Lately, many of my readers have been asking questions such as, "What's the difference between a Web site and a Web domain?" "What's a virtual root?" and "What's a subweb?"
I asked five IIS administrators to explain some of these terms, and I found out that they had many of the same questions as my readers.
The Internet functions according to a set of international standards. (You can read all about HTML, HTTP, authentication, and 50 or so other Web-related standards at http://www.w3.org.)
Even if you read all these standards, however, you might still get confused reading an article about IIS, Microsoft Visual InterDev, Microsoft FrontPage, or even about managing applications on the Web. Everyone in the Web community seems to use his or her own set of Web terms.
This glossary is a starting place—an aid for classifying and clarifying some terms commonly encountered in the web community.
Web site is probably the most generic, least specific, most overused term in the vernacular. A Web site is any addressable location that contains HTML content and, in most instances, a home page. An HTTP server (see "Internet Servers") usually hosts Web sites. However, any folder on a drive (e.g., C:\myweb) can contain HTML pages that you can view using a browser with access to that directory (e.g., file://C:\myweb\home.htm).
With respect to the Web, the term domain pertains to ownership of Web real estate. Domain owners (both Internet and intranet) have different perspectives on this topic. If your bent runs toward Web hosting or Web authoring, then a Web domain includes everything that you can reach through a specific URL. If your bent runs toward Web server administration, then a Web domain (Web site) is everything served by its Web server.
For example, you can buy an Internet domain name from an agency such as http://www.networksolutions.com, then have your Web content hosted (installed on) an HTTP server running on a server machine on the Internet. You'll reach all the Web pages, content, applications, databases, and so on, in this domain through a URL that includes your Web domain name (e.g., http://www.ideva.com/dhtml_labs/myfavorite-example.htm, where ideva.com is the domain name, and www.ideva.com means it's on the Internet). You'll also brand your other servers that run on the Internet (e.g., mail, FTP) with your domain name. For example, Ideva's mail server might be called mail.ideva.com, and the FTP server might be called ftp.ideva.com. These servers might or might not be on the Internet. As a network administrator, I can make these domain names accessible to the Internet by putting them on an Internet server machine and publishing their names in my Internet DNS. My DNS will broadcast them to the rest of the Internet, and users throughout the Internet can access them because my company owns the domain name ideva.com. Because I own the domain name ideva.com, which is already registered, I don't have to register each individual server domain.
Examples of Internet domains and Web domains include
- www.ideva.com—An HTTP-served domain running on the Internet (which the www signifies)
- www.ideva.net—A different Web domain on the Internet that could belong to someone else (the difference is in the .com or .net)
- http://training.ideva.com—A Web domain for the training division of ideva.com
- http://publishing.ideva.com—A Web domain for the publishing division of ideva.com
Although the last two examples belong to ideva.com, a browser might not automatically recognize these domains as Web sites unless the http:// identifier precedes them. The reason for this lack of recognition is that as the administrator, I can create as many of these arbitrarily named Web domains or Web sites as I want, because my company owns ideva.com. I can publish these Web site addresses to the Internet DNS, or I can keep them private behind my firewall. All these example domains have an entry in a DNS somewhere.
Realm. A realm is a protection space (i.e., a URL you have to log on to) on the server. A server might not have any realms, or it might have many realms arbitrarily partitioned. A domain is a set of URLs that defines the protection space for which a realm is the name. So, http://training.ideva.com might or might not be in the same realm as www.ideva.com, depending on whether they're in the same protection space (i.e., the same users have permissions in both). Currently, domain is the preferred term over realm for Internet sites. However, if you use Microsoft Site Server, you'll need to become acquainted with realms because the Membership Directory Service (DS) uses realm to identify the DS controlling and providing access to the Membership server's members information. The realm name (usually the company name) serves as the top node in the hierarchy of the security structure. All the Web domains or Web sites mapped to that Membership server are in the realm.
Frequently, the term server refers to the software running in the machine, and only the HTTP server is called a Web server or an Internet server. However, if you're talking about a machine on the Internet that is running server software, then that machine will most likely be called an Internet server or Web server. To further complicate things, the Internet server (machine) is probably running both FTP and HTTP servers, as well as a mail server, SMTP, or POP. So, the first point to make is whether you're talking about software (a server program) or hardware (a server machine).
HTTP servers (software) that run on the Internet are regularly called Web servers (as though the HTTP server were the only server running the machine), probably because HTTP is the language that these servers speak and the servers serve Web content (e.g., pages, graphics). HTTP services are usually associated with the Web.
The next problem is that this nomenclature leaves the impression that one server machine can have only one HTTP (Web) server running on it, which was true in the past (perhaps 18 months ago) but isn't the case today. A Web server machine today can have multiple HTTP (Web) servers running—one for each Web domain. So the term Internet server often refers to both the machine that is running the server software and to the HTTP services. For clarity, then, I call the HTTP server (software) the Web server, and refer to the machine as the Internet server.
Multihomed servers. A multihomed server (also called a multihosted or multihosting server) is a server machine that supports multiple Web domains, each one running on its own instance of an HTTP server, or a virtual server. For more information about multihomed servers, see "Using Host Headers to Set Up a Multihomed Server," October 1999.
Virtual Servers and Application Servers
A virtual server is a copy of the server executable and its attendant libraries running in memory on the server machine. In this discussion, the Internet server is IIS. Access the IIS snap-in in the Microsoft Management Console (MMC) by clicking Start, Windows NT 4.0 Option Pack, Internet Information Server. The MMC opens with the IIS snap-in displayed. Notice that each virtual server has a Web site name. In fact, the IIS snap-in in the MMC (which Microsoft calls the Internet Service Manager—ISM) calls these virtual servers Web sites. To create an instance of a Web server, or to create a new Web domain (which is the same thing), right-click the server machine name, and select New, Web Site.
