My analysis doesn't seem correct:

pushGroupManager.recordListen(participatingPushIDs, request.getHeaderAsInteger("ice.push.sequence"));

is trying to pick up the ice.push.sequence which hasn't been defined yet.

I was seeing this with portlet testing with push as well (both EE and non-EE apps).

Caused by: java.lang.NumberFormatException: null
at java.lang.Integer.parseInt(Integer.java:417)
at java.lang.Integer.parseInt(Integer.java:499)
at org.icepush.servlet.ServletRequestResponse.getHeaderAsInteger(ServletRequestResponse.java:126)
at org.icepush.http.standard.RequestProxy.getHeaderAsInteger(RequestProxy.java:65)
at org.icepush.BlockingConnectionServer$RunningServer.service(BlockingConnectionServer.java:300)
at org.icepush.BlockingConnectionServer.service(BlockingConnectionServer.java:98)
at org.icepush.SequenceTaggingServer.service(SequenceTaggingServer.java:36)
at org.icepush.ConfigurationServer.service(ConfigurationServer.java:92)
at org.icepush.servlet.ThreadBlockingAdaptingServlet.service(ThreadBlockingAdaptingServlet.java:45)
at org.icepush.servlet.EnvironmentAdaptingServlet.service(EnvironmentAdaptingServlet.java:48)
at org.icepush.servlet.PathDispatcher.service(PathDispatcher.java:39)
at org.icepush.servlet.BrowserDispatcher$BrowserEntry.service(BrowserDispatcher.java:117)
at org.icepush.servlet.BrowserDispatcher.service(BrowserDispatcher.java:45)
at org.icepush.servlet.PathDispatcher.service(PathDispatcher.java:39)
at org.icepush.servlet.MainServlet.service(MainServlet.java:116)
at org.icefaces.impl.push.servlet.ICEpushResourceHandler$ICEpushResourceHandlerImpl.handleResourceRequest(ICEpushResourceHandler.java:219)

I added some logging to the last method:

ServletRequestResponse.getHeaderAsInteger: asking for ice.push.sequence got null from org.icefaces.impl.push.servlet.ProxyHttpServletRequest@fa1567b

Seems we just need to guard against/log a warning/etc when "ice.push.sequence" isn't available.

I did notice that in SequenceTaggingServer we do guard against it:

try {
    previousSequenceNo = request.getHeaderAsInteger("ice.push.sequence");
} catch (RuntimeException e) {
    previousSequenceNo = 0;
}

Sending core/src/main/java/org/icepush/BlockingConnectionServer.java
Transmitting file data .
Committed revision 33110.

Added the similar check to BlockingConnectionServer. It looks like it's okay to set the sequenceNumber to 0 upon RuntimeException, which includes NumberFormatException). Marking this one as FIXED.