I am new to web programming with Java. I have a Client/Server written (in Java) and I want updates from the Client to be sent from the Server to a web interface for a user to view. The timing of the updates will be random, but I want to be able to dynamically update a web page with new data without the browser having to refresh.
Hope this makes sense:
I’ve tried creating a Servlet that Observes (implements Observer) my Server (which extends Observable) for updates (Strings), however I don’t know how to dynamically add these to a browser window. I have tried printing directly from the Servlet using PrintWriter out = response.getWriter(); in the doGet() method, but response.getWriter() is unavailable in the Servlet’s update() method.
My initial thoughts were to use a JSP page (I need to eventually incorporate HTML/CSS) that receives the Observer updates from the Server but I’m not sure.
I’ve done some research into Comet/PUSH, but I’m not sure if this is what I need – perhaps a bit overkill? Any advice on how to achieve what I’m after would be greatly appreciated.
The most common way to do this is for the client to poll the server for changes. Use an AJAX request on the client side to poll an endpoint on your server.
You will then need to use JQuery / Javascript to update your web page with the new data retrieved from the AJAX request.
I would suggest using JQuery in theb rowser and using the AJAX function: http://api.jquery.com/jQuery.ajax/
It allows you to do a callback after the request and in that call back you can update the content of your web page with the data retrieved from the request.