In most cases, all calls support a MessageID element in the request and a CorrelationID element in the response.
If you pass a message ID in a request, we will return the same value in CorrelationID
in the response. You can use this for tracking that a response is returned for every request
and to match particular responses to particular requests.
If you do not pass MessageID in the request, CorrelationID is not returned.
Note that some calls are designed to retrieve large sets of meta-data that only change
once a day or less often. To improve performance, these calls return cached responses
when you request all available data (with no filters). In these cases, the correlation ID
is not applicable. However, if you specify an input filter to reduce the amount data returned,
you can use MessageID and CorrelationID for these meta-data calls.
These are the meta-data calls that can return cached responses
GetCategories, GetAttributesCS, GetCategory2CS, GetAttributesXsl, GetProductFinder, GetProductFinderXsl, and GetProductSearchPage.