I would like to implement an observer design pattern. My thoughts are, if this is deployed, and another system update has occurred and restarted the server, would the observers/subscribers be lost when the server has restarted?
Sorry for this newbie question.
Your question doesn't specify any tools you are using neither the deployment methods and softwares so the best I can say is that any non-persistent data will be deleted on restart. This counts for the subscribers your server has saved in a variable, for example.
In web development, you go around this problem (and that of lost of connection) by having "temporary subscriptions" and by not implementing functionalities with solutions needing consistency in connection.
However, what you could do is give the clients some sort of unique id which could be stored in a database along with data that can restore the connection.
how observer design pattern on production behave?