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Service-Oriented Architecture with Java Web Services in Java Draw Code-39 in Java Service-Oriented Architecture with Java Web Services




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Service-Oriented Architecture with Java Web Services use jboss code39 printing tomake code 39 extended with java Visual Studio 2005/2008/2010 Overview 1.1.1 Don t Drink That Kool-Aid In early 2001, when A riba, IBM, and Microsoft published WSDL 1.1 as a W3C Note [WSDL 1.1], Web Services were envisioned as a way to make distributed computing easier.

No longer would developers need to understand CORBA to create cross-platform, distributed applications. Even better, Web Services were envisioned as a technology to make distributed computing over the Internet possible. Like me, most Java developers bought into this early Web Services vision.

It made sense given our experience with the Internet during the 1990s. HTML over HTTP had fueled the astonishing growth of the World Wide Web a distributed computing platform for people. We believed that standards (like SOAP and WSDL) for XML over HTTP would fuel similar growth for Web Services a distributed computing platform for business applications.

We all drank that Kool-Aid. We believed that Web Services would make distributed computing easy. The leaders of the Enterprise Java industry set to work implementing the Web Services vision.

Along the way to realizing this vision, the Java industry discovered that they had created some pretty daunting speci cations. The people who read the early JAX-RPC, JAXB, and other speci cations including myself became alarmed. We gured that something must have gone wrong.

We assumed that the Expert Groups leading these speci cations had gotten off-track. We became disillusioned and bitter about the lost promise of Web Services. We started bickering among ourselves about SOAP versus REST and who is to blame for the complexity of the Java Web Services speci cations.

But the complexity problem isnt a result of choosing the SOAP framework instead of REST. It s not a result of overengineering on the part of the Expert Groups. As the Expert Groups got down to brass tacks trying to make the Web Services vision happen they rediscovered that distributed computing really is a daunting challenge.

SOAP, WSDL, XML, and even REST are not going to make distributed computing easy. Certainly, the JWS speci cations are awed. But that is to be expected new technologies often come out with quirks and idiosyncrasies that make them dif cult to work with (look at EJB).

These problems are corrected as enhancements are made in subsequent versions 2 of the technology.. 2. Note that EJB 3.0 barcode 3/9 for Java continues to improve and implements the advanced Aspect Oriented Programming and Inversion of Control features its many detractors have been calling for.

. Am I Stupid, or Is Java Web Services Really Hard As one example of how servlet Code 3 of 9 the JWS speci cations have improved, consider JAX-WS 2.0. s 6 and 7 describe that speci cation in detail, so for now, I m just going to give a preview of why I think it s such a big improvement over JAX-RPC 1.

1. For starters, the JAX-RPC data binding has been removed and the speci cation has been simpli ed to focus on the WSDL to Java mapping along with support for REST endpoints. The XML Schema to Java data binding from JAX-RPC has been replaced with JAXB 2.

0, a much superior and widely used technology. Second, JAX-WS lets you use annotations to control the shape of the WSDL generated from a Java interface. The use of annotations in this manner simpli es and in some cases eliminates the need for the deployment descriptors required to deploy a JAXRPC service.

Third, JAX-WS provides interfaces (Dispatch on the client side and Provider on the server side) that enable programmers to directly access and work with XML effectively bypassing the JAXB data binding when they don t want to use it. For certain, JAX-WS 2.0 could still be improved.

The biggest improvement I can think of would be to provide an alternative binding (in addition to JAXB) that lets the developer work directly with the native XML types that are speci ed in a WSDL and its associated schema. Some type of XML extension to Java, like XJ [XJ], might do the job. Much of the complexity and confusion developers experience when working with JAX-WS relate to the dif culty of determining how the JAX-WS/JAXB-generated classes created by the JAX-WS WSDL compiler map to the XML messages speci ed in the WSDL.

However, that is a whole research area (creating a language that makes it simple to program directly with native XML types) unto itself where we are all still waiting for some breakthroughs. My point here is not that JAX-WS is ideal, but simply that is has improved on JAX-RPC, much as EJB 3.0 has improved on EJB 2.

1. To summarize, in the years since the WSDL speci cation came out, the Enterprise Java community has created from scratch a Java-centric platform for distributed computing based on Web Services technologies. This has been a Herculean task and it shouldn t surprise anyone that the speci cations are dif cult to understand! Viewed from this perspective, the JWS standards are not bad at all.

In fact, they are a huge step toward enabling Java to become an SOA development platform. These standards give us the APIs we need to wrestle with the complexities of Web Services development. So why are we disillusioned What lesson should we be learning as we wallow in our disillusionment I think it is the same lesson we learn over and over again in this business Don t drink the Kool-Aid ! If we didn t start out by assuming that Web Services were going to be a silver bullet.

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