Some of the more popular desktop search tool providers include:
- Google, www.desktop.google.com
- Yahoo, http://desktop.yahoo.com
- Microsoft, www.microsoft.com/windowsdesktopsearch/enterprise/default.mspx
- and http://desktop .msn.com
- Beagle (for Linux),
- http://beaglewiki .org/Main_Page
- Copernic, http://copernic.com/en/products/ desktop-search/index.html
- Ask, www.ask.com/?tool=des
All desktop search tools work in roughly the same way. First, all of the content on the computer's hard drives is indexed for quick lookup. This is typically performed by a set of filters, sometimes implemented as plug-in components, which understand different types of content (Figure 3). With a plug-in architecture, support for new content types is added by installing additional plug-ins. Most desktop search tools provide an API that allows developers to extend the index engine to support proprietary content. For instance, indexing media content (video, audio and images) involves the metadata associated with the content, which is included as part of the media format. If a new media format is invented, the vendor should also create filters for the common desktop search tools to let the content appear in a user's search results.
Files are indexed by filter components that understand the file's content.
The index is basically a word list, where each word (or phrase) is associated with the set of files in which it appears, along with the word's location within each file. Creating this index takes time, and most of the common desktop search tools let you adjust when and how the index is created. Once the index is created, it takes relatively little time and processing power to keep it up-to-date as files are changed, added and deleted from your hard drive.
Next, searches can be executed against the indexed content, with meaningful results presented to users. Although the mechanics of searching is similar for all of the desktop search tools, the presentation of the search results is where they diverge. Google Desktop, for instance, displays its results within a browser in similar fashion to a www.google.com Web search (Figure 2). When you click on a result, such as an e-mail message, the associated application (Outlook, for instance) launches with the associated content.
Other desktop search tools, such as Copernic and Ask, have a richer user interface, and include a higher level of application integration (Figure 4). Ask integrates with installed desktop applications, such as Office, and allows you to search for content (or files) you wish to edit instead of looking through directories on your hard drive. This is a paradigm shift: it's the content that's searched for and located, not the file that contains it. It's subtle, but it may help boost productivity for many users.
Copernic includes a rich user interface with application integration for the embedded display of content.
Ask Desktop is unique because it integrates with Web services such as MyStuff and the Ajax application, Writely. This lets you index and search documents created with Writely, even though the files don't live on your desktop. This is a key point, as it illustrates how Ajax is extending the local desktop to the Web, thereby creating a "virtual desktop" that will need to be integrated and searched. It also illustrates how Web-service integration will be crucial for future desktop applications.
