I'm using Channel API (Java) with Google App Engine for my web application. I have implemented a Token-reusing-mechanism for not exceeding the Channel API Quotas that fast.
This means, that my implementation reuses an existing channel for a user that refreshes the page as long as the expiration time of the token received by the ChannelService.createChannel()
call, is not over.
When refreshing my page I get the following exception (with x
starting at 0 and increasing for every refresh). However, my page continues to work as intended. Is there a way to avoid the exception being thrown? Or can I just ignore the exception?
com.google.appengine.api.channel.dev.LocalChannelFailureException: Client connection with ID connection-x not found.
at com.google.appengine.api.channel.dev.Channel.getClientMessageQueue(Channel.java:79)
at com.google.appengine.api.channel.dev.ChannelManager.getNextClientMessage(ChannelManager.java:300)
at com.google.appengine.api.channel.dev.LocalChannelServlet.doGet(LocalChannelServlet.java:120)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:511)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1166)
...
Im reusing tokens with the following classes:
When calling ChannelService.createChannel()
I save the expiration date and the generated token in an Entity called "Channel"
public class Channel {
private String id;
private String token;
private Date expiration;
}
Then I have a ChannelService class that returns a valid Channel with its get()
method. The channelDAO is a class that just uses a Map for storing Channels. So there is no database persistence, which would keep a token alive over a server restart.
public Channel get(String clientId) {
Calendar calendar = Calendar.getInstance();
Channel channel = channelDAO.get(clientId);
if (channel == null || calendar.getTime().after(channel.getExpiration())) {
com.google.appengine.api.channel.ChannelService channelService = ChannelServiceFactory
.getChannelService();
calendar.add(Calendar.MINUTE, CHANNEL_UPTIME);
String token = channelService.createChannel(player.toString(), CHANNEL_UPTIME);
channel = new Channel(clientId, token, calendar.getTime());
channelDAO.persist(channel);
}
return channel;
}