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diff --git a/_posts/2010-04-03-more-fun-with-tatsumaki-and-plack.textile b/_posts/2010-04-03-more-fun-with-tatsumaki-and-plack.textile deleted file mode 100644 index 7b47c0f..0000000 --- a/_posts/2010-04-03-more-fun-with-tatsumaki-and-plack.textile +++ /dev/null @@ -1,166 +0,0 @@ ---- -layout: post -category: perl -title: More fun with Tatsumaki and Plack ---- - -Lately I've been toying a lot with "Plack":http://plackperl.org/ and two Perl web framework: "Tatsumaki":http://search.cpan.org/perldoc?Tatsumaki and "Dancer":http://search.cpan.org/perldoc?Dancer. I use both of them for different purposes, as their features complete each other. - -h3. Plack - -If you don't already know what Plack is, you would want to take a look at the following Plack resources: - - * "Plack (redesigned) website":http://plackperl.org - * "Plack documentation":http://search.cpan.org/perldoc?Plack - * "miyagawa's screencast":http://bulknews.typepad.com/blog/2009/11/plack-and-psgi-screencast-and-feedbacks.html - * "Plack advent calendar":http://advent.plackperl.org/ - -.bq As "sukria":http://www.sukria.net/ is planning to talk about "Dancer":http://perldancer.org during the "FPW 2010":http://journeesperl.fr/fpw2010/index.html, I will probably do a talk about Plack. - -After reading some code, I've started to write two middleware: the first one add ETag header to the HTTP response, and the second one provides a way to limit access to your application. - -h4. Plack::Middleware::ETag - -This middleware is really simple: for each request, an "ETag":http://en.wikipedia.org/wiki/HTTP_ETag header is added to the response. The ETag value is a sha1 of the response's content. In case the content is a file, it works like apache, using various information from the file: inode, modified time and size. This middleware can be used with "Plack::Middleware::ConditionalGET":http://search.cpan.org/perldoc?Plack::Middleware::ConditionalGET, so the client will have the ETag information for the page, and when he will do a request next time, it will send an "if-modified" header. If the ETag is the same, a 304 response will be send, meaning the content have not been modified. This module is "available on CPAN":http://search.cpan.org/perldoc?Plack::Middleware::ETag. - -Let's see how it works. First, we create a really simple application (we call it app.psgi): - -{% highlight perl %} -#!/usr/bin/env perl -use strict; -use warnings; -use Plack::Builder; - -builder { - enable "Plack::Middleware::ConditionalGET"; - enable "Plack::Middleware::ETag"; - sub { - ['200', ['Content-Type' => 'text/html'], ['Hello world']]; - }; -}; -{% endhighlight %} - -Now we can test it: - -{% highlight bash %} -> plackup app.psgi& -> curl -D - http://localhost:5000 -HTTP/1.0 200 OK -Date: Sat, 03 Apr 2010 09:31:43 GMT -Server: HTTP::Server::PSGI -Content-Type: text/html -ETag: 7b502c3a1f48c8609ae212cdfb639dee39673f5e -Content-Length: 11 - -> curl -H "If-None-Match: 7b502c3a1f48c8609ae212cdfb639dee39673f5e" -D - http://localhost:5000 -HTTP/1.0 304 Not Modified -Date: Sat, 03 Apr 2010 09:31:45 GMT -Server: HTTP::Server::PSGI -ETag: 7b502c3a1f48c8609ae212cdfb639dee39673f5e -{% endhighlight %} - -h4. Plack::Middleware::Throttle - -"With this middleware":http://github.com/franckcuny/plack--middleware--throttle, you can control how many times you want to provide an access to your application. This module is not yet on CPAN, has I want to add some features, but you can get the code on github. There is four methods to control access: - - * Plack::Middleware::Throttle::Hourly: how many times in one hour someone can access the application - * P::M::T::Daily: the same, but for a day - * P::M::T::Interval: which interval the client must wait between two query - * by combining the three previous methods - -To store sessions informations, you can use any cache backend that provides *get*, *set* and *incr* methods. By default, if no backend is provided, it will store informations in a hash. You can easily modify the defaults throttling strategies by subclassing all the classes. - -Let's write another application to test it: - -{% highlight perl %} -#!