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Web Services FAQ   

This is the FAQ page for the Web Services and Related Technologies forum. Like all other page in this wiki, the page is editable by anyone, so don't hesitate to add useful stuff.

What is a Web Service?

In simple terms a Web Service is an application or business logic that is accessible using standard Internet protocols.

Can I access a web services from any application?

Yes, if your application supports HTTP-based request and response (which, thanks to a plentitude of HTTP client libraries like Apache HttpClient, just about any application should be able to do).

Are there any real web services available for testing?

Yes, check http://xmethods.net/

What are the current free and commercial implementations available for Web Services?

Can I access a web service from within a browser?

You can use the JavaScript XmlHttpRequest object. You'll have to create and process the XML requests and responses yourself, though. This works in Internet Explorer, Safari and Mozilla-based browsers like FireFox. All major JavaScript? frameworks have classes and methods built in that greatly simplify this, though, so that should be the first choice.

What are the differences between JAX-RPC, JAX-WS, JAX-RS, Apache Axis, SAAJ, Apache SOAP, JWSDP, Metro, Jersey and GlassFish?

  • JAX-RPC is a specification/API for Java developers to develop SOAP based interoperable web services. This API is now obsolete, and may be dropped from the next JEE version.
  • JAX-WS is the successor to JAX-RPC. It requires Java 5.0, and is not backwards-compatible to JAX-RPC. This article describes the high-level differences to JAX-RPC.
  • SAAJ is another specification/API for using SOAP envelopes with or without attachments. It operates on a lower level than JAX-RPC or JAX-WS, both of which will use SOAP envelopes based on SAAJ if needed.
  • Apache Axis is an open source implementation of the Java WS APIs for sending and receiving SOAP messages. Axis 1 supports JAX-RPC and SAAJ, while Axis 2 supports SAAJ and JAX-WS.
  • Apache SOAP was the first SOAP implementation. It is now obsolete, and has been superseded by Apache Axis.
  • Sun JWSDP - Sun Java Webservices Developer Pack, is an implementation of JAX-RPC, SAAJ and various other XML Java technologies. It is now deprecated in favor of the Metro stack.
  • GlassFish is the open source JEE reference implementation. As such, it contains implementations of JAX-RS and JAX-WS.
  • Metro is the SOAP stack used in GlassFish?. It supports SAAJ, JAX-WS, WS-Security and other standards.
  • JAX-RS is the standard Java API for RESTful web services.
  • Jersey is the reference implementation of the JAX-RS API, as defined in the JSR-311 standard for RESTful web services.

What is REST? 

Where can I find the relevant standards?



How do I get started building a web service? Show me some code!

Some useful code snippets

  • How can I set HTTP headers like SOAPAction or Basic Authentication in my SOAP request? (link)
  • With Axis, how can I access authentication information if I use HTTP Authentication? (link)
  • With Axis, how can I find out which service and operation was invoked? (link)
  • What is the simplest possible Java client for a web service? (link)
  • How do I handle WS-Security UsernameTokens with WSS4J? (link)


What other sources of information are available particularly for Java Web Services?

Which other software packages help implement Java Web Services?

  • jUDDI and UDDI4j implement the client and server sides of UDDI, respectively. Scout is an open source JAXR implementation.

  • SOAPUI is an excellent tool for testing web services. It allows to observe SOAP (and REST) traffic in transit, and can also act as a client. It supports WS-Security.

More articles on specific topics



Books 

Check the JavaRanch Bunkhouse Web Services And SOAP category.

The book title is linked to the publisher where sample content may reside. The ISBN links to Amazon US which tends to list reviews.

SOA Using Java™ Web Services (2007) ISBN 0130449687  Web page Bunkhouse Review

Examines web service technology in a Java EE 5 context as implemented on the Glassfish application server. Covers JAX-WS 2.0 and JAXB 2.0. Mark D. Hansen’s posts during the book promotion. Why is Java Web Services so Hard?

RESTful Web Services (2007) ISBN 0596529260 

Explains the principles of REpresentational STate transfer and Resource Oriented Architecture (ROA). Specifies design procedures for resource URIs and resource (state) representations (XML being only one option). Many examples use Ruby but one example does use the Restlet framework. Also looks at AJAX applications as REST clients. Leonard Richardson’s and Sam Ruby’s posts during the book promotion.

J2EE Web Services (2004) ISBN 0321146182  Bunkhouse Review Author's Blog

Examines web service technology in a J2EE 1.4 context. Covers XML, XML Schema, SOAP 1.1, WSDL 1.1, WS-I Basic Profile 1.0a, UDDI 2.0 as general web service standards and the Java APIs using them: (the now dated) JAX-RPC (incl. EJB endpoints), JAXR (level 0), JAXP, SAAJ, SwA; deployment descriptors are also covered.

Designing Web Services with the J2EE™ 1.4 Platform (2004) ISBN 0321205219  On-line Version PDF Version

A more design/architecture oriented examination of web service technologies in a J2EE 1.4 context.

Service-Oriented Architecture: Concepts, Technology, and Design (2005) ISBN 0131858580  Web page

SOA with SOAP web services explained. Just don't expect to see any code as this is a platform independent discussion of SOA with SOAP web services.

Service-Oriented Architecture: A Field Guide to Integrating XML and Web Services (2004) ISBN 0131428985  Web page

An examination of how XML technologies, SOAP, WSDL, UDDI, and various WS-* standards can be used to move towards a Service-Oriented Enterprise. No code as this is a platform independent exploration.

SOA Principles of Service Design (2007) ISBN 0132344823  Web page

Service-Orientation isn't Object-Orientation. Discusses the service design principles needed to develop services that can operate successfully in a SOAP-based SOA.

SOA in Practice: The Art of Distributed System Design (2007) ISBN 0596529554  Web page

Need an SOA instead of a JaBoWS (Just another Bunch of Web Services)? While not specifically written for web service based SOAs but more towards large distributed systems in general this book presents some of the benefits that you can realize by adopting service-orientation and SOA practices. More importantly it reveals that large distributed systems can turn some common sense best practices established for smaller or component-based systems on their heads (example: the perceived need for a common business object model across the entire system). Interview

Java Web Services in a Nutshell

Building Web Services with Java: Making Sense of XML, SOAP, WSDL, and UDDI

Developing Web Services with Apache Axis

Developing Java Web Services: Architecting and Developing Secure Web Services Using Java

Java Web Services Architecture

Martin Kalin Java Web Services: Up and Running



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