Web Caching FAQs
Q1. What is web
caching?
Q2. What are the
benefits of web caching?
Q3. How is web
caching different from browser caching?
Q4. Do I still
need caching if I have a high bandwidth broadband connection?
Q5. What are the
cost justifications for employing a web caching appliance?
Q6. How is the freshness of content controlled with a web caching
appliance?
Q7. How does web caching work with real-time dynamic content?
ContentCache FAQs
Q1. What web
caching solutions are available from Avantis?
Q2.
What is proactive caching?
Q3. Can ContentCache
be used to host e-learning packages from content providers
and publishers?
Q4. What is
the caching technology that powers ContentCache?
Q5. What is
the performance of ContentCache web caching appliances?
Q6. What 'realworld'
performance increases can a school using ContentCache™
expect?
Q7.
What are the advantages of ContentCache™ over a normal
server running Windows 2003 Server and ISA Server 2000?
Q8. What are
the advantages of ContentCache™ over a Linux base web
caching appliance running squid?
Q9. What network
environments can ContentCache™ support?
Q10.
Can ContentCache™ be expanded to increase storage capacity?
Q11.
Can ContentCache be purchased as a Managed Service?
Web Caching FAQs
Q1.
What is web caching?
A. A web cache is a device attached to the
local network that stores web pages visited by its users so
that when the page is next requested it can be served from
the cache rather than from the internet. This saves the delays
of requesting and retrieving data from the original site and
dramatically reduces bandwidth consumption.
For example, delivery of a 100KB web page from the originating
server to the end user would take about 17 seconds over a
56Kbps modem or 7.8 seconds over a dual channel ISDN connection,
even with no traffic congestion at the ISP or on the Internet
backbone (this is never the case). However, when caching is
employed this same page would be delivered from the caching
appliance to the end user in about one tenth of a second regardless
of Internet traffic conditions.
Q2.
What are the benefits of web caching?
A. The main benefits of web caching are:
• Dramatic reduction in the time required to view a
web page
• Accelerated access to high bandwidth e-learning content
– with or without a broadband connection (local hosting
of e-learning content can provide up to 1000 percent performance
improvement)
• Reduction in bandwidth usage (by caching frequently
requested content, dynamic caching can decrease bandwidth
usage by 40 percent)
• Optimisation of existing network bandwidth –
freeing up the connection for other bandwidth intensive activities
• More cost effective option than upgrading to a faster
internet connection
• Content can be provided to users even when the source
for the content is offline or unavailable
Within a school environment, repeat visits to the same Web
sites are very frequent. Typically up to 90% of internet traffic
is generated by pupils requesting the same web content more
than once – making caching particularly advantageous.
Q3.
How is web caching different from browser caching?
A. Internet browser applications allow
users to cache web content as files on their local hard disk.
This method serves one user well, but does not benefit other
users on the same network accessing the same web sites. By
contrast, web caching allows web content to be stored and
shared on a local network appliance, benefiting all users
on the network.
Q4.
Do I still need caching if I have a high bandwidth
broadband connection?
A. For schools or businesses that
already have very fast internet connections, web caching can
offer improvements in performance because it effectively removes
upstream contention and all the interaction delays associated
with traversing the internet (typically 10-20 hops between
the user’s web browser and the origin server). Therefore,
it will take longer for web content to travel through the
internet than the near instantaneous LAN delivery when caching
is deployed.
As new e-learning applications become available, users are
starting to expect more video in their content and this typically
increases the per-user bandwidth requirement by as much as
10 times. Even with infinite bandwidth and zero congestion,
a typical media-rich web page (containing perhaps 50 objects)
would take around 10 seconds to form due to the hundreds of
transactions required.
Although connection speeds and router
technology are improving, Internet congestion is getting worse,
not better. In fact, projected figures show that internet
usage will always exceed speed of available bandwidth.
Q5.
What are the cost justifications for employing a web caching
appliance?
A. Time spent waiting for web pages
to load is not productive. If this waiting time is reduced,
there are demonstrable cost savings. In addition, the bandwidth
economy realized through the use of a caching server will
in many cases allow schools and businesses to avoid upgrading
to a more expensive higher bandwidth Internet connection.
