diff --git a/R/ds.roc.R b/R/ds.roc.R
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+#'
+#' @title Computes server-side roc curve
+#' @description This function computes the roc curve
+#'  of a given server-side pair of prediction and reference vector. 
+#'
+#' @details  This function is similar to the function \code{roc} in pROC.
+#' 
+#' Server function called: \code{rocDS}
+#' @param reference a logical (boolean) vector refering to the "truth" on which case is positive/true or negative/false.
+#' @param prediction a numeric vector (values between 0 and 1) holding the tendency to lean towards a positive or negative outcome.
+#' @param checks logical. If TRUE  optional checks of model
+#' components will be undertaken. Default is FALSE to save time. 
+#' It is suggested that checks
+#' should only be undertaken once the function call has failed. 
+#' @param datasources a list of \code{\link{DSConnection-class}} 
+#' objects obtained after login. If the \code{datasources} argument is not specified
+#' the default set of connections will be used: see \code{\link{datashield.connections_default}}.
+#' @return \code{ds.roc} returns to the client-side plotting a roc curve.
+#' 
+#' @author Matthis A
+#' @export
+#' @examples
+#' \dontrun{
+#'
+#'  ## Version 6, for version 5 see the Wiki
+#'   
+#'   # connecting to the Opal servers
+#' 
+#'   require('DSI')
+#'   require('DSOpal')
+#'   require('dsBaseClient')
+#'
+#'   builder <- DSI::newDSLoginBuilder()
+#'   builder$append(server = "study1", 
+#'                  url = "http://192.168.56.100:8080/", 
+#'                  user = "administrator", password = "datashield_test&", 
+#'                  table = "CNSIM.CNSIM1", driver = "OpalDriver")
+#'   builder$append(server = "study2", 
+#'                  url = "http://192.168.56.100:8080/", 
+#'                  user = "administrator", password = "datashield_test&", 
+#'                  table = "CNSIM.CNSIM2", driver = "OpalDriver")
+#'   builder$append(server = "study3",
+#'                  url = "http://192.168.56.100:8080/", 
+#'                  user = "administrator", password = "datashield_test&", 
+#'                  table = "CNSIM.CNSIM3", driver = "OpalDriver")
+#'   logindata <- builder$build()
+#'   
+#'   connections <- DSI::datashield.login(logins = logindata, assign = TRUE, symbol = "D") 
+#'   
+#'   #Calculate the roc curve of prediction and reference vectors in the server-side
+#'   
+#'   ds.roc(reference = "D$muac",
+#'           prediction = "D$sex",
+#'           checks = FALSE,
+#'           datasources = connections)
+#'              
+#'   # clear the Datashield R sessions and logout
+#'   datashield.logout(connections)
+#' }
+#'
+ds.roc <- function(reference=NULL, prediction=NULL, checks=FALSE, datasources=NULL){
+
+#####################################################################################
+#MODULE 1: IDENTIFY DEFAULT DS CONNECTIONS                                          #
+  # look for DS connections                                                         #
+  if(is.null(datasources)){                                                         #
+    datasources <- datashield.connections_find()                                    #
+  }                                                                                 #
+#####################################################################################
+
+Nstudies <- length(datasources)
+
+checkarg(reference, "logical", "testing", checks, datasources)
+checkarg(prediction, "numeric", "prediction", checks, datasources)
+
+cally <- paste0("rocDS(", reference, ",", prediction, ")")
+
+ss.obj <- DSI::datashield.aggregate(datasources, as.symbol(cally))
+
+  
+
+  ret = ss.obj[[1]]
+  plot(1 - ret$Specificities, ret$Sensitivities, type="l")
+  points(ret$Threshold, col="red")
+  for(j in 2:Nstudies){
+    ret <- ss.obj[[j]]
+    lines(1 - ret$Specificities, ret$Sensitivities)
+    points(ret$Threshold, col="red")
+  }
+  return(ss.obj)
+}
+#ds.roc
+
+checkarg <- function(x, validtype, usage, checks, datasources){
+#####################################################################################
+#MODULE 2: SET UP KEY VARIABLES ALLOWING FOR DIFFERENT INPUT FORMATS                #
+  if(is.null(x)){                                                                   #
+    stop(paste0("Please provide the name of the input vector for ", usage, "!"), call.=FALSE)               #
+  }                                                                                 #
+  # the input variable might be given as a variable in a data frame (i.e. D$x)      #
+  # or just as a vector not attached to a table (i.e. x)                            #
+  # we have to make sure the function deals with each case                          #
+  xnames <- extract(x)                                                              #
+  varname <- xnames$elements                                                        #
+  obj2lookfor <- xnames$holders                                                     #
+#####################################################################################
+
+###############################################################################################
+#MODULE 3: GENERIC OPTIONAL CHECKS TO ENSURE CONSISTENT STRUCTURE OF KEY VARIABLES            #
+#IN DIFFERENT SOURCES                                                                         #
+  # beginning of optional checks - the process stops and reports as soon as one               #
+  #check fails                                                                                #
+                                                                                              #
+  if(checks){                                                                                 #
+    message(paste0(" -- Verifying the variables for ", usage, " in the model"))                                       #
+                                                                                              #
+    # check if the input object(s) is(are) defined in all the studies                           #
+    if(is.na(obj2lookfor)){                                                                     #
+      defined <- isDefined(datasources, varname)                                                #
+    }else{                                                                                      #
+      defined <- isDefined(datasources, obj2lookfor)                                            #
+    }                                                                                           #
+                                                                                                #
+    # call the internal function that checks the input object is suitable in all studies        #
+    varClass <- checkClass(datasources, x)                                                      #
+    # the input object must be a numeric or an integer vector                                   #
+    if(!(validtype %in% varClass)){                                          #
+      stop(paste0("The input vector for ", usage, " must be of type ", validtype, "."), call.=FALSE)             #
+    }                                                                                           #
+  }                                                                                             #
+###############################################################################################
+}