The Problem
Resources referenced by LOM metadata may occur in multiple formats (original, high-resolution, web-resolution, thumbnail, broadband QuickTime, etc...). Each of these resources may have different properties, including format (MIME type), location, siz e, and requirements. When implementing a learning object repository, it will be helpful to know which resource to refer to when displaying information about it to the user.
Sample Usage 1: Video
A video file typically is produced in a number of file formats and compression settings, to allow for maximum viewability by the various systems and configurations found on the user's computer. Often, a single video may be published online in several file formats, including QuickTime, Real, Windows Media, and MPEG. Additionally, there may be varying bandwidth requirements, resolutions, and compression settings.
A user should be able to select the file format of the video they want to watch (QuickTime vs. Real vs...) as well as any available resultions and data rates (full screen LAN, 640x480 broadband, 240x120 modem...).
In addition, the software used to present this metadata should be able to display a thumbnail image (or images) to represent the video prior to viewing/downloading the larger media file.
Finding the Right Information Online
Metadata is data about data, it is the language used to index and describe material. This video looks at the issues surrounding the use of metadata in educational object repositories.
Sample Usage 2: Images
Images are typically available in a number of sizes and formats, depending on the workflow used to create them. It may be necessary for users to be able to access any of these formats as they use the learning object.
As an example, an image may be originally scanned using a high-resolution slide scanner, and stored in an archival format such as TIFF for later use. It may then be converted into "web friendly" formats such as JPEG or GIF in order to allow efficient viewing of the image through a typical web browser and internet connection. A smaller thumbnail image may also be generated in order to represent the learning object in an application interface. Depending on the needs of the user, they may need to access any of these versions of the learning object as described in its LOM.
Finding the Right Information Online
Metadata is data about data, it is the language used to index and describe material. This video looks at the issues surrounding the use of metadata in educational object repositories.
Proposed Solution
It would seem as though the simplest, and yet most flexible and robust, solution to this problem is to have multiple <technical> elements in a single LOM. Each <technical> would contain a single <format>, single <size>, and on e or many <location> elements (assuming they all point to copies of the same file, posted to different servers).
In order to make sense of these multiple <technical> elements, we need a new element to describe the purpose of each. I propose the addition of a <label> element. This element would mimic the <format> element, but provide some semant ic interpretation of the <technical> instance.
I further propose that the content of the <label> element may be user-defined (or system-defined), but that some reserved values should be identified, including "thumbnail", which could be used to identify any <technical> element as a thumbnail representation of that resource.
This <label> value could be used in an interface to provide options in a menu to allow a user to select which <technical> resource to view as part of their usage of this LOM.
It should be noted that in the examples below, I am not worrying about namespace issues, or schema definition issues. I am presenting the concept only, and am hoping that the "official" solution will come out of discussion of these exampl es. Also, the <label> element was created arbitrarily, and may well be replaced by a more appropriate element name.
A minimal <technical> element (in this case, for a simple web page) may look like this:
<technical>
<format>
text/html
</format>
<size>
2421
</size>
<location>
http://commons.ucalgary.ca/
</location>
</technical>
Since this example lacks the <label> element, it is assumed to be the default <technical> for this LOM. Note that this <technical> element appears exactly as defined currently in the LOM (IMS, IEEE, etc...).
A more complicated scenario may involve a video, stored in 2 formats, and a thumbnail image, like the sample below (yes, I know the URLs won't resolve to anything useful...):
<technical>
<format>
video/quicktime
</format>
<size>
4629824
</size>
<location>
http://commons.ucalgary.ca/movies/test.mov
</location>
<label>
Broadband QuickTime
</label>
</technical>
<technical>
<format>
video/windowsmedia
</format>
<size>
7987942
</size>
<location>
http://commons.ucalgary.ca/movies/test.wmv
</location>
<label>
Broadband Windows Media
</label>
</technical>
<technical>
<format>
image/jpeg
</format>
<size>
2342
</size>
<location>
http://commons.ucalgary.ca/moviethumbnail.jpg
</location>
<label>
thumbnail
</label>
</technical>