camel-users mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Claus Ibsen <claus.ib...@gmail.com>
Subject Re: Camel Exchange Patters
Date Fri, 24 Sep 2010 12:46:50 GMT
On Fri, Sep 24, 2010 at 2:44 PM,  <patrice.godard@orange-ftgroup.com> wrote:
> Hello,
> I'm not sure I understand why I shouldn't be using getOut().
> Here is what I do at the end of my processor (that is transforming the message Body):
>
> // propagate headers
> ex.getOut().setHeaders(ex.getIn().getHeaders());
>
> Am I wrong?

No not really because you take matter in your own hand and propagate
the headers.
But the Camel routing engine will automatic handle using IN if there
is no OUT message.

Working on IN is just much easier to explain and use for end users.
And there is less message creation, copying headers, and whatnot if
you dont use OUT messages.


>
> I saw a couple of Processor samples that were only dealing with getIn() but I don't quite
understand how and when the "in" message becomes an "out" message and I noticed that if I
was propagating my headers by copying them from the "in" message to the "out" one I was no
longer losing them.
>
> I'm looking forward to the latest MEAP version of Camel In Action since it seems I got
it wrong somewhere.
>
>> -----Message d'origine-----
>> De : bengt.rodehav@gmail.com [mailto:bengt.rodehav@gmail.com] De la
>> part de Bengt Rodehav
>> Envoyé : vendredi 24 septembre 2010 12:47
>> À : users@camel.apache.org
>> Objet : Re: Camel Exchange Patters
>>
>> Perfect!
>>
>> /Bengt
>>
>> 2010/9/24 Claus Ibsen <claus.ibsen@gmail.com>
>>
>> > On Fri, Sep 24, 2010 at 10:27 AM, Claus Ibsen <claus.ibsen@gmail.com>
>> > wrote:
>> > > On Tue, Sep 14, 2010 at 2:29 PM, Bengt Rodehav <bengt@rodehav.com>
>> > wrote:
>> > >> Yeah I remember reading about the problems with losing message
>> headers
>> > >> somewhere on this list...
>> > >>
>> > >> To be perfectly honest I think that the number of mails on this
>> thread
>> > >> indicates the importance of documenting these rules and how things
>> work.
>> > >> Claus, you are most definitely the man to do it. I've got your
>> book
>> > (haven't
>> > >> read the last updates though) and it certainly warrants a place
>> there.
>> > >> Perhaps it should also be on the wiki somewhere.
>> > >>
>> > >
>> > > We have added information about this in Camel in action,
>> > > chapter 3 when we drill down and work the Processor which exposes
>> the
>> > > Exchange API.
>> > >
>> >
>> > I also added a couple of FAQs as well, such as
>> >
>> >
>> https://cwiki.apache.org/confluence/display/CAMEL/Using+getIn+or+getOut
>> +methods+on+Exchange
>> >
>> > >
>> > >> /Bengt
>> > >>
>> > >> 2010/9/14 Claus Ibsen <claus.ibsen@gmail.com>
>> > >>
>> > >>> On Tue, Sep 14, 2010 at 2:16 PM, Bengt Rodehav <bengt@rodehav.com>
>> > wrote:
>> > >>> > I think that was very useful information. I hadn't thought
of a
>> > Processor
>> > >>> as
>> > >>> > very low level - it's definitely a level that a lot of us
will
>> use.
>> > Then
>> > >>> I
>> > >>> > guess that in some circumstances (like when coding a custom
>> > processor)
>> > >>> you
>> > >>> > need to set the out messsage if the MEP is "out capable"
>> otherwise
>> > you
>> > >>> just
>> > >>> > set the in message. Are there more situations where this is
>> needed?
>> > >>> >
>> > >>>
>> > >>> If the MEP is out capable you can still just change the IN
>> message.
>> > >>> If the OUT is null, then Camel will re-use the IN (which you just
>> > >>> changed) and thus still route whatever you have changed.
>> > >>>
>> > >>> You only need to use OUT if you want to create a totally 100% new
>> > >>> message which is not related to the IN message at all.
>> > >>> And this is only needed in special cases.
>> > >>>
>> > >>> Otherwise you get the problem with: Why do I lose my message
>> headers
>> > etc.
>> > >>>
>> > >>>
>> > >>>
>> > >>> > I think that this subject is definitely complicated enough
to
>> warrant
>> > a
>> > >>> good
>> > >>> > documentation somewhere. I think it's really important for
>> developers
>> > to
>> > >>> > understand core concepts instead of just using boilerplate
>> samples
>> > >>> (although
>> > >>> > they are very useful).
>> > >>> >
>> > >>> > /Bengt
>> > >>> >
>> > >>> > 2010/9/14 Claus Ibsen <claus.ibsen@gmail.com>
>> > >>> >
>> > >>> >> On Tue, Sep 14, 2010 at 10:23 AM, Christian Müller
>> > >>> >> <christian.mueller@gmail.com> wrote:
>> > >>> >> > Hello Claus!
>> > >>> >> >
>> > >>> >> > That's not (in my opinion) how it works currently.
At
>> present I
>> > work
>> > >>> on a
>> > >>> >> > route which looks like this:
>> > >>> >> >
>> > >>> >> > errorHandler(
>> > >>> >> >  defaultErrorHandler()