A common practice is to refer to the virtual server by the Web domain name that it serves. Thus, you might see a URL such as www.ideva.com called either a virtual server (if you're talking to someone from an OS or server group, because a copy of the Internet server running in memory serves each Web domain) or an application server (if you're talking to someone involved with Visual InterDev, because another of the functions of IIS—besides handling HTTP requests—is running and managing Web applications in its Web domain). In summary, one Internet server machine can host many different types of servers and Web domains, and each Web domain runs on a virtual server, which is an instance of the HTTP server (IIS 4.0, in our case).
The highest level of content in a Web domain is the root web of the domain. For example, www.ideva.com is the name of the root web at Ideva. (Notice that earlier I called this same name a virtual server, and before that I called it a Web domain.) FrontPage calls a root web a virtual root because it's running on a virtual server.
If you've installed FrontPage Server Extensions on a root web, you can use FrontPage to edit and manage the root. To activate the FrontPage Server Extensions, from the IIS snap-in in the MMC, right-click the virtual Web server, select Properties, and click the Home Directory tab. Select the FrontPage Web check box, then click Apply, OK to close the Properties sheet. FrontPage will create the private directories and install the server extensions on them. These private FrontPage directories all start with an underscore (_). FrontPage usually hides and write-protects the private directories to prevent authors from inadvertently changing content, themes, navigation, shared borders, hit counters, application components, and so on. You might need to save the new settings before the new directories display. To save the settings, choose Action, Refresh.
Subwebs (Child Web Sites)
A Web domain can have many Web sites under it, which non-Microsoft folks often call child Web sites. A child Web site has a home page, but its URL lists it as a subdirectory under the root web (e.g., www.ideva.com/training). Each child Web site resides in a separate directory structure. If the child Web directory structure isn't physically located under the parent Web site on a hard disk, the Internet server administrator can link it to the parent Web site. A directory linked in this way is called a virtual directory. To create a virtual directory, right-click the parent web in the IIS snap-in in the MMC, then choose New, Virtual Directory, and follow the steps in the wizard.
FrontPage calls child Web sites subwebs if these sites have the FrontPage Server Extensions installed on them, which means that you can use FrontPage to edit and manage them as autonomous units. Subwebs can have different users, authors, and administrators from the parent Web site. Subwebs can also have different themes (graphical appearance), different applications, and so on. The IIS or FrontPage administrator for a particular virtual root can create subwebs under that virtual root. FrontPage 98 Server Extensions can't nest a subweb under a subweb, but FrontPage 2000 Server Extensions can.
If you have FrontPage 2000 Server Extensions installed on a virtual server, you can create a new subweb by right-clicking the Web site and selecting New, Server Extensions Web. When you select this option, the New Subweb Wizard will open and guide you through the process of naming the new directory in which the subweb will exist.
Web folders are a new feature of Microsoft Office 2000. A Web folder is like a shared directory on the network, except that it's really a shared Web site on the Internet. Web folder technology lets you use Windows Explorer instead of a browser to connect to a Web site. After you connect to a Web folder, you can read the files in that folder, copy files to and from it, and even edit files in it. The files don't even have to be Web files; they can be Microsoft Excel spreadsheets, Microsoft PowerPoint presentations, or almost any other type of file.
Your users might have to log on to the Web folder before they can view its content or publish to it. If your users are using Office 2000, you can protect Web folders on the Internet by using Windows NT Challenge/Response authentication because Office 2000 and Microsoft Internet Explorer (IE) 5.0 support it. So, with Office 2000, you can protect the Web folders on the Internet with the same security as on an NT network instead of the far less secure Basic authentication. If you use NT Challenge/Response authentication, the users will need their network ID and password and the correct NT domain name before the Web server will let them access a Web folder. The Web folders that your users connect to will be available to them any time they connect to the Internet from anywhere in the world.
To connect to Web folders,
- Access your Web folders directory, either in My Computer or in Windows Explorer.
- Use the Add Web Folder Wizard (in the Web folder directory or in My Computer), and link to a new Web folder. The location you add will be the fully qualified URL for the Web folder (e.g., http://www.mycompany.com). If you've set up NT Challenge/Response authentication, NT asks the users to provide their NT network ID, password, and the NT domain name. The users on the Internet must be browsing the Web folders with IE 5.0 for this authentication to work. If you have users on the Internet with older browsers, you must use Basic authentication in clear text to secure the Web folders, or their browsers won't be able to log on.
The wizard authenticates the users' credentials with the server and creates a Web folder that lets them use the Internet to browse the root web directory and its subdirectories, which you see in Screen 1, from anywhere in the world.
When your users double-click the Web folder, they'll see the files and subdirectories the folder contains, just like any shared directory on the network. When they've connected to a Web folder, the Web folder directory lists the folder until they delete it. Users can delete a Web folder from Windows Explorer by right-clicking the folder and selecting Delete.
If your users are going to edit or write non-HTML documents in the folder, Web folders are the way to view those documents and open them for editing—just as if they were on the users' machines. Because those files are coming across the Internet, however, it might take a bit longer to load and save them, depending on connection speed.
In the Future
This glossary is a starting point for the terms commonly used in the Web community. As technology changes, this glossary will grow and reappear in future issues of IIS Administrator.