【Table of contents】
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1. What is CDN?
CDN stands for "Content Delivery Network" and is a system to efficiently and rapidly deliver web content to users who are trying to access a website using a worldwide delivery network.
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2. CDN for beginners
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a) How does CDN work?
In general, when operating a website, the operator sets up a web server (origin) to distribute content by guiding end users to the origin. However, if the traffic to the origin and the subsequent load increases so much that the traffic spikes, it can cause the origin server to go down or the web page you are trying to access to take a long time to display. To avoid this, we use a CDN.
The CDN server caches (copies) the content retrieved from the origin and responds to the end user's request over a physically close network.
CDNs can be used to offload traffic to the origin server, improving web responsiveness and reducing the load on the origin server. This is how a CDN works in general.
・ Automatically select servers that are close to each other
The CDN automatically selects the server that is closest to the access point to download the content. For example, U.S. users can download from a cache server located in the U.S. and European users can download from a cache server located in Europe, making the download faster.The "close distance" here is a bit different than the physical distance. In the world of the Internet, it takes various points such as routers to reach the access destination from the access source. The number of points at this time is called the number of HOPs, and the smaller the number of HOPs, the closer the distance is.
・ Load balancing
A CDN is made up of multiple cache servers. In addition, there are multiple upper-level networks for each server, which can be load-balanced and reduce network latency. -
b) CDNs used in cloud services
CDNs can also be used for services over the Internet, called cloud services.
A cloud service is a system in which a variety of IT resources, including computing, databases, storage and applications, can be used via the Internet from a cloud service platform provided by a cloud service provider on the Web.
We would like to introduce how CDNs are used in AWS (Amazon Web Services), one of the cloud services.
CDN is available on AWS under the service name Amazon CloudFront, a high-speed content delivery network (CDN) service that securely delivers data, video, applications, and APIs to a global audience with low-latency, high-speed transfers in a developer-friendly environment.
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c) Benefits of AWS CloudFront
Now we're going to briefly explain what the benefits of using a service called CloudFront are.
・ Fast and Global
Amazon CloudFront is a global content delivery network deployed around the world with 210 transit points in the network, called POPs, providing superior performance and availability.・ Security on the Edge
Amazon CloudFront is a highly secure CDN that is protected at both the network and application levels. A variety of other built-in protection features are available at no extra charge.・ Highly programmable
The features of Amazon CloudFront can be programmatically customized for specific applications. Lambda@Edge function, provided by a feature called Lambda within AWS, allows you to improve responsiveness even in complex application logic.・ Tight integration with AWS
Amazon CloudFront is integrated with AWS services such as Amazon S3, Amazon EC2, Elastic Load Balancing, Amazon Route 53, and AWS Elemental Media Services. Therefore, there is no need to understand the complexities of technology or purchase new equipment to work with other features of the CDN. -
d) What is AWS?
So far, the term AWS has come up frequently, but what does it really mean in the first place? We will explain it to you in an easy-to-understand way.
AWS stands for "Amazon Web Services" and is a cloud computing service provided by Amazon Web Services, Inc.
A cloud computing service is a mechanism that makes computers, databases, and applications available through the Internet, and cloud computing has the advantage of reducing the fees and time required for the initial investment in equipment.
Among the cloud services, there are three advantages of using AWS.
i) About costs: initial costs and price reductions
AWS has no initial costs. We have a pay-as-you-go system where you pay only for what you use. For example, if you buy a server on-premises, you pay for the server at the time of purchase, so you're wasting money if something unplanned happens and you don't use that server. With AWS, you don't have to pay for things you don't use because you won't be charged for them once you stop using them. And since all the fees are published on the AWS site, there is no need to inquire or apply without knowing the fees.
In addition to the initial cost, AWS also offers regular price reductions.ii) System operation: Flexible IT resources that can be increased or decreased
If you set up your own system, it is always necessary to predict the increase in the number of users and secure IT resources such as servers. For example, if you have more users accessing your system and you don't add more servers, your system will go down. It is possible to increase the number of servers by buying more servers, but it takes time and you have to continue to maintain and manage them even if you no longer need them.
With AWS, you can increase or decrease the number of servers in a few clicks and a few minutes. You can also change the size of the server you are currently using, so you can change the specs of the server that is running during the day and night, for example.iii) About technology: Use the latest technology anytime
There are over 165 services available in AWS. This includes a number of services that make use of current technologies such as IoT and Machine Learning. Version upgrades are also frequent, with over 1430 upgrades in 2017.
More than 90% of these upgrades are based on requests from AWS users. It can be said that the really necessary version upgrades have been made to meet the needs of users.The advantage of having a wide variety of services is that you don't have to combine them with other companies' products.
As the products of other companies are combined and the number of products increases, the maintenance and operation of the system will become more complicated and more meetings will be required. If a problem occurs, it will take time to investigate the cause and formulate a countermeasure. If you can develop and maintain your system using only AWS services, you can make inquiries in one place. In return, users can spend their time on their own business.
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3. Conclusion
We explained about CDNs and cloud services.
High communication speed is a major advantage for providing web services.
Users may quickly turn away if they feel the page is slow to load or the file takes a long time to download.
So why not improve the performance of your CDN to provide a better service?
