Through my job, I can get cheap wimax but there’d be a bandwidth limit of 200MB/month
I often work on personal programming projects on the train to work. For this, I generally don’t need web access and even when I do need access; it’s usually for pages I’ve already visited.
Is there a way to cache my web visits in a way that’s relatively transparent. I’m thinking a caching proxy.
I want to be able to tell it:
Cache everything from https://developer.mozilla.org (would be nice if they provided downloadable docs)
Don’t cache google
Cache javascript, css, and images from gmail and facebook (perhaps updating once a week)
Block youtube altogether (bandwidth hog)
Thoughts?
Does Squid Cache fit your bill?
http://www.squid-cache.org/
Related
We're currently doing optimizations to our web project when our lead told us to push the use of CDNs for external libraries as opposed to including them into a compile+compress process and shipping them off a cache-enabled nginx setup.
His assumption is that if the user has visits example.com which uses a CDN'ed version of jQuery, the jQuery is cached that time. If the user happens to visit example2.com and happen to use the same CDN'ed jQuery, the jQuery will be loaded from cache instead of over the network.
So my question is: Do domains actually share their cache?
I argued that even if it is possible the browser does share cache, the problem is that we are running on the assumption that the previous sites use the same exact CDN'ed file from the same exact CDN. What are the chances of running into a user browsing through a site using the same CDN'ed file? He said to use the largest CDN to increase chances.
So the follow-up question would be: If the browser does share cache, is it worth the hassle to optimize based on his assumption?
I have looked up topics about CDNs and I have found nothing about this "shared domain cache" or CDNs being used this way.
Well your lead is right this is basic HTTP.
All you are doing is indicating to the client where it can find the file.
The client then handles sending a request to the CDN in compliance with their caching rules.
But you shouldn't over-use CDNs for libraries either, keep in mind that if you need a specific version of the library, especially older ones, you won't be likely to get much cache hits because of version fragmentation.
For widely used and heavy libraries like jQuery you want the latest version of it is recommended.
If you can take them all from the same CDN all the better (ie: Google's) especially as http2 is coming.
Additionally they save you bandwidth, which can amount to a lot when you have high loads of traffic, and can reduce the load time for users far from your server (Google's is great for this).
I was studying about browser performance when loading static files and this doubt has come.
Some people say that use CDN static files (i.e. Google Code, jQuery
latest, AJAX CDN,...) is better for performance, because it requests
from another domain than the whole web page.
Other manner to improve the performance is to set the Expires header
equal to some months later, forcing the browser to cache the static
files and cutting down the requests.
I'm wondering which manner is the best, thinking about performance and
if I may combine both.
Ultimately it is better to employ both techniques if you are doing web performance optimization (WPO) of a site, also known as front-end optimization (FEO). They can work amazingly hand in hand. Although if I had to pick one over the other I'd definitely pick caching any day. In fact I'd say it's imperative that you setup proper resource caching for all web projects even if you are going to use a CDN.
Caching
Setting Expires headers and caching of resources is a must and should be done 100% of the time for your resources. There really is no excuse for not doing caching. On Apache this is super easy to config after enabling mod_expires.c and mod_headers.c. The HTML5 Boilerplate project has good implementation example in the .htaccess file and if your server is something else like nginx, lighttpd or IIS check out these other server configs.
Here's a good read if anyone is interested in learning about caching: Mark Nottingham's Caching Tutorial
Content Delivery Network
You mentioned Google Code, jQuery latest, AJAX CDN and I want to just touch on CDN in general including those you pay for and host your own resources on but the same applies if you are simply using the jquery hosted files cdn or loading something from http://cdnjs.com/ for example.
I would say a CDN is less important than setting server side header caching but a CDN can provide significant performance gains but your content delivery network performance will vary depending on the provider.
This is especially true if your traffic is a worldwide audience and the CDN provider has many worldwide edge/peer locations. It will also reduce your webhosting bandwidth significantly and cpu usage (a bit) since you're offloading some of the work to the CDN to deliver resources.
A CDN can, in some rarer cases, cause a negative impact on performance if the latency of the CDN ends up being slower then your server. Also if you over optimize and employ too much parallelization of resources (using multi subdomains like cdn1, cdn2, cdn3, etc) it is possible to end up slowing down the user experience and cause overhead with extra DNS lookups. A good balance is needed here.
One other negative impact that can happen is if the CDN is down. It has happened, and will happen again. This is more true with free CDN. If the CDN goes down for whatever reason, so does your site. It is yet another potential single point of failure (SPOF). For javascript resources you can get clever and load the resource from the CDN and should it fail, for whatever the case, then detect and load a local copy. Here's an example of loading jQuery from ajax.googleapis.com with a fallback (taken from the HTML5 Boilerplate):
<script src="//ajax.googleapis.com/ajax/libs/jquery/1.8.2/jquery.min.js"></script>
<script>window.jQuery || document.write('<script src="js/vendor/jquery-1.8.2.min.js"><\/script>')</script>
Besides obvious free API resources out there (jquery, google api, etc) if you're using a CDN you may have to pay a fee for usage so it is going to add to hosting costs. Of course for some CDN you have to even pay extra to get access to certain locations, for example Asian nodes might be additional cost then North America.
For public applications, go for CDN.
Caching helps for repeated requests, but not for the first request.
To ensure fast load on first page visit use a CDN, chances are pretty good that the file is already cached by another site already.
As other have mentioned already CDN results are of course heavily cached too.
However if you have an intranet website you might want to host the files yourself as they typically load faster from an internal source than from a CDN.
You then also have the option to combine several files into one to reduce the number of requests.
A CDN has the benefit of providing multiple servers and automatically routing your traffic to the closest location to your client. This can result in faster delivery, optimized by location.
