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.IX Title "Plack::App::URLMap 3pm"
.TH Plack::App::URLMap 3pm 2024-01-20 "perl v5.38.2" "User Contributed Perl Documentation"
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.\" way too many mistakes in technical documents.
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.nh
.SH NAME
Plack::App::URLMap \- Map multiple apps in different paths
.SH SYNOPSIS
.IX Header "SYNOPSIS"
.Vb 1
\&  use Plack::App::URLMap;
\&
\&  my $app1 = sub { ... };
\&  my $app2 = sub { ... };
\&  my $app3 = sub { ... };
\&
\&  my $urlmap = Plack::App::URLMap\->new;
\&  $urlmap\->map("/" => $app1);
\&  $urlmap\->map("/foo" => $app2);
\&  $urlmap\->map("http://bar.example.com/" => $app3);
\&
\&  my $app = $urlmap\->to_app;
.Ve
.SH DESCRIPTION
.IX Header "DESCRIPTION"
Plack::App::URLMap is a PSGI application that can dispatch multiple
applications based on URL path and host names (a.k.a "virtual hosting")
and takes care of rewriting \f(CW\*(C`SCRIPT_NAME\*(C'\fR and \f(CW\*(C`PATH_INFO\*(C'\fR (See
"HOW THIS WORKS" for details). This module is inspired by
Ruby's Rack::URLMap.
.SH METHODS
.IX Header "METHODS"
.IP map 4
.IX Item "map"
.Vb 2
\&  $urlmap\->map("/foo" => $app);
\&  $urlmap\->map("http://bar.example.com/" => $another_app);
.Ve
.Sp
Maps URL path or an absolute URL to a PSGI application. The match
order is sorted by host name length and then path length (longest strings
first).
.Sp
URL paths need to match from the beginning and should match completely
until the path separator (or the end of the path). For example, if you
register the path \f(CW\*(C`/foo\*(C'\fR, it \fIwill\fR match with the request \f(CW\*(C`/foo\*(C'\fR,
\&\f(CW\*(C`/foo/\*(C'\fR or \f(CW\*(C`/foo/bar\*(C'\fR but it \fIwon't\fR match with \f(CW\*(C`/foox\*(C'\fR.
.Sp
Mapping URLs with host names is also possible, and in that case the URL
mapping works like a virtual host.
.Sp
Mappings will nest.  If \f(CW$app\fR is already mapped to \f(CW\*(C`/baz\*(C'\fR it will
match a request for \f(CW\*(C`/foo/baz\*(C'\fR but not \f(CW\*(C`/foo\*(C'\fR. See "HOW THIS
WORKS" for more details.
.IP mount 4
.IX Item "mount"
Alias for \f(CW\*(C`map\*(C'\fR.
.IP to_app 4
.IX Item "to_app"
.Vb 1
\&  my $handler = $urlmap\->to_app;
.Ve
.Sp
Returns the PSGI application code reference. Note that the
Plack::App::URLMap object is callable (by overloading the code
dereference), so returning the object itself as a PSGI application
should also work.
.SH PERFORMANCE
.IX Header "PERFORMANCE"
If you \f(CW\*(C`map\*(C'\fR (or \f(CW\*(C`mount\*(C'\fR with Plack::Builder) N applications,
Plack::App::URLMap will need to at most iterate through N paths to
match incoming requests.
.PP
It is a good idea to use \f(CW\*(C`map\*(C'\fR only for a known, limited amount of
applications, since mounting hundreds of applications could affect
runtime request performance.
.SH DEBUGGING
.IX Header "DEBUGGING"
You can set the environment variable \f(CW\*(C`PLACK_URLMAP_DEBUG\*(C'\fR to see how
this application matches with the incoming request host names and
paths.
.SH "HOW THIS WORKS"
.IX Header "HOW THIS WORKS"
This application works by \fIfixing\fR \f(CW\*(C`SCRIPT_NAME\*(C'\fR and \f(CW\*(C`PATH_INFO\*(C'\fR
before dispatching the incoming request to the relocated
applications.
.PP
Say you have a Wiki application that takes \f(CW\*(C`/index\*(C'\fR and \f(CW\*(C`/page/*\*(C'\fR
and makes a PSGI application \f(CW$wiki_app\fR out of it, using one of
supported web frameworks, you can put the whole application under
\&\f(CW\*(C`/wiki\*(C'\fR by:
.PP
.Vb 2
\&  # MyWikiApp looks at PATH_INFO and handles /index and /page/*
\&  my $wiki_app = sub { MyWikiApp\->run(@_) };
\&  
\&  use Plack::App::URLMap;
\&  my $app = Plack::App::URLMap\->new;
\&  $app\->mount("/wiki" => $wiki_app);
.Ve
.PP
When a request comes in with \f(CW\*(C`PATH_INFO\*(C'\fR set to \f(CW\*(C`/wiki/page/foo\*(C'\fR,
the URLMap application \f(CW$app\fR strips the \f(CW\*(C`/wiki\*(C'\fR part from
\&\f(CW\*(C`PATH_INFO\*(C'\fR and \fBappends\fR that to \f(CW\*(C`SCRIPT_NAME\*(C'\fR.
.PP
That way, if the \f(CW$app\fR is mounted under the root
(i.e. \f(CW\*(C`SCRIPT_NAME\*(C'\fR is \f(CW""\fR) with standalone web servers like
Starman, \f(CW\*(C`SCRIPT_NAME\*(C'\fR is now locally set to \f(CW\*(C`/wiki\*(C'\fR and
\&\f(CW\*(C`PATH_INFO\*(C'\fR is changed to \f(CW\*(C`/page/foo\*(C'\fR when \f(CW$wiki_app\fR gets called.
.SH AUTHOR
.IX Header "AUTHOR"
Tatsuhiko Miyagawa
.SH "SEE ALSO"
.IX Header "SEE ALSO"
Plack::Builder