Q6.
How is the freshness of content controlled with a web caching
appliance?
A. Caching
systems must ensure that users always receive identical content
to what would have been delivered had the request been forwarded
to the originating server via the internet. Web servers deliver
a ‘caching directive’ with their web pages that
determine how long content is to be cached. For example, the
directive may instruct the web caching appliance not to cache
the content or for the content to time-out after a period
of time. A professional web caching solution, such as the
Avantis ContentCache™ ? will follow the originating
server’s caching directive when setting all attributes
of cached content to ensure that content is always ‘fresh’
and identical to the originating server. If required, ContentCache™
? can also be configured to determine how often the content
should be re-loaded e.g. on a daily, weekly or monthly basis.
Q7.
How does web caching work with real-time dynamic content?
A.
Many of the objects that make up a given web page are static
and can therefore be cached. Other objects on a page can be
dynamic and should never be cached for example, share prices.
With caches, only a few dynamic objects need to be retrieved
from the origin server while the static objects are fulfilled
locally. This method provides an effective way of increasing
performance while maintaining real-time data.
ContentCache FAQs
Q1. What web
caching solutions are available from Avantis?
A. The Avantis ContentCache™ range of web caching appliances has been developed specifically
for the education sector. Three different models are available
to suit the performance and capacity requirements of Primary
schools, Secondary schools and Colleges. All models are available
in tower or rack-mount versions.
Q2. What is proactive
caching?
A. Proactive caching or pre-caching
is the ability to cache content ahead of time. For example,
ContentCache™ can be configured to pre-fetch web pages
so that the content is immediately available from the cache
the first time it is accessed. ContentCache™ can also
be configured to schedule the download of content when internet
usage is low e.g. overnight or at other off-peak times.
Q3. Can ContentCache
be used to host e-learning packages from content providers
and publishers?
A. ContentCache™ supports
local content hosting and is compatible with all of the major
content providers’ material. E-learning packages can
be pre-loaded onto ContentCache™ (downloaded via the
internet, installed from a CD/ DVD or pre-installed before
shipment) and configured to receive automatic updates to content
so that the material is always fresh. ContentCache™
is available with up to 220GB hard disk capacity and has the
capability to store and deliver multiple e-learning packages.
Q4. What is the caching
technology that powers ContentCache?
A. ContentCache™ is powered
by Microsoft Internet Security and Acceleration (ISA) Server
2000. Microsoft ISA Server offers proven technology for best
of class caching, high performance and high reliability, offering
many advantages compared to proprietary and Squid based solutions:
• Industry-Leading
Web cache Performance
ISA Server is over 11 times faster than its predecessor, Microsoft
Proxy Server 2.0 and demonstrated industry-leading Web cache
performance in the Third Annual Cache-Off, finishing in the
top tier in a field with 31 other entries and ranking first
in the price/performance category.
Q5. What is the
performance of ContentCache web caching appliances?
A. The performance of web caching
solutions is normally measured by the number of requests/second
that can be handled by the appliance. The ContentCache™
range has been optimised to meet the different performance
requirements of Primary schools, Secondary schools and Colleges.
ContentCache™ 310 can cope with up to 175 requests/sec,
ContentCache™ 320 up to 300 requests/sec and ContentCache™ 340 up to 800 requests/sec.
Q6. What ‘real
world’ performance increases can a school using ContentCache™
expect?
A. With ContentCache™ deployed
in dynamic (‘reactive’) caching mode only, a school
will automatically achieve between 35% and 50% bandwidth saving
(performance improvement). This affect is known as ‘internet
acceleration’ and gives the immediate impression that
the school has a much faster internet connection.
With ContentCache™ deployed
in ‘proactive’ caching mode and/or set-up to locally
host e-Learning packages, a school will typically achieve
up to 1000% (10 times) performance improvement. This is because
web content is being served instantaneously from ContentCache™
on the school LAN rather than the internet.
