在gwt的sessionstorage中存储对象

Question

Related questions have been asked multiple times, but I feel that my case is a bit different.

Background-

I am making my application in GWT and I wish to make a module whose object I wish to store in session. This module will be responsible to keep the persistent data in it updated by making asynchronous calls to server. I would have a timer which would fire an event to make server calls every specified time. Now, I would get this persistent data from the data structure inside this object from anywhere in my code by getting a reference to this object from session. So this java script module would basically be an interface between the server and native client java script, which would be responsible for maintaining the data structure.

Now, I have two problems (as of yet)

• sessionStorage stores all the data in key, value pairs where both of them have to be string literals. Is there anyway I can store my module object in sessionStorage in a way what it preserves my data?

• Even if I find a way to store my module object in sessionStorage , I don't think it can make async calls to server to keep the persistent data up-to-date. Is there any alternative to this design?

Thanks for your inputs.

Answer 1

You can store any Java object in session as long as it implements Serializable.

The second question is not clear. What stops you from making async calls to server?

Answer 2

If sessionStorage stores key value pairs in string literals then use JSON or XML to communicate between client and server. Finally create the object back from JSON or XML.

How to make make a async calls to server from the GWT client side?

• Use AsyncCallback to make a async call to server from GWT client side code.

• Use GWT JSNI to make a call from JavaScript to Java then use first option.