Sample code for creating binary container:

     RXmlEngDOMImplementation domImpl;
     domImpl.OpenL();        // opening DOM implementation object 
     RXmlEngDocument iDoc; 
     // create document element
     TXmlEngElement elem = iDoc.CreateDocumentElementL(_L8("doc"));
     // create binary container from buffer (str1) and CID equals cid
     TXmlEngBinaryContainer binData=iDoc.CreateBinaryContainerL(cid,*str1);  
     elem.AppendChildL(binData);      // append container to the dom tree       
     iDoc.Close();               // closing all opened objects
     domImpl.Close();