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Challenges of Migrating Legacy
Applications to AWS

Satrajit Basu


In a world of rapidly changing technology, many organizations still rely on legacy mainframes to keep their most critical operations running. These age-old systems have been tuned and customized to meet the functional requirements of the business, and as a result, have become locked-in to vendors over the years. However, maintaining and supporting these systems can be a challenge, as resources are scarce, and the lack of an integrated testing environment can limit flexibility, add risk, and increase test time. In addition, legacy technology can encounter problems with maintenance, support, improvement, integration, and user experience.
Recently my team and I were discussing how to help our clients unlock the value of their industrial and manufacturing data. These industries often wrestle with terabytes of time-series data from a myriad of sensors, machines, processes and external sources. Each data source could potentially include different features with various formats, have non-rationalized time intervals and be generated from various proprietary technologies. The challenge of making this data available on a platform where workers can exploit the data and discover its hidden value can be overwhelming. Here is where the vision of AI Democratization often hits its first significant roadblock.

Managers who are tempted to feel elated at the prospect of having access to all the data they could ever wish for, soon realize it is a data sword of Damocles* hanging by a thread, ready to snap and bury them if they can’t find a way to unlock its value.
Richard Westall’s Sword of Damocles, 1812
* The parable of the sword of Damocles teaches us that no matter how good someone’s life may appear, it’s difficult to be happy living under existential threat.

So, what's the solution?

The answer lies in application, information, and data migration. By migrating to the cloud, organizations can improve their operational efficiency, reduce IT costs, improve performance, and take their business to the next level. Modern technology solutions can introduce automation to manual processes, which are prone to errors, and enhance reporting and rich featured UI and rules engine, allowing businesses to manage data more efficiently, and changes will be reflected in real-time.

The ultimate objective

The ultimate objective is to sunset the legacy system with minimal disruption to the business and transition towards a more robust and scalable information technology platform to support current and future business needs in a cost-effective and collaborative manner. This also involves designing a common technology platform for operational applications to minimize data redundancy, decrease the cost of building, integrating, and maintaining new and existing applications.

However, migrating from legacy mainframes to modern technology solutions is not without its challenges.
The key challenges during the migration process includes:
  • Rewriting application architecture for the cloud
  • Complexity of the integration of data, systems, and processes
  • Compliance and security
  • Dealing with hybrid networking setups
  • Investing in people and tools needed to migrate successfully
  • Training users on the new systems
To overcome these challenges, businesses need to have a clear set of guiding principles in place.
Consider these solutions and guiding principles:
  • Create a reference architecture for the legacy application to migrate to a cloud-native architecture on AWS.
  • Compliance & Security, Hybrid connectivity – AWS Accounts/VPCs, including TGW, Direct Connect Gateway, multi region peering, Landing Zones, VPCs AZs Subnets, Security Groups, IAM role
  • Data Security – Encrypted at Rest (AWS KMS), Encrypted at transit (SSL/TLS)
  • Real Time Transactions and Streaming, Messaging Integrations– SNS, SQS, MSK, Kinesis
  • Adapters – On-Prem to cloud protocol bridge
  • Use Serverless components/services as much as possible – Lambda, StepFunctions for workflow
  • AWS API Gateway – Lambda functions are invoked through API Gateway
  • Computation – Application container in EKS
  • ALB – EKS pods are invoked using ALB
  • AWS Secret Manager – Store credentials securely

In conclusion, the migration from legacy mainframes to modern technology solutions, such as AWS, is no longer an option but a necessity for businesses that want to remain competitive and agile. While the migration process may seem daunting, it can be successfully achieved with careful planning and execution, along with adherence to guiding principles. By leveraging AWS’s cloud-native architecture and services, organizations can improve operational efficiency, reduce costs, and enhance their overall competitiveness. With the right strategy and tools, the migration journey can result in a more robust and scalable information technology platform that meets current and future business needs.