespace: urn:xmethods-delayed-quotes//gsoap ns service location: http://services.xmethods.net/soapint ns__getQuote(char *symbol, float *Result); /* quote.h *//* quote.c */int main(int argc, char **argv){ struct soap soap;float q;char *sym;if (argc > 1)sym = argv[1];else{ fprintf(stderr, "Usage: quote <ticker>\n");exit(1);}soap_init(&soap);if (soap_call_ns__getQuote(&soap, "http://services.xmethods.net/soap", "", sym, &q) == 0)printf("\nCompany - %s Quote - %f\n", sym, q);elsesoap_print_fault(&soap, stderr);soap_end(&soap);soap_done(&soap);return 0;}%> quote IBMCompany - IBM Quote - 86.269997%>ECE450H1S Software Engineering II 2005University of TorontoReference Architecture 1: Client/ServerWeb serviceUPLOADDOWNLOADVIMEclipsechannelchannelVIMEmacsWhenever upload is called, the state of the