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Wireless browser standard: to realize the possibilities of iMode takes "persistence". (Storage Networking).

Whether you know it as iMode, mMode, or merely as the industry-standard browser for wireless devices, there's a reason why this technology holds the potential to vastly increase the reach and grasp of rich Web payload (1) Refers to the "actual data" in a packet or file minus all headers attached for transport and minus all descriptive meta-data. In a network packet, headers are appended to the payload for transport and then discarded at their destination.  and deliver it to a population in pursuit of ultimate mobility.

Since introducing the browser in 1999, DoCoMo, the arm of Japan's NTT NTT Nippon Telegraph and Telephone Corporation
NTT New Technology Telescope
NTT National Technology Transfer, Inc
NTT Name That Tune (TV game show)
NTT National Tree Trust
NTT Number Theoretic Transform
 that developed iMode, has attracted an impressive and fast growing number of devotees around the world. In less than two years, subscribers to iMode-enabled multimedia services soared to more than 30 million in Japan. Introduced just last spring in Europe, growth is expected to top a million users over the next 12 months.

Today there are more than 3,000 official DoCoMo iMode sites. The criteria for official status are stiff, but passing muster means a direct link from the browser to a directory of registered sites. Even so, given the wide acceptance of the iMode platform as the industry standard, and the lure of customer traffic anytime anywhere, another 50,000 sites have sprung up. And more are jumping in all the time.

But outfitting yourself with a wireless device sporting an iMode-style browser is not all you'll need in your pocket to surf the net To browse the Internet. The most common Internet browsing today is done on the Web. Before the Web, the Internet was "surfed" via Archie, Gopher, WAIS and other search facilities. See surfing and how to access the Internet.  and handle everything it can dish out. Providing the interactivity necessary to securely deliver robust web services (1) Loosely, any online service delivered over the Web. Such usage appears in articles from non-technical sources, but not in IT-oriented publications, because definition #2 below describes the correct use of the term.  and successfully complete complex transactions requires a massive infusion of intelligent, application traffic management technology into web architectures. To enable your site for the iMode platform, you'll need capabilities that go well beyond security, that surpass high availability Also called "RAS" (reliability, availability, serviceability) or "fault resilient," it refers to a multiprocessing system that can quickly recover from a failure. There may be a minute or two of downtime while one system switches over to another, but processing will continue. , and exceed load balancing The fine tuning of a computer system, network or disk subsystem in order to more evenly distribute the data and/or processing across available resources. For example, in clustering, load balancing might distribute the incoming transactions evenly to all servers, or it might redirect them . While these characteristics are essential for basic website performance, the real key to enriched wireless content is wireless persistence.

The sticky Web application connection permitting a bi-directional, back-and-forth interaction is the most needed link in the application traffic management chain. That ability to keep a mobile device latched latch  
1. A fastening, as for a door or gate, typically consisting of a bar that fits into a notch or slot and is lifted from either side by a lever or string.

 on for the full duration represents Seattle based F5 Networks' contribution to a solution allowing not just ecommerce and ebusiness transactions, but even such exotica ex·ot·i·ca  
Things that are curiously unusual or excitingly strange: such gustatory exotica as killer bee honey and fresh catnip sauce.
 as interactive gaming between mobile subscribers. Making this a reality, the company's BIG-IP Controller is the intelligent traffic director that serves up the vital ingredient of wireless persistence.

Consider the example of a Web shopper. Persistence is what keeps the shopping cart loaded, allowing your shopper to browse, make selections, check out, and complete the final credit card transaction. In combination with high availability, scalability, and numerous types of load balancing capabilities, F5 Networks has offered such functionality for several years. However, serving the mobile Web shopper with transactions that require continuous, persistent availability poses a much greater challenge. To support the same high level of functionality with 100% security and reliability in the wireless world requires a staggering increase in traffic management intelligence.

Stepping through a typical iMode-enabled transaction, when a mobile subscriber first enters a site, the BIG-IP Controller's load balancing features direct traffic flow down the most optimal path. In a nutshell nut·shell  
The shell enclosing the meat of a nut.

in a nutshell
In a few words; concisely: Just give me the facts in a nutshell.

Adv. 1.
, the most available Web server in the appropriate pool is selected, receives the HTTP HTTP
 in full HyperText Transfer Protocol

Standard application-level protocol used for exchanging files on the World Wide Web. HTTP runs on top of the TCP/IP protocol.
 request, and replies. Using intelligent rules, the information about that server is written into the HTTP response. The subscriber's cookie is applied by the BIG-IP Controller and joins the reply. To continue the transaction, when the subscriber returns for each subsequent step in the interaction, the BIG-IP Controller recognizes the header information and passes the request back to the same server that was initially selected.

Breaking down the components of this scenario for a closer examination shows how the BIG-IP Controller is able to establish and maintain a persistent, reliable connection over the course of the entire transaction.

First, every iMode-enabled device has a unique identifier With reference to a given (possibly implicit) set of objects, a unique identifier is any identifier which is guaranteed to be unique among all identifiers used for those objects and for a specific purpose.  that is transmitted in the header. The BIG-IP Controller is able to recognize this identifier through its inspection engine, and using its intelligent rules feature, directs the flow of traffic back to the same server that received the original HTTP request.

Several load-balancing algorithms were also used to seek out the fastest performing server by utilizing the transaction information as sessions pass through the BIG-IP Controller.

Using rules, BIG-IP segregated the web site into appropriate resources, sending the incoming iMode request to one set of servers or caches, while sending the request from other requesting mobile devices to a different set of servers or caches.

Server maintenance and shutdown are also possible without losing customer transactions. When a server needs to be shut down, the site administrator replaces one intelligent rule with another. By switching rules, BIG-IP can redirect re·di·rect  
tr.v. re·di·rect·ed, re·di·rect·ing, re·di·rects
To change the direction or course of.

A redirect examination.

 any new traffic to other available servers. In the meantime Adv. 1. in the meantime - during the intervening time; "meanwhile I will not think about the problem"; "meantime he was attentive to his other interests"; "in the meantime the police were notified"
meantime, meanwhile
, any activity previously initiated continues on and persists unabated un·a·bat·ed  
Sustaining an original intensity or maintaining full force with no decrease: an unabated windstorm; a battle fought with unabated violence.
 until all transactions cease and customer business has been completed.

The server may then be taken offline for maintenance work without disrupting any of the site's Web services.

BIG-IP and iMode-enabled web services allow the delivery of any application to any type of mobile device at any given moment in time, granting the freedom of total mobility to the wireless client.

Chris Archey is manager of product strategy at F5 Networks (Seattle)
COPYRIGHT 2002 West World Productions, Inc.
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Author:Archey, Chris
Publication:Computer Technology Review
Geographic Code:9JAPA
Date:Oct 1, 2002
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