If you mean Adobe Flash platform shared objects function, this is client-side function, so you can use it in your client applications. We still support Flash clients, however Adobe Flash is close to death, so we do not recommend to use it.
It's yes and no. The link provided lists only SharedObject.getLocal (cookies), while SharedObject.getRemote allows for temporary (RAM) storage mechanism on the server. Wowza has this feature as well and it allows for convenient data sharing between apps. Is there a way to implement this in WCS?
You can implement a function similar to SharedObject.getRemote using websocket connection to WCS to send data from client to WCS and backend server to send data from to clients. You can find some examples in this topic. However, it requires much work both on client and backend side.