connect and interface to about 20 different endpoints, each has its own message formats, connection methodologies, protocols, and different implementations of payment transactions sets, encryption and key management considerations, On-Line vs Offline transactions, Store and Forward (SAF), and flat file based reconciliation and clearing files among other details.
Here is a basic list of steps that we perform that assist us in getting the endpoint integration right:
1) Acquire the Host Message Format specifications and communication/protocol specifications that describe the communication and connection e.g: 2||4 byte length header, other header(s), length in network or host byte order, etc. and read and understand them. Perform this same task for batch flat file based formats and file transfers.