Enables your Rails app to receive and send pingbacks as known from wordpress-like blogs.
This engine includes an XML-RPC server controller for receiving pingbacks from other blogs. You can hook into the receiving and process the incoming ping by creating a new comment record that represents that blog ping or whatever your app needs.
Note: the current version only supports receiving pingbacks (that's way harder than sending pingbacks. Sending will be implemented in the next weeks).
What are Pingbacks?
If you're writing in your blog A and refer to some other blog B, your blog system will usually inform the blog B about your article. This is known as a Pingback and is simply a small XML-RPC call saying “Hey there, blog B! We're referencing your article xy. You can find our linking article on blog A at yz.”
That's all the pure pingback does. It's up to blog B to handle the links, check if blog A is really refering, excerpt some content from the blog and display that on blog B. Usually a comment on blog B is created pointing back to blog A.
Read more in the official specification at hixie.ch/specs/pingback/pingback .
To install, simply cd to your rails app directory and run
script/plugin install git://github.com/apotonick/pingback_engine.git
Propagating your pingback server url
A blog refering to your site will scan your site for information on where to find your pingback XML-RPC server. You're on the safe side by sending the X-Pingback header as well as including the <link rel="pingback" ...> in your layout.
In the controller class, include
class MyBlogController include PingbackHelper helper :pingback def show_blog set_xpingback_header # ...
In the application layout, put
<html> <head> ... <%= pingback_link_tag %> </head>
Processing incoming pings
After the installation of the engine the XML-RPC server is automatically accessable at /pingback/xml. The server will create a Pingback instance. This object checks the origin link, retrieves the linking page and extracts the matching section from the page. If valid, the hook method you provided is executed and the Pingback object passed as argument.
Currently the hook method goes at the end of config/environment.rb, where Pingback#save_callback attaches the hook:
Pingback.save_callback do |ping| AnonymousComment.process_pingback(ping) end
You can also process the ping directly in the block:
Pingback.save_callback do |ping| comment = ArticleComment.new comment.author = ping.title comment.author_url = ping.source_uri comment.text = ping.content referenced_article = Article.find_by_url(ping.target_uri) if referenced_article comment.article_id = referenced_article.id comment.save ping.reply_ok # report success. else # report error: ping.reply_target_uri_does_not_accept_posts end end
You can use the plugins' script/send-pingback.rb tool to send an XML-RPC call to your localhost.
pingback_engine$> script/send_pingback.rb http://some.blog.com/the-linking/article http://my-own-blog.de/the-referenced-article
Copyright © 2008 Nick Sutterer <email@example.com>
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