Hi all,
I discovered what it seems to be multiple bugs while trying to implement a
REST webservice that facades an existing one.
The goal is to define on the ESB a REST webservice that simply forwards
incoming requests to the real REST webservice (that exists outside the ESB).
The facade must be transparent, i.e. it must reply with the same HTTP error
codes and the same HTTP responses as those returned by the real service.
Here is the (blueprint) route that I got nearly working (after several
hours...) :
<route id="restproxy">
<from uri="restlet:http://localhost:9080/oe/ws/offre/{id}"/>
<doTry>
<to uri="restlet:http://bla.dot.com:8080/oe/ws/offre/{id}"/>
<doCatch>
<exception>org.apache.camel.CamelException</exception>
<setOutHeader headerName="CamelHttpResponseCode">
<simple>${exception.statusCode}</simple>
</setOutHeader>
<setBody>
<simple>${exception.responseBody}</simple>
</setBody>
<log message="RB=${exception.responseBody}
SC=${exception.statusCode} URI=${exception.uri}"/>
</doCatch>
</doTry>
</route>
The problems I got/get are the following :
1) The real REST service may return a HTTP 404 with some content in the
response body. However, this body get lost by the exception handling.
In the route, this results in ${exception.responseBody} being something
like "org.restlet.data.Response@17bf0a7".
After investigation, the problem is located in the class RestletProducer
(in camel-restlet 2.6.0) at line 126. The body is taken by the statement
String copy = response.toString();
This is obviously wrong. It should be instead something like :
String copy = null;
if (response.getEntity() != null) {
// get content text
copy = response.getEntity().getText();
}
Additionnally, I would remove the statement LOG.warn(headers) that stand
the line just after (or at least set the LOG level to DEBUG).
2) Another problem is that the value of ${exception.uri} appears to be the
uri of the facade REST service (i.e.
restlet:http://localhost:9080/oe/ws/offre/{id}) while it should be instead
the uri of the endpoint that threw the exception (i.e.
restlet:http://bla.dot.com:8080/oe/ws/offre/{id}). This problem can be
corrected in the same class RestletProducer, at line 123, by replacing
String uri = exchange.getFromEndpoint().getEndpointUri();
by
String uri = response.getRequest().getResourceRef()
3) I would like to catch only
org.apache.camel.component.restlet.RestletOperationException exception, i.e.
write :
<exception>org.apache.camel.component.restlet.RestletOperationException</exception>
However, if I do this, I get a NullPointerException :
java.lang.NullPointerException
at
org.apache.camel.processor.CatchProcessor.catches(CatchProcessor.java:71)[68:org.apache.camel.camel-core:2.6.0]
at
org.apache.camel.processor.TryProcessor$DoCatchProcessor.process(TryProcessor.java:226)[68:org.apache.camel.camel-core:2.6.0]
at
org.apache.camel.util.AsyncProcessorHelper.process(AsyncProcessorHelper.java:70)[68:org.apache.camel.camel-core:2.6.0]
...
After investigation, the problem lies in CatchDefinition.java (in
camel-core 2.6.0) at line 260 where the statement
ObjectHelper.loadClass(name, getClass().getClassLoader()) on the string
"org.apache.camel.component.restlet.RestletOperationException" returns null,
unless dynamic import is turned on on the camel-core bundle.
Regards,
Cedric
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