Java Web Services

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Java Web Services

• Rajkumar Sen
• 02305035

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Outline

• Why Java Web Services
• Java Web Services Developer Pack
• A Simple Web Service scenario
• APIs provided in JWSDP
• Remaining promises
• Conclusion
• References

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Why Java Web Services

• Ability of enterprises using different computing
  platforms to communicate with each other
• Java ensures code portability
• J2EE ensures scalability
• APIs hide all the implementation details
• Components are reusable
• Development time is substantially reduced

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Java Web Service Developer Pack

• Free integrated toolkit that allows Java
  developers to build, test and deploy Web services
• Web services standards WSDL, SOAP, UDDI
• APIs provided
• Java API for XML Messaging (JAXM)
• Java API for XML Registries (JAXR)
  Java API for XML-based RPC (JAX-RPC)

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Sample Scenario-Online Book store
Book Distributor Web Service
Request prices Order books JAXM/JAX-RPC
Book Store Client
Book Store Server
HTTP
Book Distributor Web Service
JAXR Register Service
JAXR Find service
Registry Server
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JAX-RPC API for XML based RPC

• RPC-based Web service is a collection of
  procedures that can be called by a remote client
  e.g.. A stock quote service
• Ties, the low-level classes that the server needs
  to communicate with a remote client
• WSDL document used for creating stubs, the
  low-level classes that are needed by a client to
  communicate with a remote service.
• Stubs can be static or dynamic.
• Tools wscompile and wsdeploy simplify our job

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JAX-RPC Contd.

• Service consists of
• Interface
• Declares the
  service's remote procedures
• Implementation class
• Implements the
  remote procedures.
• Configuration files jaxrpc-ri.xml and
  web.xml contain all the parameters needed to
  deploy the service.
• Client is a Java program which uses the stubs
  created from the WSDL document of the service
• Configuration file config.xml contains the
  location of the WSDL document.

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JAX-RPC Contd.

• Service Interface
• public interface BookIF
• public Book getPriceList()
  
• public String orderBook(String BookName,
  int quantity)
• Implementation class
• public class BookImpl implements BookIF
• public Book getPriceList() . . .
• public String orderBook(String BookName,
  int quantity) . . .

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JAX-RPC Contd.

• Client code
• public class BookClient
• public static void main(String args)
• BookIF BookOrder new
  BookServiceImpl().getBookIF()
• Book priceList BookOrder.getPriceLi
  st()
• for (int i 0 i lt priceList.length
  i)

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JAXM API for XML Messaging

• Provides a standard way to send XML documents
  over the Internet
• Based on SOAP and SOAP with Attachments
  specifications
• Messaging provider service, which does the
  behind-the-scenes work required to transport and
  route messages
• Standalone client also possible for
  request-response type of messaging
• Very useful when Enterprise work on shared
  schemas.(e.g.. Schema for order form in Online
  Book Store)

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JAXM Contd.

• Advantages over JAX-RPC
• One-way (asynchronous) messaging
• Routing of a message to more than one party
• Reliable messaging with guaranteed delivery
• Steps
• 1.Setting up Connection with the end-point.
• 2.Creating the SOAP message and populate it.
• 3.Sending the message.

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JAXR API for XML Registries

• Provides a convenient way to
• access standard business registries
• Supports two standards ebXML and UDDI
• Standards groups have developed
• schemas for particular kinds of XML documents,
  and two businesses might for example, agree to
  use the schema which is stored in the registry.

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JAXR Contd.

• Querying a registry-Useful methods
• 1.findOrganizations
• which returns a list of organizations
  that meet the specified criteria
• 2.findServices
• which returns a set of services offered
  by a specified organization
• 3. findServiceBindings
• which returns the service bindings
  (information about how to access the service)
  that are supported by a specified service
• Similar methods exist for Managing Registry Data.

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Remaining Promises

• Security provided in JWSDP
• Features yet to be supported in JWSDP
• Simple Implementation of Sample scenarioOnline
  book store and try to see the issues/problems
  involved.
• Issues related to Distributed Transaction
  Management.

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Conclusion

• Role of Java in Web Services
• APIs hide most of the implementation details
• Developer concerned with the logical part of the
  Web Service.
• However, operability from .NET to J2EE web
  services is unclear. No standards defined.
• All is not fine
• e.g. Does not support Distributed
  Transaction processing

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References

• 1.The Java Web Services Tutorial
• http//java.sun.com/webservices/docs/1.1/tutorial/
  doc/index.html
• 2.Java API for XML-RPC web services
• http//java.sun.com/xml/jaxrpc/index.html
• 3.Java API for XML Messaging
• http//java.sun.com/xml/jaxm/index.html
• 4.Java API for XML Registries
• http//java.sun.com/xml/jaxr/index.html

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• Thank You

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JAXR Contd.
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SOAP