public class SendWaveUsingRESTAPI {
 private final String clientId = 'xxxx';
 private final String clientSecret = 'xxx';
 private final String username = 'xxxxx';
 private final String password = 'xxxxxx';
 public class deserializeResponse
 {
 public String id;
 public String access_token;
 }
 public class deserializewaveresp
 {
 public String action;
 public String responseId;
 public String results;
 public String query;
 public String responseTime;
 }
 public void ReturnAccessToken()
 {
 String reqbody = 'grant_type=password&client_id='+clientId+'&client_secret='+clientSecret+'&username='+username+'&password='+password;
 Http h = new Http();
 HttpRequest req = new HttpRequest();
 req.setBody(reqbody);
 req.setMethod('POST');
 req.setEndpoint('https://XXXXXX.salesforce.com/services/oauth2/token');
 HttpResponse res = h.send(req);
 system.debug('######access_token####'+res.getbody());
 deserializeResponse resp1 = (deserializeResponse)JSON.deserialize(res.getbody(),deserializeResponse.class);
 system.debug('@@@@access_token@@'+resp1);
 if(resp1.access_token!=null)
 {
 String endPoint ='https://XXXXXX.salesforce.com/services/data/v36.0/wave/query';
 String jsonstr ="{"query":"q = load "datasetId/versionid";n+q = group q by ('Name','Wac.cc');n+q = foreach q generate 'Name' as 'Name','Wac.cc' as 'Wac.cc', count() as 'count';n+q = order q by ('Name' asc,'wac.cc' asc);n+q = limit q 2;\"}";
 Http h2 = new Http();
 HttpRequest req1 = new HttpRequest();
 req1.setHeader('Authorization','Bearer ' +resp1.access_token);
 req1.setHeader('Content-Type','application/json');
 req1.setHeader('accept','application/json');
 req1.setBody(jsonstr);
 req1.setMethod('POST');
 req1.setEndpoint(endPoint);
 HttpResponse res1 = h2.send(req1);
 deserializewaveresp resp2 = (deserializewaveresp)JSON.deserialize(res.getbody(),deserializewaveresp.class);
 system.debug('@@@RESPONSE@@'+resp2);
 }
 }
}