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From "Andrew Lusk (JIRA)" <j...@apache.org>
Subject [jira] Created: (AMQ-681) Tight encoding not the default; wire format negotiation needs work
Date Fri, 07 Apr 2006 00:34:51 GMT
Tight encoding not the default; wire format negotiation needs work
------------------------------------------------------------------

         Key: AMQ-681
         URL: https://issues.apache.org/activemq/browse/AMQ-681
     Project: ActiveMQ
        Type: Bug

  Components: Broker  
    Reporter: Andrew Lusk


In OpenWireFormat.java, tightEncoding defaults to false, when, since it's the historical format,
it should be true.

Wire format negotiation isn't really negotiation.  Since the broker defaults to loose encoding,
it sends a loosely-encoded WireFormatInfo message to connecting clients, and expects loosely-encoded
WireFormatInfo messages from them.  This not only enforces that clients implement loose marshalling
and unmarshalling, but fails when the client sends a well-formatted but tightly-encoded WireFormatInfo
message.

The broker fails in this case because it assumes that the client and broker both have the
same concept of what encoding is the default, when in actuality the encoding of a message
should be part of the actual message, allowing the broker to handle clients who prefer either
format (and may not have the other format even implemented).

The broker should also only ever send messages in the format asked for by the client - it
should wait to send a WireFormatInfo until it has received one from the client indicating
its preferred format.

I suggest two changes:

  * adding a leading byte to all messages indicating their encoding
  * the broker should wait to send a WireFormatInfo until it has received one from the connecting
client, whose preferences override all broker defaults for that connection

The requirement that the server and client have shared, non-obvious information from the beginning
(like which encoding is default) causes ugly problem in the broker like this, when it gets
a message of a type it didn't expect:

Exception in thread "tcp:///127.0.0.1:54316" java.lang.IllegalArgumentException: Invalid version:
1297154048, could not load org.apache.activemq.openwire.v1297154048.MarshallerFactory


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