Installable File System


In Exchange 2000 Server, the ExIFS was mounted by default and was a recommended method of managing users’ data. As you might recall, the Installable File System allowed users to 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 was a browser, a MAPI client, or Microsoft Internet Explorer.

However, Microsoft has backed off from using the IFS for data and file management. In Exchange Server 2003, the IFS is not mounted by default. If you want to mount the IFS to expose the databases as a virtual file system, you must re- enable the M: drive through the following registry parameter:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\EXIFS\parameters Parameter:  DriveLetter Type:  String Value:  M

You should use the M: drive only for gaining access to non-MAPI file data. You should not share out portions of the M: drive for server message block (SMB) user access. The preferred method is to use the Web Folder client to access data in the stores for applications such as Microsoft Word, rather than use the M: drive and SMB access.

More Info

If you’d like to learn more about SMBs, go to http://probing.csx.cam.ac.uk/about/smb.html or http://wwwacs.gantep.edu.tr/foldoc/foldoc.cgi?Server+Message+Block. Essentially, SMBs are commands sent from a client to a server to request file-type actions, such as Copy, Create Directory, and Delete. Much like SMTP (Simple Mail Transport Protocol), which uses a request-response architecture, SMB commands are a series of requests from the client and responses from the server. The number and type of commands used between client and server are determined during the direct negotiation while the TCP three-way handshake is occurring, when the session is being established between the client and the server. To better understand the TCP three-way handshake, take a look at the Microsoft Windows Server 2003 TCP/IP Protocols and Services Technical Reference (Microsoft Press).

The Web Folder Client

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

WebDAV (Web Development Authoring and Versioning) 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 using the browser as your 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 (and later) are compatible with WebDAV. Here are some features of WebDAV:

  • 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 Users can conveniently manage Internet files and directories, including moving and coping files. This process is similar to file management in Explorer.

  • Property (metadata) access Users can index and search metadata information about a document, such as the author’s name, copyright, publication date, or keywords, to find and retrieve relevant documents. (For more information about this, see the “Indexing” section 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 Server 2003 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 Server 2003. The Web Folder client ships with Microsoft Windows 2000 Professional and Microsoft Windows XP.

To create a Web Folder to a resource in the Exchange store, use the Add Network Place Wizard in My Network Places and enter one of the following:

  • The server share location using a Universal Naming Convention (UNC), such as \\servername\sharename

  • A Uniform Resource Locator, such as http://www.microsoft.com

  • An FTP site using this syntax: ftp://ftp.microsoft.com

Once created, the Web Folder client can be used to access information by an application, Windows Explorer, or other client-side utilities.

This shift from using the IFS to using the Web Folder client is indicative of a much larger shift that moves us away from using SMBs to using Web-based technologies for managing and manipulating information, data files in particular. Moreover, if you get a chance to take a look at the Windows SharePoint Services service from Microsoft, you’ll find that file management is moving away from a file server–based architecture to a database architecture. This shift is part of an overall strategy to move away from what we would traditionally think of as LAN-based technologies to Web services–based technologies. This shift is well underway and is represented in nearly every new platform that Microsoft is introducing.

What if you’ve been using Exchange 2000 Server and you’ve dumped a truckload of documents into public folders that users are accessing via the IFS? Well, in Exchange Server 2003, you can continue to leave those documents in public folders and, if you really want to, you can mount the IFS and use SMBs to get at those documents. However, bear in mind that at some point in the future, all data will be held in a SQL-like database. The Web Storage System as we know it will give way to the next big database engine, which will be SQL-based. You might want to consider planning for this impending change now.




Microsoft Exchange Server 2003 Administrator's Companion
Microsoft Exchange Server 2003 Administrators Companion (Pro-Administrators Companion)
ISBN: 0735619794
EAN: 2147483647
Year: 2005
Pages: 254

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