Home > Articles > Programming > Windows Programming

Choosing Application Center to Manage a Web Farm

In this article, author Barry Bloom discusses whether Application Center 2000 is the tool you can use to manage your Web farm. Application Center 2000 solves the application replication problem, it simplifies the process of scaling so that a Web farm can handle its load easily, it centralizes management and monitoring of multiple servers, and it provides an easy way to stage and deploy new releases.
This article is excerpted from Deploying and Managing .NET Web Farms.
Like this article? We recommend

This article is excerpted from Deploying and Managing Microsoft .NET Web Farms (Sams, 2001, ISBN: 0672320576).

Many of the actions and tasks in this book have sorely needed a tool like Application Center 2000. First and foremost, Application Center 2000 solves the application replication problem. Application Center simplifies the process of scaling so that a Web farm can handle its load easily. Application Center centralizes management and monitoring of multiple servers. Finally, Application Center 2000 provides an easy way to stage and deploy new releases.

Replicating Applications with Application Center 2000

Application replication is a serious problem for medium-to-large-scale Web farms. When a Web cluster has more than a few members, the process of application replication must be scripted and automated. If it is not, then the process of manually updating a Web site with a new release could take a very long time. Until Application Center 2000, Content Replication System (CRS, also known as Site Server Publishing) was the only tool available from Microsoft that could be used for application replication. However, CRS only replicates the contents of directories and the supporting directory structure. Figure 1 is an example of the clunky CRS interface. Eight different tabs with archaic and hard-to-use features make CRS difficult to configure. Just managing file exclude and include paths for directory replication is error-prone and poorly designed. CRS cannot replicate other typical application components automatically. Replicating Registry entries, IIS metabase information, Data Source Names for ODBC, and COM+ applications is accomplished by custom scripts. These scripts run before or after a replication job. Clearly, CRS is not good enough to manage a complicated .NET Web farm.

Figure 1 The CRS user interface, a nightmare.

With Application Center 2000, application replication for Web farms issolved. The clunky interface of CRS has been abandoned for a flashy new explorerinterface. COM+ applications, IIS metabase settings, ODBC connection strings,Registry entries, and file system paths are all part of an Application Centerapplication object. This application object is easily configured from onemanagement console, and no custom scripts are required. When deploying, all thepieces of the application object sync with the configuration of the clustercontroller. Once an application object is defined, it becomes a conceptualscript that Application Center executes on each of the cluster members. Figure 2 shows the flow of an application object through an Application Center 2000cluster.

Figure 2 An application object in Application Center 2000.

The application object is easily modified to include new objects. Forexample, a change control requires a new COM+ application. In the past, thedeployment team would likely manually install the exported COM+ application oneach machine in the cluster. A manual process is likely to fail at some point.With Application Center 2000, the deployment team manually configures the newCOM+ application exactly as needed on the one cluster controller. They add theCOM+ application to the application object, telling Application Center 2000 tosynchronize the cluster. Within a matter of minutes, the new COM+ application isavailable on the other cluster members, configured exactly like the clustercontroller.


A cluster controller is an Application Center 2000 server that has the master copy of the application. All deployments and cluster synchronizations originate from this server.

If an application has pieces that don't fit within the scope of the Application Center 2000 object, it is possible to write custom scripts that will be executed from deployment events on each cluster member. Replication of any application configuration is possible with Application Center 2000 custom scripting.

Scaling with Application Center 2000

Scaling to handle load is a critical success factor for any .NET Web farm. Once an application is able to run across multiple servers, the process of scaling a site is simply adding server capacity to the stressed portion of a site. The challenge then is to replicate the application parts to the new server and add it to the cluster.

Application Center 2000 simplifies adding and removing cluster members for scaling. After installing Application Center 2000 on each new cluster member, a simple two-step process can bring a new server online. In its default configuration, Application Center 2000 uses Network Load Balancing (NLB) as its scaling solution. NLB configuration is done automatically to each server when it is added to the cluster. From the management console, the Add Cluster Member Wizard adds the server to the cluster. During the addition process, the cluster controller configures NLB and readies the new machine to coalesce with the cluster so that it can begin receiving traffic. Figure 3 shows the Add Cluster Member Wizard, the first step to smooth scaling

Figure 3 The Add Cluster Member Wizard.