/usr/bin/env perl -use strict; -use warnings; -use Plack::Builder; - -builder { - enable "Plack::Middleware::Throttle::Hourly", max => 2; - sub { - ['200', ['Content-Type' => 'text/html'], ['Hello world']]; - }; -}; -{% endhighlight %} - -then test - -{% highlight bash %} -$ curl -D - http://localhost:5000/ -HTTP/1.0 200 OK -Date: Sat, 03 Apr 2010 09:57:40 GMT -Server: HTTP::Server::PSGI -Content-Type: text/html -X-RateLimit-Limit: 2 -X-RateLimit-Remaining: 1 -X-RateLimit-Reset: 140 -Content-Length: 11 - -Hello world - -$ curl -D - http://localhost:5000/ -HTTP/1.0 200 OK -Date: Sat, 03 Apr 2010 09:57:40 GMT -Server: HTTP::Server::PSGI -Content-Type: text/html -X-RateLimit-Limit: 2 -X-RateLimit-Remaining: 0 -X-RateLimit-Reset: 140 -Content-Length: 11 - -Hello world - -$ curl -D - http://localhost:5000/ -HTTP/1.0 503 Service Unavailable -Date: Sat, 03 Apr 2010 09:57:41 GMT -Server: HTTP::Server::PSGI -Content-Type: text/plain -X-RateLimit-Reset: 139 -Content-Length: 15 - -Over rate limit -{% endhighlight %} - -Some HTTP headers are added to the response : - - * *X-RateLimit-Limit*: how many request can be done - * *X-RateLimit-Remaining*: how many requests are available - * *X-RateLimit-Reset*: when will the counter be reseted (in seconds) - -This middleware could be a very good companion to the "Dancer REST stuff":http://www.sukria.net/fr/archives/2010/03/19/let-the-dancer-rest/ "added recently":http://lumberjaph.net/blog/index.php/2010/03/19/easily-create-rest-interface-with-the-dancer-1170/. - -h3. another Tatsumaki application with Plack middlewares - -To demonstrate the use of this two middleware, "I've wrote a small application":http://github.com/franckcuny/feeddiscovery with Tatsumaki. This application fetch a page, parse it to find all the feeds declared, and return a JSON with the result. - -{% highlight bash %} - GET http://feeddiscover.tirnan0g.org/?url=http://lumberjaph.net/blog/ -{% endhighlight %} - -will return - -{% highlight javascript %} - [{"href":"http://lumberjaph.net/blog/index.php/feed/","type":"application/rss+xml","title":"i'm a lumberjaph RSS Feed"}] -{% endhighlight %} - -This application is composed of one handler, that handle only *GET* request. The request will fetch the url given in the *url* parameter, scrap the content to find the links to feeds, and cache the result with Redis. The response is a JSON string with the informations. - -The interesting part is the app.psgi file: - -{% highlight perl %} -my $app = Tatsumaki::Application->new(['/' => 'FeedDiscovery::Handler'],); - -builder { - enable "Plack::Middleware::ConditionalGET"; - enable "Plack::Middleware::ETag"; - enable "Plack::Middleware::Throttle::Hourly", - backend => Redis->new(server => '127.0.0.1:6379',), - max => 100; - $app; -}; -{% endhighlight %} - -The application itself is really simple: for a given url, the Tatsumaki::HTTPClient fetch an url, I use "Web::Scraper":http://search.cpan.org/perldoc?Web::Scraper to find the *link rel="alternate"* from the page, if something is found, it's stored in Redis, then a JSON string is returned to the client. |