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<TITLE>TDF and Portability</TITLE>
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<BODY TEXT="#000000" BGCOLOR="#FFFFFF" LINK="#0000FF" VLINK="#400080" ALINK="#FF0000">
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<H1>TDF and Portability</H1>
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<H3>January 1998</H3>
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<IMG SRC="../images/no_index.gif" ALT="document index"><P>
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<HR>
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<DL>
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<DT><A HREF="#intro"><B>1</B> - Introduction</A><DD>
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<DT><A HREF="port3.html#S2"><B>2</B> - Portability</A><DD>
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<DT><A HREF="port4.html#S22"><B>3</B> - TDF</A><DD>
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<DT><A HREF="port5.html#S51"><B>4</B> - Conclusions</A><DD>
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<H1><A NAME="intro">1. Introduction</A></H1>
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TDF is the name of the technology developed at DRA which has been
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adopted by the Open Software Foundation (OSF), Unix System Laboratories
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(USL), the European Community's Esprit Programme and others as their
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Architecture Neutral Distribution Format (ANDF). To date much of the
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discussion surrounding it has centred on the question, "How do
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you distribute portable software?". This paper concentrates on
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the more difficult question, "How do you write portable software
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in the first place?" and shows how TDF can be a valuable tool
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to aid the writing of portable software. Most of the discussion centres
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on programs written in C and is Unix specific. This is because most
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of the experience of TDF to date has been in connection with C in
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a Unix environment, and not because of any inbuilt bias in TDF.<P>
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It is assumed that the reader is familiar with the ANDF concept (although
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not necessarily with the details of TDF), and with the problems involved
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in writing portable C code.<P>
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The discussion is divided into two sections. Firstly some of the problems
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involved in writing portable programs are considered. The intention
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is not only to catalogue what these problems are, but to introduce
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ways of looking at them which will be important in the second section.
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This deals with the TDF approach to portability.<P>
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<P><I>Part of the <A HREF="../index.html">TenDRA Web</A>.<BR>Crown
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Copyright © 1998.</I></P>
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