VisualStudio引进的ASMX的确大大简化了XML Web Services的开发过程,但也存在一个比较突出的弊端,那便是VisualStudio的设计使用的是Code-first approach,先编写代码,再由.NET Framework动态生成Web Services的WSDL,而不是实施SOA更加认同的Contract-first approach。近日实践了一把在开发ASMX Web Services时运用Contract-first approach,然后通过bea Weblogic Workshop来comsume。
Step 1:生成XSD,即Web Method传入和传出XML的Schema,比如我有个叫Test1()的Web Method, 那分别为它定义Test1Request和Test1Response,如下是一个例子:
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Step 2:生成此XSD对应的.NET类,命令为:xsd.exe /classes filename.xsd,有了这个类文件就可以在Web Method中方便地使用符合Schema的XML数据了(而不是手工去分析传入的XML数据)。
Step 3:生成WSDL,我用了能集成进VisualStudio的WSCF工具来完成这个工作,其间设定了Web Method及其参数和返回值使用的Schema,以下是一个例子:
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注意:最后的service标签,工具不会自动生成,需要手工加入。
Step 4:生成.NET代码,这一步我也使用WSCF来完成,生成的是一个Interface和一个ASMX,此ASMX已经可以通过浏览器查看,只不过还未实现其中的业务逻辑。
Step 5:编写ASMX的业务逻辑代码,使Web Service能够真正运作。
注意:每次使用WSCF都会重新生成接口和ASMX,所以如果WSDL发生变化而需要更新,须注意不要覆盖了原先的代码。
Step 6:在Weblogic Workshop中新建一个Application,在Schema中import Step 1中生成的XSD文件,此时Weblogic会编译此文件并生成相应的XML Bean。
Step 7:在默认的Project中新建一个Java Control,选择Web Service,设定WSDL为Step 2中生成的文件,完成后便可通过这个控件开始使用此Web Service。
注意:Weblogic提供了完备的测试机制,可以自动生成测试文件,并可在测试过程中通过XML来传入Web Method的参数,这点比VisualStudio方便很多。
总结:目前此种开发方式虽然达到了很高的互操作能力,但由于集成开发环境的缺憾,生产效率会被大大降低,所以是否采用Contract-first approach还是的根据业务的需求来确定。