Decals represent properties of an object in a way that can be interpreted by computers. Decals are associated with an object, not embedded in it, and can include instructions that a computer can follow to update the properties, retrieve related properties, and look up related information.
Whereas traditional metadata is machine-readable, it is typically not machine-interpretable, and it is typically static rather than dynamic. Here are examples that illustrate the differences:
- Many web pages are tagged with key words, which are important for search engines. Using today’s methods, these key words are embedded in static tags that and must be updated when the content of the page is updated. A decal, on the other hand, can reference a web service that generates the key words from the content of the page.
- Suppose the title of a video is “estimating sums of three-digit numbers.” Today, this may be encoded in the video file in a way that allows software to read and display the title. This enables a teacher see the title on a list of search results, from which she can surmise how the video relates to the lessons she is teaching, to math standards, and to her students. Decals enable machines to do the same. A decal can point to a service that computes how closely the video is related to any lesson and not only tag the video with a math standard (as could be done with traditional metadata) but also provide a means to look up the test scores of students on related standards.
Try out a decal
Below is a decal. This decal can be embedded in any web page and used by any system that understands decals to retrieve this particular property of the page.
Each time you click on an action, a new decal is being generated on a remote computer and sent to yours, where it is displayed using the Web Viewer. Hover over a button for an explanation.
These demonstrations go over three major use cases, and show off the flexibility and power of Decals.
- Web Viewer
- The first demonstration is the web viewer, which emphasizes looking at a decal outside of any particular system.
- Generation, Storage and Retreival
- This second demonstration shows the ability to create, store, and retreive decals in a remote system.
- The third demonstration allows you to search a repository of about 200 CNN News Articles.