In fact, the reported example based on NASDAQ100 assumes a short time frame.
If clients are expected to reopen the page every day and the NASDAQ100 composition changes overnight, they will perform a new subscription request each morning, hence getting the right composition.
If you consider a longer time frame and accept that a client subscription can last for days, then the problem arises.
You can address the problem at application level, by having your application subscribe to a custom notification item, which will instruct the page to unsubscribe from the NASDAQ100 group, then resubscribe, when needed.
Otherwise, you could resort to COMMAND mode; a single item in COMMAND mode represents a dynamical list and would replace the whole group, allowing you to add and remove elements when the composition of the list changes (see the
PortolioDemo for a typical case).