>> > >>> >> >    .retryAttemptedLogLevel(LoggingLevel.DEBUG)
>> > >>> >> >    .retriesExhaustedLogLevel(LoggingLevel.INFO));
>> > >>> >> >
>> > >>> >> > onException(IllegalArgumentException.class)
>> > >>> >> >  .handled(true)
>> > >>> >> >  .maximumRedeliveries(0)
>> > >>> >> >  .beanRef("myResultProvider", "failureResponse");
>> > >>> >> >
>> > >>> >> > from("cxf:bean:MyCoolService")
>> > >>> >> >  .processRef("myValidator") // validates conditional
rules
>> > >>> >> >  .inOut("direct:mySubroute")
>> > >>> >> >  .beanRef("myResultProvider", "successResponse")
>> > >>> >> >
>> > >>> >> >
>> > >>> >> > If my validator throws a IllegalArgumentException
and the
>> result
>> > >>> provider
>> > >>> >> > writes the response into the in message, the web
service
>> will
>> > return
>> > >>> >> null.
>> > >>> >> > But if I write the response into the out message,
the web
>> service
>> > will
>> > >>> >> > return it. So, I changes my bean to the following
"pattern":
>> > >>> >> >
>> > >>> >>
>> > >>> >> Well that could CXF Bean component having a bug.
>> > >>> >>
>> > >>> >> If you decide to use a Processor and work on Exchange
then you
>> use
>> > the
>> > >>> >> low level Camel API and then you have to handle the IN/OUT
>> stuff
>> > >>> >> yourself.
>> > >>> >>
>> > >>> >>
>> > >>> >>
>> > >>> >>
>> > >>> >> > if (exchange.getPattern().isOutCapable()) {
>> > >>> >> >  exchange.getOut().setBody(response);
>> > >>> >> > } else {
>> > >>> >> >  exchange.getIn().setBody(response);
>> > >>> >> > }
>> > >>> >> >
>> > >>> >> > And that's the same how the
>> > >>> >> org.apache.camel.processor.ConvertBodyProcessor
>> > >>> >> > works (I know you know this, but for the other guys..
:o) )
>> > >>> >> >
>> > >>> >> > public class ConvertBodyProcessor implements Processor
{
>> > >>> >> > ...
>> > >>> >> >    public void process(Exchange exchange) throws
Exception {
>> > >>> >> >        Message in = exchange.getIn();
>> > >>> >> >        if (charset != null) {
>> > >>> >> >            exchange.setProperty(Exchange.CHARSET_NAME,
>> charset);
>> > >>> >> >        }
>> > >>> >> >        Object value = in.getMandatoryBody(type);
>> > >>> >> >
>> > >>> >> >        if (exchange.getPattern().isOutCapable())
{
>> > >>> >> >            Message out = exchange.getOut();
>> > >>> >> >            out.copyFrom(in);
>> > >>> >> >            out.setBody(value);
>> > >>> >> >        } else {
>> > >>> >> >            in.setBody(value);
>> > >>> >> >        }
>> > >>> >> >    }
>> > >>> >> > ...
>> > >>> >> > }
>> > >>> >> >
>> > >>> >> > Should our custom processors/beans/.. not work in
the same
>> way?
>> > >>> >> >
>> > >>> >> > Cheers,
>> > >>> >> > Christian
>> > >>> >> >
>> > >>> >>
>> > >>> >>
>> > >>> >>
>> > >>> >> --
>> > >>> >> Claus Ibsen
>> > >>> >> Apache Camel Committer
>> > >>> >>
>> > >>> >> Author of Camel in Action: http://www.manning.com/ibsen/
>> > >>> >> Open Source Integration: http://fusesource.com
>> > >>> >> Blog: http://davsclaus.blogspot.com/
>> > >>> >> Twitter: http://twitter.com/davsclaus
>> > >>> >>
>> > >>> >
>> > >>>
>> > >>>
>> > >>>
>> > >>> --
>> > >>> Claus Ibsen
>> > >>> Apache Camel Committer
>> > >>>
>> > >>> Author of Camel in Action: http://www.manning.com/ibsen/
>> > >>> Open Source Integration: http://fusesource.com
>> > >>> Blog: http://davsclaus.blogspot.com/
>> > >>> Twitter: http://twitter.com/davsclaus
>> > >>>
>> > >>
>> > >
>> > >
>> > >
>> > > --
>> > > Claus Ibsen
>> > > Apache Camel Committer
>> > >
>> > > Author of Camel in Action: http://www.manning.com/ibsen/
>> > > Open Source Integration: http://fusesource.com
>> > > Blog: http://davsclaus.blogspot.com/
>> > > Twitter: http://twitter.com/davsclaus
>> > >
>> >
>> >
>> >
>> > --
>> > Claus Ibsen
>> > Apache Camel Committer
>> >
>> > Author of Camel in Action: http://www.manning.com/ibsen/
>> > Open Source Integration: http://fusesource.com
>> > Blog: http://davsclaus.blogspot.com/
>> > Twitter: http://twitter.com/davsclaus
>> >
>
> *********************************
> This message and any attachments (the "message") are confidential and intended solely
for the addressees.
> Any unauthorised use or dissemination is prohibited.
> Messages are susceptible to alteration.
> France Telecom Group shall not be liable for the message if altered, changed or falsified.
> If you are not the intended addressee of this message, please cancel it immediately and
inform the sender.
> ********************************
>
>



-- 
Claus Ibsen
Apache Camel Committer

Author of Camel in Action: http://www.manning.com/ibsen/
Open Source Integration: http://fusesource.com
Blog: http://davsclaus.blogspot.com/
Twitter: http://twitter.com/davsclaus

Mime
View raw message