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Strategies to avoid disruptions in Payment Solutions

Some call them the most important invention of the 20th century; others don't like them because they took their jobs away. Many of us love them because they are available 24/7, easily accessible, and open our gates to a new world of possibilities. But have you ever looked under the hood of such payment systems?


ATM/POS means all Automated Teller Machines or Point-of-Sale machines operated or affiliated with a Bank.


ATM stands for Automated Teller Machine. This computerized machine lets customers access their bank account with a magnetically encoded plastic card and a code number. It allows withdrawing money, making deposits, paying bills, obtaining bank statements, checking account balances, and transferring money.


A point-of-sale terminal combines software and hardware that allows retail locations to process card payments. It reads the information of a customer's Credit and debit card and checks whether the funds

are sufficient in a customer's bank account. It also transfers the funds from the customer's account to the seller's account, records the transaction, and the terminal prints the receipt for the customer after the transaction is approved.


ATM/POS in T24 Transact Core Banking

The ATM interface is developed as a middle layer between the ATM switch and Temenos Transact. The interface consists of a plug-in for the application server to receive the messages via a dedicated port and translate the ISO messages.

The application server sends the ISO message to Temenos Transact, where the ISO message is converted to OFS message format based on the mapping files specified in the interface.

After the transaction has been completed in Temenos Transact, the response ISO messages are formatted within the scope of the ATM interface. The response messages are indicated with the appropriate error or ok status depending upon the Temenos Transact applications reply status requested in the framework.


Communication Format for ATM/POS Transactions

The protocol used for communication between the host and the switch is usually TCP/IP via sockets. ATM interface provides a high-performance multi-threaded synchronous socket listener with custom functionality and built-in intelligence for handling ISO messages with length prefixes through TCP/IP.

The ATM Interface supports ISO 8583:87 and ISO 8583:93 versions only. Support for different versions will require modifications to the ISO message parser routines. The application servers supported by the ATM interface are TC Server, JBoss, Websphere, and Weblogic.


The purpose of ISO 8583 is to allow different financial networks and systems to carry out those key exchange transactions and responses safely and securely.


ISO message consists of three major parts: the header, application data, and the trailer. The header and trailer envelop the application data and are used for routing and message integrity. The ISO 8583 protocol is used for systems that exchange electronic transactions initiated by cardholders using payment cards. Basically, when a cardholder uses a payment card, the electronic transaction data is exchanged throughout the network using ISO 8583 data elements, messages and code values.

The ISO 8583 standard is officially titled "Financial Transaction Card-Originated Messages — Interchange Message Specifications".


Processing ATM/POS transactions

To process a financial transaction, the switch (ATM provider) must provide a request to financial institutions to process; financial institutions should perform the transaction and send the bank a response, which completes the transaction cycle. The request and response should adhere to ISO standards.


Mismatched ATM/POS transactions

Reconciliation is a process where the ATM/POS transaction entries are matched between the banking system and the network switch provider. For the reconciliation process, the banking system does the following:

  • Generate a report containing all ATM/POS transaction entries posted in a day.

  • Receive the file from the network switch provider about the transaction executed in an ATM.

  • Match the entries between the banking system and the network system provider.

Reconciliation Process
  • Reconciliation: There would be a discrepancy in the customer's accounts due to network or timeout errors. These discrepancies are traced by comparing the transactions posted to the customer's account in the banking system with the transactions posted in the switch.

  • Customer Service: Any corrections to a member's account are made in a proactive manner.

  • Settlement: Ensure that correct payments of funds take place.


What might be the problems involved?

From a technical perspective, several areas could result in reliability problems for this crucial ATM/POS application.

  • Network Error

  • Timeout

  • Messages lost in transit

  • Component outage

Strategies to avoid ATM/POS disruptions?

There are several built-in strategies to improve reliability and ensure that transactions get processed as expected. These reconciliation measures are suitable to handle missing transactions. Still, suppose the services responsible for the reconciliation are terminated due to errors, and you have no problem detection and recovery. In that case, it won't do its job and put your organization at risk.


ATM/POS interface-level strategies

  • Check communication on ports

  • Monitoring incoming traffic

  • Analyse network error rates


ATM/POS Application level strategies

  • Improve the application server configuration

  • Check the messaging configuration

  • Provide observability for the entire stack

  • Establish SLOs

  • Send out alerts if SLOs are at risk


Payment solutions are amongst the number one mission-critical applications in Banks. To avoid expensive outages, you should observe their health 24/7.


Keep up the great work! Happy Performance Engineering!



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