Q7. What are the advantages
of ContentCache™ over a normal server running Windows
2003 Server and ISA Server 2000?
A. ContentCache™ offers many
advantages over a normal server running Windows 2003 Server
and ISA Server 2000:
a) ContentCache™
is a hardened, dedicated purpose appliance
• There is no need for a screen and keyboard except
for a 5 minute install
• No additional software can be installed on ContentCache™
which increases resilience and reliability
• Caching is a high performance application and is best
run on a dedicated platform without other software to degrade
the performance
• ContentCache™ provides automatic download and
installation of Microsoft security patches approved by Avantis
• ContentCache™ hardware has been stress tested
to match the application for optimum performance and reliability
b) ContentCache™ has a user friendly Web administration
interface. This includes Administrator menus, Teacher content
planner menus and Pupil content menus. This is much easier
to configure and manage than ISA Server and Windows management.
c) ContentCache™ can be deployed
and installed in 5 minutes - compared to hours or days if
a customer goes it alone.
d) ContentCache™ has many enhancements on the basic
ISA Server 2000 software including:
• Teacher and Pupil web login
• Local content hosting and various content ingestion
techniques
• Enhanced pre-caching techniques
• Support for manifest lists
• Reporting
• Filtering system integration options
• True streaming media support
• "Central Management" software to allow publishers
or LEAs / School Districts to manage groups of ContentCaches
Q8.
What are the advantages of ContentCache™ over a Linux
based web caching appliance running Squid?
A. ContentCache™ offers many
advantages over a Linux appliance running Squid:
a) ContentCache™
integrates fully as a member server into Microsoft Active
Directory and Microsoft Domains.
• Reports generated by ContentCache™ utilise Active
Directory User Descriptions to provide clear and granular
reporting on user/group usage
• Active Directory
Groups can be used within the ContentCache Web Admin interface
to provide more stringent filtering control and access to
web content
Linux based solutions that claim to
have ADS support use a rudimentary “Get Name”
function which lacks the richness offered by ContentCache’s
full ADS integration.
b) ContentCache™ is based upon
Windows 2003 Server and inter-operates reliably with other
Windows based Servers and PCs
c) Windows Server 2003 Server and
ISA Server 2000 are professionally designed and professionally
benchmarked solutions that beat Squid based Linux solutions
on performance when compared on like for like hardware. In
a performance test carried out by Veritest of Windows Server
2003 vs. Red Hat Linux Advanced Server 2.1 in April 2003,
Windows delivered between 66 and 100% better file server performance
depending on hardware platform.
d) ContentCache™ is based upon
Windows Server 2003 for which Microsoft’s primary development
goal has been resilience and reliability. Microsoft has a
large team of rapid response engineers who provide MS Security
Patches rapidly to fix any emerging security threat. ContentCache™
automatically downloads and installs all new patches pre-qualified
by Avantis. There is no equivalent for Linux based solutions.
e) ContentCache™ provides a
future proof investment because it will automatically benefit
from any new Microsoft technology developed for the Windows
platform. These solutions are professionally engineered and
tested by Microsoft and their partners. With Linux and Squid,
support for new technologies usually depends on the Open Source
community.
f) ContentCache™
is simple to install, set-up and administer. Recent studies
of Linux vs. Windows for server applications have shown that
the TCO of Windows is lower than for Linux despite the fact
that the up front cost for Linux is lower.
Q9. What network environments
can ContentCache™ support?
A. ContentCache™ can be used
in all network environments that support TCP/IP including
Windows, MAC, UNIX and Linux. ContentCache™ is built
on Windows 2003 Server and provides complete integration with
all Windows networks including Active Directory and Microsoft
Domains.
Q10.
Can ContentCache™ be expanded to increase storage capacity?
A. All ContentCache™ models
can be doubled in capacity. This is a return-to-base service
that can only be undertaken by Avantis.
Q11.
Can ContentCache™ be purchased as a Managed Service?
A. Avantis offers a Managed Service
to UK schools for ContentCache™ . The Managed Service
includes Installation, Support, On-Site Maintenance and Software
Maintenance. Schools must purchase the Managed Service for
a minimum three year term. Other Managed Service agreements
are available for ContentCache™ through Avantis UK Education
Partners.
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FAQs
