Xinuos Developer Network

Guide to Software Development Kits on Xinuos Systems

C and C++
    Compilers and ABIs
    Which Compilers to Choose?
       UnixWare OpenServer Development Kit, Open UNIX Development Kit
       OpenServer Development System
    Binary Compatibility Modules and Runtime Library Packages
    Still Not Sure?
Other Languages
Older Platforms
Further Information


I want to develop an application for a Xinuos platform or port an existing application to a Xinuos platform.  What development system should I use?

A good question, and we're glad you're interested in building applications for Xinuos!

The answer can sometimes get a little complicated. Xinuos has several different operating system product lines:

  • UnixWare 7 and Open UNIX 8
  • OpenServer 5

and several different development systems packages that can be used on those operating systems. But this guide will help you figure out what is the right one to use.

To begin with, what language(s) are you developing in?


If you are developing in Java, the answer is simple. Use the Java 2 Standard Edition, Software Development Kit for either UnixWare 7, OpenServer 5, or OpenServer 6).

It's free, and if the version you want isn't already pre-installed on your system, it can be downloaded from our web site.

Of course, if your application is 100% Java and already exists on another platform, you may well not need to modify or port it at all for Xinuos; just take the bytecodes and move them onto a Xinuos machine and run them. Most current Xinuos operating systems come with a Java 2 Standard Edition runtime environment pre-installed on them.

C and C++

There are multiple choices of C and C++ compilers for many of Xinuos's operating system platforms.

Compilers and ABIs

The following chart shows what C/C++ development kits are available on what Xinuos operating system platforms, and what ABI each development kit's compiler generates and supports.

An ABI (application binary interface) is the binary layout of structures, stack frames, register assignments, etc. that a compiler generates, as well as the compiled representation of system header file constants, function calls, and directory locations. ABIs are a function of the underlying machine architecture, the operating system, and the compiler.

Within a single process it is usually not possible to mix object files compiled with different ABIs, meaning you cannot link together .o, .a, or .so files that were generated with different ABIs.

Open UNIX 8 UnixWare 7 OpenServer 5
Open UNIX Development Kit [OUDK] U U
UnixWare OpenServer Development Kit [UDK] U U   U*
OpenServer Development System O

ABI key:
U UnixWare/SVID i386 ABI
O OpenServer i386 ABI

*UnixWare ABI programs can run on OpenServer 5 when the OSRcompat compatibility package is installed.

The above ABIs refer to what is generated for the C programming language. For C++, every compiler has a different ABI; you can never combine the object code from two different C++ compilers.

Which Compilers to Choose?

The following sections will describe the different C and C++ compilers available on Xinuos platforms, the advantages and limitations of each of them, and how you obtain them.


GCC is the GNU Compiler Collection set of compilers and tools such as gcc and g++. These are well-known, high-quality, open source tools that are heavily used on many platforms.

Advantages. As you can see from the chart above, the GNU GCC compilers are the one choice that is available on all SCO platforms. If you use GCC on other platforms, you'll experience no learning curve in using it on a SCO platform. If your application has been built with GCC on other platforms, it will be quickest to port if you use GCC on a SCO platform. The C++ compiler in GCC implements many of the new C++ language and library features from the 1998 ANSI/ISO C++ standard. GCC is free.

Limitations. The GCC compilers are idiosyncratic in language interpretation, and you must be careful if you want source code built with them to be portable to non-GCC compilers. The C compiler in GCC only implements a few of the new C language and library features from the 1999 ANSI/ISO C standard. Debugging with multi-threaded and multi-process applications can be problematic. Performance of generated code is generally not as good as with the other SCO compilers discussed here, although only very performance-sensitive applications will notice the difference. Using GCC to build UnixWare 7 or OpenServer 5 device drivers is possible but not recommended. GCC cannot be used to build JNI native code on OpenServer 5, and it cannot be used to build JNI Invocation native code on UnixWare 7.

Availability. On SCO OpenLinux and UnixWare 7 with LKP, GCC is available as part of the rpm packages contained on the distribution. On UnixWare 7, the official and best GCC version may be found in the Open Source Tool Kit at On SCO OpenServer 5, GCC may be found in the Skunkware collection at in the development tools area. As of SCO OpenServer Release 5.0.7, an official version of GCC will be included as part of the operating system.

UnixWare OpenServer Development Kit, Open UNIX Development Kit

SCO provides the UnixWare and OpenServer Development Kit (UDK, sometimes also referred to as UODK) for UnixWare 7. (During the Open UNIX 8 period of this product, this was known as the Open UNIX 8 Development Kit, or OUDK. This was very similar to the UDK except that it could not be used on or for OpenServer 5.)

As suggested by its full name, the UDK also has to ability to be installed and used on OpenServer 5. In order for a UDK-built application to execute on OpenServer, the OSRcompat Binary Compatibility Module package must be installed on both development and application deployment systems.

Advantages. This is the choice if you want the generated code of your applications to have the best performance, especially on Pentium Pro, Pentium II, and subsequent IA-32 machines; performance is usually superior to either GCC or the OpenServer Development System. The UDK C and C++ compilers support almost all of the language and library features in the 1999 C and 1998 C++ ANSI/ISO standards. On OpenServer 5, you must use the UDK compiler if you are writing Java native code (JNI). The UDK debugger is generally the strongest debugger of all these choices. The UDK/OUDK should be used if you are writing an UnixWare 7 or Open UNIX 8 device driver.

