Cannot Initialize Streamer that is already in use

Data Abstract
1

Delphi Xe3, DA 8
Sometimes I get error:
An exception was raised on the server: Cannot Initialize Streamer that is already in use.
on the server.
How I can on the server log this error? I can’t catch this error
How I can detect the source (table) of this error?
How use OnInitialized event handle of data streamer to log table?

Thanx, Teo

2

this error usually appears when DataStreamer isn’t finalized correctly.
correct usage should be

  DataStreamer.Initialize(stream, aiWrite);
  try
...
  finally
    DataStreamer.Finalize;
  end;

usage of above construction, should solve this error.

also datastreamer isn’t thread-safe so this error can be raised if several threads tried to use datastreamer simultaneously

3

On the server side I use thread on the following way (from ServerForm):
(refrer to Calling a service method from inside the server?)

begin
    ClientID:=ServerDataModule.Message.ClientID;
    fClassFactory:=GetClassFactory('SaldoService');
    fClassFactory.CreateInstance(ClientID, instance);

    try
	  try
          	(instance as ISaldoService).GetMyData;
          except
              on e:exception do begin
                ServerForm.LOG4(DateTimeToStr(now)+' -SaldoService '+e.Message);
              end;
          end;
    finally
        fClassFactory.ReleaseInstance(ClientID,instance);
    end;

Is this correct way?
And always I use initialize/finalize construction for WriteDataset and ReadDataset

4

yes, this is correct.
where are you using ReadDataset/WriteDataset ? inside _Impl or other server-side units like server datamodule ?

5

I use it inside SaldoService_impl. From above service (GetMyData) I call PrepareStreamData. ReadDataset use on the Client side

procedure TSaldoService.PrepareStreamData(aSQL, aDatasetLogicalName: String;
  var bDataOut: TROBinaryMemoryStream);
var
  LZip: TZCompressionStream;
  bs: TROBinaryMemoryStream;
  bd: TROBinaryMemoryStream;
  cmd: IDADataset;
  con: IDAConnection;
begin

  con := ServerDataModule.ConnectionManager.NewConnection
    	(ServerDataModule.ConnectionManager.GetDefaultConnectionName);
  cmd := con.NewDataset(aSQL, aDatasetLogicalName);
  cmd.Open;

  bs := TROBinaryMemoryStream.Create();
  bd := TROBinaryMemoryStream.Create();

  CS.Enter;
  try
    try
      DataStreamer.Initialize(bd, aiWrite);
      try
        DataStreamer.WriteDataset(cmd, [woSchema, woRows], -1);
      finally
        DataStreamer.Finalize;
      end;
    except

                on e: exception do begin
                  raise exception.Create('bd: '+inttostr(bd.Size) + aSQL + ' - ' + e.Message);
                end;
    end;
   :::........Here compress bd stream...........

  finally
    CS.Leave;
    bs.Free;
    bd.Free;
    bs := nil;
    bd := nil;
    cmd.Close;
    con.Close;
  end;

end;
6

your code looks correct and shouldn’t cause Cannot Initialize Streamer that is already in use exception.