Let Camel handle various URI types - apache-camel

Question

I would like to write a Camel Route that gets in a URI (can be http, ftp, file, ...) and then fetches the data and stores it locally in a file.
This URI-String could be, for example:
"ftp://localhost/example.txt"
"file://tmp/example.txt"
"jms:queue:dataInputQueue"
...
Based on this string, the correct Camel Component should be used to access the data. Something like a case/switch in Java:
(1) Receive URI (from uri="vm:incomingUri")
(2) Chose "right" Camel Component
switch(URI)
case HTTP: use Camel HTTP component
case FTP: use Camel FTP component
case JMS: use Camel JMS component
...
(3) Read data from that URI, using the "right" Camel component
(4) Store file locally (to uri="file://...)
Example:
From "vm:incomingUri" I read a String "ftp://localhost/example.txt". That what finally needs to happen now should be equivalent to this:
<route>
<from uri="ftp://localhost/example.txt"/>
<to uri="file://tmpDir/example.txt"/>
</route>
How would this look like in Camel?

Answer 1

I believe one difficulty will be that, for the components you mention (HTTP, FTP, file, JMS), you may want to use either a producer or a consumer:
FTP, File: definitely a consumer to read a file.
HTTP (or HTTP4): definitely a producer, to send a request to the server (the server's reply will by the new message body)
JMS: depends on wether you want to read from a queue (consumer), or send a message to a queue with a ReplyTo header, then wait for the answer (producer).
Producers :
If you are using Camel 2.16+, you can use the new "dynamic to" syntax. It's basically the same as a regular "to", except that the endpoint uri can be evaluated dynamically using a simple expression (or, optionnaly, another type of expression). Alternatively, you can use the enrich flavor of the content-enricher pattern, wich also supports dynamic uris starting with Camel 2.16.
If you are using an older version of Camel, or if you need to dynamically route to several endpoints (not just one), you can use the recipient list pattern.
Here's an exemple. We will transform the message body by calling an endpoint; the uri for that endpoint will be found in a header named TargetUri and will be evaluated dynamically for each message.
// An instance of this class is registered as 'testbean' in the registry. Instead of
// sending to this bean, I could send to a FTP or HTTP endpoint, or whatever.
public class TestBean {
public String toUpperCase(final String str) {
return str.toUpperCase();
}
}
// This route sends a message to our example route for testing purpose. Of course, we
// could send any message as long as the 'TargetUri' header contains a valid endpoint uri
from("file:inbox?move=done&moveFailed=failed")
.setHeader("TargetUri").constant("bean:testbean?method=toUpperCase")
.setBody().constant("foo")
.to("direct:test");
// 1. The toD example :
from("direct:test")
.toD("${header.TargetUri}")
.to("log:myRoute");
// 2. The recipient list example :
from("direct:test")
.recipientList(header("TargetUri"))
.to("log:myRoute");
// 3. The enrich example :
from("direct:test")
.enrich().simple("${header.TargetUri}") // add an AggregationStrategy if necessary
.to("log:myRoute");
Consumers :
With Camel 2.16+, you can use the pollEnrich flavor of the content-enricher pattern.
For older versions of Camel, you can use a ConsumerTemplate in a processor.
// 4. The pollEnrich example (assuming the TargetUri header contains, e.g., a file
// or ftp uri) :
from("direct:test")
.pollEnrich().simple("${header.TargetUri}") // add an AggregationStrategy if necessary
.to("log:myRoute");
// 5. The ConsumerTemplate example (same assumption as above)
from("direct:test")
.process(new Processor() {
#Override
public void process(Exchange exchange) throws Exception {
String uri = exchange.getIn().getHeader("TargetUri", String.class);
ConsumerTemplate consumer = exchange.getContext().createConsumerTemplate();
final Object data = consumer.receiveBody(uri);
exchange.getIn().setBody(data);
}
})
.to("log:myRoute");
Producer or consumer?
Sadly, I can't think of any really elegant solution to handle both - I think you will have to route to two branches based on the uri and known components... Here's the sort of thing I might do (with Camel 2.16+), it's not very pretty:
// This example only handles http and ftp endpoints properly
from("direct:test")
.choice()
.when(header("TargetUri").startsWith("http"))
.enrich().simple("${header.TargetUri}")
.endChoice()
.when(header("TargetUri").startsWith("ftp"))
.pollEnrich().simple("${header.TargetUri}")
.endChoice()
.end()
.to("log:myRoute");

Answer 2

It is possible by using
<to uri="{{some.endpoint}}"/>
But you would require to add it in property .
<cm:property name="some.endpoint" value="SomeEndPoint"/>
And you can add any endpoint you want http, ftp, file, log, jms, vm etc.
Value of SomeEndPoint.
Log Component: log:mock
JMS Component: activemq:someQueueName
File Component: file://someFileShare
VMComponent: vm:toSomeRoute