this.awsCredentials = awsCredentials;
exceptionUnmarshallers = new ArrayList<Unmarshaller<AmazonServiceException, Node>>();
exceptionUnmarshallers.add(new InternalServerErrorExceptionUnmarshaller());
exceptionUnmarshallers.add(new StandardErrorUnmarshaller());
setEndpoint("elasticmapreduce.amazonaws.com");
requestHandlers = new HandlerChainFactory().newRequestHandlerChain(
"/com/amazonaws/services/elasticmapreduce/request.handlers");
client = new HttpClient(clientConfiguration);