flow: Full resynchronization of client is not implemented

Occasionally, due to connectivity issues, client RPCs might get duplicated (?) or lost (?) (according to the ServerRpcHandler.handleRpc). The server must initiate client resync in this case, but it’s not there yet.

No matter what, the exception is thrown instead.

java.lang.UnsupportedOperationException: FIXME: Implement resync and call it above
at com.vaadin.server.communication.ServerRpcHandler.handleRpc(ServerRpcHandler.java:298)
at com.vaadin.server.communication.UidlRequestHandler.synchronizedHandleRequest(UidlRequestHandler.java:87)

About this issue

Original URL
State: closed
Created 7 years ago
Reactions: 3
Comments: 25 (18 by maintainers)

Commits related to this issue

Improve reporting related to syncid mismatches Related to #2210 — committed to vaadin/flow by Legioth 6 years ago
Improve reporting related to syncid mismatches * Show sync ids in the exception message instead of logging separately with various logging levels * Include the beginning of the actual message in the ... — committed to vaadin/flow by Legioth 6 years ago
Improve reporting related to syncid mismatches (#3726) * Show sync ids in the exception message instead of logging separately with various logging levels * Include the beginning of the actual messa... — committed to vaadin/flow by Legioth 6 years ago

Most upvoted comments

Thank you, @mpilone, for sharing.

m-emelchenkov on Aug 20, 2019

I implemented a very poor workaround that handles the resynchronization request and simply sends a full refresh command to the client. It is far from perfect and not the correct implementation, but I rather have the user’s page reload than have them see an internal error notification and call our help desk. You might be able to use it directly or at least get some ideas for your own workaround.

You can use it by implementing VaadinServiceInitListener and adding the handler in the serviceInit method like:

// This is a workaround for bug:
// https://github.com/vaadin/flow/issues/2210
serviceInitEvent.addRequestHandler(new RefreshingResynchronizeHandler());

RefreshingResynchronizeHandler.java.zip

mpilone on Aug 20, 2019