Re: Basic CGIDEV2 problem

[David FOXWELL <David.FOXWELL@xxxxxxxxx>]

Ok so now I understand why Raul said I was missing the <p>!

Thanks Scott, it's a great feeling learning new stuff like that, and I'm happy that my post has benefited others on the list too.


> -----Message d'origine-----
> De : web400-bounces@xxxxxxxxxxxx
> [mailto:web400-bounces@xxxxxxxxxxxx] De la part de Scott Klement
> Envoyé : jeudi 4 juin 2009 18:57
> À : Web Enabling the AS400 / iSeries
> Objet : Re: [WEB400] Basic CGIDEV2 problem
>
> Hi David,
>
> > I wish I fully understood all those Alias and
> ScriptAliasMatch lines, though.
>
> Alias, AliasMatch, ScriptAlias and ScriptAliasMatch aren't
> too hard to understand.  I'll try to explain them, but please
> ask questions if you still don't understand.
>
> BACKGROUND
> ----------
> When you configure Apache, you give it a DocumentRoot.  This
> is an IFS pathname to the start of your web server.  In the
> simplest configuration, everything on your server would be
> under DocumentRoot.
> So you might have this:
>
> DocumentRoot /www/myserver/htdocs
>
> HTTP was designed for fetching documents (originally, that's
> all you could do, just fetch a document, nothing else).  So a
> browser would code something like this:
>
> http://www.example.com/mydir/mydoc.html
>
> This tells the browser (a) use the http protocol.  (b),
> connect to www.example.com, and (c) ask for the document
> named /mydir/mydoc.html
>
> Apache will get that request, but it'll add the DocumentRoot
> to it.  So the actual IFS path to the document will be
> /www/myserver/htdocs/mydir/mydoc.html
>
> That's the simplest behavior.  It lets you designate some
> part of your IFS (DocumentRoot) where all subfolders will be
> accessible via URLs.
> That's the basic configuration.
>
> ALIAS
> -----
> What if you want something OUTSIDE of that area to be
> accessible to the browser?  How would you do it?  You declare
> an Alias.
>
> DocumentRoot /www/myserver/htdocs
> Alias /foo /home/scott/bar
>
> This says that all URLs go under /www/myserver/htdocs, just
> as in the previous example... EXCEPT for /foo.  Any URL
> starting with /foo will point to /home/scott/bar
>
> So this works just as it did before:
> http://www.example.com/mydir/mydoc.html
>
> But this works differently.
> http://www.example.com/foo/mydir/mydoc.html
>
> In this second case, the /foo is an alias for
> /home/scott/foo, so the URL points to
> /home/scott/bar/mydir/mydoc.html.
>
> That's all an alias does.  It provides a way to specify
> directories in the URL that are "redirected" to another area
> of the IFS, outside of the document root.
>
> ALIASMATCH
> ----------
> AliasMatch does the same thing that Alias does, except it
> allows "wildcards" (technically... Regular Expressions.)  For
> example, I could do something like this:
>
> AliasMatch /foo/(.*jpg) /images/jpg/foo/$1
>
> In a regular expression, a single dot matches any one
> character.  An asterisk says "zero or more of the preceding
> character".  So when you have .* it matches any number of any
> character.  In this example, any URL that begins with /foo/
> and ends with jpg will match the alias.
>
> In Apache, the parenthesis designate a section of the URL o
> be copied to the resulting URL.  So in this example, the
> /foo/ is not in parenthesis, but the .*jpg is.  So whatever
> matches the wildcard of .*jpg will be considered "variable
> number 1".  You'll notice the result is
> /images/jpg/foo/$1 -- that $1 will be replaced at runtime
> with whatever matched the .*jpg pattern.
>
> Example:
>
> http://www.example.com/foo/goofy/scott_dancing.jpg
