The document explains web caching, which temporarily stores data to enhance website performance, particularly for dynamic sites that rely on databases and handle significant traffic. It details various caching methods and benefits, including reduced CPU usage, alleviating bottlenecks, and improving user interface speed. Additionally, it presents several caching solutions and extensions, emphasizing the importance of implementing caching for optimal site performance.

1. Web Cache

2. What is Cache?
Cache is the storing of data temporarily to improve
performance. Cache exist in a variety of areas such as
your CPU, Hard Disk and DNS.
CPU Cache Hard Disk Cache DNS Cache
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3. Our Focus
Our focus on this tutorial will be web cache. Web cache is
temporary storing of data that is used with delivering a
webpage (html, php, javascript, etc).

4. Why and How
Many sites today are dynamic websites that
1. Use a database connection
2. Written with a scripting language
3. Have changing content
With the amount of technology behind making these sites
work combined with larges volumes of traffic going to these
sites, cache is very important to improve the user
experience and lowering cost of your hardware.
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5. Basic Flow Without Cache
Server
User Database

6. This Is Ok If…..
1. Not a lot of content
2. Small amount of users/pageviews
This Is Bad If…..
1. Lots of contents
2. Lots of users/pageviews
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7. Flow With Cache
Server
2. Server gets content that
is cached
Database only needed to be called for
new content
User Database

8. Cache Benefits
 CPU Cycle Billing: If you are billed by the CPU Cycle,
cache can save you money because less of the cpu is
used when reading a file rather than a complex database
query.
 Bottleneck: If there is a bottleneck on your web service
such as with your database, not calling the database as
often and using cached database queries could help with
that bottleneck
 Faster UI: Storing cached files, whether in a file in the
browser or a location on the server, can lower the amount
of time need to load a page. This can make a faster user
experience.
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9. Basic Caching Methods
 Headers: PHP has a cache option set in the headers. This
can be useful for caching external files such as JavaScript
and CSS files.
 Basic File Cache: Basic file cache is an easy to implement
solution for writing and reading cache on a server.
 Memcache: A PHP extension for caching files on multiple
servers.
 Cache Lite: A PHP extension installed through PEAR that
caches whole pages or sections of pages.
 APC : APC, short for Alternative PHP Cache, is another php
extension that cache’s PHP code. It is installed through
PECL.
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10. Higher Level Caching
 Varnish: A HTTP accelerator(reverse proxy) that
caches data in virtual memory.
 Squid: A caching server that can cache DNS, FTP,
HTTPS, HTTP, TSL, and SSL protocols.
 Apache Traffic Server: A reverse proxy and forward
proxy caching server that despite its name, works with
Nginx.
 XtraDB: If you are using a Mysql database, this
caching solution can help optimize performance of your
database better than the standard InnoDB.
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11. Server Cache(Squid or Varnish)
Server
The actual server and the
database server are not
called unless new content
1. User request goes to server is needed
Cache Server
2. Cache servers returns cached data
User Database

12. Database Cache
Server
User 3. Use cached query Database

13. Review
As you can see, caching can occur at many levels.
 Database (ex: XtraDB)
 Server ( ex: Memcache)
 DNS/Networks ( ex: Squid)
 Client’s Browser (ex: Headers)
Take the time to research these solutions further to see
how can they improve your site’s performance.
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14. ProdigyView and Caching
 Natively, ProdigyView offers two type of caching: file
cache and memcache. Bot are easy to setup and use.
 Caching solutions can be extended by using a third
party caching solution or writing an adapter that will
change how the cache works.
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15. API Reference
For a better understanding of cache in ProdigyView, visit
the api by clicking on the link below.
PVCache
More Tutorials
For more tutorials, please visit:
http://www.prodigyview.com/tutorials
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