Also, static content doesn't require special application servers (like dynamic content) so for you to be able to offload it to a CDN means you completely reduce that traffic. A streaming video clip may be too big to cache or should not be cached. But you don't neccessarily want to support that bandwidth. A CDN will take on that traffic for you.
It is not always about the cache. A small application web server may just want to provide the dynamic content but needs a solution for the heavy hitting media that rarely changes. CDNs handle the scaling issue for you.
Agree with #Anthony_Hatzopoulos (+1)
CDN complements Caching; also in some cases, it will help optimize Caching directives.
For example, a company I work for has integrated behavior-learning algorithms into its CDN, to identify and dynamically cache generated objects.
Ordinarily, these objects would be un-Cachable (i.e. [Cache-Control: max-age=0] Http header). But in this case, the system is able to identify Caching possibilities and override original HTTP Header directions. (For example: a dynamically generated popular product that should be Cached, or popular Search result page that, while being generated dynamically, is still presented time over time in the same form to thousands of users).
And yes, before you ask, the system can also identify personalized data and very freshness, to prevent false positives... :)
Implementing such an algorithm was only possible due to a reverse-proxy CDN technology. This is an example of how CDN and Caching can complement each other, to create better and smarter acceleration solutions.
Above those experts quotes, the explanation are perfect to understand CDN tech and also cache
I would just provide my personal experience, I had worked on the joomla virtuemart site and unfortunately it will not allow update new joomla and virtuemart version cause it was too much customised fields in product pages, so once the visitor up to 900/DAY and lots user could not put their items in their basket because each time to called lots js and ajax called for order items takes too much time
After optimise the site, we decide to use CDN, then the performance is really getting good, along by record from gtmetrix, the first YSlow Score was 50% then after optimise + CDN it goes to 74%
https://gtmetrix.com/reports/www.florihana.com/jWlY35im
and from dashboard of CDN you could see which datacenter cost most and data charged most to get your improvement of marketing:
But yes to configure CDN it has to be careful of purge time and be balancing numbers of resource CDN cause if it down some problem you need to figure out which resource CDN cause
Hope this does help
I have seen some general questions regarding speed of SSL, but most answers are generic and ask for specifics to give a better answer.
Well, here are my specifics, i really hope someone can help me with some advice what to do.
Question:
I would prefer to keep SSL on throughout the site, instead of only at default Magento SSL behavior such as logging in, account edits, orders and payments. So basically, also during product browsing, reading CMS pages, etc.
But at what performance cost will this be. I'm only worried about actual performance a user may notice.
I'm running a Magento multistore site on a dedicated server with 4GB memory and dualcore processor with gigabit internet connectivity, running Centos 5 and latest LAMP versions. I run a Comodo SSL multidomain Extended Validation (the 'green bar').
Ask me for any details that are relevant to make a better advice :-)
In short, the answer is you will most definitely see a performance hit. This is why Magento was built the way it was. Secure the pages the have private content, and leave the rest open.
Each HTTPS request made using HTTPS, the client and server must deal with verifying the certificate, passing keys, encrypting and decrypting the data. This adds quite an overhead to apache and the OS. You will also loose the efficiencies of local caching of static content, such as stylesheets, javascript pages, images, etc.
As a result, the client will see a increase in load times, Google will ding you for a slow website, conversion will most likely decrease, and possibly other unforeseen consequences.
Here's a conversation from Magentocommerce about constant HTTPS: magentocommerce
In the end, it's not a great idea. Magento does a very good job knowing which pages should be secure and which are fine without.
But, if you MUST, it is possible. Watch your conversion and analytics numbers closely. If you have Google Analytics installed, add page_speed _trackPageLoadTime to your site. Then, at least, you will know what the dammage is.
If you need caching in your website to make database use lower, do you have to do it using memcache or memcached (in PHP, for example) or can you achieve this by using professional services like CloudFlare, Incapsula or others like that do some caching for you?
Services like Cloudflare cache your HTML and/or assets like images and CSS files in a CDN, so that your entire server is hit less often. This is great for semi-static sites but may not be the best fit for highly dynamic sites.
Local caches like memcached just store any data in a way that's fast to access. You can use that to cache database queries and lower your database activity, but you can also use it to store pre-computed data that would be expensive to re-create all the time or whatever else you may want to store non-permanently in a fast-to-access way.
Both solutions solve different problems. You may use both together, or either, or neither. It really depends on where exactly your bottleneck is and which solution fits your problem better.
I'm the CEO of CloudFlare and I'd say: more (intelligent) caching is almost always a good thing. While we can significantly decrease the load coming to your web server, to get the best performance it's still extremely important to optimize your web application and it's interaction with your database. To that end, memcache and other fast caching layers can play an important role and I'd never discourage them.
PS - we work great with dynamic sites. 95%+ of our sites are highly dynamic web applications.
I need to implement Google Analytics for a mobile site that is behind a CDN. This means that every page of content (including any tracking pixel references) is going to be cached for anywhere between 15 seconds and 5 minutes. I see that the GA tracking code implements a random number (utmn) in constructing the pixel, possibly to distinguish separate requests, separate users or simply to bust their own cache.
Does anyone know if it is safe to leave the page content cached? (I assume it is) Will we lose much tracking data?
Also, is it safe to serve the ga.aspx pixel itself from the CDN (where it would get cached) or does each GA pixel URL need to be uniquely addressed?
Does anyone have any recommendations on how best to implement GA? Server load from traffic is a huge concern for us, but we also want accurate numbers.
The mobile code will not work properly unless the utmn is generated for each call, so if you can serve the content so that it won't get cached (on server side), that would solve the problem.