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Plack::App::URLMap - Map multiple apps in different paths


  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("" => $app3);

  my $app = $urlmap->to_app;


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 SCRIPT_NAME and PATH_INFO (See "HOW THIS WORKS" for details). This module is inspired by Ruby's Rack::URLMap.


  $urlmap->map("/foo" => $app);
  $urlmap->map("" => $another_app);

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).

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 /foo, it will match with the request /foo, /foo/ or /foo/bar but it won't match with /foox.

Mapping URLs with host names is also possible, and in that case the URL mapping works like a virtual host.

Mappings will nest. If $app is already mapped to /baz it will match a request for /foo/baz but not /foo. See "HOW THIS WORKS" for more details.


Alias for map.

  my $handler = $urlmap->to_app;

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.


If you map (or mount with Plack::Builder) N applications, Plack::App::URLMap will need to at most iterate through N paths to match incoming requests.

It is a good idea to use map only for a known, limited amount of applications, since mounting hundreds of applications could affect runtime request performance.


You can set the environment variable PLACK_URLMAP_DEBUG to see how this application matches with the incoming request host names and paths.


This application works by fixing SCRIPT_NAME and PATH_INFO before dispatching the incoming request to the relocated applications.

Say you have a Wiki application that takes /index and /page/* and makes a PSGI application $wiki_app out of it, using one of supported web frameworks, you can put the whole application under /wiki by:

  # 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);

When a request comes in with PATH_INFO set to /wiki/page/foo, the URLMap application $app strips the /wiki part from PATH_INFO and appends that to SCRIPT_NAME.

That way, if the $app is mounted under the root (i.e. SCRIPT_NAME is "") with standalone web servers like Starman, SCRIPT_NAME is now locally set to /wiki and PATH_INFO is changed to /page/foo when $wiki_app gets called.


Tatsuhiko Miyagawa