Briefcase: The File Synchronizer

Briefcase is a Windows 95 application for keeping files up to date when youhave your laptop away from the office. In the spirit of cross-platformcompatibility, Microsoft has now added this functionality in Windows NT 4.0.

My first reaction is some surprise. Briefcase is for users who are away fromtheir networks. One area where Windows 95 still scores heavily over Windows NT4.0 is in laptop support for such features as hot-plugging PC Card (formerlyPCMCIA) and power management. Nevertheless, many users want NT on a laptop, andfile synchronization is a big issue.

The basic concept is to create a special area where you can place copies offiles. When you're away from the office, you work on the copies. When you getback, the Briefcase checks whether your files are the same as those on thenetwork. If you've changed them, Briefcase can update the network copy. If thenetwork has a newer version, Briefcase can bring the updated data down to yourmachine. If changes have occurred at both ends, Briefcase can offer aconflict-resolution schema.

Briefcase in Operation
Let's see how Briefcase works. You open "My Briefcase"--thedefault object name--from the desktop. Then suppose you create a new Worddocument called "Word Document" in a folder called "SourceDocuments." Screen 1 shows how easy Briefcase setup is.

Once you store the file copy in the Briefcase, you can leave the office.The Briefcase time stamps both the copy and the source. Away from the office,you change the file stored in the Briefcase. Because you're not connected to thenetwork server, you can't change the master version.

If you change the document on your laptop, My Briefcase reflects that factwhen you select View Refresh. The Status field changes to "Needs updating,"indicating that the copy in your Briefcase is out of synch with the last knowncopy on the server. More accurately, the change in your copy's Modified Datereflects that changes have occurred.

Resynchronizing the file is also easy. When you're back in the office, justreconnect to the relevant servers and select Briefcase Update All.

A dialog appears that shows the status of the changes. The simplest option,which screen 2 illustrates, is to change the copy on the laptop, so the servercopy remains untouched. The dialog tells you the Briefcase version is morerecent than the network version and suggests replacing the original with theworking copy in the Briefcase to synchronize the two.

If the server copy changed while you were away from the network and yourBriefcase copy remained untouched, you get the other version of this dialog. Ittells you to copy the file to the Briefcase, as you see in screen 3.

No Conflict Resolution
These two scenarios are straightforward. Briefcase detects a change in thedate on either side and makes the appropriate suggestion.

But what happens if you make changes, and changes occur on thenetwork? Because both sides of the equation have changed, Briefcase asks you tochoose manually. The default setting is "skip," meaning that you don'twant to update one version automatically. Screen 4 shows this setting. Two otheroptions are the replace options already mentioned. As you can see, no conflictresolution is built into the combination of Briefcase and Office 95, so thecombination's usefulness is blunted.

Does the situation improve if you work with composite documents? Let's see.Suppose you check out a Word document that has an Excel table embedded in it. Ifyou change the Word part and your partner in the office changes the Excel part,can Briefcase create a new composite document? Unfortunately, not. Briefcaselooks at the single structured-storage document and makes its decision based onthat version.

This situation is extremely weird. If you check out a Binder Object with anExcel object and a Word object in it and one person changes the Word objectwhile another changes the Excel object, Briefcase can merge the twosections. Binder Objects are just structured-storage files like Word files,Excel files, PowerPoint slides, and so on (see "Exploring Cairo: ObjectFile System," Windows NT Magazine, December 1995). WhyBriefcase can't merge other structured-storage objects isn't clear. There's nogood reason why it shouldn't work.

Be warned, however, that Binder Objects can't resolve conflicting updateswithin one document. If you change a Word document and a colleague changes thesame document, you can't merge those two versions of the document automatically.You have to do a classic file compare to find out what has happened.

If you have Microsoft Access 95 on your computer, it can take advantage ofBinder Objects to do replication. Access uses a sophisticated engine forreplication, and it doesn't require Binder. Access can fire off all the relevantreplication systems for you as part of a unified user interface.

Is Briefcase Worthwhile?
Briefcase is an interesting idea that works. It helps keep track of work inprogress and is ideal for updating rarely changed data. Databases of phonenumbers and work that others are doing in office applications are goodcandidates.

My main concern with Briefcase is that it makes an "application"out of a task that really should be built into the file system. Knowing whetherchanges have occurred and how to replicate those changes among users is the filesystem's job. Using an application program to provide this functionality merelypoints out the file system's shortcomings.

When Microsoft gets its Cairo act together, some of this functionalityshould migrate to the file system, where it belongs. For example, the ability todeconstruct embedded structured-storage objects should let different people workon individual parts of a composite document at once. Currently, only one usercan have read/write access to a structured-storage file, while everyone else islimited to read-only, even though the design allows for multi-user access.

The implementation of Public folders in Exchange Server gives us an idea ofwhat Microsoft is thinking. You can replicate documents around an organization,but the level of conflict resolution in Exchange Server is woefully weak--and itdoesn't help the intra-document problem. A lot more work needs to be done onexposing the inner contents of documents to their outside-world containers.Then, automatic conflict resolution will be possible at the individual wordlevel within, for example, a word-processing document.

The simple fact, that in 1996, we are relying on the mindset and basetechnology of 15 to 20 years ago speaks volumes for the lack of attention thatthe major software vendors have paid to the actual uses of data in theworkplace. It's about time file systems were considered active repositoriesinstead of dumb filing cabinets. Replication and conflict resolution are justtwo of the problems that need to be solved.