Extending/Modifying OpenIso8583.Net

Question

I'm using the excellent OpenIso8583Net to send/receive ISO messages. However, since every organization has its own definition and customization, I want to be able to customoize the format with as little touch to the projects' source as possible to be able to upgrade to new versions more easily.
So here are three customizations I am facing right now:

• How can I make Bitmap to use AsciiFormatter instead of BinaryFormatter? since bitmap is a private field of AMessage class, I cannot access it even if I directly derive a new custom class from AMessage. And the constructor uses BinaryFormatter by default. Currently, I have modified Bitmap.cs parameterless constructor to use AsciiFormatter.
• Same story goes for variable length formatter. It uses AsciiFormatter by default. But I'd like it to use BcdFormatter. I have Modified this part to use BcdFormatter by default in VariableLengthFormatter.
  I'd appreciate if anyone shows me a better way to handle these customizations by extending, not modifying.
• Suppose I want to display fields in a log file. An example would be what I have displayed at Generating MAC by encrypting data in the Fields section. Right now, I have to make Template property public and use the following snippet: for (var i = 2; i

How can I access the fields without making the Template public? I want to access the Display method of fields in my main program for logging purposes.

Answer 1

I have just made changes to the project to allow this. As of version 0.5.0 (Update your NuGet package)

Bitmap Formatter

You can set the bitmap formatter in the Template for your message class. Here is some sample code:

public class AsciiIsoMsg : Iso8583
{
    // First you need to customise the template
    // The message 
    private static readonly Template template;

    static AsciiIsoMsg()
    {
        // Get the default template for the Iso8583 class
        template = GetDefaultIso8583Template();
        // change the bitmap formatter
        template.BitmapFormatter = new AsciiFormatter();
    }

    // override the base class using the template and you will be using the bitmap formatter
    public AsciiIsoMsg():base(template)
    {

    }
}

Set Length Formatter of a field

In the static AsciiIso() method, if you modify in this manner, you'll change field 2 to use a BCD length formatter:

// Set field 2 to use BCD formatter
template[2] = FieldDescriptor.BcdVar(2, 19, Formatters.Bcd);

Log File

To display the message in the log file, use the .ToString() method on the message class, e.g.

var msg = new AsciiIsoMsg();
msg.MessageType = Iso8583.MsgType._0200_TRAN_REQ;
msg[3] = "010000";
Console.WriteLine(msg.ToString());

Which gives:

0200:
   [Fixed    n         6 0006] 003 [010000]