Deploy an Application Update to a Web Cluster

Deploying application updates to the Web tier has to be handled differently, depending on whether or not your updates involve COM+ components.

Deploying Applications Without COM+ Components

To deploy updated HTML-based and ASP-based applications, you should use a phased-deployment strategy. This involves deploying the modified application to part of the cluster first, and then deploying it a second time to members that weren't updated in the first pass.

NOTE


Staged deployment for application updates in this case make sense only if:
  • The Web site is very large and only small portions of the site require updating.
  • Page version control and consistency are major considerations.

Let's use the Web Guide application as an example, with the cluster illustrated in Figure 8.16 as our target cluster. (For testing purposes we made some changes to some of the HTML pages.)

NOTE


Because none of the graphics in the Web Guide application were altered, this update scenario provided an opportunity to test the exclusions aspect of synchronization. We opened the Synchronizations Properties dialog box, and then under GUIDE, added the Images directory to the exclusion list.

Deploy the Web Guide Update

Use the following steps to deploy the updated files for the Web Guide application.

  1. Take the controller (WC - ACDW516AS) and one member offline (W2 - ACDW802AS), and then disable automatic synchronization on WC.
  2. Deploy the Web Guide application to WC and W2 by using the steps described in "Deploy the Web Guide" earlier in this chapter.

    This completes the first phase of the deployment.

    NOTE


    You have two choices at this point in the deployment:
    • If you want to ensure that stale content isn't served to your clients, you should execute the next two steps in their sequence (step 3, step 4). However, there will be several seconds when the site may not be available to service client requests. For high traffic sites, notify users that site maintenance is in process and that they might experience a disruption of service.
    • If uninterrupted service is your operational priority, you should bring online the members with the refreshed content before setting the remaining member(s) offline. In this case, execute step 4 before step 3.

  3. Set the remaining member, W1, offline for load balancing.

    In addition to draining the existing connections, this action ensures that this member does not accept any new requests.

  4. Set the controller and W2 back online immediately after step 3.
  5. Re-enable synchronization on the cluster controller, and then force a synchronization of the cluster.
  6. Set W1 back online.

Deploying Applications with COM+ Components

Because this deployment scenario is for an application that contains COM+ components, you must restart the target(s). Therefore, you'll have to handle this case slightly differently. Let's use the Pre-Flight Check application as an example.

NOTE


The assumption made for this scenario is that the component interfaces are backwards compatible with the old components and the existing ASP pages can call either set of components without errors.

Deploy an Update to the ACPFApp Components

The process for deploying ACPFApp Update is similar to the one we've described for the Web Guide; however, there is one notable difference that affects our deployment strategy. Because ACPFApp contains COM+ components that have to be installed and registered on the targets, we can't use controller synchronization to update the application for the remaining part of the cluster after we've done the initial deployment.

Instead, we have to deploy the application to each member, as well as the controller. Figure 8.17 illustrates how we deployed ACPFApp to the Web cluster. As you will note, we used two deployments from the stager to install the application on all the targets. The first deployment was to the controller and the member ACDW802AS, and the second was to the remaining member, ACDW518AS.

click to view at full size

Figure 8.17 Deploy dynamic content and components to the Web tier

We'll step through this deployment in detail shortly. But first, let's create a subset to illustrate how you can stage and deploy parts of an application rather than replicating unnecessary files across the network.

Create the ACPFApp Update Application

The first thing we have to do is mark the components for load balancing by running the PFSetupCOMDLB.bat batch file (in the ACPF directory). Next, create a new application that identifies the COM+ applications (AC_PF_VB and AC_PF_VC) as its resources.

  • Create a new Application Center application named ACPFCOM.
  • In the Resource Type list, click COM+ Applications, and the add AC_PF_VB and AC_PF_VC as resources.

Now that the application update is ready, we can deploy it to the members on the target cluster. (Once again, we activated the PreFlight Check script in WAS and ran it against the Web cluster to simulate a load while deploying the application.)

Deploy ACPFCOM

We deployed the ACPFCOM application by using the following steps. (Use Figure 8.17 as a reference for this operation.)

CAUTION


If you previously installed the Pre-Flight application's COM+ applications on the target by using the batch files that are provided, make sure that you remove these applications before proceeding with deployment. The reason for this is that the components on the target and stager will have different program identifiers but the same name.

  1. Starting with the W2 member, take the WC controller and the W2 member out of the load-balancing loop.
  2. Change the draining period from the default (20 minutes) to 5 minutes, and then click OK.
  3. Observe the RKWebCluster status indicators to confirm that WC and W2 are offline for load balancing.
  4. In the console tree, right-click the stager, ACDW822AS, and then on the pop-up menu, click Deploy Applications to open the New Deployment Wizard.
  5. Respond to wizard pages by using the following responses as guidelines.
    • Deployment Target Options: Append the default deployment name (date/time stamp) with ACPFCOM, and then select the Deploy content outside the current cluster check box.
    • Deployment Target Authentication: Provide logon information for an account with administrative privileges on all targets.
    • Deployment Targets: Add the Web cluster controller and member names (ACDW516AS and ACDW802AS).
    • Deployment Content: Click ACPFCOM.
    • Deployment Options: Clear the default, folder, and file permissions, select the Deploy COM+ applications check box, and then click Next to launch the deployment.
  6. Observe the Synchronizations view as it provides real-time status information about the deployment. When the deployment is finished, activate the Applications node for RKWebCluster and verify that ACPFCOM was replicated. You should also verify that the COM+ applications were installed by checking for their presence in the Component Services console tree on the cluster controller.

    NOTE


    Once again, you have to decide which is a priority, serving stale content or briefly interrupting service. This will determine the ordering for the next two steps.

  7. Bring the cluster controller and member (W2) back online for load balancing.
  8. As soon as the controller comes online, set the next deployment target, ACDW518AS (W1) offline with a 5-minute draining period.
  9. Deploy the ACPFCOM application again (steps 3 and 4), this time using ACDW518AS as the deployment target, and verify the success of the deployment as you did in step 5.
  10. Bring the remaining member back online for load balancing.
  11. As a final test of the success of the deployment, open the Web browser, and then on the Web cluster, open PFWelcome.asp to see if the components are created on the Web tier—they should be.
  12. On the cluster controller, in the Applications list, delete ACPFCOM.

You can use the preceding technique for larger clusters—the basic approach is the same, take approximately one-half of the members out of the load-balancing loop, and then deploy the application to them. Bring the members back online, and then deploy to the remaining members (after you set them offline for load balancing).



Microsoft Application Center 2000 Resource Kit 2001
Microsoft Application Center 2000 Resource Kit 2001
ISBN: N/A
EAN: N/A
Year: 2004
Pages: 183

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