One feature I really miss in ICN right now is a 2 ways communication channel between service and client. At this moment, you call your service and then it returns something when the execute method is done. That creates an issue, because users have no patience… More than one minute on the same loading spinner and you can be sure most of them will refresh the page thinking ICN crashed. That won’t stop your service, but if this one is not done by the time the user comes back, he will run the service again…
So here is a way to push information from the server to the client.
Principle
I used CometD to implement that because ICN is already shipped with some CometD client libraries (actually not all of them, discussed below)). The reason for that is ICN uses CometD for the Sync and Share feature. That way we don’t need to add any library to the client. About the server, the PluginService class is not a servlet or a web service, it is actually called by a Struts action so forget about asynchronous servlet, websocket and so on since we are not master of our servlet. On the other hand, we can’t change the navigator application either (well we could and redeploy but we want to be update proof), so we can’t add support for any “push” framework and ICN doesn’t have that natively. That’s why I’ve decided to use another light web application to achieve that. Here is the schema to help you understand how it works.
