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FUNNELWEB MANUAL WEB PAGE
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Copyright (c) Ross N. Williams 1992,1999. All rights reserved.
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Permission is granted to redistribute and use this manual in
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modifications since the manual's original release by Ross N.
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Williams (www.ross.net) consist of translations or other
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content. THIS MANUAL IS PROVIDED "AS IS" AND WITHOUT ANY
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<A HREF="intro.html"><FONT COLOR="#FFFFFF">1 Introduction</FONT></A><BR>
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<P><FONT SIZE="5">1.4 Diagnostics</FONT><BR>
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<P>During execution, FunnelWeb proceeds cautiously with
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each of its phases, only proceeding with the next phase if
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the previous phase has been successful. This means that,
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when debugging a FunnelWeb file, you may find that the
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number of errors <I>increases</I> after you fix some of
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them, as you will be exposing yourself to the next FunnelWeb
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<P>FunnelWeb employs five levels of
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diagnostics at different
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levels of severity. Severity is defined in
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terms of the level of activity at which the diagnostic
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causes FunnelWeb to abort.
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<P><BLOCKQUOTE><B>Warning:</B> A
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warning does not cause FunnelWeb
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to terminate or curtail its operation in any way, but serves
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merely to warn the user of particular conditions that might
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be symptomatic of deeper problems.</BLOCKQUOTE>
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<P><BLOCKQUOTE><B>Error:</B> An error
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causes FunnelWeb to terminate processing of the current
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input file at the end of the current phase. For example, if
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an error occurs during scanning, FunnelWeb will continue
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scanning (and possibly generate further scanning
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diagnostics), but will not invoke the parser.</BLOCKQUOTE>
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<P><BLOCKQUOTE><B>Severe Error:</B> A
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severe error (or "severe" for short) is the same as
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an error except that FunnelWeb terminates the current phase
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immediately.</BLOCKQUOTE>
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<P><BLOCKQUOTE><B>Fatal Error:</B> A
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fatal error causes FunnelWeb not only to terminate the
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current phase and run immediately, but also to terminate
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total FunnelWeb processing immediately. A severe error will
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not cause a FunnelWeb script to terminate, but a fatal error
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will. A fatal error causes FunnelWeb to return control to
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the operating system.</BLOCKQUOTE>
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<P><BLOCKQUOTE><B>Assertion
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Error:</B> An assertion error
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occurs if FunnelWeb detects an internal inconsistency, in
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which case FunnelWeb terminates immediately and
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ungracefully. Such an error can occur only if there are
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bugs in FunnelWeb. With luck, such errors will be extremely
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<P>FunnelWeb indicates the level of severity of each
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diagnostic that it issues by starting each diagnostic either
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with the full name of the severity level or with just the
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first letter of the severity level followed by a colon.
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<P>FunnelWeb conveys the presence or absence of
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diagnostics at the operating system level by returning
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<SAMP>EXIT_SUCCESS</SAMP> status if no
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diagnostics occurred during the run and
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<SAMP>EXIT_FAILURE</SAMP> status if one or more diagnostics
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(including warnings) occurred during the run. (From
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the symbols of the ANSI standard C library
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<SAMP>stdlib.h</SAMP>. See <STRONG>[Kernighan88]</STRONG>, p.252.)
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