Book Image

Modernizing Legacy Applications to Microsoft Azure

By : Steve Read, Larry Mead
Book Image

Modernizing Legacy Applications to Microsoft Azure

By: Steve Read, Larry Mead

Overview of this book

Organizations have varying circumstances, objectives, and prerequisites when contemplating a hyper-scale cloud solution transformation to a platform such as Azure. Modernizing Legacy Applications to Microsoft Azure uncovers potential scenarios and provides choices, methodologies, techniques, and prospective possibilities for transitioning from legacy applications to the Microsoft Azure environment. You’ll start by understanding the legacy systems and the main concerns regarding migration. Then, you’ll investigate why distributed architectures are compelling and the various components of the Azure platform needed during migration. After that, you’ll explore the approaches to modernizing legacy applications and the Rs of modernizing (i.e., rehost, refactor, rearchitect, and retire). You’ll also learn about integration approaches and potential pitfalls. By the end of this book, you’ll be well equipped to modernize your legacy workloads while being aware of pitfalls and best practices.
Table of Contents (18 chapters)
1
Part 1: Legacy Estate Options
3
Chapter 2: Strategies for Modernizing IBM and Unisys Mainframes
6
Part 2: Architecture Options
10
Part 3: Azure Deployment and Future Considerations

Where we are today

Today, Azure can successfully run mainframe applications in the following ways:

  • Rehost: Take COBOL/PL/I/Assembler on VMs and containers that provide source compatibility for these languages
  • Refactor: Take legacy languages and refactor them into more modern languages such as C# or Java, then run the converted code in VMs, containers, or microservices
  • Rewrite: Take legacy mainframe systems and rewrite them to be Azure-native

While these approaches can work for most legacy systems, there are several downsides. The following table compares the advantages and disadvantages of the currently available approaches:

Approach

Time to Complete

Cost

Risks

Comments

Rehost

9 to 24 months

Low to medium

Low

...