Limitations. The UDK cannot be used for OpenServer device drivers. The UDK cannot be used on OpenServer for APIs that are not common to both OpenServer and UnixWare 7. Most significantly, the UDK cannot be used on OpenServer if you need to link against existing third-party object files or libraries that were built with the OpenServer compiler.

Availability. The UDK and OUDK are licensed products from SCO; discounts are available if you join the SCO Developer Network. The UDK is available as part of the UnixWare 7 media kit, and can also be installed on Open UNIX 8 and the older UnixWare 7.1.1.

OpenServer Development System

The SCO OpenServer Development System is the development system specifically designed for use with OpenServer; it is sometimes referred to as the "native" OpenServer development system.

Advantages. This is the best development system to use if you are writing an OpenServer 5 device driver. It also provides the best integration with OpenServer system headers and system libraries, and with existing third-party objects and libraries. It is the compiler to use when generating older object formats (COFF).

Limitations. These compilers do not produce code specifically optimized for Pentium Pro, Pentium II, or later IA-32 architectures. The C compiler represents the 1990 level of the language and does not include any of the new language or library features of the 1999 ANSI/ISO C standard. The C++ compiler represents the 1992 level of the language and does not include any of the new language or library features of the 1998 ANSI/ISO C++ standard. Debugger support of C++ is weak. These compilers lack the 64-bit long long integer type and have limited flexibility in incorporating inline assembly code. Java JNI native code cannot be built with these compilers. No enhancements have been made to these compilers in a number of years and none are planned.

Availability. This is a licensed product available from the OpenServer media kit; discounts are available if you join the SCO Developer Network.

It is important to avoid confusion between this and the UnixWare and OpenServer Development Kit (UDK), since both are included in the OpenServer 5 media kit. Using one when the other is required will always lead to failure!

Binary Compatibility Modules and Runtime Library Packages

Here are a couple of cases where you may need to install an additional package to enable your development system of choice.

In order for either Java applications or for UDK-built applications to run on OpenServer 5, the appropriate Binary Compatibility Module (package OSRcompat) must be installed on the OpenServer system. The Binary Compatibility Module is free and you may redistribute it with your application. The latest version of the Binary Compatibility Module for OpenServer 5 is available from the UnixWare 7 media kit and also from the SCO download site.

In order for some UDK-built applications to run on older UnixWare 7 systems, the UDK runtime libraries must be installed on the UnixWare 7 system. These libraries are free and you may redistribute them with your application. The libraries are available from the UnixWare 7 media kit.

Still Not Sure?

Thanks for all this information, but I'm still a bit confused about which C and C++ compilers I should be using.

OK, let's look at it from a different angle. What operating system are you developing on or for?

If it's UnixWare 7, you have two choices, GCC or the UDK. Most of the time this is a matter of personal preference; both are good toolsets. If you are interfacing at the object code level with an existing application, use the compiler that was used to build that. If you are writing device drivers or a certain kind of Java JNI native code, UDK is the better choice. If you are building open source code, GCC is often the path of least resistance.

If it's OpenServer 5, then you have three choices, and this is where people tend to experience the most uncertainty. But your circumstances will often narrow your choices down:

  • If you are writing device drivers, use the OpenServer 5 Development System.
  • If you are generating COFF, use the OpenServer 5 Development System.
  • If you are writing Java JNI native code, use the UDK.
  • If you linking against legacy or third-party libraries, don't use the UDK. *
  • If you are using an API that doesn't exist in UnixWare, don't use the UDK.
  • If you are writing in C++, avoid the OpenServer 5 Development System.
  • If you are building open source code, GCC usually works best.

If none of these considerations apply, then the decision is often just a matter of personal preference.

* Yes, if you are writing Java native code to interface to a third-party library, you have a problem! Split your native code into a separate process and communicate via a socket.

Other Languages

Languages other than Java, C, and C++, such as Fortran, COBOL, and Ada, as well as fourth-generation languages associated with databases and scripting languages, aren't discussed here. Development tools for these languages are provided by third-party vendors for SCO. Also there may be open source solutions that you can use, such as the GNU g77 Fortran compiler or the GNU-based GNAT Ada 95 compiler.

Older Platforms

There are some older SCO operating systems that pre-date OpenServer and UnixWare 7, such as UnixWare 2, SCO UNIX, and Xenix, that are still in use.

Development systems for these are not covered here, but you can find out about some of them in the comp.unix.sco.programmer FAQ.

These older operating systems are no longer supported by SCO, and we recommend that you upgrade your platform and your development tools to currently supported SCO products if possible.

Further Information

So that's the whole story?

Well, it's the introduction. Additional material about each of the development systems can be found by following the links shown above. Also, consult the appropriate SCO product documentation, all of which is based at

The Usenet newsgroups comp.unix.sco.programmer and comp.unix.unixware.misc are also a good place to read about these development systems and to ask questions about their use.

We hope you enjoy your experience in developing on SCO platforms!