[JDEV] Developing client for Palm / SonyEricsson P800

Matthias Wimmer m at tthias.net
Mon Sep 15 13:12:15 CDT 2003

Hi Ulrich!

Ulrich B. Staudinger schrieb am 2003-09-15 19:38:34:
> >I have never seen J2ME implementations with AWT support. J2ME has its
> >own display classes (lcdui). 
> True and false. j2me uses a form and you have to put stuff into that form.
> anyway there are implementations around which fully support AWT. I 
> remember a screenshot on a palm with a j2me (it was not jeode) 
> implementation and awt.

I havn't read the original posting very carefully and did not notice
that it only had to be implemented for one phone. If you want to be
portable you can not use manufactor based extensions like an AWT

> >For loading MIDlets over the air you only
> >need internet access, something that is available by nearly all
> >providers I know since they support WAP for all customers. If you can't
> >install MIDlets over the air you won't need a Jabber client on the
> >phone, but you would still be able to install it with a serial cable, an
> >IR link or over bluetooth.
> this is not true. if you have a prepaid card for a telekom mobile phone, 
> you will be able to surf and WAP as much as you want to. but access to 
> JAR files and access to files loaded from within the JAD file is 
> blocked. believe me, it's true. i spent a whole day with non informed 
> telekom service clerks on the phone and they all told me the same as you 
> do - until i finally reached a guy who told me WAP and java applications 
> are not the same - neither are the terms "internet services" and 
> "downloading java applications". krass but true.

I did not say that all providers allow you to access MIDlets but that
nearly all will allow it. And I said that you will always be able to
install them over a local connection to your PC.

It is true that WAP and Internet are different in the networks of may
mobile phone companies. You have to use different APNs if you use GPRS.
On the WAP-APN you can only access the WAP gateway and on the
Internet-APN the standard port numbers 920x are blocked. Technically
they are not really different its just a matter of accounting. I am
operating my own WAP gateway for myself as my provider sells Internet
traffic cheaper than WAP traffic.

JAR and JAD files are loaded by the phone over the the internet
connection, with many phones (like the Nokia 6310i) you can even not
configure a different APN for Internet and MIDlet download. The reason
why it is not downloaded over the WAP gateway is that the WAP phone
communicates with the gateway over UDP. Files requested over the WAP
gateway have to fit in one UDP packet which is not possible for files of
the typical size of a MIDlet.

If your provider blocks download of JAD/JAR files, I expect he is
routing all traffic to port 80 over a transparent proxy and filters
these files on the proxy. You might be able to trick your provider by
using other ports for the server where you download the MIDlets. In any
case: If you configure your phone to access the internet over CSD
instead of GPRS your provider has no access to your internet connection
as you can use any PPP dialin. They only thing it has to allow is to
establish data calls (again something most (not all) providers allow even for
prepaid accounts since the time of WAP)

> whenever i renamed the jar file on my server to something else (ie. .JA) 
> the file could be downloaded/accessed (but not started, since the jar 
> file required to be loaded from a jad file). when i loaded it through 
> the jad file i had no entry in my server's log file - try it.

I have neither a Telekom Austria nor an prepaid account. My provider
allows me nearly full access to the internet. It only filters the
standard UDP ports of WAP gateways on its Internet APN.

Tot kijk

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