FastInfoset is already using namespaceAware APIs, the difficulty arises from the very strict behavior of Document.createAttributeNS():

NAMESPACE_ERR: Raised if the qualifiedName is a malformed qualified name, if the qualifiedName has a prefix and the namespaceURI is null, if the qualifiedName has a prefix that is "xml" and the namespaceURI is different from " http://www.w3.org/XML/1998/namespace", if the qualifiedName or its prefix is "xmlns" and the namespaceURI is different from "http://www.w3.org/2000/xmlns/", or if the namespaceURI is "http://www.w3.org/2000/xmlns/" and neither the qualifiedName nor its prefix is "xmlns".

It could be argued that not passing "http://www.w3.org/2000/xmlns/" for the namespaceURI for "xmlns" is a bug in the FastInfoset implementation, but this is not the only case where namespaces might be used without following the rules strictly. The solution is to disable error checking during FastInfoset compression (which will also improve performance). If strict DOM correctness is desired, this can be added as a later feature that specifically enables error checking.

Server:Tomcat6
Browser: FF3.6

Compat Component-showcase: scripts ran successfully but following error was seen on the server console:

SEVERE: Error Rendering View[/showcase.xhtml]
java.lang.NullPointerException
at org.icefaces.event.WindowAndViewIDSetup$1.encode(WindowAndViewIDSetup.java:52)
at org.icefaces.event.UIOutputWriter.encodeBegin(UIOutputWriter.java:32)

Compat AuctionMonitor: test scripts ran successfully but following error seen on the server console:

SEVERE: Error Rendering View[/auctionMonitor.xhtml]
java.lang.NullPointerException
at org.icefaces.event.WindowAndViewIDSetup$1.encode(WindowAndViewIDSetup.java:52)

java.lang.NullPointerException
at org.icefaces.event.WindowAndViewIDSetup$1.encode(WindowAndViewIDSetup.java:52)
at org.icefaces.event.UIOutputWriter.encodeBegin(UIOutputWriter.java:32)

Auction: still cannot load the application, Still seeing error on the browser:
java.lang.NoClassDefFoundError: com/sun/xml/fastinfoset/dom/DOMDocumentSerializer

auction appears to be missing FastInfoset.jar, so please ensure that the .jar is present in auction.war.

The NullPointerException will require further investigation.

Glimmer revison# 21717
Server: Tomcat6
Browser: FF3.6

Tested by manually placing FastInfoset.jar in lib folder.
Auction: all pass
Basic: all pass
ElementUpdate: all pass
Fajax: all pass
Scopes: Window Scope test failes. counter is reset when user revisited the page. Rest pass.

QA confirms that the Window Scope test issue is not related to the compressDOM setting. Fixed!