Web Science and Digital Libraries Research Group

When an archived web page is viewed using the Wayback Machine, the archival datetime is easy to determine from the URI and the Wayback Machine's display.  The archival datetime of embedded resources (images, CSS, etc.) is another story.  And what stories their archival datetimes can tell.  These stories are the topic of my recent research and Hypertext 2015 publication.  This post introduces composite mementos, the evaluation of their temporal (in-)coherence, provides an overview of my research results.   What is a composite memento?   A Memento is an archived copy of web resource ( RFC 7089 )  The datetime when the copy was archived is called its Memento-Datetime .  A composite memento is a root resource such as an HTML web page and all of the embedded resources (images, CSS, etc.) required for a complete presentation.  Composite mementos can be thought of as a tree structure.  The root resource embeds other resources, which...

One of the key contributions of the Memento Framework is the HTTP response header " Memento-Datetime " (previously called "Content-Datetime" in our earlier publications & slides). Memento-Datetime is the sticky, intended datetime* for the representation returned when a URI is dereferenced. The presence of the Memento-Datetime HTTP response header is how the client realizes it has reached a Memento. Rather than formally explain what we mean by "sticky, intended datetime", it is easier to explain how it is neither the value in the HTTP response header Last-Modified , nor is it the creation date of the resource (which has no corresponding HTTP header, for reasons that will become clear). For the examples below, we'll define the following abbreviations: CD (Creation-Datetime) = the datetime the resource was created MD (Memento-Datetime) = the datetime the representation was observed on the web LM (Last-Modified) = the datetime the resource last cha...