1. IBM Labs in Haifa J2EE Technologies: Web Services II Benny Rochwerger Research Staff Member

2. IBM Labs in Haifa J2EE Technologies - Web Services II © 2003 IBM Corporation 2 Agenda  Web Services: What is it about  XML Primer  Simple Object Access Protocol – SOAP  Describing Web Services – WSDL  Discovering Web Services – UDDI  Web Services in the Marketplace  What is next  The Open Grid Services Architecture

3. IBM Labs in Haifa J2EE Technologies - Web Services II © 2003 IBM Corporation 3 The Service Oriented Architecture (SOA) Service Provider Service Registry Service Requestor Publish Bind Find

4. IBM Labs in Haifa J2EE Technologies - Web Services II © 2003 IBM Corporation 4 The Web Services Stack Service Publication/Discovery Service Description XML Messaging Transport Network UDDI WSDL SOAP HTTP, SMTP, MQSeries, etc.

5. IBM Labs in Haifa J2EE Technologies - Web Services II © 2003 IBM Corporation 5 Web Services Description Language (WSDL)  Why service descriptions are needed ?  SOAP is the format of the envelope  It does not specify what message goes into the envelope  A formal mechanism to describe  What goes into the body  What messaging protocol to use  What address to send the message to

6. IBM Labs in Haifa J2EE Technologies - Web Services II © 2003 IBM Corporation 6 Web Services Description Language (WSDL)  Application level service description (abstract interface)  What a service does  Operations, parameters, return values  Protocol-specific details needed to access the service end points (concrete binding information)  How a service is accessed  Data formats and protocols necessary  Where a service is located  Network address of service provider

7. IBM Labs in Haifa J2EE Technologies - Web Services II © 2003 IBM Corporation 7 WSDL Elements  WHAT  portType  An abstract interface definition  Consist of operation elements  Abstract method signature  message  Set of parameters referred to by method signatures  It is decomposed into part elements  type  The collection of all the data types used in the Web Service

8. IBM Labs in Haifa J2EE Technologies - Web Services II © 2003 IBM Corporation 8 WSDL Elements (cont.)  HOW  binding  Details of how elements in abstract interface are to be converted into a concrete representation  Data formats  Network protocols  WHERE  port  How a binding is deployed at a particular network endpoint  service  A named collection of ports

9. IBM Labs in Haifa J2EE Technologies - Web Services II © 2003 IBM Corporation 9 The portType Element............

10. IBM Labs in Haifa J2EE Technologies - Web Services II © 2003 IBM Corporation 10 The operation Element  Request-response style of operation  input, output and zero or more faults  Most common style  Maps nicely to HTTP <fault message="StockAvailableRegistrationError" name="StockAvailableNotificationErrorMessage"/> <fault message="StockAvailableExpirationError" name="StockAvailableExpirationError"/>

11. IBM Labs in Haifa J2EE Technologies - Web Services II © 2003 IBM Corporation 11 The operation Element (cont.)  One-way style of operation  input message only  Useful to change state of service provider  HTTP response is an acknolegment of the message with no application level semantics

12. IBM Labs in Haifa J2EE Technologies - Web Services II © 2003 IBM Corporation 12 The operation Element (cont.)  Notification style of operation  output message only  Asynchronous one-way push from service provider  Useful for notifying state information back to requestor

13. IBM Labs in Haifa J2EE Technologies - Web Services II © 2003 IBM Corporation 13 The operation Element (cont.)  Solicit-response style of operation  output, input and zero or more faults  Initiated by service provider as in the notification style  Response is expected from service requestor <fault name=“RequestorIDNotAvailableError” message=“RequestorIDNotAvailableErrorMessage”>

14. IBM Labs in Haifa J2EE Technologies - Web Services II © 2003 IBM Corporation 14 The message and part Elements  A message  A named collection of parts  Can be used as input, output or fault within an operation  A part  A tuple Use simple types directly or complex types defined in the types element Types are a complexType or an element

