Continuous XML stream protocol decoder implementation

[Johan Haleby]

Hi,

I'm using Apache Mina to parse continuous XML streams. I.e. a client 
connects to Mina and holds a connection for its entire life-cycle. 
During this time the client may send and receive a lot of (small) XML 
messages. I wonder how I should implement this is in a good way? Right 
now my protocol decoder is a singleton that make use of cached thread 
pool because each client creates a new custom made inputstream 
implementation that is read in a separate thread by XStream. When new 
data arrives to the decode method it just pushes this data to the 
inputstream. The inputstream itself uses a blocking queue, so the read 
method waits until it has data or that an "end of stream marker" has 
been found, e.g. until </request> has been found. I'm letting XStream 
(configured with XPP3) take care of marshalling the data in the XML 
inputstream in this other thread. So whenever XStream has found the "end 
of stream marker" and created a new object from the data in the 
inputstream it calls the ProtocolDecoderOutput.write(..) with that 
object. The inputstream implementation is then "reset" so that it 
accepts additional data. I have my worries that this may not be optimal, 
especially since I "create a new thread" (well I'm using the cached 
thread pool) for XStream for each connection in the ProtocolDecoder. So 
how could I improve on this? (Comments on the XML parsing technique are 
also welcome).

Thanks
Johan