node-pingback

Pingbacks have come to node.js. If you're writing a blog, you may be interested in this. It conforms to the pingback specification, as well as the XML-RPC spec, however, it may need more testing.

It protects against spam, has no dependencies, and can be used right out of the box. Connect/Express middleware is included.

Usage

Receiving Pingbacks (contrived example for clarity)

app.use('/pingback', Pingback.middleware(function(source, target, next) {
  var self = this;
  Posts.get(target.pathname, function(err, post) {
    if (err) {
      return next(Pingback.TARGET_DOES_NOT_EXIST); 
    }
    if (post.pingbacks[source.href]) { 
      return next(Pingback.ALREADY_REGISTERED);
    }
    if (post.pingbacksDisabled) {
      return next(Pingback.TARGET_CANNOT_BE_USED); 
    }
    // or pass zero above for a generic error
    post.pingbacks.push({
      from: source.href, // e.g. "http://domain.tld/hey_check_out_this_guys_post"
      title: self.title, // e.g. "Joe's blog"
      text: self.excerpt // e.g. "hey, check this out: <a href="your_site">...</a>"
    });
    post.save();
    next(); // send a success response
  });
}));

What you see above is merely the abstracted interface of the bundled middleware. See example.js/test.js for more in-depth and lower-level examples.

Sending Pingbacks

// ping a target - err will be a fault code if present
Pingback.send('[target]', '[source]', function(err, pingback) {
  if (!err) console.log('Pinged ' + pingback.href + ' successfully.');
});

// scan an html string for links to ping
var text = 'a link here: <a href="http://localhost:9000/article">a post</a>';
Pingback.scan(text, '[source]', function(err, pingback) {
  // optional callback - will get called for every pingback sent
  if (!err) console.log('Pinged ' + pingback.href + ' successfully.');
});

Again, see example.js/test.js for more examples and explanation.

Reference

Fault Code Constants

Pingback.METHOD_NOT_FOUND = -32601;
Pingback.GENERAL_ERROR = 0;
Pingback.SOURCE_DOES_NOT_EXIST = 16;
Pingback.NO_LINK_TO_TARGET = 17;
Pingback.TARGET_DOES_NOT_EXIST = 32;
Pingback.TARGET_CANNOT_BE_USED = 33;
Pingback.ALREADY_REGISTERED = 48;
Pingback.ACCESS_DENIED = 49;

Pingback properties

• source: a parsed url object of the source
• target: a parsed url object of the target
• excerpt: an excerpt from the source's page
• title: the title of the source page

Events for receiving pingbacks

• ping: An optional event to validate and handle errors/faults. If bound, this will be triggered as the first event and passed a next callback, which can be passed a fault code to trigger a fault response, otherwise it will continue handling the pingback. Arguments: source, target, next.
• fault: Emitted when a fault occurs. Passed the fault code and string. Arguments: code, msg.
• error: Emitted for non-fault related errors. Calls the next middleware layer in the bundled connect/express middleware function. Arguments: err.
• end: Emitted if no ping listeners have been bound, and after a pingback has been received and verified. Arguments: source, target, next. next has the same effect as the callback passed for ping.
• success: Emitted if a ping listener was bound, and after the pingback has been received and handled. Arguments: source, target.

License

(c) Copyright 2011, Christopher Jeffrey (MIT License). See LICENSE for more info.