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CDN (content delivery network)
Posted by Thang Le Toan on 23 May 2018 02:25 AM
A CDN (content delivery network), also called a content distribution network, is a group of geographically distributed and interconnected servers that provide cached internet content from a network location closest to a user to accelerate its delivery. The primary goal of a CDN is to improve web performance by reducing the time needed to transmit content and rich media to users' internet-connected devices.
Content delivery network architecture is also designed to reduce network latency, which is often caused by hauling traffic over long distances and across multiple networks. Eliminating latency has become increasingly important, as more dynamic content, video and software as a service are delivered to a growing number of mobile devices.
CDN providers house cached content in either their own network points of presence (POP) or in third-party data centers. When a user requests content from a website, if that content is cached on a content delivery network, the CDN redirects the request to the server nearest to that user and delivers the cached content from its location at the network edge. This process is generally invisible to the user.
A wide variety of organizations and enterprises use CDNs to cache their website content to meet their businesses' performance and security needs. The need for CDN services is growing, as websites offer more streaming video, e-commerce applications and cloud-based applications where high performance is key. Few CDNs have POPs in every country, which means many organizations use multiple CDN providers to make sure they can meet the needs of their business or consumer customers wherever they are located.
In addition to content caching and web delivery, CDN providers are capitalizing on their presence at the network edge by offering services that complement their core functionalities. These include security services that encompass distributed denial-of-service (DDoS) protection, web application firewalls (WAFs) and bot mitigation; web and application performance and acceleration services; streaming video and broadcast media optimization; and even digital rights management for video. Some CDN providers also make their APIs available to developers who want to customize the CDN platform to meet their business needs, particularly as webpages become more dynamic and complex.
How does a CDN work?
The process of accessing content cached on a CDN network edge location is almost always transparent to the user. CDN management software dynamically calculates which server is located nearest to the requesting user and delivers content based on those calculations. The CDN server at the network edge communicates with the content's origin server to make sure any content that has not been cached previously is also delivered to the user. This not only eliminates the distance that content travels, but reduces the number of hops a data packet must make. The result is less packet loss, optimized bandwidth and faster performance, which minimizes timeouts, latency and jitter, and it improves the overall user experience. In the event of an internet attack or outage, content hosted on a CDN server will remain available to at least some users.
Organizations buy services from CDN providers to deliver their content to their users from the nearest location. CDN providers either host content themselves or pay network operators and internet service providers (ISPs) to host CDN servers. Beyond placing servers at the network edge, CDN providers use load balancing and solid-state hard drives to help data reach users faster. They also work to reduce file sizes using compression and special algorithms, and they are deploying machine learning and AI to enable quicker load and transmission times.
History of CDNs
The first CDN was launched in 1998 by Akamai Technologies soon after the public internet was created. Akamai's original techniques serve as the foundation of today's content distribution networks. Because content creators realized they needed to find a way to reduce the time it took to deliver information to users, CDNs were seen as a way to improve network performance and to use bandwidth efficiently. That basic premise remains important, as the amount of online content continues to grow.
So-called first-generation CDNs specialized in e-commerce transactions, software downloads, and audio and video streaming. As cloud and mobile computing gained traction, second-generation CDN services evolved to enable the efficient delivery of more complex multimedia and web content to a wider community of users via a more diverse mix of devices. As internet use grew, the number of CDN providers multiplied, as have the services CDN companies offer.
New CDN business models also include a variety of pricing methods that range from charges per usage and volume of content delivered to a flat rate or free for basic services, with add-on fees for additional performance and optimization services. A wide variety of organizations use CDN services to accelerate static and dynamic content, online gaming and mobile content delivery, streaming video and a number of other uses.
What are the main benefits of using a CDN?
The primary benefits of traditional CDN services include the following:
How do you manage CDN security?
A representative list of CDN providers in this growing market include the following:
Why you need to know about CDN technology
A wide variety of organizations use CDNs to meet their businesses' performance and security needs. The need for CDN services is growing, as websites offer more streaming video, e-commerce applications and cloud-based applications, where high performance is essential.
CDN technology is also an ideal method to distribute web content that experiences surges in traffic, because distributed CDN servers can handle sudden bursts of client requests at one time over the internet. For example, spikes in internet traffic due to a popular event, like online streaming video of a presidential inauguration or a live sports event, can be spread out across the CDN, making content delivery faster and less likely to fail due to server overload.
