Installable File System

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One of the problems with document management for an organization has traditionally been the need to choose a technology for saving users' data. Until now, users have had to choose between saving their documents in a file system, on the Web, or in a public folder. Once they chose the location, they were locked into using a single interface to retrieve and work with their information.

Installable File System changes all of this. With IFS, users can place any kind of document in the native content file (the streaming file) and then access it from almost any client, regardless of whether that client is a browser, a MAPI client, or Microsoft Internet Explorer. This section expands on how ExIFS can be managed and how it will revolutionize the way you think about file and document management.

Data Access Through IFS

IFS treats each item of information in its database as an individual object that is exposed to network clients as a normal file, which means any folder, mailbox, or other information object can be accessed as though it were a normal network share. Clients can map drives to information objects in the database and have the ability to read and write data directly to and from the native content store.

The store is mapped automatically as the M: drive for the Exchange 2000 client. The share name on this store is BackOfficeStorage. Hence, clients can map a drive to \\servername\BackOfficeStorage. The M: drive is called a portal into the Store.exe process. If you run the Dir command on your M: drive, it becomes a Win32 call for a list of files. The ExIFS driver moves this call into the database, which determines which files are being requested and returns the results of the call to the user, in the form of a listing of files in the database (Figure 2-10).

Figure 2-10. Using the Dir command to list files in the native content file.

Inside this share will be two folders: Mbx and Public Folders. The Mbx folder is the root folder for all mailboxes on the server. Users with permissions to do so can navigate the hierarchy using explicit folder names that equate to the mailbox alias names.

Information in the IFS can also be subject to full-text indexing and can be accessed by HTTP clients. This means that Internet users can utilize the Exchange Web client to query the information store for document properties as well as for search terms, get the results quickly, and then view the results in their browser with an Outlook-style view. Moreover, with Extensible Markup Language (XML), a user can make changes to a document over the Internet via the browser and save the document in the same way that one would save a document on a file server.

Web Access to IFS

As we mentioned earlier, information that is held in the native content file can be accessed over the Web, using HTTP. This is accomplished by giving each object in the file a unique URL that lets the object be accessed from the browser, allowing a customized application to call directly into the Exchange store to retrieve data from both mailboxes and public folders.

WebDAV, an update to the HTTP protocol, is now available to meld Internet technologies with file and print technologies. WebDAV is an extension of the HTTP protocol and represents a standards-based layer that is built on top of HTTP 1.1. Specifically, it supports a more complex command structure, adding commands such as COPY or MOVE that manipulate individual objects on a Web server. In addition, this new protocol allows read/write access to the information store over HTTP for any client. It supports relational database structures, semistructured databases (such as Exchange databases), and standard file systems. Furthermore, WebDAV clients can be synchronized to server-side stores over the Internet through replication, allowing efficient online access and offline usage of data. This feature enables you to, for example, publish an hourly update of current inventory to a nationwide sales force. Each salesperson would be able to view this information over the Internet, enter orders and comments, and have current information at a client site as long as Internet access was available.

WebDAV can accommodate all types of content, which means users can use WebDAV to work collaboratively on a word processing document, a spreadsheet, or an image file. Potentially, anything you can put in a file can be authored using WebDAV. WebDAV makes the Web, from the point of view of the client, a writable medium. Microsoft Internet Explorer 5 and Microsoft Office 2000 are WebDAV compatible. Some of the features of WebDAV include the following:

• Overwrite protection (file locking) Users can write, edit, and save shared documents without overwriting another person's work, regardless of which software program or Internet service they are using. This is a key collaborative support feature.
• Namespace management Enables users to conveniently manage Internet files and directories, including the ability to move and copy files. This process is similar to file management in Explorer.
• Property (metadata) access Permits metadata information about a document, such as the author's name, copyright, publication date, or keywords, to be indexed and searched to find and retrieve relevant documents. (For more information on this, see the section "Indexing," later in this chapter.)

Web folders are designed to let clients access a Web server in the same way they access a file server. Exchange 2000 Server allows a client to access directories and items in the information store just as it would access them on a file server and to manage the data in the Web folder as if it were a file server. Public folders are also exposed as Web folders in Exchange 2000 Server.