Total Recall - C. Gordon Bell [19]
In his memex paper, Bush had expressed hope that the search algorithms of the future would be better than simple index-lookup on some attribute like author or date. He held up the human brain’s associative memory as the ideal. In an associative network, items are linked together by contingency in time and space, by similarity, by context, and by usefulness. There are often numerous paths to each item.
Bush was right that trails and associative linking were critical components of an effective e-memory machine. But his dismissal of indexing was one of his rare failures of imagination. In his day, indexing meant alphabetical lookup in a predefined, noncompre hensive list of topics or keywords, as in a library card catalog. With the speed of modern computers, it has become possible to index every single word and phrase in every document and to search all of them in an instant. When indices are so comprehensive, and lookup by the index instantaneous, then indexing is actually the mechanism by which associative memory becomes possible.
The MyLifeBits research project revealed that any system that aspires to be sold as an e-memory machine in the age of Total Recall will have to use a database storage engine, including full-text indexing. Only a database will allow you to create two-way links between items (including annotations) and to regroup and recat egorize items and collections of items in an open-ended fashion. Only full-text indexing will give you keyword access to all of your e-memory.
With MyLifeBits we could find all items that share a certain property, such as having the same creation date, or having been edited during a particular meeting, or having been viewed within a certain span of hours after a particular phone call.
To make a database-style system work, we needed to include what is called metadata, or “data about data.” Metadata is essentially digital annotation about a file or other software object. Metadata may be embedded inside a file, or it may be “attached” to it from the outside. Conceptually, it’s a bit like a sticky label on a manila folder that characterizes its contents.
Your computer’s operating system keeps a little metadata on each file for bookkeeping, such as its creation date, the date last modified, the size of the file, and who is allowed to access it. Certain file types support additional metadata. For instance, the Microsoft Word document I am typing in right now lets me enter author, title, subject, keywords, category, status, and comments. Pictures in JPEG format can record things like the date taken, location, camera model, focal length, f-stop, and exposure time. Nearly all music formats include artist, album, composer, genre, and length.
Some of this metadata gets filled in automatically. Digital cameras fill in the JPEG fields when they take a picture. CD-ripping programs look up the album information on the Web and populate the metadata for each song. In contrast, the metadata for Microsoft Office documents must be manually entered. Your name, which you were prompted for when you installed Office, is prepopulated as the author in new documents, but everything is blank—and tends to stay that way. Many of these manual-entry attributes will remain blank until we have systems more like MyLifeBits so that there is an actual payback for doing the work of entry.
One kind of metadata attribute that is getting a lot of attention these days is called a tag. A tag is simply a single word or short phrase. Tags aren’t much different than the keywords attribute I have for this Word document. But they are creating a stir because there are some great photo applications, such as Flickr, that make tags easy to create and very useful for finding things again. You can add any number of tags