"Call" is not a prefix, it execution command.
a procedure parameters can be supplied two different ways, when some of the parameters can be null/optional or have default values. When you are using
invoke(binding,action)
you need to provide input values for all parameters of the procedure, and parameter positioning must match with procedure definition. when using parameter named syntax like
invoke(binding=>'HTTP')
you can omit the parameters where you want to use the default values, or pass in NULL. Also positioning of parameters is not significant.
What's the difference between
invoke(binding=>'HTTP', action=>'GET') and invoke(binding, action)? In this occasion, no parameter used to set request xml, how request soap xml be passed to?
I also remove prefix of procedure.