No matter how much we may try to ignore it, human communication always takes place in a context, through a medium, and among individuals and groups who are situated historically, politically, economically, and socially. This state of affairs is neither bad nor good. Bias is a small word that identifies the collective influences of the entire context of a message.
Why do people use them? A Web cache sits between one or more Web servers also known as origin servers and a client or many clients, and watches requests come by, saving copies of the responses — like HTML pages, images and files collectively known as representations — for itself.
Then, if there is another request for the same URL, it can use the response that it has, instead of asking the origin server for it again. There are two main reasons that Web caches are used: To reduce latency — Because the request is satisfied from the cache which is closer to the client instead of the origin server, it takes less time how to write a news backgrounder meaning it to get the representation and display it.
This makes the Web seem more responsive. To reduce network traffic — Because representations are reused, it reduces the amount of bandwidth used by a client. This saves money if the client is paying for traffic, and keeps their bandwidth requirements lower and more manageable.
The browser cache works according to fairly simple rules.
It will check to make sure that the representations are fresh, usually once a session that is, the once in the current invocation of the browser. Proxy Caches Web proxy caches work on the same principle, but a much larger scale.
Proxies serve hundreds or thousands of users in the same way; large corporations and ISPs often set them up on their firewalls, or as standalone devices also known as intermediaries.
Proxy caches are a type of shared cache; rather than just having one person using them, they usually have a large number of users, and because of this they are very good at reducing latency and network traffic.
Requests can be routed to gateway caches by a number of methods, but typically some form of load balancer is used to make one or more of them look like the origin server to clients. Content delivery networks CDNs distribute gateway caches throughout the Internet or a part of it and sell caching to interested Web sites.
Speedera and Akamai are examples of CDNs. This tutorial focuses mostly on browser and proxy caches, although some of the information is suitable for those interested in gateway caches as well. Why should I help them?
Web caching is one of the most misunderstood technologies on the Internet. If this is a big concern for you, this tutorial will teach you how to get the statistics you need without making your site cache-unfriendly. Another concern is that caches can serve content that is out of date, or stale.
However, this tutorial can show you how to configure your server to control how your content is cached. However, even when you use a CDN, you still have to consider that there will be proxy and browser caches downstream. On the other hand, if you plan your site well, caches can help your Web site load faster, and save load on your server and Internet link.
The difference can be dramatic; a site that is difficult to cache may take several seconds to load, while one that takes advantage of caching can seem instantaneous in comparison.
Users will appreciate a fast-loading site, and will visit more often. Think of it this way; many large Internet companies are spending millions of dollars setting up farms of servers around the world to replicate their content, in order to make it as fast to access as possible for their users.
The fact is that proxy and browser caches will be used whether you like it or not. Some of these rules are set in the protocols HTTP 1. If the request is authenticated or secure i. A cached representation is considered fresh that is, able to be sent to a client without checking with the origin server if: It has an expiry time or other age-controlling header set, and is still within the fresh period, or If the cache has seen the representation recently, and it was modified relatively long ago.
Fresh representations are served directly from the cache, without checking with the origin server.for Web Authors and Webmasters. This is an informational document. Although technical in nature, it attempts to make the concepts involved understandable and applicable in real-world situations.
(At this point, the backgrounder delves into the important details of the situation. Use this sample to discern the format of these details.) This group often enters into routine actions or situations to perform an action within the community.
The backgrounder consists of several elements, the first usually being a summary of the topic. The remaining components are arranged in the order that best suits the particular backgrounder.
A paragraph may be devoted to one particular element or consist of a combination of multiple elements. Email comment by Alex Jones: Alex Jones. (Feb. 23, ). VIDEO: PRIVATE SCHOOL TRAINS STUDENTS/STAFF TO NEUTRALIZE ACTIVE SHOOTER.
Infowars. Vice News interviewed students and staff at a New Mexico private school who work with local law enforcement to train for an active shooter situation. Fukuoka | Japan Fukuoka | Japan. New federal exercise recommendations include the first-ever federal activity parameters for 3-year-olds, as well as a few surprising omissions.