Transcript Yongqun He
Web Services Part II Yongqun He J2EE-based Web Services Types in Client Tier Type of client Examples How this client connects Business Partners Distributors, resellers, large customers XML-based web services technologies (SOAP, UDDI, WSDL, ebXML) Thin Clients Web browsers, PDAs, wireless devices Lightweight protocol (HTTP) Thick Clients Applets, applications, existing systems Heavyweight protocol (IIOP) ** PDAs: Personal Digital Assistants ** Thick Clients: e.g. within a company’s internal LAN topology. May use more efficient protocol such as Java RMI-IIOP (Java Remote Method Invocation over the Internet Inter-ORB Protocol). Using JAXR,UDDI, and WSDL ** JAXR (Java APIs for XML Registries) For publishing, querying, & editing An EJB Business Layer JAX* APIs to Invoke a Business Web Service The Java API for XML registries (JAXR): look up the business partner’s web service that is published in a UDDI registry. The Java API for XML RPC (JAX/RPC): perform RPC requests to the external web service. The Java API for XML Messaging (JAXM): send SOAP or ebXML messages to the external web service. The Java API for XML parsing (JAXP) and the Java API for XML Binding (JAXB): transform Java data into an XML format suitable for the partner; convert the received XML data back into a Java language construct; perform XSLT transforms to convert schemas. JAX* APIs to Invoke Business Web Service Relationship of Web Services Architecture to MS Windows DNA (n-tier) Architecture Microsoft.NET-based Web Services Analogies between J2EE and .NET Feature J2EE .NET Type of technology Standard Product Middleware Vendors 30+ Microsoft Interpreter JRE CLR Dynamic Web Pages JSP ASP.NET Middle-Tier Components EJB .NET Managed Components Database access JDBC SQL/J ADO.NET SOAP, WSDL, UDDI Yes Yes Implicit middleware (load-balancing, etc) Yes Yes More Components XLANG: used by web services to perform complex undo operations. XAML (Transaction Authority Markup Language): provides a more traditional twophase commit style transactional semantics over web services. XLANG/XAML provides transactional support for complex web transactions involving multiple web services. More Components (cont’d) XKMS (XML Key Management Specification): ongoing work by Microsoft and Verisign to support authentication and registration. Key idea: delegate the signature processing to a trust server on the web. Rely on XML signature and encryption specification by W3C. Two parts: X-KISS (XML Key information Service Specification) X-KRSS (XML Key Registration Service Specification) ebXML (e-business XML) A suite of XML specifications and related processes and behavior designed to provide an e-infrastructure for B2B collaboration and integration. Enables enterprises of any size and in any geographical location to conduct business over the Internet. Sponsored by UN/CEFACT and OASIS. UN/CEFACT: United Nations Center for Trade Facilitation and Electronic Business OASIS: Organization for the Advancement of Structured Information Standards ebXML (e-business XML) Key components: Collaboration Protocol Profile (CPP): describes a company’s offerings in a standard, portable way. Collaboration Protocol Agreement (CPA): describes the exact requirements and mechanisms for the transactions. Business Process and Information Modeling: in XMLCore Components: a set of XML schemas Messaging: built on top of SOAP-encapsulated message-passing invocations; extend SOAP by adding layered frameworks. Registry/Repository: a service that stores CPPs, CPAs, core components, and other ebXML documents and fragments. Dynamic e-business Definition: the next generation of e-business focusing on the integration and infrastructure complexities of B2B by leveraging the benefits of Internet standards and common infrastructure to produce optimal efficiencies for intra- and inter-enterprise computing. Service-Oriented Architecture (SOA): conceptual architecture for implementing dynamic ebusiness. SOA includes three participants and three fundamental operations. SOA Architecture ** Service providers publish services to a service broker. Service requesters find required services using a Service Broker and bind to them. Comparison with CORBA/DCOM Competing approaches Using the same principles CORBA/DCOM success is limited Discovery of distributed services Interaction through a common protocol Dependent on vendor’s implementation Weak for client-to-server communications, esp. when the client machines are scattered across the Internet. Web Services: existing Internet standards or widely-accepted specifications: HTTP, XML, SOAP, WSDL, UDDI. References A Web Services Primer: http://www.xml.com/lpt/a/2001/04/04/webservices/index.html Developer’s Guide to Building XML-based Web Services: http://www.theserverside.com/resources/article.jsp?l=WebServices -Dev-Guide Getting Started on Developing Web Services: http://dcb.sun.com/practices/howtos/developing_webserv.jsp A Platform for Web Services: http://msdn.microsoft.com/library/default.asp?url=/library/enus/dnwebsrv/html/websvcs_platform.asp J2EE vs. Microsoft.NET: http://www.theserverside.com/resources/articles/J2EE-vsDOTNET/article.html IBM Web Services Zone: http://www-106.ibm.com/developerworks/webservices/