"Craig R. McClanahan" wrote:
>
> James Duncan Davidson wrote:
>
> > > - map a servlet X to "/"
> > > - map a servlet Y to ".html"
> > > - map a servlet Z to "/file.html"
> > > - map a servlet A to "/catalog"
> > > - map a servlet B to "/catalog/foo"
> > >
> > > - request "/file.html" should be served by Z
> > > - request "/foo.html" should be served by X
> > > - request "/catalog/foo/bar" should be served by B
> > >
> > > It would be nice if James Davidson can confirm this.
> >
> > As requested -- this is the way that the spec is intended to work.
> >
>
> OK, now I have a question ... how does a servlet engine know the difference
> between the mapping for servlet Z and servlet A? In other words, is the
> difference between a file mapping and a directory mapping because of the
> existence of the period in the Z mapping, or what?
>
> I'm mostly concerned about how you tell the difference between an "individual
> URL" match (which might be followed by some extra path information!) and a
> "directory path" match. For example, what would you do with
> "
But then /file.html is just a dir in the URL path... Not a file any
more. Actually, technically, there is no such thing as "file" in URL
strings -- everything describes a resource. But that's neither here nor
there.
The way we really have it (the way that the rules describe, it's just
non obvious on first read), is that we first treat the URL path as a '/'
seperated list of tree nodes. We walk the list till we find a match.
Note that doing this, we don't make any assumption about a node being a
file or a directory. -- /catalog/foo/bar/index.html becomes a list of
"catalog"+"foo"+"bar"+"index.html".
If we don't get a match, then we look for a case where we can make an
extension match -- now we are making some assumptions about the
distinction between files and dirs in the URL space -- it's not exactly
fair, but it's damn useful, so we do it.
If we still don't get a match, we give up.
> The rules that make the most sense to me are:
> * "Longest prefix" match (except for "/"); else
> * Extension match (which cannot include extra path info); else
> * "/" match (i.e. the default servlet) if nothing else matches
> without any special cases for exact pathname matching.
The way these rules apply does pretty much this...
How it's implemented in servletrunner is the following (this is
pseudocode for clarity, not the actual code used in the impl!):
String path = request.getRequestURI();
ServletWrapper s = null;
while (nomatch && path.length > 1) {
s = container.lookup(path);
if (s != null) {
nomatch=false;
} else {
path = path.substring(0, path.lastIndexOf("/"));
}
}
if (s == null) {
// see if path has a '.' in it, grab that and try to make
// an extension match
String ext = path.substring(path.indexOf('.'), path.length());
s = container.lookupOnExt(ext);
}
if (s == null) {
s = defaultServlet;
}
Given the rules above we'd do a search for a servlet on path
"/file.html/extra/path/info" like:
/file.html/extra/path/info --> No
/file.html/extra/path --> No
/file.html/extra --> No
/file.html --> Yes, cool
So you get the behavior that you are describing the the way that you say
the rules make sense....
Have I totally scrambled you neurons? Or does this make sense? It is
first thing in the morning for me after a long long night so I wont take
offense if you say "What the heck are you talking about James!" :)
.duncan
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