Invoking Rest with Jersey Client

[Nikhil Jain]

Hello Experts,

I am trying to invoke Rest service through Jersey Client, that expect custom mime type or media type "application/vnd.com.oracle.oracloud.datagrid.Service+json". I get the below error

Exception in thread "main" com.sun.jersey.api.client.ClientHandlerException: com.sun.jersey.api.client.ClientHandlerException: A message body writer for Java type, class com.sun.jersey.core.util.MultivaluedMapImpl, and MIME media type, application/vnd.com.oracle.oracloud.datagrid.Service+json, was not found
at com.sun.jersey.client.urlconnection.URLConnectionClientHandler.handle(URLConnectionClientHandler.java:155)
at com.sun.jersey.api.client.Client.handle(Client.java:652)
at com.sun.jersey.api.client.WebResource.handle(WebResource.java:682)
at com.sun.jersey.api.client.WebResource.access$200(WebResource.java:74)
at com.sun.jersey.api.client.WebResource$Builder.post(WebResource.java:570)
at com.oracle.demo.OracleCloudControllerAPIs.OracleCloudAPIs.addCoherenceDataTierCluster(OracleCloudAPIs.java:112)
at com.oracle.demo.OracleCloudControllerAPIs.OracleCloudAPIs.main(OracleCloudAPIs.java:129)
Caused by: com.sun.jersey.api.client.ClientHandlerException: A message body writer for Java type, class com.sun.jersey.core.util.MultivaluedMapImpl, and MIME media type, application/vnd.com.oracle.oracloud.datagrid.Service+json, was not found
at com.sun.jersey.api.client.RequestWriter.writeRequestEntity(RequestWriter.java:288)
at com.sun.jersey.client.urlconnection.URLConnectionClientHandler._invoke(URLConnectionClientHandler.java:217)
at com.sun.jersey.client.urlconnection.URLConnectionClientHandler.handle(URLConnectionClientHandler.java:153)
... 6 more

The code which I have is below. The below code works for the rest services which expects JSON or XML as mime type.

WebResource wr = Client.create(new DefaultClientConfig()).resource(
            "https://jaas.oraclecloud.com/paas/service/jcs/api/v1.1/instances/"+iDomain+"/"+serviceID);
        String authKey = "Basic " + authStringEnc;
        
        ClientResponse r= wr
                .header("Content-Type", "application/json;charset=UTF-8")
                .header("Authorization", authKey)
                .header("X-ID-TENANT-NAME", iDomain)
                .get(ClientResponse.class);
     
		System.out.println(r);
	    String result = r.getEntity(String.class);

I am trying to programatically invoke this REST API

I have never come across custom mime type. The code works for all other mime types. Is there any other configuration which one has to make?

[Simon Roberts]

Do you really have to send that mime type? It seems like an excuse for "applicatin/json". Have you tried sending it as such?

If you cannot, then I think what you'll need to do is to create a class that implements MessageBodyReader and MessageBodyWriter, dive into the infrastructure and find the Provider class that's already installed that handles application/json, and proxy to that, converting the type blah-blah-oracle-blah/json into application/json and back accordingly, so that the "real" handler doesn't get it's knickers in a twist.

This:

https://jersey.java.net/documentation/latest/message-body-workers.html#d0e6814

gives an overview of the MessageBodyReader/Writer process; it's not hard really, thought.

HTH
Simon

[Nikhil Jain]

I tried with application/json, but it replied with error "Not Supported Content Type", i am not even able to invoke this from other rest clients like Chrome rest client, I don't see any option of setthign this mime type.

Can someone explain me, why one would have used custom mime type?

Thanks

[Simon Roberts]

Well, there might be more to it that just JSON, but that would seem odd. Perhaps it's certain pre-agreed elements in the JSON. Does seem a little odd though.

[Ron McLeod]

application/vnd.com.oracle.oracloud.datagrid.Service+json specifies the json-formatted schema for the representations exchanged between the server and clients. In your code you are performing a GET, so the it should probably be specified in an Accept header, rather than a Content-Type header.

There are some curl examples here.

[Frits Walraven]

In your code you are performing a GET, so the it should probably be specified in an Accept header, rather than a Content-Type header.

Agreed, you can check Jersey client examples here.

[Nikhil Jain]

I am trying to perform post.

   String input = "{\"clusterType\":\"DG\", "
                + "\"scalingUnitCount\":\"1\", \"clusterName\":\"ExampleDGCluster\", "
                + "\"scalingUnitCount\":\"SMALL\"}";


 ClientResponse r= wr
                .header("Authorization", authKey)
                .header("X-ID-TENANT-NAME", iDomain)
                .accept("application/vnd.com.oracle.oracloud.datagrid.Service+json")
                .post(ClientResponse.class, input);

I still get "Content Not Supported Error". I am able to invoke this from Chrome Client (Attached Screen Shot)

I set the body as Raw & sent the json request.

[Ron McLeod]

My comment regarding Accept was for the code that you had originally posted, which was doing a GET operation. The example that you have now is doing a POST operation. For POST you do need Content-Type set to application/vnd.com.oracle.oracloud.datagrid.Service+json.

Are you trying to do a GET or POST?

[Bear Bibeault]

Nikhil Jain, I have removed your screen shot from your post. Not only is it a poor way to show text information (please post text as text, and UseCodeTags to preserve formatting), but also it revealed your login credentials to anyone who could see the post. I'm sure that that was not your intention.

[Nikhil Jain]

Apologies for attaching screen shot. Just wanted to convey the configuration on my rest client. Thanks for removing it.

I am trying to do POST operation.

[Tim Holloway]

Jersey works with plug-in converters that accept the request inputstream and convert it to javabean parameters. There are a number of options available. I've used MoXy, myself.

https://jersey.java.net/documentation/latest/media.html

application/json won't work (be accepted) without one of the JSON converters being wired in.