A Jax-RS client that does a post with a request body of a JSON string

I am using JaxRS to create client side code that interacts with a vendor's API. I have been able to write code that performs GET and POST, both of which do not have a request body. I am currently running into a problem trying to do a POST where there is only a request body being sent. I am trying to send a simple JSON string:

{"server":{"name":"HelloKitty","imageId":71,"flavorId":1}}

The following is the definition for the WebClient I am using (written in Scala, but I know that the headers and authorizations are being done correctly):

def postClient: WebClient = {
   val authClient = WebClient.create(authServer)
   authClient.header("X-Auth-User", apiUsername)
   authClient.header("X-Auth-Key", apiKey)

   val response = authClient.get
   val metadata = response getMetadata () map { case (k, v) => k -> v(0).toString }

   val client = WebClient.create(metadata.get("X-Server-Management-Url").getOrElse("Error in authentication response"))
   client.header("X-Auth-User", apiUsername)
   client.header("X-Auth-Key", apiKey)
   client.header("X-Auth-Token", metadata.get("X-Auth-Token").getOrElse("Error in authentication response"))
   client.header("Content-Type","application/json")
}

Here is my resource interface:

@Produces(Array("text/json"))
trait RackspaceServerApi {
    @Path("/servers.json")
    @GET
    def listServers(): String

    @Path("/servers/detail.json")
    @GET
    def listServersDetailed(): String

    @POST
    @Path("/servers")
    @Consumes(Array("application/json"))
    def createServerData(server: String)
}

Here is my method that creates a proxy and tries to send the request

def createServer(name: String, imageId: Long, flavorId: Int) = {
    // this creates a simple pojo for the server
    val serverObject = new RackspaceCreateServerObject(name, imageId, flavorId, None, None)

    // i am using lift-web to handle the json
    // here I am unmarshalling the serverObject into a json string
    val jsonServerData = write(serverObject)

    val postProxy = JAXRSClientFactory.fromClient(RackspaceConnection.postClient, classOf[RackspaceServerApi], true)
    postProxy.createServerData(jsonServerData)
}

And here is the specific WebApplicationException I get:

Status code: [500]

Entity: [No message body writer found for response class : JAXBElement.]

However, if I try to send the request using a webclient instead of a proxy like so:

def createServer(name: String, imageId: Long, flavorId: Int) = {
    // this creates a simple pojo for the server
    val serverObject = new RackspaceCreateServerObject(name, imageId, flavorId, None, None)

    // i am using lift-web to handle the json
    // here I am unmarshalling the serverObject into a json string
    val jsonServerData = write(serverObject)

    val webClient = RackspaceConnection.postClient
    webClient.path("/servers")
    webClient.post(jsonServerData)
}

It works. Am I doing something wrong in the interface (missing some magical combinatio开发者_C百科n of annotations?)? Or did I not set something up? I am using Jax-RS 2.3.2.

What JAX-RS implementation are you using?

The error message indicates that you need to register a plugin/module to handle the marshalling of JAXB beans to JSON. Some JAX-RS implementations will do this automatically, some require some initialisation.