15. IBM Labs in Haifa J2EE Technologies - Web Services II © 2003 IBM Corporation 15 From Java to WSDL … public class StockQuoteService { public float getQuote (String symbol) throws Exception { return com.ibm.wstk.util.Quote.getQuote( symbol ); }

16. IBM Labs in Haifa J2EE Technologies - Web Services II © 2003 IBM Corporation 16 The binding Element  How to format messages  How WSDL relates to SOAP headers, bodies, encoding, etc.  The binding element tells service requestor how to format messages in a protocol-specific manner  Each portType can have more than one binding associated

17. IBM Labs in Haifa J2EE Technologies - Web Services II © 2003 IBM Corporation 17 The binding Element <binding name="StockAvailableNotificationSOAPBinding" type="StockAvailableNotificationPortType"> <soap:binding style="rpc" transport="http://schemas.xmlsoap.org/soap/http"/> <soap:operation soapAction= http://www.skatesTown.com/StockAvailableNotification/registration/> <soap:header message="StockAvailableRegistrationRequest" part="expiration" use="encoded“ namespace="http://www.skatestown.com/ns/registrationRequest“ encodingStyle="http://schemas.xmlsoap.org/soap/encoding/"/>

18. IBM Labs in Haifa J2EE Technologies - Web Services II © 2003 IBM Corporation 18 <binding name="StockAvailableNotificationSOAPBinding" type="StockAvailableNotificationPortType"> <soap:binding style="rpc" transport="http://schemas.xmlsoap.org/soap/http"/> <soap:operation soapAction= http://www.skatesTown.com/StockAvailableNotification/registration/> <soap:header message="StockAvailableRegistrationRequest" part="expiration" use="encoded“ namespace="http://www.skatestown.com/ns/registrationRequest“ encodingStyle="http://schemas.xmlsoap.org/soap/encoding/"/> Unique name The binding Element The type attribute is used to identify portType Use SOAP messaging RPC or document SOAP/HTTP Set the soapAction HTTP header. Can be used as a routing hint Put the “expiration” part of the message into the SOAP header Encode data, i.e., serialize/deserialize Put the “registration” part of the message into the SOAP body Do not encode data, i.e., pass XML to/from application

19. IBM Labs in Haifa J2EE Technologies - Web Services II © 2003 IBM Corporation 19 The binding Element (cont.) <soap:body use="encoded" namespace="http://www.skatestown.com/ns/registrationRequest" encodingStyle="http://schemas.xmlsoap.org/soap/encoding/"/> <soap:fault name="StockAvailableNotificationErrorMessage" namespace="http://www.skatestown.com/ns/registrationRequest" encodingStyle="http://schemas.xmlsoap.org/soap/encoding/"/>

20. IBM Labs in Haifa J2EE Technologies - Web Services II © 2003 IBM Corporation 20 The service and port Elements  service  Container of port elements  port  Identify network address of endpoint <port name="StockAvailableNotificationPort“ binding="StockAvailableNotificationSOAPBinding">

21. IBM Labs in Haifa J2EE Technologies - Web Services II © 2003 IBM Corporation 21 Using WSDL  Service client development  Input to proxy generator which produces client code  Service invocation  Input to dynamic invocation proxy which generates, at run time, correct service requests

22. IBM Labs in Haifa J2EE Technologies - Web Services II © 2003 IBM Corporation 22 Application SOAP Engine Network Protocol Service Requestor Service Invocation Web Service SOAP Engine Network Protocol Service Provider Y Web Service SOAP Engine SMTP Service Provider X HTTP

23. IBM Labs in Haifa J2EE Technologies - Web Services II © 2003 IBM Corporation 23 Application SOAP Engine Network Protocol Service Requestor Service Invocation Web Service SOAP Engine HTTP Service Provider Y Web Service SOAP Engine SMTP Service Provider X SMTP

24. IBM Labs in Haifa J2EE Technologies - Web Services II © 2003 IBM Corporation 24 WSDL Summary  Elements to define abstract interface of a service  What a service does  Elements to specify concrete binding information  How a service is accessed  Where a service is located

