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February
13, 2001
PC Magazine Internet Business
100
Performance Enhancement |
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| September
21, 1999 |
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The Main Problem: The Web Is
Too Slow!
Although the Web has significantly
increased the productivity and
effectiveness of its users,
everybody complains that loading
Web pages takes too long. The
speed of accessing the Web directly
affects a user's productivity.
If the users in a corporation
are suffering long or highly
variable delays, their productivity
and therefore the competitiveness
of the entire corporation suffers.
The only way to speed up Web
access is to store the majority
of frequently requested objects
closer to their users by using
web caching server which some
time call proxy server. But
the performance,
management, scalability
and reliability
of first generation proxy solutions-
software-based applications
running on general-purpose operating
systems degrade under today's
heavy Internet and Intranet
usage load.
The
Solution
Blue
Coat System CA-800 Series Security
Gateway, CA-6000 Series Client
Accelerator and CA-700/CA-7000
Server Accelerator
utilized Blue Coat System's
Award winning Content Delivery
Architecture provide a next-generation
proxy solution that delivers
business and technology benefits
to Web-dependent enterprises
and service providers
All Blue Coat System Appliance
solutions run the purpose-built
CacheOS™ operating system.
CacheOS leverages a number of
patent-pending algorithms to
minimize the response time for
the delivery of web pages while
ensuring the highest standards
of content freshness.
Object
Pipelining: Fast Content Retrieval,
The First Time
When a browser requests content,
dozens of round trips must take
place between the browser and
the distant Web server. This
is because a Web page is typically
composed of dozens of objects,
and for each object there typically
must first be a TCP session
setup followed by an HTTP "get"
request. This serial retrieval
of objects presents a major
delay for the end user. With
Blue Coat System deployed, a
large portion of this delay
is eliminated. The client connection
terminates at the Blue Coat
System device, which leverages
the latency-attacking algorithms
in CacheOS called Object
Pipelining. Instead of
retrieving objects serially,
this patent-pending algorithm
opens as many simultaneous TCP
connections as the origin server
will allow and retrieves objects
in parallel. As a result of
Object Pipelining, Blue Coat
System typically accelerates
first-time Web page retrievals
by 50%, as shown in Figure 1.
Adaptive
Refresh : Delivery Fresh Content
The Adaptive
Refresh algorithm:
Using the Adaptive Refresh algorithm,
the Blue Coat System Security
Gateway automatically performs
"freshness checks"
with the origin server to ensure
that old content is expunged
and replaced with fresh content.
For example, if the objects
within the www.nbcnews.com home
page are popular among the population
of users that are accessing
the cache, CacheOS will update
the objects that change frequently
(e.g., "top story"
object) but will not refresh
those objects that do not change
(e.g., "NBC logo"
object). This ensures that current
content will be delivered to
end users quickly.
While Object Pipelining improves
response times for first-time
Web page requests, Adaptive
Refresh significantly speeds
subsequent requests by removing
the latency involved in refreshing
the objects. Figure 1 illustrates
the performance improvements
up to 10 time by Blue Coat System
Appliance.
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