April 1999 Introducing the NetShow Services Part of Service Pack 4, the NetShow Services are a quick and easy way to deliver streaming multimedia content to your Web audience. Figure A shows the NetShow Administrator, the central administration tool for the NetShow services. Figure A: The NetShow Administrator makes it easy to publish multimedia content to the Web. In this article, we'll explain the basic concepts of NetShow and multimedia streaming. In addition, we'll show you how to install NetShow on your server. NetShow concepts There are two ways to implement a NetShow server. The first, known as multicast, is very similar to owning a television station. The second, called unicast, is more like the traditional client/server model on which the Internet was built. When you use multicast broadcasting, you send out a single stream of media to many clients. When you use unicast broadcasting, you're delivering streaming media to one client that requested it. The difference between multicasting and unicasting is much like the difference between watching broadcast television and ordering a movie from pay-per-view. When you receive an ASF file using multicasting, you may be one of many clients who are getting that file. You can't control when the file starts sending, you just have to time your viewing to coincide with the beginning of the file transmission. When you receive a unicast transmission, you request the file, and the broadcast begins. You can request the file at any time, always getting the entire file, from the beginning. Advanced Streaming Format NetShow broadcasts its media using the Advanced Streaming Format (ASF). ASF content can be a live stream or a stored ASF file. ASF has been developed to deliver content from a NetShow server to Microsoft Windows Media Player client. ASF files are scaled to fit within a network's available bandwidth. Most ASF files are converted from existing media files, such as WAV sound files and AVI movie files. You can create ASF files by using an encoding tool, such as the NetShow Encoder. Once you've created an ASF file, you should place it on a NetShow server. The simplest way to do this is to place the file in your NetShow content directory, which you'll create when you install the NetShow services. You can also use an HTTP server to stream ASF files, but no HTTP server can duplicate all of the functionality of the NetShow server. Using the right bandwidth As a streaming content creator, you need to be concerned with the amount of network bandwidth available to your NetShow server. Not only must you think about the bandwidth available for your server, but you must also estimate just how fast your target audience will be able to receive the data. For media targeted at an Internet audience, you won't want to use anything higher than 28.8 kilobits per second. If your audience consists of intranet users who all share the same LAN, you can choose to format your ASF files to use a higher bandwidth. It's important to realize that when you create your ASF files, the bandwidth they are created in is the bandwidth they'll be delivered in. If you create an ASF file at 28.8, all clients will view it at 28.8, even if they're on a direct T3. If you create your ASF files for a LAN, clients trying to view them at 28.8 will be out of luck. The only way to ensure that all users will be able to see your content at the best possible bandwidth is to create ASF files in each of the available bandwidths. Getting and installing the NetShow services You can download the NetShow services directly from Microsoft at http://www.microsoft.com/windows/windowsmedia/en/default.asp or you can find it on the NT 4.0 Service Pack 4 CD-ROM. If you download the software from Microsoft, you'll be asked if you want the Service Pack 3 or Service Pack 4 version. Make sure you download the correct version for your system. If you haven't already installed Service Pack 4, this might be a good time to get that as well. Once you've downloaded the NSSERVER.EXE file, execute it, and you'll see a screen like the one shown in Figure B. Figure B: Before installing the NetShow services, the program will ask if you wish to continue. Click Yes to continue the install. Next, you'll see the first screen of the NetShow install wizard, shown in Figure C. This screen lists many of the features of the NetShow services. Click Next to continue. Figure C: NetShow version 3.0 is a fully featured media-streaming server. The next screen, shown in Figure D, asks which type of install you wish to perform. Figure D: Select the Complete Installation option if you wish to install the NetShow server on your system. If you want to install the NetShow services, as well as the NetShow Administrator and Microsoft Windows Media Player, select the Complete Installation option. If you only wish to install the Administration components, or if you wanted to configure a system to remotely administer a NetShow server, you can select the Administration Components Only option. After you've made your selection, click Next to continue. On the next screen, shown in Figure E, you can change the directory in which to install the NetShow Services. Figure E: If you wish to select a different directory to install the NetShow Services, click Browse. By default, the install program will place the software in the Program Files\NetShow Services directory. If you want to change this, you can either type in a new directory, or choose one by clicking Browse. If you select a directory that doesn't already exist, the install program will display a confirmation box. Click Yes to create the new directory. The next installation screen asks where you wish to place your ASF content. By default, the install program will place them in C:\asfroot. If you have IIS installed, you most likely have an InetPub directory already. It's a good idea to keep your entire Internet content in one area of your system. As you can see in Figure F, we changed the default location and typed in our InetPub directory. Not only is this easier to organize and maintain, but it will also make implementing security on your Internet content less of a hassle. Figure F: We picked the InetPub\asfroot directory as our NetShow content directory. Shown in Figure G, the next installation screen determines if you want to support HTTP streaming of your ASF files. Figure G: You can enable HTTP streaming if you wish to broadcast content through a firewall. By enabling HTTP streaming for either unicasting or multicasting, you'll be able to broadcast streaming media through a firewall using port 80. Because most Web servers bind to port 80, you'll need to turn off any Web servers you've installed if you wish to use this option. While this can be a very useful method of distributing streaming content through a firewall, you won't be able to use port 80 for anything else. This solution works best when you have one system as your Web server and another as your NetShow server. Once you've decided if you're going to use this feature, select the appropriate option and click Next to continue. Next, you'll be asked which account you want to use when running the NetShow Services. As shown in Figure H, the install program will automatically create a NetShowServices account for you, or you can use an already existing account. Figure H: NetShow services must run under an NT account; you can use an existing one, or create a NetShowServices account. If you do create the NetShowServices account, make sure it has the right permissions to access the files in your ASF content directory. Click Finish to begin the software installation process. Before the install program can copy the NetShow files, it needs to shut down any existing Internet Information Servers (IISs). The program will prompt you with a confirmation box like the one seen in Figure I. Figure I: You must shut down all Web servers in order to install the NetShow server. The server will be down for a number of minutes, so it's a good idea to reserve some time to perform the NetShow services install. Make sure all your Web server clients know the server is coming down. After the program has copied all of the necessary files, you'll see the final screen of the installation wizard, as shown in Figure J. You can automatically launch the NetShow Administrator by clicking OK while the Launch NetShow Administrator check box is checked. Figure J: Once setup is complete, you're ready to begin broadcasting. If you wish to test your NetShow server, you'll need to move an ASF file into your NetShow content directory. If you move a file named welcome.asf into that directory, you'll be able to access it by opening the Microsoft Windows Media Player and selecting File | Open from the menu bar. Then, type in the following URL: mms://hostname/welcome.asf hostname is the name of your server. If all went smoothly, the ASF file should be playing in your Media Player. Conclusion The NetShow server is a great addition to the family of Microsoft Internet servers. Using NetShow, you can distribute multimedia files to clients on the Web and on your own LAN. Companies can broadcast live events, like speeches from management and award ceremonies, to every desktop in the company. And, best of all, it costs you nothing to install and use. Copyright © 1999, ZD Inc. All rights reserved. ZD Journals and the ZD Journals logo are trademarks of ZD Inc. Reproduction in whole or in part in any form or medium without express written permission of ZD Inc. is prohibited. 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