Question

We’re using GWT Atmosphere to send strings from the server to the client and it works quite well.

However, we would like to send whole entities from the server to the client, serialized by the GWT RequestFactory. Without the need for a request by the client!

So I tried working with SimpleRequestProcessor#createOobMessage(domainObject) and sending that payload to the client. Computing the payload works.

I would then decode that message using AutoBeanCodex#decode and read the domainObject as the correct EntityProxy from the invocation list of the ResponseMessage – however when I do so, it requires some sort of serverId being set to proceed in AbstractRequestFactory#getId (around line 260: assert serverId != null : "serverId")

Any advice on how I can decode a Proxy payload without a request being sent by the client?

Update

The use case for this question is chat-like communication. The client doesn’t request the messages from the server but instead will be notified of new messages. And we’d like to include the messages and info on who’s sent the message in the notification payload. Since we’re using RequestFactory in our project anyway, we want to take advantage of having set up all the Proxy wiring and now simply push the relevant object graph to the client.

Answer 1

Why are you trying to serialize RF messages and send them just as entities? RequestFactory is much more than justa way to send data over the wire – it has at least three different kinds of messages that can be sent from the client to the server: create instances, call setters, and invoke service methods. Based on what happens on the server, not only can data be returned to the client, but messages about what changes were made and if those setters made changes that are not valid under the JSR303 rules.

Are you trying for a simpler, interface way of describing, sending, and receiving entities? Or do you actually want the RF wiring on both client and server so you can batch requests, refer to EntityProxyId instances and have the client only send diffs?

If you just want simpler object declarations, try just using AutoBeans and the AutoBeadCodex you have already looked at – you’ll be able to create and marshal instances on both client and server easily, and you can pass them as strings over atmosphere’s transports.

If you actually want RequestFactory, but running over something other than AJAX, there are other options. Rather than sending/receiving strings through Atmosphere (which I believe is intended to provide push support for RPC calls), consider using that underlying push layer to implment a new request transport in RequestFactory.

com.google.web.bindery.requestfactory.shared.RequestTransport can be implemented (see com.google.web.bindery.requestfactory.gwt.client.DefaultRequestTransport for the default AJAX version) to use any communication mechanism you would like – and to build the server, take a look at com.google.web.bindery.requestfactory.server.RequestFactoryServlet for what actually must be done to push messages through the Locator, ServiceLocators, etc.

If you really want to use Atmosphere and RF, then consider building a RequestTransport that wraps a simple Atmosphere interface to call to the server with the string – the cometd/websocket calls will already be taken care of for you, and you’ll just have to translate the string message into invocations (again, see how RequestFactoryServlet does it).