Apache CXF is just one implementation of the JAX-WS API,. There are other implementations, such as the JAX-WS RI (reference implementation), which is included in Java and part of the Metro framework (which includes some other things like WSIT).
Your question: what are the reasons for choosing Apache CXF? There are many of them, for example:
- support for RESTful services (becoming more and more popular)
- simple integration with Spring (if it is important for you)
- WS- * support (i.e., support for many important WS specifications, such as WS-Security).
- maturity (thanks @sourcedelica)
Literature:
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