Parsing REST API output from JSON to class object

[ttob...@gmail.com]

Hello everyone,

I've created a REST server method [1] and a REST client method. My goal is to communicate java class objects between two camunda systems.

So far the server is able to receive a customer class object, I created, as a JSON String from the server. Which looks like the following:

{
"name": "Jon",
"address": "Samplestr.",
"registered": true
}

But my problem is that I can't get the client to parse this string back into a customer class object.

My client code looks like the following:

---------------------------
public class JerseyClientGet implements JavaDelegate {

public void execute(DelegateExecution delegateExecution){

Client client = Client.create();

WebResource webResource = client
.resource("http://ipaddress:8080/project-name/rest/customer/get");

ClientResponse response = webResource.accept("application/json").get(ClientResponse.class);

if(response.getStatus() != 200){
throw new RuntimeException("Failed : HTTP error code: "+response.getStatus());
}

Response output = response.getEntity(String.class);
---------------------------

I tried to replace the last row with:
"Customer outputCustomer = response.getEntity(Customer.class);"
And to replace it with:
"Customer outputCustomer = response.getEntity(new GenericType<SkiOrder>(){});"

Both resulting in this error:

---------------------------
FATAL: A message body reader for Java class org.camunda.bpm.getstarted.projectname.Customer, and Java type class org.camunda.bpm.getstarted.projectname.Customer, and MIME media type application/json was not found
Jul 10, 2015 5:40:04 PM com.sun.jersey.api.client.ClientResponse getEntity
FATAL: The registered message body readers compatible with the MIME medi
a type are:
application/json ->
com.sun.jersey.json.impl.provider.entity.JSONJAXBElementProvider$App
com.sun.jersey.json.impl.provider.entity.JSONArrayProvider$App
com.sun.jersey.json.impl.provider.entity.JSONObjectProvider$App
com.sun.jersey.json.impl.provider.entity.JSONRootElementProvider$App
com.sun.jersey.json.impl.provider.entity.JSONListElementProvider$App
...(many more rows like the ones before)...
com.sun.jersey.api.client.ClientHandlerException: A message body reader for Java class org.camunda.bpm.getstarted.frogtravel.SkiOrder, and Java type class org.camunda.bpm.getstarted.frogtravel.SkiOrder, and MIME media type application/json was not found
at com.sun.jersey.api.client.ClientResponse.getEntity(ClientResponse.jav
a:549)
...(many more rows like the one before)...
---------------------------

And I also tried to parse the JSON String with the following code and imports (whereat I certainly put the imports on top of the class under the package row):

---------------------------
import static org.camunda.spin.Spin.*;
import static org.camunda.spin.DataFormats.*;
import org.camunda.spin.json.SpinJsonNode;

SpinJsonNode json = S(output, json());

Customer customer = json.mapTo(Customer.class)
---------------------------

This approach resulted in this error message:
---------------------------
log4j:WARN No appenders could be found for logger (org.camunda.spin).
log4j:WARN Please initialize the log4j system properly.
log4j:WARN See http://logging.apache.org/log4j/1.2/faq.html#noconfig for more in
fo.
---------------------------

I tried to load some log4j dependencies in my pom:
---------------------------
<!-- SLF4J Logger -->

<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-api</artifactId>
<version>1.7.2</version>
</dependency>

<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-log4j12</artifactId>
<version>1.7.2</version>
</dependency>
---------------------------

And I'm searching solutions for that problem but I have problems solving it.
[2] It seems like the problem could be that the SLF4J logger gets wrong input. But since I'm not using the logger myself I dont know how to figure out whats wrong.

I would be very thankful for help, because I don't know how to proceed exactly from here on.

Best regards,
Tassilo

[1] https://groups.google.com/forum/#!topic/camunda-bpm-users/TiHwL0ANx9o
[2] http://stackoverflow.com/questions/6608775/please-initialize-the-log4j-system-properly-while-running-web-service

[thorben....@camunda.com]

Hi Tassilo,

Your first approach makes use of the Jersey client API. It is not directly related to camunda and since we are not familiar with it ourselves, I think we can't really help you with that.

As for the second approach, did you actually get an error of something not working? You posted a snippet of warnings, which should not affect the executed code.

Cheers,
Thorben