Returns server-side messages to the client-side

This function allows for error messages arising from the running of a server-side assign function to be returned to the client-side.

ds.message(message.obj.name = NULL, datasources = NULL)

Arguments

message.obj.name

is a character string specifying the name of the list that contains the message.

datasources

a list of DSConnection-class objects obtained after login. If the datasources argument is not specified the default set of connections will be used: see datashield.connections_default.

Value

ds.message returns a list object from each study, containing the message that has been written by DataSHIELD into $studysideMessage.

Details

Errors arising from aggregate server-side functions can be returned directly to the client-side. But this is not possible for server-side assign functions because they are designed specifically to write objects to the server-side and to return no meaningful information to the client-side. Otherwise, users may be able to use assign functions to return disclosive output to the client-side.

Server-side functions from which error messages are to be made available are designed to be able to write the designated error message to the $serversideMessage object into the list that is saved on the server-side as the primary output of that function. So only valid server-side functions of DataSHIELD can write a $studysideMessage. The error message is a string that cannot exceed a length of nfilter.string a default of 80 characters.

Server function called: messageDS

Author

DataSHIELD Development Team

Examples

if (FALSE) { # \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") 
  
  #Use a ds.asCharacter assign function to create the message in the server-side
  
  ds.asCharacter(x.name = "D$LAB_TRIG", 
                 newobj = "vector1",
                 datasources = connections)
                 
  #Return the message to the client-side
  
  ds.message(message.obj.name = "vector1",
             datasources = connections)
  
  # clear the Datashield R sessions and logout
  datashield.logout(connections)
} # }