[ https://issues.apache.org/activemq/browse/AMQ-681?page=all ]
Hiram Chirino resolved AMQ-681:
-------------------------------
Resolution: Won't Fix
There is no historical tight encoding since 4.0 is the first release where
openwire gets used. The wire negocation rule is, always start with loose
encoding and version 1 of the protocol with all extra options off.
Loose encoding is much simpler to implement than the tight encoding. That is
way it was choosen to be the default. With all the options off + loose
encoding, it makes it much simpler to implement a simple openwire client. The
initial WireFormatInfo then allows the client to switch on any number of
options incuding the tightEncoding.
> 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
> Assignee: Hiram Chirino
>
>
> 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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