Mr. Script

Spinning a Web of Control

Now that the real millennium is upon us, it’s time to properly administer our Web sites—and ADSI IIS Provider is just the tool to make it happen.

• By Chris Brooke
• 01/01/2001

Happy millennium! No, I haven’t been in a coma for the past 12 months. As all real geeks know, the 21st century officially starts Jan. 1, 2001. Time flies, doesn’t it? Why, it seems like only yesterday I was holed-up in my Y2K bunker — with extra water and ammunition by my side — working on how to jockey for the best position in the “new world order” that would arise from the imminent destruction. What a disappointment Yawn2K turned out to be! Oh well, no such plans this year. Once bitten, twice shy.

Since the 21st century will likely go down in the annals of history as the time our society truly realized the power and potential of a connected world, what better topic for this — my first column published in said century — than a tool that’ll help make it all happen: The ADSI IIS Provider! OK, I realize that it’ll be IIS, not the IIS provider for ADSI that actually wields the power of the World Wide Web; but ADSI will allow you to script the administration of Web sites, so that’s sort of revolutionary, isn’t it?

Oh, What a Tangled Web…
As with the WinNT provider, the IIS provider exposes vast amounts of functionality for administering your IIS Web servers. Indeed, I could devote an entire series of articles to any one of the ADSI providers. These are the things 700-page books are made of. Since I only have two or three more months budgeted for this topic, I’ll try to cover the highlights and give you some good foundations for future exploration. Let’s get started.

Man-made Bottlenecks
For any given IIS server, there are several global settings that we can access via ADSI. These include log file settings, MIME mapping information, and bandwidth throttling. Let’s take a look at the latter.

IIS allows you to configure a limit to the amount of bandwidth used by the WWW and FTP services. There may be many reasons why you’ll want to do this, not the least of which is to test site performance for clients. When you’re creating your Web sites, it’s easy to forget that you’re connected via LAN speeds to your server. This can often cause you to include dynamic content that works fine locally, but can cause a remote site visitor to lose interest before your page finishes loading. By configuring a limit, you can see how your site will respond to clients on a slower connection, like 56K or even DSL (yes, DSL is slow compared to the 100Mb speeds common on today’s LANs). Let’s see how our site performs over a 56K connection.

' SlowItDown.vbs
Dim objServer
Set objServer=GetObject("IIS://servername")
objServer.MaxBandwidth=4778
objServer.SetInfo

4778? I thought we were slowing it down to 56K! Yes, we are. Remember that network bandwidth is measured in Kbits per second. The MaxBandwidth setting is in bytes per second. In order to accurately simulate a 56K dial-up connection, we must convert Kbits into Kbytes, remembering also to account for modem sync information. Since there are eight bits in a byte, you’d think we’d simply divide 56 by eight to determine the number of kilobytes to set the throttle to. However, don’t forget that part of the 56K bandwidth is dedicated to keeping the connection up and not used for data. As such, we actually divide 56 by 12 to arrive at the correct number. We then multiply by 1,024 to turn Kbytes into bytes. This results in 4,778 and change. You can keep the change.

Once we’ve completed our testing, we can turn off bandwidth throttling by setting MaxBandwidth to -1.

What’s This Site For?
We’re now ready to look at our individual sites. To do this we need to bind to the IIS site we wish to manage. This requires a bit of advanced knowledge about the Web server to which we’re connecting. As any of you who’ve performed administration on IIS know, there can be several WWW “Virtual Servers” running on a given IIS computer, each with its own IP address and virtual directory hierarchy. Also, you can extend IIS through the use of host headers. In this case, you assign several DNS names to a single IIS IP address. Each inbound packet has the destination host name embedded in its header. IIS then uses this information to direct the packet to the correct Web site.

As each virtual server is created, it’s assigned an index number. The default site is 1; subsequent sites are assigned 2, 3, 4, and so on in the order that they’re added. It’s with this index number that you bind to the correct site. What’s that? You say you forgot to write down the order in which your sites were added? No worries! We can get that information from ADSI.

' GetSites.vbs
Dim objWWW, colSites

Set objWWW=GetObject("IIS://servername/W3SVC")
For Each colSites in objWWW
If IsNumeric(colSites.Name) Then
Wscript.Echo "Site index:" & colSites.Name
& " Site Name:"& colSites.ServerComment
End If
Next

Since ADSI “sees” the site name as the index number, in order to equate it to something more memorable, we must look at the ServerComment property. Remember that this is only for our edification so that we know which site we’re dealing with. When we reference it in code, we must use the index number, not the “friendly name.”

Next month, I’ll look at creating, editing, and managing virtual directories for both FTP and WWW services. So crawl out of that bunker, donate all the canned goods you’ve been hoarding, and get back to doing what you’re good at: server administration!