from the request at step 320 and then uses identity data within the address data to validate at step 330 whether the request has been routed to the correct target server and if so which web service instance on the target server should handle the request validator 230 such identity data uniquely identifies the target server identity and the state data information associated with the web services instance that has been the subject of previous related requests from the client such state data has been built up as a result of such previous requests the form that this identifier will take is partly dependent upon the type of web service i the web service may be what is known as u201c fragile u201d in this case it is only acceptable to use the state data that exists on the particular server holding the web service instance at which the client 39 s first request was routed thus the identity data preferably includes the server 39 s id ii in some cases state data is shared between a cluster of servers and thus any web service instance within the relevant cluster will have access to the same state data consequently the identity data preferably includes a cluster id and iii sometimes a web service is classified as a u201c highly available u201d ha web service this means that it is managed by an ha service which keeps track of which server the web.