Webservices can be called per script and are used to read out information, set data, assign tasks, etc.
A list of webservice name kan be seen in Firebug. per selected webservice name you can find the available methods.
Via a click on the method it is possible to see which parameters need to be given.
In this example the fucntion getuserByName is called in the IdentityManager. This method calls a callback method (userCallback) in the script. THe callback gets the found user. In this callback the information of the received user can be worked with.
var userCallback=function(userGot){ //do sth } webService.IdentityManager.getUserByName("tim.support", userCallback);