What are porting, integration, and compatibility?

The terms porting, integration, and compatibility have commonly understood meanings with regard to operating systems and the services they provide to applications:

``Porting''

The process of making software that was written for one operating environment work in another operating environment. Porting can be done at the binary (application) level, or at the source code level.

UnixWare 7 is designed to allow most UnixWare and SCO OpenServer applications to run without modification to the source code of the applications. You should be able to install most UnixWare and SCO OpenServer applications using custom(1M) or pkgadd(1M), and they will run.

Some applications will require a recompile and possibly a rewrite of the source code in order to work on UnixWare 7.

``Integration''

The process of packaging an already ported application for installation on the new system. This can range in complexity from just re-packaging the existing source code to use the new system's packaging tools, to making additional source code changes to make the application conform to the new system's user interface, internationalization tools, and program execution environment.

``Compatibility''

The degree to which an application, or the program execution environment of the target system, must be altered to allow the application to install and run on the target system.

The degree to which the target system provides workarounds to the compatibility issues which arise between the native and the target systems is the compatibility provided by the new system.

Compatibility issues are, in general, defined by:

• the sum of the differences between the services offered to your application by the operating system on which you originally wrote the application to run (the ``native'' system) and the new operating system (the ``target'' system)

• the degree to which the application adheres to application programming standards and uses industry standard interfaces

Compatibility issues generally span all porting and integration activities.

Applications that use portable coding practices and use only those interfaces supplied by the operating environment that adhere to industry standards are called ``portable applications''. A particular application is more or less portable depending on the way it is coded and the system services on which it depends.

What makes portable applications difficult to write are the differences between the way in which system services (and their access points in system calls and libraries) are implemented on the target systems on which you want your application to work.