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

IBM iSeries

The IBM iSeries was developed in the mid-1980s to address a market for applications where a mainframe was either too large or too expensive. The original systems included IBM System 34/36/38 and the AS/400 systems. iSeries is often referred to as AS/400. These systems were cost-effective and efficient alternatives to the mainframe and required far less ongoing administration and maintenance.

OS/400 overview

While AS/400 refers to the hardware, OS/400 refers to the operating system for iSeries. OS/400 is an operating system where the data, applications, scripting, and communications work tightly together. This makes OS/400 very efficient, but this also can make it difficult to migrate the applications without transforming the entire environment (apps, data, administration).

OS/400 runs applications written in both Cobol and RPG, with RPG having the lion’s share (80%) of the applications. OS/400 uses a scripting language called Control Language (CL), which...