CompuServe Brings NT Online

CompuServe, one of the world's largest and oldest online informationservices, gives its 4.5 million customers unique content, discussion forums, and Internet connections. Currently, CompuServe is migrating its entireoperation from its aging DEC-10 architecture to a distributed network of WindowsNT servers. Leading this migration is Bruce MacNaughton, CompuServe's vicepresident and chief architect. Since 1978, MacNaughton has led severalCompuServe projects, including the deployment of the H&R Block (CompuServe'sparent company) Rapid Refund System.

MacNaughton became interested in NT because Dave Cutler, the architect ofDigital's VAX OS, was leading Microsoft's NT development team. "NT 3.1 wasthe best first release of any operating system I've seen," MacNaughtonsaid. (See the "Interview with Bruce MacNaughton,"for some of MacNaughton's comments on NT.)

Why NT?
CompuServe chose NT because it provides a good development platform forbuilding large, distributed applications. With its modular design andextensibility, NT shows its advanced architecture through its services-baseddesign, support for diverse and scaleable processors, and secure andinterprocess communications functions. MacNaughton appreciated NT's consistentuser interface throughout its numerous configuration points.

Another reason CompuServe converted to NT was because of its support fordevelopment tools. CompuServe develops a lot of its business-support softwareinternally, so powerful development tools and support for programmers areimportant. With its legacy systems, CompuServe had to write and supportcompilers, linkers, and debuggers.

At present, CompuServe's development workhorse is Microsoft Visual C,supported by Microsoft Visual SourceSafe, NuMega's BoundsChecker, andMicroQuill's SmartHeap. With NT emerging as the premier OS, MacNaughton'sdevelopers are looking forward to even more sophisticated debugging and teamdevelopment tools.

Migrating the Business
CompuServe's initial thrust to convert to NT began in spring 1995. A primarygoal was to move the company's user forums to NT. This step was significantbecause most of CompuServe's customers are active in one or more forums.

CompuServe chose to convert the forums as the first major task because thecompany supports the forums with 1000 similarly configured servers. Thisarchitecture let CompuServe's teams develop an initial NT Server configuration,or cookie-cutter, and rapidly deploy the standard on the remaining machines. Asof August 1996, this method had let CompuServe deploy 250 forum servers.

CompuServe has spread the forum computers among the company's threeregional centers, providing redundancy and fault tolerance for its customers anda challenge for its systems administrators. However, NT's built-in monitoringand administration tools help meet this challenge.

CompuServe uses IBM's NetView for network management. The company wants tosupplement NetView with Microsoft's Systems Management Server (SMS) although SMSis still a somewhat immature product. Other management tools that CompuServe isconsidering include Computer Associates's Unicenter, Hewlett-Packard'sOpenView, and Cabletron's SPECTRUM.

How It Works
A CompuServe customer can dial in to one of thousands of local accessnumbers available worldwide. Once connected, a server routes the user's requeststo email servers (which use Microsoft's SQL Server) or forum servers (which usePOET Software's POET--to find out why CompuServe chose POET for its forumservers, see the sidebar, "Why POET?

").

POET is an object-oriented database management system (OODBMS). POET letsCompuServe store and manage messages in the threaded message libraries, apopular feature among CompuServe's customers. According to MacNaughton, anobject-oriented database is best for the message library, where users can postand respond to messages from other users and system operators. Besides storingmessages for later retrieval, the database links the messages so that users canfollow the complete chain, or thread, of the conversation. CompuServe chose POETbecause of POET Software's commitment to open database standards and willingnessto work hard with customers. When CompuServe began its NT project, very fewobject-oriented database vendors were considering porting their offerings to NT.POET Software was the exception--that company had an NT version and was willingto work quickly to fix any problems. CompuServe liked POET Software's overallcompany picture, its commitment to customer service, and its technology.