At this point, if the cluster controller is set up with the default configuration options, the applications on the cluster controller will automatically synchronize to the new member. Once this synchronization is complete, the new cluster member is ready to be brought online through the management console. Since Application Center 2000 is highly integrated with Network Load Balancing, the server can begin handling Web requests immediately. A two-step process scales any Web farm.

This flexibility in scaling allows for some creative management of resources. In a large Web farm, there could be any number of under-utilized servers at one time. With the dynamic cluster member management and automated synchronization processes, those servers could stop serving the under-utilized content and begin serving the stressed content in a matter of minutes. Scenarios like those in Figure 4 show creative ways to maximize return on hardware investments.

Figure 4 Using Application Center 2000 to maximize hardware utilization.

Using Application Center 2000 for COM+ Load Balancing

COM+ is a great way to create component-based services. COM+ also greatly simplifies the process of deploying and accessing COM+ application services locally and remotely. Application Center adds to this architecture by allowing COM+ applications to replicate with a Web application. For example, if a Web site uses a COM+ application to handle login or credit card authorization, Application Center can be configured to group these objects with the Web pages and replicate them as one unit. Application Center also introduces the concept of COM+ routing clusters and COM+ application clusters to provide fail-over and redundancy.

Without Application Center, a COM+ application proxy installed on a Web server pointing to a COM+ application server is a single point of failure. If that COM+ application server fails, there is no built-in mechanism for COM+ to begin making remote component requests to a backup machine automatically. While it is possible to use standard load balancing technology like Network Load Balancing to achieve COM+ application server scaling, in reality this only provides high availability. In any case, Application Center solves these problems with COM+ application and routing clusters.

A COM+ application cluster is a group of servers configured with the same COM+ applications. With Application Center 2000, these members are managed and synchronized in the same way as a Web cluster. Once again, a deployment team has only to configure a new COM+ application on the cluster controller. Then, with the same synchronization technology as a Web cluster, Application Center deploys the COM+ application to all members of the cluster. COM+ clusters can use Component Load Balancing or Network Load Balancing to achieve scalability and availability of COM+ clusters.

A COM+ routing cluster is the third type of cluster supported by Application Center 2000. A COM+ routing cluster allows a single client server to address more than one COM+ cluster that uses CLB, a limitation of the current implementation of CLB in Application Center 2000. Figure 5 shows a COM+ routing cluster associated with a COM+ cluster.

Figure 5 A COM+ routing and application cluster.

Another important aspect of the COM+ Application Center enhancements is the addition of a WMI provider (see the following section for more on WMI) for COM+. With this, it is possible to monitor the health of COM+ applications using Application Center 2000. The provider is also used by Application Center 2000 Component Load Balancing to decide which member of a COM+ application cluster activates a component for any request.

By providing scalable COM+ solutions, Application Center eliminates the single point of failure when accessing a COM+ object remotely. When a COM+ application cluster member fails and is taken offline, requests are not sent to the ailing member until the problem is resolved. Application Center 2000 finally delivers a highly available, highly scalable COM+ solution for the enterprise.

Monitoring a Web Farm Is Centralized

Like application replication, monitoring a Web farm is a complex problem. With large application clusters, the administration of monitoring tasks can become time consuming and error prone. Worse than that, monitoring a Web farm for a specific problem is sometimes the only way to tell if an application is failing. Sometimes a problem has no solution, and alerting an administrator who can address the problem manually is the only way to restore functionality. With no simple way to deploy monitoring configurations, the deployment team will bog down in the day-to-day operations and monitoring tasks of a Web farm.

Currently there are a number of different monitoring tools from Microsoft but nothing centralized and useful. For instance, Performance Monitor can alert at different thresholds in a real-time log. This is useful, but hardly an enterprise solution. There are third-party tools that provide an all-in-one solution, but they are proprietary.

