MACROMEDIA COLDFUSION MX-CLUSTERCATS Manuel d'utilisateur télécharger pdf (Page 82)

72 Chapter 4 Configuring Clusters

Session-aware load balancing

Managing a web application’s state in a clustered environment can be challenging. By

default, web application, session, and server variables that are stored in memory or a

repository during a user session do not persist during a server redirection. Consequently,

the web server cannot maintain the application’s state correctly.

To overcome this problem, ClusterCATS provides a session-aware load-balancing feature

that lets you maintain application state in a clustered environment.

One way to maintain your web application’s state is to create session variables that are

stored on the web server. For an e-commerce website that is clustered, it is vital that users

do not get redirected to another server in the middle of their session. If they did, their

online transactions would be interrupted, making for an unsuccessful and frustrating user

experience.

To ensure that users are not redirected from the server on which they start their session,

ClusterCATS provides a built-in feature for enabling session-aware load balancing.

Sometimes referred to as a “sticky” server, session-aware load balancing guarantees that

users will not get bumped from the server on which they start their session until the

session is complete, regardless of the load thresholds that have been defined for that

server.

Note: Session-aware load balancing may not work if you use absolute hyperlinks in your

web pages. Absolute links route the HTTP request back to the cluster entry point and

redirect according to the current load threshold without regard to the state of the requesting

client. To avoid inadvertent loss of state, use only relative linking in your web pages.

This section describes the following:

• “Enabling session-aware load balancing on Windows” on page 72

• “Enabling session-aware load balancing on UNIX” on page 72

Enabling session-aware load balancing on Windows

To enable session-aware load balancing:

1 Open the ClusterCATS Explorer and select a cluster.

2 Select Configure > Administration or right-click the cluster and select Configure >

Administration.

The cluster Properties dialog box appears.

3 Select the Session State Management check box.

4 Click OK.

Enabling session-aware load balancing on UNIX

To enable session-aware load balancing:

1 In ClusterCATS Web Explorer, click the Show Cluster link.

2 Enter the fully qualified host name of a server for which you want to configure

session-aware load balancing in the Web Server Name field.

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MACROMEDIA COLDFUSION MX-CLUSTERCATS Manuel d'utilisateur Page 82