While this does allow Common Ground to be easily extensible (instead of forcing Hummingbird to write hundreds of document conversion filters), it does have real performance penalties. Document conversion is performed one document at a time. Perform ance depends entirely on how long each application can load and print a document. A large batch (I converted 167 Microsoft Offi ce documents) can take well over an hour to convert. Hummingbird argues that this performance penalty is a small price to pay for the convenience of unattended operation. Given the alternative of converting each document by hand, manually writing HTML indexes and copying the files to a Web server, we tend to agree.

Digital Paper Using Hummingbird's Digital Paper (DP) format, Common Ground lets any Web-capable client browse fully formatted, indexed and full-color documents as if they were printed documents. Like Adobe's Acrobat format, DP documents can be viewed onscreen, searched and printed using a viewer application. Hummingbird offers DP viewers for Windows and Macintosh environments, which can work independently or as Web browser plug-ins. Common Ground also includes a client-side Java viewer. Instead of generating a separate HTML page for each DP document to load the Java viewer, Hummingbird includes a small server application designed to automatically "wrap" each DP document with the appropriate HT ML code. Also written in Java, this server applet (DPserve) can run on any Web server, so you can use any Java-capable OS as the document server.

Hummingbird's Common Ground is a Windows NT 4.0 application. While it doesn't specifically require NT Server over NT Workstation, Microsoft's licensing agreement may require a copy of NT server if you expect many concurrent clients. While some Java components (such as the DPserve and NetResults, a server-side Java-based search engine) can run on any operating system with a Java Virtual Machine (JVM), Common Ground's document conversion functions are married to the NT platform, since they rely upon individual desktop applications to "print" documents into the Digital Paper format.

First Hand I installed Common Ground, configured it to search for documents in a shared directory and specified a destination directory in the Web server's do cument tree. I copied 167 documents into the directory through standard Windows NT file sharing. After creating a batch pro cess to access that directory (Common Ground requires a separate batch for each directory), Common Ground began converting my files into DP documents and building appropriate Web pages.

There are a couple features I didn't particularly like. First, because Digital Paper Express launches applications to process documents into DP files, it cannot run as an NT service. While Common Ground is designed to run unattended, the NT server must be manually logged-in when rebooted, which could be a concern when you place a Common Ground server in production mode. Also, I found that the Digital Paper Express application processes batches in only one directory. Common Ground was unable to handle directories of documents in the shared folder. This was a limiting factor when publishing large numbers of documents, as it takes time to define a separate batch process for each directory. Users can't automatically create their own directory hierarchies on the server.

While functionally equivalent to the widespread Adobe Acrobat format, Digital Paper does require a separate document. This necessity can make Common Ground unattractive to organizations that need to publish documents to the Internet at large. If your organization already supports Adobe Acrobat (PDF), Common Ground requires Digital Paper viewers installed on each desktop. While the Java-based viewer is a convenient touch, the 328KB applet takes time to download (it took approximately 3 minutes to download and view a small text document via a 56KB dial-up connection).

Dan Backman can be reached at dbackman@nwc.com.