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The Benefits of Semantically Structured Metadata, Part the First

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The Benefits of
Semantically Structured Metadata

(Part One)

You mean there are benefits?

Last week I compared the semantic structures approach to metadata with the modularized approach to building homes from Lincoln Logs. I also contrasted this method with the approach to building homes from monolithic, prefabricated parts. I hinted at my feeling that flexibly providing for future extensibility should be a goal of any metadata standard. This week I would like to propose some future scenarios that demonstrate the benefits of a flexible, semantically structured metadata standard.

My, what an intelligent tool you have!

People (including myself) have been playing up the relationship between the metadata implementation and the tool that searches through it. We keep implying that there's some way that the tool can understand the metadata. What could we possibly mean by that? Let me give an example.

The IMS metadata dictionary contains a list of terms (or little notched logs, in last week's example) from which metadata can be built. Last week I used the examples

Meta-metadata.Create.Person, and


the person who created the metadata, and a person who contributed to the creation of the resource, respectively. See how I got the meanings? Basically just by reading backwards - seems easy enough. You might say, "So how does that make semantically structured metadata special? I could just read the field name backwards regardless of whether the metadata is semantically structured or not." Sure you could. But unless there was a dictionary and grammar, as I described last week, your search tool couldn't.

Say I took some terms from the IEEE LOM dictionary and arranged them in a new way (recognizing, of course, that a monolithic metadata standard won't even let me create this new arrangement -- it only provides me with predetermined parts), like this:


Now even if a structured metadata implementation would let me create this kind of entry, the information in this metadata field is worthless to a tool that doesn't know how to use a dictionary and grammar -- the tool has no way of interpreting it. The "dumb" tool only understands the metadata fields defined by the "master schema." So how could an understanding, or "intelligent" tool help me use metadata based on this new combination of terms?

Imagine yourself searching through an archive of learning objects, looking for an image of the Mona Lisa. Your search tool might know the most common image formats and return only search results that describe an object of one of those types (say, .jpg or .tif). If the only Mona Lisa available was in a format your search tool wasn't aware of it might not report it. And if the metadata was built from large prefab parts, you and your intelligent search tool would be left out in the cold.

However, if the metadata was semantically structured, then your intelligent tool might see a metadata entry like Technical.Format.Description and be able to infer that there is a description of this file format it doesn't recognize. It might then respond: "I found one Mona Lisa entry in an unknown format -- however, the word 'image' appears in the format description. Would you like to read the description?" You could then learn about a wonderful new image format, and get the object you needed to support your instruction.

You can't have one without the other...

When used in combination, semantically structured metadata and a tool that understands semantic structures have enormous potential. Even if the kind of interface to information I described above were the only application of the structured approach it would be well worth it. I should stress here that these benefits a reaped only when the semantic structure approach is applied to both the metadata and the tool. Separately, a structured metadata standard and a tool that understands structure are about as useful as a key without a lock, or vice versa. I believe that the additional functionality and improvements in user interface that semantic structures make possible justifies the additional effort necessary to create client and server implementations.

But perhaps you prefer a doomsday argument. I mean, if everyone in the world will just implement the IEEE LOM standard exactly as specified, as long as the standard keeps pace with users' needs functionality like this will never be required. However, as long as there is a chance of people "extending" the standard (as web browser vendors have done with HTML, for example), I believe we should provide for these "improvements," legitimate and otherwise, to the degree that we can.

Compared with a monolithic approach, semantic structures allow us to achieve greater functionality while providing an cleaner, easier path to extension.
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Last modified 2004-06-14 10:08 PM