Upgrade to Reactor snapshot builds to take advantage of TcpClient's
reconnect support that was added post-M1. Now, the system relay session
will try every 5 seconds to establish a connection with the broker, both
when first connecting and in the event of subsequently becoming
disconnected.
A more sophisticated reconnection policy, including back off and
failover to different brokers, is possible with the Reactor API. We may
want to enhance the relay's reconnection policy in the future.
Typically, a broken connection is identified by the failure to forward
a message to the broker. As things stand, the message id then discarded.
Any further messages that are forwarded before the connection's been
re-established are queued for forwarding once the CONNECTED frame's been
received. We may want to consider also queueing the message that failed
to send, however we would then need to consider the possibility of the
message itself being what caused the broker to close the connection
and resending it would simply cause the connection to be closed again.
Components that are using a StompBrokerRelayMessageHandler may want
to know whether or not the broker's unavailable. If they're sending
messages to the relay via an asynchronous channel there's currently
no way for them to find this out.
This commit enhances StompBrokerRelayMessageHandler to publish
application events when the broker's availability changes:
BrokerBecameAvailableEvent and BrokerBecameUnavailableEvent.
Irrespective of the number of relay sessions only a single event is
published for each change in the broker's availability.
A SockJS message frame is an array of JSON-encoded messages and before
this change the use of the Jackson 2 library was hard-coded.
A Jackson 2 and Jackson 1.x implementations are provided and
automatically used if those libraries are present on the classpath.
Issue: SPR-10800
Update META-INF/MANIFEST.MF for spring-instrument to include
necessary attributes for running under Java 7:
Can-Redefine-Classes : true
Can-Retransform-Classes: true
Can-Set-Native-Method-Prefix : false
(see http://docs.oracle.com/javase/7/docs/api/java/lang/instrument/
package-summary.html)
Prior to this commit `InstrumentationSavingAgent.getInstrumentation().
addTransformer(t, true);` would fail under Java 7.
Issue: SPR-10731
A new type MessageHeaderAccesssor provides read/write access to
MessageHeaders along with typed getter/setter methods along the lines
of the existing MessageBuilder methods (internally MessageBuilder
merely delegates to MessageHeaderAccessor). This class is extensible
with sub-classes expected to provide typed getter/setter methods for
specific categories of message headers.
NativeMessageHeaderAccessor is one specific sub-class that further
provides read/write access to headers from some external message
source (e.g. STOMP headers). Native headers are stored in a separate
MultiValueMap and kept under a specific key.
Since JDK 8 is required to build Spring framework 4, and permanent
generation is gone from Java 8, to eliminate warnings about no longer
available MaxPermSize switch, it should be removed or replaced with new
MaxMetaspaceSize switch.
This fix replaces old with new switch to limit the amount of native
memory used for class metadata.
Issue: SPR-10571
JOpt 4.4 has enumerable options, so this change can be made
if we upgrade. The only awkward thing is that JOpt allows
aliases for options, so we have to pick one to avoid double
counting. This implementation picks the last one in the list
which is the alphebtically last of the long options, if there
are any (e.g. "o1", "option1" returns "option1"). Most of the
time there will only be one or two aliases for each option so
it won't matter.
Issue: SPR-10579
