Print-friendly Version

Guidelines, Patterns, and code for end-to-end Java applications.

Java Pet Store Demo 1.3.1 > Changes made to enable Web-services

Changes made to enable Web-services in the Demo

The pet store sample application has four distinct parts:

1. The PetStore Website application that implements the interaction with the user and submits the user's order
2. The Order Processing Center (OPC) application that implements the workflow involved in processing the orders
3. The Supplier application that satisfies the approved orders from OPC and sends back the invoice to the OPC
4. The Admin application that interacts with the OPC. The Admin application provides a JavaWebStart enabled Swing client for use by the administrator

Web-services for Document-Oriented Interactions

The document-oriented interaction style facilitates loosely-coupled Web-services. In this case, the Web-service applications interact with each-other by exchanging XML documents. To demonstrate this scenario, we changed the OPC-Supplier communication to use the Java API for XML based RPC (JAXRPC) for passsing XML documents. The application design also illustrate how to extend your existing J2EE applications to use Web-services. 

The communications that happen between the OPC and the Supplier are

• The OPC submits the approved purchase order to the Supplier
• The Supplier returns back the invoice back to the OPC for the Items that have been shipped

• The Supplier has been changed to provide a Web-service that processes purchase orders from the OPC.
• The OPC has been changed to provide a Web-service that processes invoices from the Supplier.
• Both the purchase order and invoice processing Web-services, offered by the Supplier and OPC respectively, follow the Asynchronous Service model as described in the BluePrints for Web-services document. This is because both Web-services can take some time for processing and the service requestor should not be made to wait until the service is completed.
• Both the Web-services receive an XML document (namely purchase order or invoice), validate them, place the validated XML document on an appropriate JMS queue for processing and return the answer to the requestor.
• The interface and implementation of the WebServices provided by the OPC have been implemented in files /font><petstore.home>src/webservices/apps/opc/src/com/sun/j2ee/blueprints/opc/webservice/OPC*.java .
• The interface and implementation of the WebServices provided by the Supplier have been implemented in files <petstore.home>/src/webservices/apps/supplier/src/com/sun/j2ee/blueprints/supplier/webservice/Supplier*.java.
• To make the OPC communicate with the Supplier through JAXRPC and vice versa, two new Transition Delegates have been implemented (one for OPC-Supplier communication and the other for communication in the opposite direction). These files are <petstore.home>/src/webservices/apps/opc/src/com/sun/j2ee/blueprints/opc/webservice/transitions/OrderApprovalTD.java and <petstore.home>/src/webservices/apps/supplier/src/com/sun/j2ee/blueprints/supplier/webservice/transitions/SupplierOrderTD.java.
• This implementation uses the Java Web Services Developer Pack (JWSDP) for implementing the Web-services. Accordingly, the configuration required by the JWSDP has been implemented in files <petstore.home>/src/webservices/apps/opc/src/xrpcc-config.xml and <petstore.home>/src/webservices/apps/supplier/src/xrpcc-config.xml.
• All the ejb-jar.xml, web.xml for both the Supplier as well as the OPC were changed to reflect the fact that the Web-services are implemented with a servlet endpoint and that the installation of the JWSDP changes the port of operation to 8080 from 8000.

Web-services for RPC-Oriented Interactions

The JavaWebStart-enabled admin application in the PetStore demonstrates how to provide rich user interfaces for your applications. This Swing application invokes several well-defined operations on the server, for example, to get sales statistics, to approve pending orders and so on. The non-Web-services version of this application uses a proprietary XML format to send these commands to the server over HTTP POST.  This required a lot of code to create, parse, and send these commands and process their results. We now provide an alternate Web-service, AdminWebService, for administration that reduces this complexity significantly by providing a RPC-oriented JAXRPC interface. Here are the changes that we made:

• We create a new Web-service, AdminWebService, that is implemented by the JAXRPC interface <petstore.home>/src/webservices/apps/admin/src/com/sun/j2ee/blueprints/admin/webservice/AdminService.java
• The Swing client uses a Web-services specific proxy class to communicate to the server <petstore.home>/src/webservices/apps/admin/src/client/com/sun/j2ee/blueprints/admin/client/WebServicePetStoreProxy.java. You can run this client by going to <petstore.home>/webservices (or <petstore.home>/src/webservices/apps/admin/build if you have rebuilt the source code) directory and running adminwsclient.bat (on Windows) or adminwsclient.sh (on Unix) file. 
• Note that the JavaWebStart enabled client still uses the HTTP POST for communicating to the server. This client uses the HTTP POST specific proxy class to communicate to the server <petstore.home>/src/apps/admin/src/client/com/sun/j2ee/blueprints/admin/client/HttpPostPetStoreProxy.java