AWS GPU instance type slashes cost of streaming apps
The cost of graphics acceleration can often make the technology prohibitive, but a new AWS GPU instance type for AppStream 2.0 makes that process more affordable.
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Amazon AppStream 2.0, which enables enterprises to stream desktop apps from AWS to an HTML5-compatible web browser, delivers graphics-intensive applications for workloads such as creative design, gaming and engineering that rely on DirectX, OpenGL or OpenCL for hardware acceleration. The managed AppStream service eliminates the need for IT teams to recode applications to be browser-compatible.
The newest AWS GPU instance type for AppStream, Graphics Design, cuts the cost of streaming graphics applications up to 50%, according to the company. AWS customers can launch Graphics Design GPU instances or create a new instance fleet with the Amazon AppStream 2.0 console or AWS software development kit. AWS’ Graphics Design GPU instances come in four sizes that range from 2-16 virtual CPUs and 7.5-61 gibibytes (GiB) of system memory, and run on AMD FirePro S7150x2 Server GPUs with AMD Multiuser GPU technology.
Developers can now also select between two types of Amazon AppStream instance fleets in a streaming environment. Always-On fleets provide instant access to apps, but charge fees for every instance in the fleet. On-Demand fleets charges fees for instances when end users are connected, plus an hourly fee, but there is a delay when an end user accesses the first application.
New features and support
In addition to the new AWS GPU instance type, the cloud vendor rolled out several other features this month, including:
BPM in cloud evolves to suit line of business, IoT
While on-premises BPM tools have caused a tug of war between lines of business and IT, the cloud helps appease both sides. Here's what to expect from this cloud BPM trend and more.
Business process management tools rise in importance as companies try to make better use -- and reuse -- of IT assets. And, when coupled with cloud, this type of software can benefit from a pay-as-you-go model for more efficient cost management, as well as increased scalability.
As a result, cloud-based BPM has become a key SaaS tool in the enterprise. Looking forward, the growth of BPM in cloud will drive three major trends that enterprise users should track.
BPM is designed to encourage collaboration between line departments and IT, but the former group often complains that BPM tools hosted in the data center favor the IT point of view in both emphasis and design. To avoid this and promote equality between these two groups, many believe that BPM tools have to move to neutral territory: the cloud.
Today, BPM supports roughly a dozen different roles and is increasingly integrated with enterprise architecture practices and models. This expands the scope of BPM software, as well as the number of non-IT professionals who use it. Collaboration and project management, for example, account for most of the new features in cloud BPM software.
Collaboration features in cloud-based BPM include project tools and integration with social networks. While business people widely use platforms like LinkedIn for social networking, IT professionals use other wiki-based tools. Expect to see a closer merger between the two.
This push for a greater line department focus in BPM could also divide the BPM suites themselves. While nearly all the cloud BPM products are fairly broad in their application, those from vendors with a CIO-level sales emphasis, such as IBM's Business Process Manager on Cloud or Appian, focus more on IT. NetSuite, on the other hand, is an example of cloud BPM software with a broader organizational target.
Software practices influence BPM
Cloud, in general, affects application design and development, which puts pressure on BPM to accommodate changes in software practices. Cloud platforms, for example, have encouraged a more component-driven vision for applications, which maps more effectively to business processes. This will be another factor that expands line department participation in BPM software.
BPM in cloud encourages line organizations to take more control over applications. The adoption of third-party tools, rather than custom development, helps them target specific business problems. This, however, is a double-edged sword: It can improve automated support for business processes but also duplicate capabilities and hinder workflow integration among organizations. IT and line departments will have to define a new level of interaction.
The third trend to watch around BPM in cloud involves internet of things (IoT) and machine-to-machine communications. These technologies presume that sensors will activate processes, either directly or through sensor-linked analytics. This poses a challenge for BPM, because it takes human judgment out of the loop and requires instead that business policies anticipate human review of events and responses. That shifts the emphasis of BPM toward automated policies, which, in the past, has led to the absorption of BPM into things like Business Process Modeling Language, and puts the focus back on IT.
What do you expect from cloud BPM in the future?
In theory, business policy automation has always been within the scope of BPM. But, in practice, BPM suites have offered only basic support for policy automation or even for the specific identification of business policies. It's clear that this will change and that policy controls to guide IoT deployments will be built into cloud-based BPM.