DamExchange Protocol Basics 

The interface between two Draughts computer programs is implemented in a two layer structure. Layer 1 offers reliable interchange of messages between the two Draughts computer programs. Layer 2 describes the contents of the exchanged messages.

The layer 1 protocol can, in principle, be replaced by any protocol that is able to reliably exchange messages between two computer programs. However, to be able to communicate between two computer programs, they both should of course use the same layer 1 protocol.

In DamExchange, two layer 1 protocols are defined so far: the NULMODEM and the SOCKET protocol (IPv4 and IPv6). The description of the NULMODEM protocol contains pseudo code to ease implementation.

The layer 2 protocol (DamExchange messages) is fixed and independent of the chosen underlying layer 1 protocol. DamExchange is designed in such a way that it can be extended to future enhancements or changes.

For Draughts computer programs running in Windows 7 / 8.1 / 10 / 11 a DLL (with accompanying header file) containing the layer 1 and 2 protocols, is available for download.

Design criteria for DamExchange:

• The DamExchange messages (layer 2) should be independent of the hardware platform or machine-specific encoding. Also alignment or byte ordering (big endian vs. little endian) should not be an issue. Because of these design criteria, the Draughts computer programs exchange messages based only on the ASCII character set with values 1 up to and including 127.
• The layer 1 protocol should be able to send messages of 1 to 127 characters in length.
• The content and format of the DamExchange messages (layer 2) should be independent of the underlying layer 1 protocol.
• The layer 2 protocol (DamExchange messages) assumes correct implementation of the protocol in both communicating computer programs. I.e. the layer 2 protocol implementation should not try to detect or fix implementation errors in the other computer program. Also the layer 2 implementation should not try to detect or fix communication errors in layer 1. Reliable communication in layer 1 should be assumed in layer 2.
• The DamExchange protocol should be suitable to play a computer Draughts tournament with a DamExchange Tournament Server as Initiator. All (simultaneously) connected Draughts computer programs act as Followers. The DamExchange Tournament Server is outside the scope of this document.

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