MACROMEDIA COLDFUSION MX-CLUSTERCATS, Use Manual

Page: 26 / 156

16 Chapter 2 Scalability and Availability Overview
cleanly display all technologies, such as cascading style sheets (CSS), Java applets, and
frames, you must carefully evaluate their use in your applications.
Bear in mind these presentation guidelines, to aid your applications’ performance and
user experience, and be sure to plan and test for the lowest common denominator that all
browsers can accommodate.
Often, partitioning business services to a separate business logic application server from
the primary application server, if necessary, can yield better application organization and
easier maintenance. You can maximize your application’s data services by carefully
constructing them and by ensuring that a separate database server (in this case, a separate
computer) is used to increase processor capacity for any database transactions.
These are several of the most important topics you and the developers creating your web
applications should consider early on. In doing so, you ensure that your web applications
are designed and coded with scalability in mind.
Avoiding common bottlenecks
In addition to application design and construction considerations, you must plan to
avoid common bottlenecks that can negatively affect a web application’s performance.
Following are typical bottlenecks that can affect an application’s ability to perform and
scale well:
•
Poorly written application logic — inefficient programming is probably the most
common reason applications perform poorly. Instituting industry best practices, such
as coding standards, design reviews, and code walkthroughs, can significantly help to
alleviate this problem.
•
Processor capacity — even a well-architected and programmed web application can
perform poorly if the web server’s CPU is unable to provide sufficient processing
power. Ensure that heavy-load, mission-critical applications reside on hardware that
can effectively do the job.
•
Memory — insufficient random access memory (RAM) limits the amount of
application data that can be cached. Ensure that the amount of memory installed on
the application server computer is commensurate with the needs of the web
application.
•
Server congestion — server congestion refers to all types of servers, not just the web
server. Your application, proxy, search and index, and back-office servers can
periodically experience high volume that indirectly degrades the performance of your
web application. When planning the physical design of the system, investigate
carefully the network topology that will be implemented to ensure that existing
servers are sufficient. If they are not, you may need to add new servers to the topology
to ensure uninterrupted service and performance expectations.
•
Firewalls — some dynamic applications that must restrict anonymous access because
they present or share confidential information must pass through a corporate firewall,
which can slow down requests and responses. Ensure that the correct ports are open
on the firewall to ensure valid security authentication and to enable appropriate
client/server communications. (You may be able to open additional secure ports to
accommodate increased traffic.)