Default Type Conversions

[Tom Ellis <te...@gmail.com>]

Hi,

Is there some documentation around the strategy Camel takes when deciding
what to convert the body of an exchange to before sending to an endpoint?

For example, I have set a File object in the body of an exchange and send
this to a JMS endpoint. When the exchange is obtained from that endpoint,
the body contains a byte array of the contents of the file the File object
represents.

Given the File object is serializable I expected a File object to be
available at the other end. I could just send the File URI string and
create a new File object on the other side, but I wondered where/if the
conversion strategy for Camel is documented?

Cheers,

Tom

Re: Default Type Conversions

[Tom Ellis <te...@gmail.com>]

Thanks Christian, sounds like Claim Check is what we're doing.

Cheers,

Tom


On 8 October 2013 22:35, Christian Müller <ch...@gmail.com>wrote:

> Hi Tom!
>
> Find my comments inline.
>
> Best,
> Christian
>
>
>
> On Tue, Oct 8, 2013 at 7:19 PM, Tom Ellis <te...@gmail.com> wrote:
>
> > Hi,
> >
> > Is there some documentation around the strategy Camel takes when deciding
> > what to convert the body of an exchange to before sending to an endpoint?
> >
> Camel will not convert the body of an exchange to BEFORE sending to an
> endpoint. The endpoint may convert the body to a know type which the
> endpoint can handle.
>
> >
> > For example, I have set a File object in the body of an exchange and send
> > this to a JMS endpoint. When the exchange is obtained from that endpoint,
> > the body contains a byte array of the contents of the file the File
> object
> > represents.
> >
> This is because the JMS component converts the body to a know type it can
> handle well (using the Camel type converter mechanism).
>
> >
> > Given the File object is serializable I expected a File object to be
> > available at the other end. I could just send the File URI string and
> > create a new File object on the other side, but I wondered where/if the
> > conversion strategy for Camel is documented?
> >
> This doesn't make sense. The "other end" could be a server on a different
> continent... You may looking for the claim check pattern (
> http://camel.apache.org/claim-check.html)?
>
> >
> > Cheers,
> >
> > Tom
> >
>

Re: Default Type Conversions

[Christian Müller <ch...@gmail.com>]

Hi Tom!

Find my comments inline.

Best,
Christian



On Tue, Oct 8, 2013 at 7:19 PM, Tom Ellis <te...@gmail.com> wrote:

> Hi,
>
> Is there some documentation around the strategy Camel takes when deciding
> what to convert the body of an exchange to before sending to an endpoint?
>
Camel will not convert the body of an exchange to BEFORE sending to an
endpoint. The endpoint may convert the body to a know type which the
endpoint can handle.

>
> For example, I have set a File object in the body of an exchange and send
> this to a JMS endpoint. When the exchange is obtained from that endpoint,
> the body contains a byte array of the contents of the file the File object
> represents.
>
This is because the JMS component converts the body to a know type it can
handle well (using the Camel type converter mechanism).

>
> Given the File object is serializable I expected a File object to be
> available at the other end. I could just send the File URI string and
> create a new File object on the other side, but I wondered where/if the
> conversion strategy for Camel is documented?
>
This doesn't make sense. The "other end" could be a server on a different
continent... You may looking for the claim check pattern (
http://camel.apache.org/claim-check.html)?

>
> Cheers,
>
> Tom
>

Re: Default Type Conversions

[Chris <cw...@gmail.com>]

I think if you turn on TRACE logging on the class
org.apache.camel.impl.converter.BaseTypeConverterRegistry,
you should see the type converter logic in action.

I also saw in a Camel core unit test, code along the lines of:

                 from("file://target/gf")
                     .convertBodyTo(File.class)
                     .to("mock:result");
...then

mock.message(0).body().isInstanceOf(File.class);
...which means it expects it to be still of type File at the other end.

I don't know how you're sending the File object (ProducerTemplate or 
replacing In Message) if you are not using a ProducerTemplate, you could 
try the 2-arg version of setBody(...), i.e.:

exchange.getIn().setBody(body, File.class);

or just try explicit conversions via the DSL:

  .convertBodyTo(File.class)


    -Chris

On 10/8/2013 1:19 PM, Tom Ellis wrote:
> Hi,
>
> Is there some documentation around the strategy Camel takes when deciding
> what to convert the body of an exchange to before sending to an endpoint?
>
> For example, I have set a File object in the body of an exchange and send
> this to a JMS endpoint. When the exchange is obtained from that endpoint,
> the body contains a byte array of the contents of the file the File object
> represents.
>
> Given the File object is serializable I expected a File object to be
> available at the other end. I could just send the File URI string and
> create a new File object on the other side, but I wondered where/if the
> conversion strategy for Camel is documented?
>
> Cheers,
>
> Tom
>