With Windows 2000, Microsoft introduced Windows Management Instrumentation (WMI). WMI is Microsoft's unified monitoring API. WMI is a collection of COM interfaces that provide programmatic monitoring information in real-time. Similar to SNMP, WMI provides makers of server technologies, device drivers, and other system-level devices a way to expose monitoring information to a common, scriptable API. All .NET enterprise servers come with some level of WMI support.

With Application Center 2000, Microsoft delivers its unified application health-monitoring console, aptly named Health Monitor. Health Monitor provides a way to examine the state of a Web farm centrally in real-time. Health Monitor examines each member of a cluster and can report back information to a single management console. This console creates a Web farm command station where deployment status, application health, and availability are measured. Figure 6 shows the Health Monitor console.

Figure 6 The Health Monitor console.

Health Monitor can alert on the entire standard performance counter list. Administrators can create alerts for low disk space conditions and on high CPU utilization conditions. Health Monitor reacts to user-definable alerts and responds with user-definable actions. Any WMI provider can be used to generate alerts. Actions include sending e-mail, launching scripts, running batch jobs, writing events to a file, and adding entries in the event log.

Managing the Staging of Releases with Application Center 2000

Application Center 2000 makes multiple stage deployment of Web applications easy. Without Application Center 2000, deployment from testing to staging and staging to production is at best a conglomeration of actions such as copying directories, running scripts, and other manual tasks. The staging of releases is as simple as scheduling a task. Application Center can replicate applications across clusters by using the same technology for deploying applications between members of the same cluster.

InformIT Promotional Mailings & Special Offers

I would like to receive exclusive offers and hear about products from InformIT and its family of brands. I can unsubscribe at any time.


Pearson Education, Inc., 221 River Street, Hoboken, New Jersey 07030, (Pearson) presents this site to provide information about products and services that can be purchased through this site.

This privacy notice provides an overview of our commitment to privacy and describes how we collect, protect, use and share personal information collected through this site. Please note that other Pearson websites and online products and services have their own separate privacy policies.

Collection and Use of Information

To conduct business and deliver products and services, Pearson collects and uses personal information in several ways in connection with this site, including:

Questions and Inquiries

For inquiries and questions, we collect the inquiry or question, together with name, contact details (email address, phone number and mailing address) and any other additional information voluntarily submitted to us through a Contact Us form or an email. We use this information to address the inquiry and respond to the question.

Online Store

For orders and purchases placed through our online store on this site, we collect order details, name, institution name and address (if applicable), email address, phone number, shipping and billing addresses, credit/debit card information, shipping options and any instructions. We use this information to complete transactions, fulfill orders, communicate with individuals placing orders or visiting the online store, and for related purposes.


Pearson may offer opportunities to provide feedback or participate in surveys, including surveys evaluating Pearson products, services or sites. Participation is voluntary. Pearson collects information requested in the survey questions and uses the information to evaluate, support, maintain and improve products, services or sites, develop new products and services, conduct educational research and for other purposes specified in the survey.

Contests and Drawings

Occasionally, we may sponsor a contest or drawing. Participation is optional. Pearson collects name, contact information and other information specified on the entry form for the contest or drawing to conduct the contest or drawing. Pearson may collect additional personal information from the winners of a contest or drawing in order to award the prize and for tax reporting purposes, as required by law.


If you have elected to receive email newsletters or promotional mailings and special offers but want to unsubscribe, simply email information@informit.com.

Service Announcements

On rare occasions it is necessary to send out a strictly service related announcement. For instance, if our service is temporarily suspended for maintenance we might send users an email. Generally, users may not opt-out of these communications, though they can deactivate their account information. However, these communications are not promotional in nature.

Customer Service

We communicate with users on a regular basis to provide requested services and in regard to issues relating to their account we reply via email or phone in accordance with the users' wishes when a user submits their information through our Contact Us form.

Other Collection and Use of Information

Application and System Logs

Pearson automatically collects log data to help ensure the delivery, availability and security of this site. Log data may include technical information about how a user or visitor connected to this site, such as browser type, type of computer/device, operating system, internet service provider and IP address. We use this information for support purposes and to monitor the health of the site, identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents and appropriately scale computing resources.

