I think an accurate technical explanation is of interest of you guys.
There seems to be many articles in English mentioning i-mode, but most
of them are technically shallow and sometimes wrong.
** What exactly i-mode is **
I-mode is an email/web service for cell phone provided by the majority
share holding cell phone operator in Japan -- NTT DoCoMo. NTT DoCoMo
has three kinds of nation wide coverage cell phone services -- 800MHz,
1.5GHz, and 1.9GHz services. All of these three have their own
national wide base station networks. The 800MHz service is their
mainstream service and i-mode is a service option of it.
As of this writing, there are 9.5 million i-mode subscribers. And now
all new handsets for the 800MHz service are capable of i-mode service.
** I-mode and WAP basically look similar **
+ From content providers' point of view, i-mode handsets as well as
WAP
handsets are regarded as HTTP clients. I-mode contents as well as WAP
contents are served by ordinary HTTP servers.
+ Handsets themselves don't speak HTTP natively. What handsets talk
directly to is a gateway. Gateway translates handsets' native
protocol
and HTTP. This is the case both with i-mode and WAP.
handset ------------------ gateway -------- content servers
cellular network HTTP
+ Users reach a content they want either by
+ traversing hyper links from a portal
+ using book marked URL
+ entering URL manually
** fundamental difference between i-mode and WAP **
The fundamental difference between i-mode and WAP is markup language
of
contents. I-mode employs Compact HTML (cHTML), a subset of HTML 4.0.
You can get the specification of cHTML from WWW Consortium's web site
at www.w3.org since it was proposed to the consortium. Whereas WAP
employs WML (Wireless Markup Language) based on XML. From web
servers'
point of view, WML is just another data format. So there is no hassle
needed to provide WML contents on an ordinary HTTP server -- just add
a
new MIME data type, namely text/WML.
** one gateway vs multiple gateways **
There is only one i-mode gateway, which is operated by NTT DoCoMo.
Physically, the i-mode gateway is implemented by many machines, and
NTT
DoCoMo will soon start operating 2nd gateway plant. But from
handsets'
and users' point of view, there is only one gateway.
There is no way to change gateways with i-mode handsets. This is also
the case with the start page. This scheme is inflexible, but the flip
side is there is no configuration needed for users.
With WAP handsets, users have to configure their handsets regarding
where and how to connect to a gateway.
Actually, this is not always the case. In Japan all WAP phones are
pre-configured and there is no way to change configuration.
** SSL/HTTPS **
I-mode is capable to handle HTTPS in addition to HTTP. But the
encryption/description are done on the gateway, not on handsets. The
next generation of i-mode handsets planned to debut by the end of the
year would have end to end SSL capability.
I'm not sure with WAP, but I guess it depends on gateway. Some WAP
gateways support SSL, but others don't.
** packet switched vs circuit switched **
I-mode is provided on packet switched data connection, not circuit
switched. Users are charged based on data volume sent and received,
not time. Whereas there is no packet switched cellular data network
commercially available now outside Japan.
In Japan there is a cell phone operator providing a WAP service over a
packet switched data service.
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Received on Thu Aug 3 05:59:58 2000