eirikb / gwt-channel-api Goto Github PK

Your Server code uses "send" but your client code used "onMessage"

This also means there is a compiler error initially because it says you have not implemented "onMessage" in the server code

ChannelServer.java:
protected static void send(String channel, Object o) { AutoBean bean = AutoBeanUtils.getAutoBean(o); String serialized = AutoBeanCodex.encode(bean).getPayload(); ChannelServiceFactory.getChannelService().sendMessage(new ChannelMessage(channel, serialized)); }
Client:
public void send(String message, AsyncCallback<Void> callback) {
channelService.onMessage(token, channelName, message, callback);
}

I created one myself:

package no.eirikb.gwtchannelapi.client;

import com.google.gwt.user.client.rpc.AsyncCallback;

public interface ChannelListenerAsync { void onMessage(String message,AsyncCallback<Void> asyncCallback);
void onOpen(AsyncCallback<Void> asyncCallback);
void onError(int code, String description, AsyncCallback<Void> asyncCallback);
void onClose(AsyncCallback<Void> asyncCallback);
}

I am trying to control the disconnection of a client from a channel, trying to distinguish when a user close the browser of when the token was expired (to renew or create a new token in this last case).

Following the Channel API of Google (https://developers.google.com/appengine/docs/java/channel/overview#Tokens_and_Security), when a token expires 'the socket’s onerror() and onclose() callbacks are called' but I only can find the onReceive method within the ChannelListener, how can I access to this events?

Or how could I control the session of a user (expiration time) in other way?

Thanks so much.

Hi there, thanks for the great library.
In the Channel.join() method I noticed that the onError() callback for the RPC is empty, i.e. it will hide errors on failed calls to the server:

    public void join() {
        channelService.join(channelName, new AsyncCallback<String>() {
            @Override
            public void onFailure(Throwable throwable) {
                // Exceptions disappear here
            }

            @Override
            public void onSuccess(String t) {
                token = t;
                join(token);
            }
        });
    }

This is probably a rare event, but potentially tricky to debug when it happens.
I can think of a few potential solutions. Here's the first two:

1. Add onJoinError() to ChannelListener:

public interface ChannelListener extends RemoteService {

    void onJoinError(Throwable caught);

    void onMessage(String message);

    void onOpen();

    void onError(int code, String description);

    void onClose();
}

2. Add something like FailedJoinCallback and join(FailedJoinCallback callback) to Channel:

public interface FailedJoinCallback {
    void onFailedJoin(Throwable caught);
}

    public void join(FailedJoinCallback callback) {
        channelService.join(channelName, new AsyncCallback<String>() {
            @Override
            public void onFailure(Throwable caught) {
                callback.onFailedJoin(caught);
            }

            @Override
            public void onSuccess(String t) {
                token = t;
                join(token);
            }
        });

I am trying to get up and running with gwt-channel-api in an existing project. I have set up the required JARs and classpaths in Eclipse, and when I launch GWT Dev mode everything compiles properly.

However, when I load the app web page in the browser, I see an error for a missing resource:
/_ah/channel/jsapi

This is included in the index.jsp, as instructed here.

What is this? A JavaScript file? If so, should it be:
/_ah/channel/jsapi.js?

Where does this come from?
Is it generated by GWT compile?

Thanks,
Don

Hi there.
I ran into a minor hurdle with this. It would be helpful to be able to configure the channel duration when creating the channel. For example, with the burstiness of my current project, I would be setting the duration to just 30 minutes or less, whereas the default is 2 hours.

For reference, the Channel API has rate-limiting for the number of channel-hours requested per minute...

• Free Tier: 12 hours requested/minute (i.e. max of 6 people open channels within a minute).
• Paid Tier: 180 hours requested/minute (i.e. max of 90 people open channels within a minute).

One possible approach (which is also backwards-compatible) might look like this:

public abstract class ChannelServer extends RemoteServiceServlet implements ChannelService {

    // ADDED THIS
    /**
     * Defaults to 2 hours. Override if needed.
     */
    protected int getChannelDuration() {
        return 2*60;
    }

    protected static void send(String channel, Object o) {
        AutoBean bean = AutoBeanUtils.getAutoBean(o);
        String serialized = AutoBeanCodex.encode(bean).getPayload();

        ChannelServiceFactory.getChannelService().sendMessage(new ChannelMessage(channel, serialized));
    }

    @Override
    public final String join(String channelName) {
        // MODIFIED THIS
        String token = ChannelServiceFactory.getChannelService().createChannel(channelName, getChannelDuration());

        onJoin(token, channelName);
        return token;
    }

    protected abstract void onJoin(String token, String channelName);
}

That's my 2 cents.
Cheers :)