Hi, I responded inline.
On 11/1/13, Shawn Jones sjone@cs.odu.edu wrote:
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):
- 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?
Special Page vs Action is usually considered equally ok for this sort of thing. However creating an api module would probably be the preferred method to return such machine readable data about a page.
- 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?
Use existing wrapper functions around DB calls where you can, but if you need to its ok to query the db directly.
For the last part, probably something along the lines of WikiPage::factory( $titleObj )->getRevision()->getTimestamp()
- 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?
$wgServer is always filled out (Setup.php sets it if user doesn't). However you probably shouldn't be using it directly. What the most appropriate method to use depends on what sort of urls you want, but generally the Title class has methods like getFullURL for this sort of thing.
- We use exceptions to indicate when showErrorPage should be run; should
the hooks that catch these exceptions and then run showErrorPage also return false?
I haven't looked at your code, so not sure about the context - but: In general a hook returns true to denote no futher processing should take place. Displaying an error message sounds like a good criteria to return true. That said, things may depend on the hook and what precisely you're doing.
- 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?
FlaggedRevisions manages to set old version of an image, so its possible. I think you might want to do something with the BeforeParserFetchFileAndTitle hook as well. For the time parameter, make sure the function you're using has the $time parameter marked as pass by reference. Also note: the time parameter is the timestamp that the image version was created, it does not denote get whatever image would be relavent at the time specified (I believe).
- Are there any additional coding standards we should be following besides
those on the "Manual:Coding_conventions" and "Manual:Coding Conventions - Mediawiki" pages?
Those are the important ones. As a rule of thumb, try to make your code look like it fits in with the rest of mediawiki.
- 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?
First reaction would be that the 302, as it more clearly indicates your viewing an old page, and people could copy and paste the url in order to get to see the exact same version. It also seems better to have different urls for different objects (caching and all). [That's just a first reaction, I haven't thought about it deeply]
- 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?
That's going to be a political issue that varries by project probably. As a first approximation maybe default only to things in $wgContentNamespaces.
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 _______________________________________________ Wikitech-l mailing list Wikitech-l@lists.wikimedia.org https://lists.wikimedia.org/mailman/listinfo/wikitech-l
Good luck on developing your extension. Last of all I don't want to sound negative, but please keep in mind that if your goal is deployment on Wikipedia, that is not just a technical issue, but also a political one, and a goal that is rather hard to accomplish...
Cheers, Brian