Web Analytics

Pearson may use third party web trend analytical services, including Google Analytics, to collect visitor information, such as IP addresses, browser types, referring pages, pages visited and time spent on a particular site. While these analytical services collect and report information on an anonymous basis, they may use cookies to gather web trend information. The information gathered may enable Pearson (but not the third party web trend services) to link information with application and system log data. Pearson uses this information for system administration and to identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents, appropriately scale computing resources and otherwise support and deliver this site and its services.

Cookies and Related Technologies

This site uses cookies and similar technologies to personalize content, measure traffic patterns, control security, track use and access of information on this site, and provide interest-based messages and advertising. Users can manage and block the use of cookies through their browser. Disabling or blocking certain cookies may limit the functionality of this site.

Do Not Track

This site currently does not respond to Do Not Track signals.


Pearson uses appropriate physical, administrative and technical security measures to protect personal information from unauthorized access, use and disclosure.


This site is not directed to children under the age of 13.


Pearson may send or direct marketing communications to users, provided that

  • Pearson will not use personal information collected or processed as a K-12 school service provider for the purpose of directed or targeted advertising.
  • Such marketing is consistent with applicable law and Pearson's legal obligations.
  • Pearson will not knowingly direct or send marketing communications to an individual who has expressed a preference not to receive marketing.
  • Where required by applicable law, express or implied consent to marketing exists and has not been withdrawn.

Pearson may provide personal information to a third party service provider on a restricted basis to provide marketing solely on behalf of Pearson or an affiliate or customer for whom Pearson is a service provider. Marketing preferences may be changed at any time.

Correcting/Updating Personal Information

If a user's personally identifiable information changes (such as your postal address or email address), we provide a way to correct or update that user's personal data provided to us. This can be done on the Account page. If a user no longer desires our service and desires to delete his or her account, please contact us at customer-service@informit.com and we will process the deletion of a user's account.


Users can always make an informed choice as to whether they should proceed with certain services offered by InformIT. If you choose to remove yourself from our mailing list(s) simply visit the following page and uncheck any communication you no longer want to receive: www.informit.com/u.aspx.

Sale of Personal Information

Pearson does not rent or sell personal information in exchange for any payment of money.

While Pearson does not sell personal information, as defined in Nevada law, Nevada residents may email a request for no sale of their personal information to NevadaDesignatedRequest@pearson.com.

Supplemental Privacy Statement for California Residents

California residents should read our Supplemental privacy statement for California residents in conjunction with this Privacy Notice. The Supplemental privacy statement for California residents explains Pearson's commitment to comply with California law and applies to personal information of California residents collected in connection with this site and the Services.

Sharing and Disclosure

Pearson may disclose personal information, as follows:

  • As required by law.
  • With the consent of the individual (or their parent, if the individual is a minor)
  • In response to a subpoena, court order or legal process, to the extent permitted or required by law
  • To protect the security and safety of individuals, data, assets and systems, consistent with applicable law
  • In connection the sale, joint venture or other transfer of some or all of its company or assets, subject to the provisions of this Privacy Notice
  • To investigate or address actual or suspected fraud or other illegal activities
  • To exercise its legal rights, including enforcement of the Terms of Use for this site or another contract
  • To affiliated Pearson companies and other companies and organizations who perform work for Pearson and are obligated to protect the privacy of personal information consistent with this Privacy Notice
  • To a school, organization, company or government agency, where Pearson collects or processes the personal information in a school setting or on behalf of such organization, company or government agency.


This web site contains links to other sites. Please be aware that we are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of each and every web site that collects Personal Information. This privacy statement applies solely to information collected by this web site.

Requests and Contact

Please contact us about this Privacy Notice or if you have any requests or questions relating to the privacy of your personal information.

Changes to this Privacy Notice

We may revise this Privacy Notice through an updated posting. We will identify the effective date of the revision in the posting. Often, updates are made to provide greater clarity or to comply with changes in regulatory requirements. If the updates involve material changes to the collection, protection, use or disclosure of Personal Information, Pearson will provide notice of the change through a conspicuous notice on this site or other appropriate way. Continued use of the site after the effective date of a posted revision evidences acceptance. Please contact us if you have questions or concerns about the Privacy Notice or any objection to any revisions.

Last Update: November 17, 2020