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Ada Flyer STRIC: A Full-Scale Proof
of Reuse & Portability

The System
The STRIC system is a large command, control and communication system for the Swedish Air Force. Its tasks are fighter interceptor control and all the additional functions that are needed in such a system. In total, the system will comprise between 1 and 2 million lines of code. The development is well under way, and the final system will be delivered in a few years time. This system development has involved two interesting challenges: porting a system architecture to a new application area, and porting to a new platform.
Applying the Architecture
CelsiusTech had earlier developed a number of ship systems based on the Ship System 2000 system architecture (SS2000), but wondered if the architecture could also be applied on a system in a completely new application area. During the preliminary design, the answer appeared to be "YES." It was estimated that more than 50% of the system could be reused. The degree of reuse would vary among the different layers. In the general application framework, the base system, almost everything could be reused. Moreover, much of the application layer also had similar functionality, with a corresponding degree of reuse. Other areas were completely different, offering little or no opportunity for reuse. The table below shows the estimated level of reuse; the percentages listed here document the portion of the delivered code that is reused from SS2000:
Command and control 10%
Surveillance 40%
Communications 20%
MMI 80%
Base system 80%
Changing the Platform
The other challenge to this system design was the change of computer platform. The ship systems are based on M68k computers, running a realtime kernel called OS9; the STRIC system, however, should preferably be based on a Posix platform. The SS2000 was designed to be portable. The application does not directly use the existing OS-calls, but uses only the base system components, which define a relatively narrow interface. By porting only the base system components that isolated the OS, the complete application could be ported. An initial project was set up to verify the portability. In less than 1000 man hours, the initial port was done: 400,000 lines of code in 6,000 modules. The porting rate was more than 500 lines per hour.
Ada’s Role
How much of STRIC’s success is due to Ada? While no system is portable or reusable just because it is written in Ada, the use of the programming language has made it possible to ensure that the intent of the system architecture is followed and that no short cuts are taken. By reducing the amount of programmers’ unscheduled system improvizations, the design team was able to recognize in full the benefits of reuse and portability.
This flyer is based on an article by Bjorn Kallberg, PhD, Senior Scientist, CelsiusTech Systems AB, printed in “Ada-Europe News,” October 1994, No. 19, pp.25-26.

Copyright 1998. IIT Research Institute
All rights assigned to the US Government (Ada Joint Program Office). Permission to reprint this flyer, in whole or in part, is granted, provided the AdaIC is acknowledged as the source.
Form U190 stric.txt

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