Cloud + Legacy Integration with IBM AS400

Introduction

Our partner's Diesel Advance program relies on a legacy IBM i AS400 system, which serves as a mission-critical platform for managing customers, accounts, cards, transactions, and payments. However, the payment process had become outdated and cumbersome. Customers were required to contact the call centre to manually lodge payments, a process that involved capturing payment details over the phone and manually associating them with accounts and cards to clear outstanding balances.

This method not only caused inefficiencies—such as long call centre wait times—but also restricted payment availability to business hours, frustrating customers. Our partner needed a modern, automated solution to allow customers to make payments at their convenience, while seamlessly integrating with their legacy AS400 system without risk of breakage or excessive cost.

The Challenges

Our partner faced a number of issues with their existing system. The AS400 system had been a reliable and functional server system. However it'd been in place for years, and continued use came with a number of challenges:

Operational Knowledge Gaps:

There was operational knowledge gaps — due to churn over time among technical staff. Upgrades were challenging, and considered risky and expensive.

Integration Issues:

Integration with modern cloud systems had several unknowns. Although our partner had externally hosted payment gateways in place for other services, integrating this with the AS400 system was complex, and came with potential PCI compliance issues.

Manual Processing:

Because of above limitations payments were processed manually. Customer service staff had to handle calls and put through payments, available only in business hours. The whole process was inefficient as well as restrictive on customers.

DevSecOps Compliance:

Any new solution would need to comply with our partner’s existing IT governance, including CI/CD pipelines, on-premises hosting, and integration with monitoring systems like Splunk and ServiceNOW.

Our Solution

Suffice to say the above was causing considerable friction and limitations on our partner's business. As experts in legacy migration Flowmoco was asked to come up with an appropriate solution. The big ask was an automated low-risk integration between their existing payment gateway and their AS400 system, without affecting PCI compliance. Their customers expected the ability to make real-time payments online, at any time.

Here’s how we addressed the challenges:

Containerised Middleware for Integration:

To bridge the gap between the payment gateway and the AS400 system, we developed a containerised, headless middleware solution. This middleware received webhooks from the payment gateway whenever a successful payment was made, and used vendor-supplied libraries to interact with the AS400 system.

IBM provide a handy JDBC driver, which we were able to utilise to execute SQL commands against the AS400 database from a JVM-based environment. This ensured data was updated correctly and in real time.

Rapid Deployment via CI/CD Pipelines:

We leveraged the client’s existing DevOps platform and implemented a CI/CD pipeline that integrated with our partner’s on-prem Kubernetes cluster, where the AS400 is hosted. The solution was containerised with Docker for local development and Kaniko for client DevOps, ensuring a smooth and efficient development cycle.
The deployment pipeline was designed to be fully compatible with our partner’s governance and security protocols, including full engagement with DevSecOps teams and integration into their structured monitoring systems.

Compliance with IT Operations and Governance:

As we touched on above, our approach was designed to integrate seamlessly with our partner’s existing monitoring and alerting systems (using Splunk and ServiceNOW), and fit into their existing change control and release processes. Production deployments were carried out by their Release Control team, with full approval from their Change Advisory Board (CAB).

Engagement and Collaboration:

As always we work closely as a strategic development partner, and with their network and DevOps teams. This allowed us to put in place smooth connectivity between the AS400 system and the Kubernetes environment. Additionally, our knowledge of the requirements for DevSecOps engagement allowed for a swift approval process, minimising delays and ensuring timely delivery.

Some details on the Tech Stack

Containerisation: Docker for local development, with Kaniko for DevOps.
Languages: Clojure, SQL, JVM, vendor JARs for AS400 interaction.
Monitoring: Structured JSON logs sent to Kubernetes, with alerting through Splunk and ServiceNOW.
Governance: CI/CD pipeline integrated, with production deployment via Release Control after CAB approval.
Hosting: On-prem Kubernetes cluster, interacting directly with the AS400 database.

Outcomes

We feel this solution is the best of both worlds. Our partner was able to completely avoid any risk in changing their legacy platform, and at the same time leverage a modern containerised middleware solution to automate a critical service. By approaching the problem this way we enabled our partner to achieve their 24/7 automated payment processing goal for Diesel Advance fuel cards. They got to be heroes to their customers, and reduce their call centre overheads.