Hi Serge,

IMHO is a design issue that you must resolve depending on your specific
requirements. Either way the basic goal is one - passing values. If you are
going to implement a small framework in your project and you can call your
web services from one central location may be it is better to use soap
headers. That way you will minimize method arguments, but it will be harder
to debug unless you provide some mechanism for this.
If you need to expose this web service for various devices and client may be
it is better to pass the value as an argument to each of your methods. Your
callers will be much happier :).
Still the decision is up to you.

Regards,