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”.

Returning to the topic of caching, it is the process in which reusable responses are stored for the purpose of rendering subsequent requests faster. There are various types of caching available with their own characteristics. With regard to web caching, it is an important design feature of the HTTP protocol that is meant for the purpose of minimizing network traffic and enhancing the responsiveness of the overall system. Web caching functions by caching requests’ HTTP responses in accordance with certain rules. Cached content’s subsequent requests get fulfilled from a cache that is closer to the user which eliminates the need to send the request to the web server. Any web content encounters caches at different levels while it is transmitted from the original server to the browser. Hence, the components that exist in the entire delivery path cache items to ensure that subsequent requests are speedier. This is subject to certain caching policies that have been established and declared for the particular content.

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.

Where is Web Content Cached?

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.