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From Quinn Stevenson <qu...@pronoia-solutions.com>
Subject Re: Polling http endpoints
Date Mon, 07 Mar 2016 15:23:43 GMT
Sorry - I forgot that the loop DSL doesn’t take a predicate.

How about this - configure redelivery handling on your main route, and then have the direct
route throw an exception if the payload isn’t ready.

Here’s a mocked example:
public class MyRouteBuilder extends RouteBuilder {
    Processor responseProcessor = new ResponseProcessor();

    public void configure() {
        onException(MyException.class)
                .logRetryAttempted(true)
                .retryAttemptedLogLevel(LoggingLevel.INFO)
                .redeliveryDelay(2000)
                .retryWhile(exchangeProperty(ResponseProcessor.RESPONSE_PROPERTY).isNotEqualTo(true))
        ;

        fromF("timer://%s?period=%d", "my-timer", 5000)
                .log("Waiting for processor")
                .to( "direct://wait-for-response")
                .to("mock://complete")
        ;

        from("direct://wait-for-response")
                .errorHandler(noErrorHandler())
                .log( "looking for response")
                .process(responseProcessor)
                .choice()
                    .when( exchangeProperty(ResponseProcessor.RESPONSE_PROPERTY).isNotEqualTo(
true ) )
                        .throwException( MyException.class, "Not Ready" )
                    .otherwise()
                .end()
        ;
    }

}
My simple processor just sets an exchange property - nothing fancy but hopefully it illustrates
what I’m suggesting.

> On Mar 6, 2016, at 6:18 AM, jelmer <jkuperus@gmail.com> wrote:
> 
> It does not look like loop takes a predicate, it expects the expression to
> be a number, which i think makes it unsuited for this sort of thing.
> 
> I would this expect this to be a fairly common case, i am surprised its
> this difficult to figure out how to do this
> 
> On 4 March 2016 at 16:25, Quinn Stevenson <quinn@pronoia-solutions.com>
> wrote:
> 
>> The “direct:await-import-complete” calling itself makes me a little
>> nervous - the call stack could get pretty deep if it has to wait very long.
>> 
>> Could you use the loop DSL (http://camel.apache.org/loop.html <
>> http://camel.apache.org/loop.html>)?
>> 
>> 
>>> On Mar 3, 2016, at 11:44 AM, jelmer <jkuperus@gmail.com> wrote:
>>> 
>>> Since no one answered I came up with this :
>>> 
>>>   from("file:/Users/jkuperus/foo")
>>>     .process(ToMultiPartRequestProcessor)
>>>     .setHeader(Exchange.HTTP_METHOD, constant(HttpMethods.POST))
>>>     .setHeader(Exchange.CONTENT_TYPE, constant("multipart/form-data"))
>>>     .setHeader(Exchange.HTTP_PATH, constant("/api/tasks"))
>>>     .to("http4://localhost:11380")
>>>     .transform().header("Content-Location")
>>>     .to("direct:await-import-complete")
>>> 
>>> 
>>>   from("direct:await-import-complete")
>>>     .setHeader(Exchange.HTTP_METHOD, constant(HttpMethods.GET))
>>>     .setHeader(Exchange.HTTP_PATH, body().convertToString())
>>>     .to("http4://localhost:11380")
>>>     .transform(body().convertToString())
>>>     .choice()
>>>       .when().jsonpath("[?(@.state == 'completed')]")
>>>         .transform().jsonpath("@.campaignId")
>>>         .to("direct:do-stuff")
>>>       .otherwise()
>>>         .log("Task was not yet completed retrying in 2 seconds")
>>>         .delay(2000)
>>>         .transform().header(Exchange.HTTP_PATH)
>>>         .to("direct:await-import-complete")
>>> 
>>> 
>>> Does this make any sense ?
>>> 
>>> On 2 March 2016 at 21:27, jelmer <jkuperus@gmail.com> wrote:
>>> 
>>>> Hi as part of a camel route i upload a file to a REST service, the
>> service
>>>> will return status 202 and a Content-Location header that points to a
>> json
>>>> resource with a status field
>>>> i want to wait for the status of this resource to change to completed,
>> and
>>>> only then continue. so i need some sort of polling
>>>> But i don't see an obvious way to do this in camel
>>>> can anyone offer any suggestions?
>>>> 
>> 
>> 


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