>
> Once the hostname is removed, it starts with /foo/ and ends
> with jpg, so it matches the Alias.  The (.*jpg) part will
> match goofy/scott_dancing.jpg, so Apache will access the
> /images/jpg/foo/goofy/scott_dancing.jpg file in the IFS
>
> FWIW, I tend to avoid AliasMatch (or ScriptAliasMatch) since
> they run slower, and IMHO, they're more complicated than I
> need for my projects.
>
> SCRIPTALIAS
> -----------
> If you understood Alias, then ScriptAlias should be easy.
> There's really only one difference.  Alias is for fetching a
> document... it tells Apache which document in the IFS to
> fetch.  By contrast, ScriptAlias is for running a script or
> program.  Instead of downloading the program object to the
> browser (that's what Alias would do), ScriptAlias tells
> Apache to run the program.  The output of the program will be
> sent to the browser, instead of downloading the program object itself.
>
> Without ScriptAlias:
>
> DocumentRoot /www/myserver/htdocs
>
> http://www.example.com/qgpl/pmu010.pgm
>
> This tells Apache to go to the /www/myserver/htdocs/qgpl
> directory and download a program named pmu010.pgm to the browser.
>
> With ScriptAlias:
> DocumentRoot /www/myserver/htdocs
> ScriptAlias /qgpl /QSYS.LIB/QGPL.LIB
>
> http://www.example.com/qgpl/pmu010.pgm
>
> Hopefully you already understand that /QSYS.LIB in the IFS
> provides access to your traditional libraries and their
> contents.  With that in mind, Apache will build the IFS
> pathname of /QSYS.LIB/QGPL.LIB/PMU010.PGM and it will
> therefore be equivalent of CALL PGM(QGPL/PMU010)
>
>
> SCRIPTALIASMATCH
> ----------------
> Same as ScriptAlias, except it now has regular expressions
> ("wildcards") available. ScriptAliasMatch is to ScriptAlias
> what AliasMatch is to Alias.
>
> The installer for CGIDEV2 likes to set things up like this:
>
> ScriptAliasMatch /mylibp(.*).pgm /qsys.lib/mylib.lib/$1.pgm
> AliasMatch /mylibh/(.*)\.htm  /QSYS.LIB/MYLIB.LIB/HTMLSRC.FILE/$1.mbr
> Alias /mylibh/ /QSYS.LIB/MYLIB.LIB/HTMLSRC.FILE/ Alias /mylib/ /mylib/
>
> The ScriptAliasMatch at the top says that any URL that begins
> with /mylibp and ends with .pgm should be run as a program in
> /qsys.lib/mylib.lib.  Contrast these two statements:
>
> ScriptAlias /mylibp /qsys.lib/mylib.lib
> ScriptAliasMatch /mylibp(.*).pgm /qsys.lib/mylib.lib/$1.pgm
>
> In the first case, anything that starts with /mylibp
> (including files, data areas, queues, user spaces, etc) will
> be run as a program from the /QSYS.LIB/MYLIB.LIB library. Of
> course, if you list a program object, no problem, it'll run
> it.  If you list a non-program object, however, Apache will
> still try to call it (though, it'll fail with an error.)
>
> In the second case, only URLs that end in .PGM are called.
> Apache will forcibly add the .pgm extension to it when it
> tries to call it.
> Therefore, non-programs will not match this script alias.
> Instead, they'll match this one (also from the configs, above)
>
> Alias /mylib/ /mylib/
>
> This tells it to go to the /mylib/ folder of the IFS instead
> of the library.  So program objects go to the library,
> non-program objects go to an IFS folder.  If you left off
> this extra Alias, it would go to the DocumentRoot instead --
> and go to /www/myserver/htdocs/mylib.
>
> Shrug... I personally prefer to go in and delete the CGIDEV2
> provided instructions and insert my own.  I don't like the
> instructions they provide.  They're more complicated than
> they need to be, IMHO.
>
> But, anyway... hope this all made sense.
> --
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