Hi,
I'm currently working on the Memento Extension for Mediawiki, as announced earlier
today by Herbert Van de Sompel.
The goal of this extension is to work with the Memento framework, which attempts to
display web pages as they appeared at a given date and time in the past.
Our goal is for this to be a collaborative effort focusing on solving issues and providing
functionality in "the Wikimedia Way" as much as possible.
Without further ado, I have the following technical questions (I apologize in advance for
the fire hose):
1. The Memento protocol has a resource called a TimeMap [1] that takes an article name
and returns text formatted as application/link-format. This text contains a
machine-readable list of all of the prior revisions (mementos) of this page. It is
currently implemented as a SpecialPage which can be accessed like
http://www.example.com/index.php/Special:TimeMap/Article_Name. Is this the best method,
or is it more preferable for us to extend the Action class and add a new action to
$wgActions in order to return a TimeMap from the regular page like
http://www.example.com/index.php?title=Article_Name&action=gettimemap without using
the SpecialPage? Is there another preferred way of solving this problem?
2. We currently make several database calls using the the select method of the Database
Object. After some research, we realized that Mediawiki provides some functions that do
what we need without making these database calls directly. One of these needs is to
acquire the oldid and timestamp of the first revision of a page, which can be done using
Title->getFirstRevision()->getId() and
Title->getFirstRevision()->getTimestamp() methods. Is there a way to get the latest
ID and latest timestamp? I see I can do Title->getLatestRevID() to get the latest
revision ID; what is the best way to get the latest timestamp?
3. In order to create the correct headers for use with the Memento protocol, we have to
generate URIs. To accomplish this, we use the $wgServer global variable (through a layer
of abstraction); how do we correctly handle situations if it isn't set by the
installation? Is there an alternative? Is there a better way to construct URIs?
4. We use exceptions to indicate when showErrorPage should be run; should the hooks that
catch these exceptions and then run showErrorPage also return false?
5. Is there a way to get previous revisions of embedded content, like images? I tried
using the ImageBeforeProduceHTML hook, but found that setting the $time parameter
didn't return a previous revision of an image. Am I doing something wrong? Is there
a better way?
6. Are there any additional coding standards we should be following besides those on the
"Manual:Coding_conventions" and "Manual:Coding Conventions -
Mediawiki" pages?
7. We have two styles for serving pages back to the user:
* 302-style[2], which uses a 302 redirect to tell the user's browser to go
fetch the old revision of the page (e.g.
http://www.example.com/index.php?title=Article&oldid=12345)
* 200-style[3], which actually modifies the page content in place so that it
resembles the old revision of the page
Which of these styles is preferable as a default?
8. Some sites don't wish to have their past Talk/Discussion pages accessible via
Memento. We have the ability to exclude namespaces (Talk, Template, Category, etc.) via
configurable option. By default it excludes nothing. What namespaces should be excluded
by default?
Thanks in advance for any advice, assistance, further discussion, and criticism on these
and other topics.
Shawn M. Jones
Graduate Research Assistant
Department of Computer Science
Old Dominion University
[1]
http://www.mementoweb.org/guide/rfc/ID/#Pattern6
[2]
http://www.mementoweb.org/guide/rfc/ID/#Pattern1.1
[3]
http://www.mementoweb.org/guide/rfc/ID/#Pattern1.2