From 4b8e43f75b394a4e6169884fbfb4c606865c6a22 Mon Sep 17 00:00:00 2001 From: Franck Cuny Date: Sat, 2 Jul 2016 20:06:31 -0700 Subject: Import migration from Jekyll to Hugo. All the posts were converted, and the layout is created. This looks like it works just fine. --- ...2010-04-03-more-fun-with-tatsumaki-and-plack.md | 166 +++++++++++++++++++++ 1 file changed, 166 insertions(+) create mode 100644 content/post/2010-04-03-more-fun-with-tatsumaki-and-plack.md (limited to 'content/post/2010-04-03-more-fun-with-tatsumaki-and-plack.md') diff --git a/content/post/2010-04-03-more-fun-with-tatsumaki-and-plack.md b/content/post/2010-04-03-more-fun-with-tatsumaki-and-plack.md new file mode 100644 index 0000000..abfcf15 --- /dev/null +++ b/content/post/2010-04-03-more-fun-with-tatsumaki-and-plack.md @@ -0,0 +1,166 @@ +--- +date: 2010-04-03T00:00:00Z +summary: In which I have fun with Tatsumaki. +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. + +## 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/) + +> 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. + +### 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): + +```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']]; + }; +}; +``` + +Now we can test it: + +```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 +``` + +### Plack::Middleware::Throttle + +[With this middleware](http://git.lumberjaph.net/p5-plack-middleware-throttle.git/), 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 from git. 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: + +```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']]; + }; +}; +``` + +then test + +```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 +``` + +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](/easily-create-rest-interface-with-the-dancer-1.170/). + +## another Tatsumaki application with Plack middlewares + +To demonstrate the use of this two middleware, [I wrote a small application](http://git.lumberjaph.net/p5-feeddiscovery.git/) with Tatsumaki. This application fetch a page, parse it to find all the feeds declared, and return a JSON with the result. + +```bash +% GET http://feeddiscover.tirnan0g.org/?url=http://lumberjaph.net/blog/ +``` + +will return + +```javascript +% [{"href":"http://lumberjaph.net/blog/index.php/feed/","type":"application/rss+xml","title":"i'm a lumberjaph RSS Feed"}] +``` + +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: + +```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; +}; +``` + +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. -- cgit v1.2.3