You can use a composite field, but you have to do the bitmap yourself. Or you can simply create a separate IsoMessage, get its debugString and put that inside field 48.
IsoMessage has a writeData method that returns the byte array that can be written to a stream, without any length headers. You can measure it and write your own length header, followed by that buffer.
So, jpos expects a binary bitmap? Or a hex-encoded bitmap (the standard in ascii-encoded ISO) but with secondary bitmap included? The standard way the bitmap works for ascii messages is: If there are any fields above 64, a secondary bitmap is included The bitmap is hex-encoded so it can be either 16 chars or 32 chars If you set the binaryBitmap property then it won't be hex-encoded but will be sent as raw binary instead If you need to send an empty secondary bitmap, set forceSecondaryBitmap.
Are you having problems sending, or parsing a message? Do you need the bitmap to be sent in binary, or hex-encoded?
Please report issues in https://github.com/chochos/j8583/issues Don't configure field 1. If you need to parse secondary bitmap even if it's empty, then set the forceSecondaryBitmap flag in the message factory.
ISO headers are optional. You don't have to set ISO headers for your message type....
Sure, just set the encoding in the message factory, as well as the forceCharacterEncoding...