I have started looking into JAX-WS study material, and following terms are used on very first page,
tools to use Java to WSDL & WSDL to Java (wsimp - client side; wsgen - endpoint side)
My question is regarding using tools like wsimp & wsgen, the word tool has created a doubt in my mind that is it valid to use these tools or we need to learn core process (performed by these tools) from CERT prepration point of view.
Well, I have not written the certification so I cannot say for sure, but:
If you did not have tools like wsgen and wsimport, then goodies like the annotations provided by JAX-WS simply would not work.
Thus, if you ask me, I'd say that using these tools is not an option, but a requirement and that they are a essential part of JAX-WS.
JAX-WS does provide a two-layered programming model with a lower layer that is more API-centric and does not require the use of annotations, but I feel this is more for special cases and nothing one would commonly use.
You should note that, in section 4, there is this objective:
Describe the architecture of JAX_WS including the Tools SPI that define the contract between JAX-WS tools and Java EE.
With this objective in mind, I'd say that you have to have at least some basic understanding of the Tools SPI and how it enables you to customize the tools.