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)
Part 1: Legacy Estate Options
Chapter 2: Strategies for Modernizing IBM and Unisys Mainframes
Part 2: Architecture Options
Part 3: Azure Deployment and Future Considerations

What is a monolith?

For the purposes of this book, a monolithic application has the following characteristics:

  • It is a single overall application where individual pieces have strong dependencies—in other words, a single overall code base where the code in modules does not function independently and changes to one module affect other modules.
  • If required, it typically scales up rather than scales out.
  • It depends on OS-specific services for functionality, making them tightly coupled to a specific vendor.
  • It is difficult to separate functionality to modernize code a piece at a time, usually requiring a big bang or modernizing the entire mainframe at the same time approach to modernization. This includes testing required for the whole system.
  • It is difficult to make changes in one place in the code without breaking functionality in a different place.

The obvious question that comes up deals with why anyone would develop a monolithic system in the first...