R DataFrame object with WCF

Question

I have a very vague understanding of WCF but after a bit of research I figured out that WCF does not like handling custom objects. I am looking for a feasible workaround.

This is my objective. I aim to create a WCF service that accepts certain values from a client machine, sends them to the server where it invokes an R instance and executes a set of DataFrame transformations and return the resulting DataFrame. DataFrames seem to be in the format of a vector / 2D array. The error I am getting is: the operation is not supported in wcf because it uses type system.object[][]

see example code below -

        public string R_to_SQLstring_InsertTable(string table_name, DataFrame Table)
    {
        string query2 = "INSERT INTO table_name (";

        for (int x = 0; x < Table.ColumnCount; x++)
        {
            if (x == (Table.ColumnCount) - 1)
            {
                query2 = query2 + Table.Names[x] + "";
            }
            else
            {
                query2 = query2 + Table.Names[x] + ", ";
            }

        }
        query2 = query2 + ") Values (";


        for (int count1 = 0; count1 < Table.RowCount; count1++)
        {
            for (int count2 = 0; count2 < Table.ColumnCount; count2++)
            {
                if (count2 == (Table.ColumnCount) - 1)
                {
                    query2 = query2 + " " + Table[count2][count1];
                }
                else
                {
                    query2 = query2 + " " + Table[count2][count1] + ",";
                }

            }

            if (count1 == (Table.RowCount) - 1)
            {
                query2 = query2 + ");";
            }
            else
            {
                query2 = query2 + "), (";
            }

        }
        return query2;
    }



    public DataFrame R_Transformation_MergeTable(string tableloca1, string tableloca2)
    {

        StartupParameter rinit = new StartupParameter();
        rinit.Quiet = true;
        rinit.RHome = @"C:\Program Files\R\R-3.4.4\";
        rinit.Home = @"C:\R";
        REngine.SetEnvironmentVariables();
        REngine engine = REngine.GetInstance(null, true, rinit);

        try
        {
            engine.Evaluate("Table1 <- read.csv(file='" + tableloca1+")");
            engine.Evaluate("Table2 <- read.csv(file='" + tableloca2 + ")");

            DataFrame Table = engine.Evaluate("Merge <- merge(Table1,Table2)").AsDataFrame();
            return Table;
        }
        catch (Exception x)
        {

            throw new Exception("Please Upload .CSV file");

        }


    }

Answer 1

I pass generic objects over WCF by manually serializing them to byte[] and passing in the type definition (as a string, Type cannot go over WCF either) then casting it back to the proper type using reflection. Given an object[][], you may have to iterate over it and use reflection to determine the type of each entry for this purpose though.

A better technique if possible would be to cast the objects to a data contract type before sending them over the service.