25. IBM Labs in Haifa J2EE Technologies - Web Services II © 2003 IBM Corporation 25 UDDI – Universal Description, Discovery and Integration  XML-based mechanism to build centralized registry of services  Facilitate service discovery both at design time and dynamically at runtime  UDDI is a:  Business Registry  Public online business/services registry  Available since 2001  Consists of replicas hosted at UDDI Operators  Currently there are two: IBM and Microsoft  Operators should be indistinguishable  Set of APIs and data structures  Enable programmatically registration and inquiry of services

26. IBM Labs in Haifa J2EE Technologies - Web Services II © 2003 IBM Corporation 26 The UDDI Data Structures  The businessEntity data structure  White pages  Name, address and contact information  Yellow pages  Classification information about the types and location of the services the entity offers  Green pages  Technical data, e.g., how to invoke the offered services  The tModel data structure  An abstract technology model that is used to represent the reusable definition of a service (the interface)  The bindingTemplate data structure  Holds the technical information for the service to actually be invoked

27. IBM Labs in Haifa J2EE Technologies - Web Services II © 2003 IBM Corporation 27 The UDDI APIs  A set of Create, Read, Update and Delete (CRUD) operations BusinessServiceBindingtModel Save/Updatesave_businesssave_servicesave_bindingsave_tModel Deletedelete_businessdelete_servicedelete_bindingdelete_tModel Findfind_businessfind_servicefind_bindingfind_tModel GetDetail get_businessDetailget_serviceDetailget_bindingDetailget_tModelDetail

28. IBM Labs in Haifa J2EE Technologies - Web Services II © 2003 IBM Corporation 28 UDDI Pointers  The UDDI initiative  http://www.uddi.org  IBM  http://www.ibm.com/services/uddi  Microsoft  http://uddi.microsoft.com

29. IBM Labs in Haifa J2EE Technologies - Web Services II © 2003 IBM Corporation 29 The Web Services Landscape (partial)  The J2EE world  BEA – WebLogic Server  http://www.bea.com/products/weblogic/server  Iona – XMLBus  http://www.xmlbus.com/  Macromedia – JRun  http://www.macromedia.com/software/jrun  Sun – Sun ONE Application Server  http://wwws.sun.com/software/products/appsrvr/home_appsrvr.html  IBM – WebSphere  http://www.ibm.com/websphere

30. IBM Labs in Haifa J2EE Technologies - Web Services II © 2003 IBM Corporation 30 The Web Services Landscape (partial) .NET  Microsoft’s platform for distributed computing  Common Language Runtime (CLR)  Similar to Java’s virtual machine  bytecode generated from C#, C++, Visual Basic, COBOL  Core classes  Similar to Java class library  ASP.NET  A programming framework built on CLR that can be used on a server to build Web applications  Equivalent to J2EE container ?

31. IBM Labs in Haifa J2EE Technologies - Web Services II © 2003 IBM Corporation 31 The Web Services Landscape (partial)  Other languages and environments  SOAP::Lite  Perl interface to the SOAP. Both client and server  http://www.soaplite.com/  SOAPPy  Python interface to the SOAP. Both client and server  http://sourceforge.net/projects/pywebsvcs  eSOAP  A C++ library that provides a SOAP engine for embeddeding systems  Available on  RTEMS, eCos, QNX  Microsoft Windows - NT/2000/98/ME  Linux  http://www.embedding.net/eSOAP

32. IBM Labs in Haifa J2EE Technologies - Web Services II © 2003 IBM Corporation 32 The Apache eXtensible Interaction System (AXIS)  A very flexible SOAP engine from Apache  Open and pluggable architecture  Design to cope with various deployment configuration  From very simplistic to highly sophisticated configurations  The Java Web Services facility (JWS)  Drop-in development  Simplest and quickest way to deploy a Java-base Web Service  Rename source file from xxx.java to xxx.jws  Drop xxx.jws into JWS directory

33. IBM Labs in Haifa J2EE Technologies - Web Services II © 2003 IBM Corporation 33 Axis Components  Axis Engine  Main entry point into message processing model  Coordinate message flow  Handlers  Message processing logic  Chains  Ordered collections of handlers (invoked sequentially)  Pre/post processing of messages is achieved by defining chains  Dispatcher (the pivot handler)  The bridge between Axis and the business logic (i.e., the Web Service)  The RPCDispatcher  SOAP body to/from Java objects  Location and Invocation of code

