hi,

One of the toughest problems in desktop management is letting offline users work just as if they were working online. The need is greater than you might think—users are a lot more mobile than they were even five years ago. Though there are a number of cases where you might need to work

offline, the three most common are when you disconnect your laptop from the office network and go on the road, when you connect over a slow or intermittent link, and when your branch office loses connectivity to the main office.

In these circumstances, how do you maintain a copy of a file on the offline computer while the original is on the main server? More importantly, how do you handle a conflict if someone in the home office changes the file on the server while someone else changes it on the road? Fortunately, these issues are handled by the Offline Files engine, which is built into Windows^® 2000, Windows XP, and Windows Vista^®.
Caching Is the Answer

The Offline Files engine is really a giant caching machine. Indeed, underneath the hood (and inside Microsoft) it's referred to as client-side caching (CSC). The Offline Files engine is configurable and flexible enough to let users decide what they want to cache as well as help you get the system to cache what you want. It allows you to access the same files offline as online—and the namespace doesn't change. That is, files are accessed using the same UNC path or drive letter whether you're working online or offline.

You can set up the files to be cached either manually or automatically. If you know you often use particular files or folders while on the road, you can simply designate a file or folder as one that will travel with you. To do this, a Windows XP user would right-click on a file that is stored locally or on a network share and select the option to make files available offline (see Figure 1). In Windows Vista the option is called Always available offline. Manually making a file available offline is sometimes called pinning a file.

Figure 1 Making a file available offline (Click the image for a smaller view)

The share you're using can be connected via UNC path or mapped with a drive letter. Indeed, the file doesn't even need to be one that's stored on a machine running Windows Server^®. It can reside on anything that serves up the SMB (Server Message Block) protocol, such as a Samba server or NAS device (with some rare exceptions), which also adhere to the SMB protocol.

The first time you choose to pin a file, Windows XP walks you through a series of wizard screens, asking when to synchronize. If you click Next on every screen and take the defaults, synchronization happens every time you log on or log off, and also in the background when idle. When the wizard completes, you'll see an icon change indicating that the file is now available offline.Once you disconnect from the network, all other files on the share become unavailable except those chosen for offline use. That's sometimes problematic: the icon shows which files are always available offline, but it's not immediately clear before you've disconnected that not all the other files will be available.