MACROMEDIA COLDFUSION MX-CLUSTERCATS Use Manual page 14

Session state management and failover
For some applications, it is important that a user session is completed on one server.
ClusterCATS offers a session state management option that ensures that the same web
server services requests from a user. When enabled, this option sends the user to the
best-performing server. The user session then remains on that server until completion.
ClusterCATS defines a new session for the following:
A user comes from a different domain
A user enters a new URL
A user employs a bookmark
This approach has distinct advantages over other methods, such as using a source IP
address to define a user session. The ClusterCATS definition of a session is particularly
beneficial if many visitors come from a large proxy server (for example, America Online).
In that scenario, web servers could easily become overloaded.
Should user state be lost completely due to a resource failure, ClusterCATS provides
graceful state failover. This capability automatically displays an administrator-defined
URL for a custom HTML page or JRun page upon resource failure. This page can be
designed to apologize for the failure and, if replicated resources are available, direct the
user to restart the application at the beginning via a specific URL.
Distributed operations
ClusterCATS uses a distributed operations model, eliminating traffic bottlenecks and
maximizing performance. While other hardware and software load-balancing solutions
force all user requests and, typically, all responses through a single special-purpose
network device or server, each ClusterCATS Server can receive a request, respond to a
request, manage traffic load, and support failover. Unlike hardware load-balancing
solutions, ClusterCATS performance is not throttled by network media limitations and
ClusterCATS is network media independent. Consequently, performance scales linearly
as servers and resources are added.
Centralized management
ClusterCATS Explorer, operating in conjunction with an administrative agent on each
ClusterCATS Server, provides all the required tools for building and managing a website
from any location, whether it be an operations center, hotel, or home.
ClusterCATS Explorer features a familiar Windows Explorer-like user interface and
provides both detailed and high-level status views of one or more websites and all
resources within a website.
ClusterCATS Explorer views include:
Simplifies user interface for the configuration tasks of building a website, including
adding and removing resources, setting load thresholds, selecting alarms, designating
administrators, configuring replication, and state management capabilities
Real-time graphs of the actual application or HTTP server load and load thresholds
4 Chapter 1 Before You Begin