Figure 1 shows CompuServe's server configuration. Each CompuServe forum isa sophisticated, distributed system. The front end of each forum, thePresentation Specific Application Program (PSAP), runs on NT Server. PSAPcommunicates outwardly through CompuServe's Host Machine Interface (HMI)protocol to the CompuServe Information Manager (CIM), WinCIM, Navigator, orother offline reader software running on the user's PC. (If the user is runningApple or Amiga hardware, the PSAP communicates through ASCII.) PSAP thenprocesses the user's requests to the forum server, which also runs on NT Server.The forum server, in turn, is connected to various component servers, includingfile libraries, message libraries, a membership database, and a conferencingfacility. CompuServe can install these servers on one or more computers,depending on load-balancing requirements. Forum daemon applications running onthe forum servers communicate among these forum components through remoteprocedure calls (RPCs).

PSAP can communicate with different forums, so CompuServe has acomponent-based architecture. This architecture is independent of CompuServe'spresentation interface and provides flexibility and scaleability. At any givenmoment, many forum daemons can be transmitting messages simultaneously. NT'smultithreaded capabilities provide enhanced performance for these transmissions.CompuServe's developers have written daemons running on NT servers as NTservices, providing the robustness and performance that characterizeserver-based applications.

For MacNaughton, another major portion of the NT conversion project wasswitching CompuServe's heavily used email system to run on NT Server. Theprevious mail application was a proprietary system CompuServe developed to runon its 36-bit machines. CompuServe has rewritten its mail system to run under NTand uses Microsoft's SQL Server as the storage medium for mail messages,addressing information, and user information. CompuServe takes advantage of SQLServer's built-in database replication to provide redundancy in the event of afailure and to add reliability for its customers.

Hardware Considerations
No discussion of an NT conversion is complete without addressing thehardware platform. CompuServe has had great success with single- anddual-processor 90MHz Pentiums. MacNaughton has estimated that one Pentium 90running NT can adequately support a 100-user forum. He's keeping an eye on thenew Pentium Pro 200 and expects it to be a viable solution for large forums,particularly when some of the multiprocessing bugs are worked out.

CompuServe uses a few Compaq ProLiant servers (for a review of the CompaqProLiant 4500, see Joel Sloss, "The Compaq Report," August 1996), butMacNaughton and his team don't like Compaq's use of a proprietary NT hardwareabstraction layer (HAL). The special HAL can result in additional support callsto Compaq for minor changes that are easy to make on other vendors' hardware.

CompuServe's technologists also were unimpressed with Compaq's SmartStartutilities, which assist you in configuring a new Compaq computer. In particular,CompuServe's need to call Compaq for a key number to modify and unlock parts ofthe system is bothersome.

On the positive side, MacNaughton likes the fact that Compaq is shippingits machines with NT preinstalled and preconfigured. The new systems includemonitoring features that help predict hardware failures. Compaq is changing itswarranty policy to include replacement of machines that the monitoring featurespredict will fail. For these reasons, CompuServe's relationship with Compaq willprobably continue to grow.

One of NT's best features is its ability to run on a variety of hardwareplatforms. MacNaughton is experimenting with ALR, Micron, and HP, and likeshaving the option to upgrade to high-performance Digital Equipment Alphas, ifand when necessary.

Into the Future
As 1996 draws to a close, MacNaughton and CompuServe are in the thick of theInternet revolution. CompuServe will continue to replace its remaining legacysystems with NT-based solutions. The company will also replace its HMI protocolwith the evolving Hypertext Markup Language (HTML) protocol of the Web.

CompuServe will expand its services to the Internet with a recentlylicensed version of Microsoft Internet Explorer (IE), the Normandy servers, andother services. Although IE will provide a quick fix, CompuServe can't alwaysaccept off-the-shelf solutions. Forums are one area where CompuServe excels overcurrent Internet-based newsgroup technology. CompuServe will need to marry thebest of the existing forum features, such as offline reading, with the bestfeatures of the Web.

CompuServe is working rapidly to expand Internet performance and access. Itis re-engineering its systems to be more modular and object-like so the companycan rapidly integrate new enhancements and services with existing technology.

CompuServe will continue to apply new technologies, such as NT 4.0,improved development tools, evolving interprocess communication methods, andforthcoming Cairo technologies, to keep current with the pace of change. Withthe guidance of MacNaughton, his colleagues, and their teams, CompuServe'scustomers will be well served into the next century.