Java Web Services

ITP866 - Java Web Services

Course description
This one-week course prepares Java programmers to develop Web services and clients according to the Web Services Interoperability (WS-I) Organization’s WS-Basic profile: that is, using SOAP 1.1, WSDL 1.1 and XML Schema 1.0. (WS-Basic also calls for UDDI, which has more to do with publishing than development.) Students get an overview of the interoperable and Java-specific Web services architectures, and then learn the standard APIs for SOAP messaging and WSDL-driven, component-based service development. Both document-style and RPC-style messages and services are covered in depth.

The first module provides an overview of the world of Java-based Web services. It is designed to be equally useful to Java developers and to project managers and technologists. There is a great deal of hands-on demonstration of running Web services, inspecting SOAP traffic, WSDL definitions, and a little bit of Java code, but no Java coding. The focus is on the artchitecture itself, and on the roles that various protocols, APIs, tools, and application components play in a working Web service and/or client. The module can also be effective as a standalone seminar and introdution to Web services. (UDDI and JAXR for publishing and discovery are also included here, even though the remaining modules focus on development only.)

The second module develops an understanding of the Simple Object Access Protocol (SOAP) 1.1, and skills in using the Java API for XML Messaging (JAXM) and SOAP with Attachments API for Java (SAAJ) 1.1 to build SOAP-based Web services and clients. Students will learn to read SOAP and to write it by hand, and then will proceed to use the JAXM and SAAJ to develop servlets that respond to SOAP/HTTP messages. Intermediate and advanced techniques, such as integrating JAXP code with SAAJ, JSPs for Web services, and working with SOAP attachments, are also covered. The standard SOAP “Section 5” data encoding is studied in the module’s final chapter.

The final module teaches students how to develop Web services using SOAP, WSDL, and Java, with the help of the Java API for XML-Based RPC, or JAX-RPC. JAX-RPC abstracts almost all the details of SOAP messaging using WSDL as a description language for interface and implementation; this allows the Java developer to concentrate on application and service specifics. (In this way JAX-RPC is analogous to Java RMI and the EJB architecture, and SOAP/HTTP is treated as nothing more or less than an RPC transport protocol.) JAX-RPC specifies service development either from WSDL documents as a starting point or beginning with Java code and generating the WSDL for client use; this module addresses both possible development paths and analyzes their relative advantages. Also, both servlet and EJB endpoint models are studied, and the module concludes with exercises in handling SOAP headers and sharing message context information between various JAX-RPC classes.

Prerequisites


Experience in Java Programming, including object-oriented Java and the Java streams model, will be helpful, but is not necessary. All of the hands-on coding in this module is in instructor-led demonstrations, and the student can choose to participate or just to observe.

Some understanding of XML and XML Schema will be helpful, but is not strictly necessary. Prior study of Object Innovations Module 501, “Introduction to XML,” and 504, “Introduction to XML Schema,” would be helpful.

Various related technology is discussed in the course: JAXP, SAX, DOM, XSLT, XPath, JSP and JSTL. None of these is a formal prerequisite for the course, and labs are built to allow students without experience in these things to work through successfully. Experience in these areas will be helpful, however.

What you will achieve

• Describe the motivation for developing and using Web services in business software.


• Describe the Web services architecture.


• Describe common scenarios for Web-service implementation and client-side use.


• Describe the Java Web services architecture:


• Identify the Java specifications that relate to key Web-service protocols.


• Identify the major models for Web-service endpoint implementation, and relate the Java Web services architecture to the Java 2 Enterprise platform.


• Understand the importance of SOAP to the Web services architecture.


• Learn the structure of SOAP and how it is designed to travel over existing standard protocols including HTTP, SMTP, and FTP.


• Understand the role of the SOAP header in extending messaging capabilities and semantics, for instance for routing, security or transaction support.


• Understand the role of JAXM and SAAJ in the Java Web services architecture.


• Build a Java Web service as a JAXM/SAAJ servlet.


• Implement simple point-to-point SOAP communications using JAXM and SAAJ from a standalone client application.


• Mix and match SAAJ, SAX and DOM code in a Web-service implementation.


• Implement a simple Web service using JSP and JSTL XML tags.


• Implement a JSP Web-service client using custom tags that wrap JAXM.


• Create, send, receive, and read SOAP attachments using SAAJ.


• Understand the role of WSDL in providing type information for Web services.


• Write WSDL documents to describe messages, interfaces and services.


• Understand the role of the JAX-RPC in the Java Web services architecture.


• Identify the alternatives for development paths through Java code and WSDL artifacts on server and client sides, and describe the advantages of each.


• Understand the mapping of WSDL to Java classes and components.


• Analyze Java domain models and identify the useful JAX-RPC mappings.


• Add a SOAP interface to an existing Web application by generating SOAP messaging code using JAX-RPC tools.


• Build a Web service based on an existing WSDL document.


• Build a Web-service client based on a WSDL document.


• Describe the relationship between the EJB 2.1 and JAX-RPC 1.0 specifications, and how EJBs can implement Web-service endpoints.


