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Linkback(Refback, Trackback, and Pingback)

 

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A linkback is a method for Web authors to obtain notifications when other authors link to one of their documents. This enables authors to keep track of who is linking to, or referring to their articles. The three methods (Refback, Trackback, and Pingback) differ in how they accomplish this task.

Any of the four terms -- Linkback, Trackback, Pingback, or (rarely) Refback -- might also refer colloquially to items within a section upon the linked page that display the received notifications, usually along with a reciprocal link; Trackback is used most often for this purpose. Also, the word Trackback is often used colloquially to mean any kind of Linkback.

Linkback is also the name of an OLE-like open source framework for Mac OS X.

Refback
Trackback
Pingback

Trigger mechanism
Visitor to linking site clicks on the link, and his browser takes him to the linked site
Code on linking server examines added or updated documents, extracts links, and sends notification to linked server for each link found
Code on linking server examines added or updated documents, extracts links, and sends notification to linked server for each link found

Notification medium
HTTP referer value
HTTP POST
XML-RPC call

Capture mechanism
Examination of incoming HTTP referer values
Trackback capture script
XML-RPC function

Information sent by linking server
None

  • Linking site name (Optional)
  • Linking post title (Optional)
  • Linking post excerpt (Optional)
  • Linking post URL
  • Linked post URL
  • Linking post URL

Additional information presented to linked server
HTTP referer sent by a visitor's browser upon clicking the link
IP address of linking server
IP address of linking server

Autodiscovery mechanism (how the linking server finds out how and where to send the notification)
None
Specially-formatted information within the body of the linked page
Special HTTP header or LINK tag on the linked page

Action required when notification is received

  • Extract referrer value from incoming HTTP headers
  • Retrieve referring page
  • Parse retrieved page for desired information
  • Gather desired information from
    • Given parameters
    • or retrieving and parsing the given URL
  • Retrieve page at "linking post URL"
  • Parse retrieved page for desired information

Advantages
Requires no special code on linking server (the link itself becomes the notification when someone clicks on it)
All the information desired by the linked server (Linking site name, post title, excerpt) is present in the notification itself

  • Notification mechanism has a complete technical specification
  • Less susceptible to spamming

Disadvantages

  • No notification unless someone actually clicks on the link
  • Relies upon visitors' browsers sending proper HTTP referer information
  • Linked site must retrieve and parse linking site's page to extract the information it wants
  • Notification requires positive action by linking server
  • Notification mechanism has only a partial technical specification
  • Autodiscovery information may prevent XHTML validation
  • Notification requires positive action by linking server
  • Linked site must retrieve and parse linking site's page to extract the information it wants

[edit] See also

[edit] External links

posted on 2010-03-18 21:54  linlu11  阅读(482)  评论(0)  编辑  收藏  举报

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