34. IBM Labs in Haifa J2EE Technologies - Web Services II © 2003 IBM Corporation 34 Axis Components (cont.)  Transport Listeners  Deal protocol specific encapsulation  Responsible for Axis Engine instantiation  The AxisServlet  A transport listener for HTTP  Deployment/Configuration  Add/remove Web Services to Axis  Creation of service specific chains  Configuration of transport and global chains  Serializers/Deserializers  Convertion of native data types to/from XML

35. IBM Labs in Haifa J2EE Technologies - Web Services II © 2003 IBM Corporation 35 Request Handlers Response Handlers Axis on the Server Dispatcher Axis Engine Axis Engine Transport Request Chain Global Request Chain Transport Response Chain Global Response Chain TL Transport Requestor TL Transport Requestor Web Service Web Service Web Service specific chain

36. IBM Labs in Haifa J2EE Technologies - Web Services II © 2003 IBM Corporation 36 Axis on the Client Transport Application Transport Sender Transport Sender Axis Engine Axis Engine Transport Request Chain Global Request Chain Transport Response Chain Global Response Chain Web Service specific request handlers Web Service specific response handlers

37. IBM Labs in Haifa J2EE Technologies - Web Services II © 2003 IBM Corporation 37 What is missing in the Web Services Model ? getQuote(“BMW”) Stock Quotes Provider BMW (ISE:BMW) Time: 7:11 Last Price: 1961.00 Change: +18.00 Open: 1942.00 High: 1977.00 @ 5:41 ET Low: 1927.00 @ 3:16 ET Currency: GBX Used Motorcycle dealer 1. BMW K 1200 RS Mileage: 8266 Year: 1999 Price: £6950 2. BMW R 1100 S Mileage:10347 Year: 1998 Price: £5750 3. BMW R 1100 S Mileage : 7284 Year: 1999 Price: £6250 4. BMW R 1100 S Mileage: 9000 Year: 2000 Price: £6350

38. IBM Labs in Haifa J2EE Technologies - Web Services II © 2003 IBM Corporation 38 What is missing in the Web Services Model ?  Service description captures interface syntax  The service accepts an operation request with a particular signature  Service description does not capture semantics  The Open Grid Services Architecture  Operation should respond as expected  “As expected” is usually defined offline in specifications  Use names as basis for reasoning about semantics  Standardize common services and operations

39. IBM Labs in Haifa J2EE Technologies - Web Services II © 2003 IBM Corporation 39 What is Next – The Open Grid Services Architecture  Standard interfaces and behaviors that address key distributed system issues:  Service description & information access  Notification  Policy management  Lifetime management  Service naming  Authentication  Reliable invocation  Transient stateful service instances

40. IBM Labs in Haifa J2EE Technologies - Web Services II © 2003 IBM Corporation 40 The OGSA Framework

41. IBM Labs in Haifa J2EE Technologies - Web Services II © 2003 IBM Corporation 41 The Grid Service: Interface/Behaviors & Service Data

42. IBM Labs in Haifa J2EE Technologies - Web Services II © 2003 IBM Corporation 42 Tools and Information  Suggested reading  Building Web Services with Java by Graham et.al., 2002, Sams Publishing  AXIS, Next Generation Java SOAP by Irani ant Basha, 2002, Wrox Press  Web Services Standards  http://www.w3.org/2002/ws/  Apache’s AXIS  http://xml.apache.org/axis/  IBM developerWorks : Web Services  http://www.ibm.com/developerworks/webservices  IBM developerWorks : WebSphere  http://www7b.software.ibm.com/wsdd/  Other Web Services good sites  www.webservices.org  www.gotdotnet.com  The OGSA Working Group  http://www.gridforum.org/ogsa-wg/

43. IBM Labs in Haifa J2EE Technologies: Web Services II Benny Rochwerger Research Staff Member