plack::middleware::conditionalget(3pm) [debian man page]

Plack::Middleware::ConditionalGET(3pm)			User Contributed Perl Documentation		    Plack::Middleware::ConditionalGET(3pm)

NAME

       Plack::Middleware::ConditionalGET - Middleware to enable conditional GET

SYNOPSIS

	 builder {
	     enable "ConditionalGET";
	     ....
	 };

DESCRIPTION

       This middleware enables conditional GET and HEAD using "If-None-Match" and "If-Modified-Since" header. The application should set either or
       both of "Last-Modified" or "ETag" response headers per RFC 2616. When either of the conditions is met, the response body is set to be zero
       length and the status is set to 304 Not Modified.

SEE ALSO

       Rack::ConditionalGet

perl v5.14.2							    2012-05-17				    Plack::Middleware::ConditionalGET(3pm)

Plack::Builder(3pm)					User Contributed Perl Documentation				       Plack::Builder(3pm)

NAME

       Plack::Builder - OO and DSL to enable Plack Middlewares

SYNOPSIS

	 # in .psgi
	 use Plack::Builder;

	 my $app = sub { ... };

	 builder {
	     enable "Deflater";
	     enable "Session", store => "File";
	     enable "Debug", panels => [ qw(DBITrace Memory Timer) ];
	     enable "+My::Plack::Middleware";
	     $app;
	 };

	 # use URLMap

	 builder {
	     mount "/foo" => builder {
		 enable "Foo";
		 $app;
	     };

	     mount "/bar" => $app2;
	     mount "http://example.com/" => builder { $app3 };
	 };

	 # using OO interface

	 my $builder = Plack::Builder->new();
	 $builder->add_middleware('Foo', opt => 1);
	 $app = $builder->mount('/app' => $app);
	 $app = $builder->to_app($app);

DESCRIPTION

       Plack::Builder gives you a quick domain specific language (DSL) to wrap your application with Plack::Middleware subclasses. The middleware
       you're trying to use should use Plack::Middleware as a base class to use this DSL, inspired by Rack::Builder.

       Whenever you call "enable" on any middleware, the middleware app is pushed to the stack inside the builder, and then reversed when it
       actually creates a wrapped application handler. "Plack::Middleware::" is added as a prefix by default. So:

	 builder {
	     enable "Foo";
	     enable "Bar", opt => "val";
	     $app;
	 };

       is syntactically equal to:

	 $app = Plack::Middleware::Bar->wrap($app, opt => "val");
	 $app = Plack::Middleware::Foo->wrap($app);

       In other words, you're supposed to "enable" middleware from outer to inner.

INLINE MIDDLEWARE

       Plack::Builder allows you to code middleware inline using a nested code reference.

       If the first argument to "enable" is a code reference, it will be passed an $app and is supposed to return another code reference which is
       PSGI application that consumes $env in runtime. So:

	 builder {
	     enable sub {
		 my $app = shift;
		 sub {
		     my $env = shift;
		     # do preprocessing
		     my $res = $app->($env);
		     # do postprocessing
		     return $res;
		 };
	     };
	     $app;
	 };

       is equal to:

	 my $mw = sub {
	     my $app = shift;
	     sub { my $env = shift; $app->($env) };
	 };

	 $app = $mw->($app);

URLMap support
       Plack::Builder has a native support for Plack::App::URLMap with "mount" method.

	 use Plack::Builder;
	 my $app = builder {
	     mount "/foo" => $app1;
	     mount "/bar" => builder {
		 enable "Foo";
		 $app2;
	     };
	 };

       See Plack::App::URLMap's "map" method to see what they mean. With builder you can't use "map" as a DSL, for the obvious reason :)

       NOTE: Once you use "mount" in your builder code, you have to use "mount" for all the paths, including the root path ("/"). You can't have
       the default app in the last line of "builder" like:

	 my $app = sub {
	     my $env = shift;
	     ...
	 };

	 builder {
	     mount "/foo" => sub { ... };
	     $app; # THIS DOESN'T WORK
	 };

       You'll get warnings saying that your mount configuration will be ignored. Instead you should use "mount "/" => ..." in the last line to set
       the default fallback app.

	 builder {
	     mount "/foo" => sub { ... };
	     mount "/" => $app;
	 }

       Note that the "builder" DSL returns a whole new PSGI application, which means

       o   "builder { ... }" should normally the last statement of a ".psgi" file, because the return value of "builder" is the application that
	   actually is executed.

       o   You can nest your "builder" block, mixed with "mount" (see URLMap support above):

	     builder {
		 mount "/foo" => builder {
		     mount "/bar" => $app;
		 }
	     }

	   will locate the $app under "/foo/bar" since the inner "builder" block puts it under "/bar" and it results a new PSGI application which
	   is located under "/foo" because of the outer "builder" block.

CONDITIONAL MIDDLEWARE SUPPORT

       You can use "enable_if" to conditionally enable middleware based on the runtime environment. See Plack::Middleware::Conditional for
       details.

SEE ALSO

       Plack::Middleware Plack::App::URLMap Plack::Middleware::Conditional

perl v5.14.2							    2012-05-17						       Plack::Builder(3pm)