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From David Hoffer <dhoff...@gmail.com>
Subject Re: How to retain exchange headers through RoutingSlip
Date Mon, 11 Jul 2016 20:05:16 GMT
I'm back now trying to find a solution to this problem.

First I changed the RoutingSlip to be a RecipientList, not sure that is
significant but wanted to mention it.

Let me try to better explain what this application does.  We use Camel to
route/transfer files from one location to a dynamic list of other
locations.  It's dynamic in the sense that we have a GUI app that enables
destinations.  E.g. any input source can be routed to any number of
destination locations.  We use the RecipientList to specify the
dynamic/multiple destinations.

So for every source folder we use a custom CamelContextAware bean to be the
RecipientList (actually it contains the RecipientList instance).  This bean
(routeManager in example below) has a route(Exchange exchange) method that
is called in each of the source routes.  We define all routes in XML, e.g.

<route id="from_externalDropbox"
autoStartup="{{gp.camel.externalDropbox.isConfigured}}">
    <from
uri="file://{{gangplank.data}}/../fromExternalDropbox/?delete=true&amp;exclusiveReadLockStrategy=#fileLock&amp;delay=500"/>

    <convertBodyTo type="byte[]"/>

    <bean ref="routeManager" method="route(*)"/>
</route>

So in the CamelContextAware bean's route method we set the exchange's
getFromRouteId() value as a  property and/or header on the exchange and/or
input message.  E.g.

exchange.getIn().setHeader(GP_DYNAMIC_FROM_ID, fromId);
exchange.setProperty(GP_DYNAMIC_FROM_ID, fromId);


Then in one of the destination routes we use a custom Processor to handle
the file being routed.  It's in this custom processor that I need to
extract the FromRouteId that was stored in the exchange property and/or
input message header.  However this value is always null here, and that is
the problem.  E.g.

String fromIdHeader = (String)
exchange.getIn().getHeader(GP_DYNAMIC_FROM_ID);
String fromIdProperty = (String) exchange.getProperty(GP_DYNAMIC_FROM_ID);

I need to propagate this metadata about the file to the Processor but Camel
is removing the headers & properties and I don't know why.
 (Both fromIdHeader & fromIdProperty are null).

What is the right way to pass metadata between related routes?

Note I printed out the ExchangeId in both the source and destination and I
see the trailing 2 digits are different.

RouteManagerImpl ExchangeId=ID-ISS206486-54382-1468259188590-0-24
CopyFileProcessor ExchangeId=ID-ISS206486-54382-1468259188590-0-32

Also we don't use exchange.getOut() at all so I don't think that is why
headers/properties are getting lost.

-Dave






On Sun, Oct 4, 2015 at 11:36 PM, Claus Ibsen <claus.ibsen@gmail.com> wrote:

> Hi
>
> Sorry I think you confuse us. You talk about routing slip and show
> some code of a route that starts from a file, and without any routing
> slip.
>
> Also see this FAQ
>
> http://camel.apache.org/why-do-my-message-lose-its-headers-during-routing.html
>
> On Sun, Oct 4, 2015 at 4:20 PM, David Hoffer <dhoffer6@gmail.com> wrote:
> > I'm not trying to add any headers to the file when reading and
> > writing...I'm just adding them to the Camel Exchange so that when the
> file
> > is written in my Processor I have some 'metadata' about the file.  I need
> > the 'metadata' so I know where to write the file.  I get the bytes to
> write
> > from the exchange it seems only natural to get the 'metadata' from the
> same
> > exchange.  Why does Camel throw the headers away?  I'm pretty new to
> > Camel...not sure how to add a custom message transformation...any
> examples
> > of that?
> >
> > Btw, I have no need for the header information after I write the file in
> my
> > processor...only before.
> >
> > -Dave
> >
> > On Sun, Oct 4, 2015 at 12:15 AM, Claus Ibsen <claus.ibsen@gmail.com>
> wrote:
> >
> >> Hi
> >>
> >> Ah yeah read from a file and a file does not include any headers when
> >> you write to a file. The body is the content of the file. And all
> >> headers is not stored. You need to do some kind of custom message
> >> transformation if you want to include headers, and also when you read
> >> the file. eg where should the headers be stored in the file?
> >>
> >> On Sat, Oct 3, 2015 at 2:33 PM, David Hoffer <dhoffer6@gmail.com>
> wrote:
> >> > We add the headers where we create and/or call process on the routing
> >> > slip...
> >> >
> >> > exchange.getIn().setHeader("customHeader1", somedata1);
> >> > exchange.getIn().setHeader("customHeader2", somedata2);
> >> > exchange.getIn().setHeader(routingSlipHeaderName, toUris);
> >> > routingSlip.process(exchange);
> >> >
> >> > But then when when the message is handled by a processor bean we try
> to
> >> get
> >> > the header back via
> >> >
> >> > String data1 = (String) exchange.getIn().getHeader("customHeader1");
> >> >
> >> > This always returns null and it removed the 'routingSlipHeaderName'
> >> header
> >> > too that used used by the routing slip.  (Its okay that it removed
> this
> >> > one...but need the others.)
> >> >
> >> > Here is the XML config for the receiving route.  The
> CopyFileProcessor is
> >> > the one that does not get the custom headers.
> >> >
> >> > <bean id="backupProcessor"
> >> > class="com.issinc.jms.gangplank.impl.CopyFileProcessor">
> >> >     <property name="path" value="${gp.camel.backup.dir}"/>
> >> > </bean>
> >> >
> >> > <routeContext id="backup-endpoint"
> >> > xmlns="http://camel.apache.org/schema/spring">
> >> >     <route id="to_backup"
> autoStartup="{{gp.camel.backup.isConfigured}}">
> >> >         <from
> >>
> uri="file://{{gangplank.data}}/toBackup/?delete=true&amp;moveFailed=.error&amp;filter=#partialFilter&amp;delay=200"/>
> >> >         <process ref="backupProcessor" />
> >> >         <onException redeliveryPolicyRef="redeliveryProfile">
> >> >             <exception>java.lang.Exception</exception>
> >> >             <handled>
> >> >                 <constant>false</constant>
> >> >             </handled>
> >> >         </onException>
> >> >     </route>
> >> > </routeContext>
> >> >
> >> >
> >> >
> >> >
> >> > -Dave
> >> >
> >> > On Sat, Oct 3, 2015 at 2:27 AM, Claus Ibsen <claus.ibsen@gmail.com>
> >> wrote:
> >> >
> >> >> Where do you set those custom headers?
> >> >>
> >> >> On Fri, Oct 2, 2015 at 8:20 PM, David Hoffer <dhoffer6@gmail.com>
> >> wrote:
> >> >> > I'm using a RoutingSlip to route files but all custom headers
set
> on
> >> the
> >> >> > Exchange are discarded.  I assume that's because Camel assumes
> custom
> >> >> > headers are not useful for file messages but I need a way to pass
> >> source
> >> >> > information from the RoutingSlip to the file Processors.
> >> >> >
> >> >> > How can I do this?  Is there a way I can override the default
> >> behavior of
> >> >> > removing all custom headers?
> >> >> >
> >> >> > -Dave
> >> >>
> >> >>
> >> >>
> >> >> --
> >> >> Claus Ibsen
> >> >> -----------------
> >> >> http://davsclaus.com @davsclaus
> >> >> Camel in Action 2nd edition:
> >> >> https://www.manning.com/books/camel-in-action-second-edition
> >> >>
> >>
> >>
> >>
> >> --
> >> Claus Ibsen
> >> -----------------
> >> http://davsclaus.com @davsclaus
> >> Camel in Action 2nd edition:
> >> https://www.manning.com/books/camel-in-action-second-edition
> >>
>
>
>
> --
> Claus Ibsen
> -----------------
> http://davsclaus.com @davsclaus
> Camel in Action 2nd edition:
> https://www.manning.com/books/camel-in-action-second-edition
>

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