Caching
Caching content is an
effective way to improve the user experience of a site’s visitors. It stores
temporarily the content that is related to previous requests and is a part of
the strategy that is implemented for content delivery within the HTTP
(Hypertext Transfer Protocol) protocol. At this juncture, it is important to
mention that every website that is accessible over the Internet is made
available to us by web hosting companies that provide the service of web
hosting. Web hosting is a service in which server space along with the essential
technology and services are provided to website owners, so that they can store
their websites’ files on these servers and deliver those on request. The most
reliable website hosting companies are often referred to as the “Best Website
Hosting Company”, the “Best Windows Hosting
Company” and the “Top Cloud Hosting
Company”.
Cached
Content
All types of web content are
capable of being cached but that doesn’t necessarily mean that every content
should be cached. For ease of understanding, cached content can be classified
into three groups.
The first of these categories
includes the content that is cache-friendly. This type of content does not
change frequently. Hence, it can be cached for longer periods of time. Media
content, style sheets, icons, images, logos and JavaScript libraries are some
of its examples.
The next category is of
content that is moderately cache-friendly. This type of content usually changes
regularly. Hence, extra caution needs to be exercised for such content.
Moderately cache-friendly content includes HTML pages, JS and CSS that is
modified frequently and those content requests which require authentication
cookies.
Last but not the least is the
content that should never be cached. Certain types of content should never be
cached due to security concerns. Such content includes content that is highly
sensitive and/or confidential. Moreover, any content that is specific to users
should not be cached. This is because it is usually updated regularly.
As mentioned previously, web content gets cached
at various points in the content delivery path. Some of these will be touched
upon now, which are capable of caching and most often do cache content based on
the caching policies. A small cache is maintained by web browsers. Usually a
policy is set by the browser that specifies the items that are important enough
to be cached. This can include user-specific content or such content that has a
likelihood of being requested again. Then there are the intermediary caching
proxies. Any server that exists between a client and one’s infrastructure is
capable of caching content. Such caches might be maintained by independent
parties or ISPs (Internet service providers). Moreover, one’s server
infrastructure is capable of implementing its own cache for the purpose of
backend services. This aids in serving content from the point-of-contact,
eliminating the need to rely on backend servers for each request.
Benefits of
Caching
Both, the consumer and the provider,
benefit through caching. Its main advantages shall be discussed now. It helps
to reduce bandwidth costs. Web content can be cached at different points with
regard to the path of the HTTP request. Each time that the content gets cached
closer to the user, the request covers lesser distance which results in a
decrease in the bandwidth costs. Another advantage is improvement in
responsiveness. Maintaining caches closer to the user ensures that responses
are more instantaneous. It results in accomplishing a better user experience.
Moreover, the same hardware is able to deliver better performance. This is due
to the fact that similar requests are being catered by the cache which helps
server hardware to focus on such requests that require processing power.
Another major benefit of caching is the availability of content even in the
event that there are network failures. Depending on the cache policies, even if
there is a server failure, the end users can have content served to them from
the cache for a certain, usually short, period of time. This proves to be
extremely helpful for clients as it enables them to perform the most basic
tasks without letting the origin server’s failure hinder them.
Downside of
Caching
The major downside of caching is that the
cache gets deleted whenever the server is restarted. This occurs due to the
fact that cache is lost whenever there is power outage. It happens because
cache is volatile. This can be redressed by maintaining such policies which
enable one to write the cache to one’s disk at regular intervals which helps to
retain the cached data during server restart. Another challenge with caching is
that it serves stale data, which is data that hasn’t been updated. Hence, it
consists of a previous version of the data.
Conclusion
It goes without saying that a significant
improvement can be achieved in the performance of web sites and applications
with the aid of reusing resources that have been fetched previously. Latency as
well as network traffic, are both reduced by web caches. This helps to reduce
the time that is usually needed to display a resource’s representation. Hence,
the use of web application caching is regarded as an important tool for making
websites more responsive.
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