Migration or Coexistence?

With a large code base of installed UNIX applications, you are probably unlikely to relish the thought of throwing the entire environment out and starting again with an unfamiliar platform. Fortunately, as this guide shows, you do not necessarily have to ” there are methods that will allow you to preserve your investment in UNIX applications while developing under or moving to Windows over a longer period.

This guide deals with the four possible options for migration or coexistence between UNIX and Windows. These are:

• Using a quick port.

• Completing a full port.

• Rewriting the application.

• Allowing two versions to coexist.

The following subsections describe these options in greater detail.

Using a Quick Port

One of the simplest migration paths possible is to port the code directly to Microsoft Services for UNIX 3.0. Services for UNIX 3.0 includes Microsoft Interix, which provides a UNIX environment that runs on top of the Windows kernel, allowing your native UNIX applications and scripts to work alongside Windows-based applications.

Completing a Full Port

A full port involves migrating your software to Windows with the minimum changes necessary to allow the application to run. Unlike the quick port, this does entail alterations to the source code, although the number of modifications will depend on the level of standards compliance within the original application.

Rewriting the Application

Rewriting the application is the ideal approach if you want to make full use of all the benefits of migrating to the Windows platform. While initially requiring the greatest amount of work, this course also promises the greatest rewards.

Allowing Versions to Coexist

With coexistence, you retain the original application alongside the new version while simultaneously porting or rewriting the application. Taking this approach significantly reduces risk, because it allows you to use the original system if unexpected issues appear with the new application. However, you will need to employ a cross-platform source code control system to allow concurrent development on both UNIX and Windows simultaneously.

Chapter 3, The Migration Process, and Chapter 4, Assessment and Analysis, cover these options in greater detail, allowing you to decide which is the most appropriate choice or combination of choices for your particular environment.