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From Brad Johnson <>
Subject Re: Can't understand what inOnly is doing
Date Sat, 24 Sep 2016 15:58:20 GMT
InOnly is a fire-and-forget, asynchronous style of messaging.  InOut is a
synchronous or pseudo-synchronous* request-reply messaging as Matt points

Part of the confusion is about the pattern set on the exchange to indicate
whether the data flow is InOut or InOnly.  The other In/Out on the Exchange
is about the data coming in and going out and is pretty much invariant in
its existence and data structure.  Unfortunately even that's a bit
misleading terminology as the data is always on the in except when an In
data on the Exchange follows the route all the way "In" to the last
endpoint and then if it is an InOut route the Out is what is returned. If
it is an InOnly then if there's a message at the end it is thrown away.

InOut/InOnly are message flow patterns to set on the exchange. In/Out are
the data elements associated with the exchange at any given moment in the

*When I say pseudo-synchronous it is because Jetty continuations do not
hold the calling thread but make callbacks.  JMS InOut/request-reply
actually set up two queues under the covers, one to send the request and
one to send the reply. I'd have to check again on whether the calling
thread waits or if a callback mechanism is deployed.  Obviously the latter
is preferable in terms of threading and performance.


On Sat, Sep 24, 2016 at 2:33 AM, Matt Sicker <> wrote:

> I thought InOnly and InOut had to do with whether or not you were using a
> one-way message or a request-reply message, but I could be wrong here.
> On 24 September 2016 at 01:30, cacert <> wrote:
> > Perfect question which also confuses me a lot. I wish there could be a
> > upvote
> > button and I hope someone will clarify it soon.
> >
> >
> >
> > --
> > View this message in context: http://camel.465427.n5.nabble.
> > com/Can-t-understand-what-inOnly-is-doing-tp5787961p5787986.html
> > Sent from the Camel - Users mailing list archive at
> >
> --
> Matt Sicker <>

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