Breaking the Monolith: Creating Serverless Functions (Microservices) from an IBM Mainframe Application (Done In 60 Seconds)

September 1st, 2018
A scene from the movie: Gone In 60 Seconds (Touchstone Pictures & Jerry Bruckheimer Films)

Square Pegs in Round Holes

I understand; you may already be skeptical. The application modernization arena has not done itself any favors with years of vendor misdirection and misleading claims (permeating from whitepapers and glossy write-ups that attempt to recast tired proprietary technology as modern & relevant — square pegs in round holes). We encounter that hurdle with every new client. Often, they are exasperated; so we simply show them exactly how we modernize their code using open software and the sense of mistrust quickly evaporates, replaced by the understanding that Heirloom can make their trusted legacy applications, agile. In the same vein, I am going to show you how Heirloom can take a function from a monolithic IBM Mainframe COBOL/CICS application and deploy it to a serverless environment as a microservice (using AWS Lambda coupled with the recent release of AWS Lambda Layers).

What is Heirloom?

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Heirloom is already the industry-leading solution for refactoring IBM Mainframe applications to the cloud. It is the only solution that was built for the cloud, delivering cloud-native deployment by automatically & accurately transforming online and batch COBOL & PL/I applications to 100% Java.

In 2018, we worked with Amazon to refactor an industry-standard TPC-C transaction processing benchmark written in COBOL/CICS from the IBM Mainframe to AWS Elastic Beanstalk, delivering 1,018 transactions per second — equivalent to the processing capacity of a large 15,200 MIPS IBM Mainframe — with a dramatically reduced annual infrastructure cost of $365K vs $16M. You can read more about this showcase on Amazon’s APN site.

What is Serverless Computing?

Beyond instance-oriented infrastructures (like AWS Elastic Beanstalk), are serverless compute/store infrastructures (like AWS Lambda) that deploy discreet functions as microservices.

With serverless computing, you run code without provisioning or managing servers (zero administration effort), required resources are continuously scaled (automatically), and costs are only incurred when your code is running (measured in sub-seconds).

Microservices provide a model for delivering high-quality applications that are agile, scalable, and available.

Breaking an IBM Mainframe Monolith into a Microservice

In the video below, we start with an IBM Mainframe COBOL/CICS application that has been refactored with Heirloom and is now running under a local instance of a Java Application Server (Apache Tomcat). The next steps taken with Heirloom to extract, create and deploy the microservice are:

  1. Create the application layer: The Heirloom “Facade Factory” is used to extract and refactor the “Get Credit Limit” logic from the monolithic application, as a discreet callable function (encapsulated in a Java jar package), and deployed as an AWS Lambda Layer (this is the “getAccount” application layer).
  2. Create the AWS Lambda service: We overlay a simple AWS Lambda service sample with the code to call “getAccount” with its defined inputs, and process the output (this is the “AccountLimit” service).
  3. Construct the microservice: Finally, we associate the “AccountLimit” service with the “getAccount” (application) layer and the Heirloom AWS Lambda (runtime) layer.

The combination of these components represents the entirety of the microservice stack. More simply stated, the stack looks like this:

[client] — invoke the microservice
    [AWS Lambda Service: AccountLimit] — service interface
        [AWS Lambda Layer: getAccount] — facade and extracted function
            [AWS Lambda Layer: Heirloom runtime] — Java framework for executing mainframe apps

The Heirloom AWS Lambda runtime layer provides everything you need to deploy microservices derived from your online and batch IBM Mainframe applications. It’s much more than just a language runtime — it’s a mainframe platform (implemented as a Java framework).

In summary, Heirloom can quickly & accurately refactor your IBM Mainframe applications to agile cloud infrastructures like AWS Elastic Beanstalk, Azure App Service, Pivotal Cloud Foundry, Red Hat OpenShift & Google Cloud Platform.

It can also enable & accelerate your transformation from monolithic application architectures to microservices running on serverless computing infrastructures like AWS Lambda.