Executive in wait

Website on steroids September 26, 2007

When a user types in a URL to request a Web page, the page is created by an application server, which executes a script that builds the page. This script contains actions such as calls to database systems to retrieve content. The result is an HTML “blueprint” for the requested page.

The page is then delivered back to the browser in a quick, text-only, nonbandwidth-intensive transfer that does not incorporate graphics. Finally, the browser must fetch the graphics, requesting each object from the appropriate server address based on the embedded URLs in the HTML page.

Because browsers are limited to downloading two to four objects at a time and a typical Web page may contain 30 to 40 embedded objects, a good deal of back-and-forth handshaking between the browser and server is required to complete the loading of a page

Solutions to speed up

Address both Network latency & Server latency.

Network Latency
Network Caching addresses network latency. By storing and serving objects from the network edge, caching slashes the time it takes a browser to load an object. Hardware applicances which help caching are NetCache from NetApp and Cache Server Director from Radware. Even for dynamic content, static elements like logos etc could be cached.

Edge delivery is another option.

Caching is now a sophisticated programmable tool. You cannot just enable caching after an application is written. You have to start thinking about using caching right from the architectural stage. Caching doesn’t effectively address dynamic page generation, which typically accounts for 40% of the time required to deliver a Web page

Dynamic content accelerators

A dynamic-content accelerator is positioned between the Web server and back-end resources to field and fill logic requests. Relying on the expectation that even personalized content will make use of some recycled data, content accelerators reduce the number of application server and database calls needed to compose an HTML page response.

One such product from Chutney and spider cache

ESI

Edge Side Includes (ESI), HTML-based language, which has been proposed to the World Wide Web Consortium as an industry standard, defines fragments of Web pages, allowing them to be assembled and updated at the edge of the Internet. With ESI, companies can set rules within Web pages, alerting the cache when it is necessary to retrieve fresh information from an origin server and when cached content can be used. Then new content from origin servers can be combined with cached content so that an entire Web page can be assembled at the network’s edge – no need to retrieve complete pages from origin infrastructure.

Cantos uses ESI and Akamai

Tangosol can be used to cache data from the database.

Links:
Original Article
Another Article
Creating a cache friendly website
Edge servers and how it works
MTV Case Study
Jcache
Spiritsoft