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Thursday, July 09, 2015

Web ٍٍServices Round-trip development

The two primary methods of Web services development are top-down and bottom-up. Some developers have also used a third method, primarily because of shortcomings or defects in tools, and a lack of thorough understanding of Web services tools and technologies. In what is called round-trip development, the developer uses part of the top-down process followed by parts of the bottom-up process. First, Steps 1-3a of the top-down method are used, primarily to produce the so-called DTOs (possibly based on standards-based XSDs). The DTOs are used in the interface of a POJO or EJB, which is created manually, offering public methods corresponding to the portType operations defined in the WSDL document. Then, Steps 2-4 of the bottom-up method are used. Step 3b from top-down is skipped because the WSDL from Step 3 of bottom-up is used for the client-side.

  • Evaluation of the round-trip approach
The advantages of the round-trip approach are:
The primary advantage of the approach is that it you can use it to circumvent tooling problems, or to compensate for insufficient knowledge of Web services tools and technologies. This approach allows customization of an existing schema and Web service via code changes rather than schema changes. You can also use it if the tooling does not support implementation of the service in the desired form, such as an EJB.

The disadvantages of the round-trip approach are:
Some Java base types do not round-trip to schema types very well, which can cause additional rework.
The additional steps required for round-trip unnecessarily complicate the development process.
The WSDL produced is much less reusable than the original WSDL and its imported schema.
The namespaces of the data types from the original WSDL and the final output WSDL may become different because of the namespace to package mapping and package to namespace mapping. This must be carefully managed by the server-side developer.

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