• Add a SOAP interface to an existing system of EJBs, and build an EJB implementation of a Web service based on a predefined WSDL descriptor.


• Describe the usefulness of SOAP headers in Web service design and implementation.


• Describe the use of the JAX-RPC message context in reading and managing SOAP headers.


• Implement a JAX-RPC message handler to adapt an existing Web service.


• Implement a session-aware JAX-RPC Web service that relies on HTTP sessions based on cookies.

What you will learn

• Volume 1 Overview of Java Web Services
  
  1. The Web Services Architecture
  
  


• Evolution of Web Services


• Motivation for Web Services


• HTTP and XML


• Interoperability Stacks


• The Wire Stack


• Simple Object Access Protocol (SOAP)


• The Description Stack


• Web Service Description Language (WSDL)


• The Discovery Stack


• Universal Description, Discovery and Integration (UDDI)


• Hosting Web Services: Scenarios


• Demonstration: A Running Web Service and Client
  
  2. The Java Web Services Architecture
  
  


• Java and Web Services


• Web Services and the J2EE


• The Java API for XML Processing (JAXP)


• The SOAP With Attachments API for Java (SAAJ)


• The Java API for XML Messaging (JAXM)


• Demonstration: A SOAP-Based Web Service Using JAXM and SAAJ


• The Java API for XML-Based RPC (JAX-RPC)


• Demonstration: A WSDL-Enabled Web Service Using JAX-RPC


• WSDL-to-Java vs. Java-to-WSDL


• The Java API for XML Registries (JAXR)


• The Registry Server
  
  3. Java Web Services Case Study
  
  


• Multi-Tier Architecture


• Moving to Web Services


• Mapping Domain Classes Using JAX-RPC


• Demonstration: Creating the SOAP Interface and Generating WSDL


• Demonstration: Building the Client with JAX-RPC Stubs


• The UDDI Information Model


• White, Yellow and Green Pages


• Demonstration: UDDI Publishing with JAXR


• UDDI as a Web Service


• Demonstration: Discovering a Web Service via UDDI
  
  Volume 2 The Java APIs for SOAP Messaging
  
  1. The Simple Object Access Protocol (SOAP)
  
  


• SOAP Messaging Model


• SOAP Namespaces


• SOAP over HTTP


• The SOAP Envelope


• The Message Header


• The Message Body


• SOAP Faults


• Attachments


• XML Schema


• Validating Message Content
  
  2. The Java APIs for SOAP Messaging (SAAJ)
  
  


• The SAAJ Object Model


• Parsing a SOAP Message


• Reading Message Content


• Working with Namespaces


• Creating a Message


• Setting Message Content
  
  3. The Java API for XML Messaging (JAXM)
  
  


• Messaging Scenarios


• Point-to-Point Messaging


• JAXM Message Providers


• The JAXM Messaging Model


• Creating a Connection


• Sending a Message
  
  4. Parsing and Transformations
  
  


• The Java API for XML Processing (JAXP)


• SAX and DOM Parsing


• XSLT Transformations


• Piping Between SAAJ and JAXP


• Streaming Between SAAJ and JAXP


• Validating Request Content
  
  5. Web Services and JSP
  
  


• JSP and XML


• The JSTL


• Core and XML Actions


• JSP, JSTL and SOAP


• Reading SOAP Using XPath


• JSPs as Web-Service Clients


• Custom Tags for JAXM and SAAJ
  
  6. SOAP Attachments
  
  


• SAAJ Object Model, Revisited


• The SOAPMessage Class


• MIME


• The Java Activation Framework


• The MimeHeaders Class


• The AttachmentPart Class


• Adding SOAP Attachments


• Identifying Attachments


• Reading Attachments
  
  7. SOAP Encoding
  
  


• The Need for a Common Encoding


• The SOAP Section-5 Encoding


• Type Model


• Relationship to XML Schema


• Values


• Accessors


• Structures


• Arrays


• Multiple-Reference Values


• Mapping SOAP Types to Java
  
  Volume 3 The Java API for XML-Based RPC
  
  1. Web Services Description Language (WSDL)
  
  


• Web Services as Component-Based Software


• The Need for an IDL


• Web Services Description Language


• WSDL Information Model


• The Abstract Model - Service Semantics


• Message Description


• Messaging Styles


• The Concrete Model - Ports, Services, Locations


• Extending WSDL - Bindings


• Service Description
  
  2. The Java API for XML-Based RPC (JAX-RPC)
  
  


• The Java Web Services Architecture


• Two Paths


• How It Works - Build Time and Runtime


• Mapping Between WSDL/XML and Java


• Generating from WSDL


• Generating from Java


• Which Way to Go?


• Passing Objects


• Another CORBA?
  
  3. Generating Web Services from Java Code
  
  


• The Java-to-XML Mapping


• Primitive Types and Standard Classes


• Value Types and JavaBeans


• The Java-to-WSDL Mapping


• Simple and Complex Types


• Arrays and Enumerations


• Service Endpoint Interface


• Scope of Code Generation


• Inheritance Support


• Multi-Tier Application Design


• Analyzing the Domain


• When Things Don't Fit


• Conversational State


• Extensible Type Mapping