Hi

Finaly I did it with the eeml library and took the eeml_manual_PUT example.
It seems it works only if you Name your channels 0, 1, 2 ect ..
The Problem with this method is that it is blocked from my Company Firewall not knowing why?
(got this in the logfile: TCP https_t_7200 64.94.18.120 1385) 
I am still looking for a different method and althoug think to have more Options with json.

1. import eeml.*;
   DataOut dOut;
   float lastUpdate;
   
   void setup(){
       // set up DataOut object; requires URL of the EEML you are updating, and your Pachube API key  
       dOut = new DataOut(this, " http://api.xively.com/v2/feeds/1234567.xml", "asdfdääöLöJöÄjTGdeRtDsfsdfsdbsdfssdfTsdfsdfW");
        //  and add and tag a datastream    
       dOut.addData(0,"arduino,sensor1");
       dOut.addData(1,"something,sensor2");
       dOut.addData(2,"something,sensor3");
   }
   
   void draw()
   {
       // update once every 5 seconds (could also be e.g. every mouseClick)
       if ((millis() - lastUpdate) > 5000){
           println("ready to POST: ");
           dOut.update(0, random(1000)); // update the datastream
            dOut.update(1, random(100)); // update the datastream
            dOut.update(2, random(50)); // update the datastream
           int response = dOut.updatePachube(); // updatePachube() updates by an authenticated PUT HTTP request
           println(response); // should be 200 if successful; 401 if unauthorized; 404 if feed doesn't exist
           lastUpdate = millis();
       }  
   }