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necessity of JAD in OTA ???

Punit Raizada
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Joined: Mar 20, 2004
Posts: 156
Hi All,

This is my understanding of the OTA :
- JAD is required.
- JAD contains the URL that points to the JAR file in the MIDlet-Jar-URL attribute..(This is where the phone finds the JAR)

Now,
I was reading the MIDP 2.0 spec (JSR 118) and something is bothering me .. i just might be understanding it incorrectly.

on Page 13 (PDF) , Chapter 2 OTA , Section MIDlet Suite Discovery
2nd Paragraph
"Using the DA, the user SHOULD be able to access a network location and see a description of the MIDlet suite along with a link that, when selected , initiates the installation of the MIDlet suite. If the link refers to a JAR file as described in the MIDP specification, the JAR and its URL are passed back to the AMS on the device to start the installation process. ....."


My question :

Is it possible to implement the download of a MIDlet suite by only giving the jar and not the JAD .. isnt the MIDlet size also checked in the JAD to determine if there is enough memory on the device ??? and some other stuff...

I will try it out at work tommorrow ... I am sure I am understanding the wording of this paragraph incorrectly...

Any one has any comments ???


SCJP 1.4
Everything that can go wrong will go wrong -Murphy
Roseanne Zhang
Ranch Hand

Joined: Nov 14, 2000
Posts: 1953
Yes, you can, just you download any zip/rar/jar file by using a browser.

Try it, then you would know.
Punit Raizada
Ranch Hand

Joined: Mar 20, 2004
Posts: 156
hmmm...

I send only the JAR file through bluetooth during our development stage and it gets installed ... but i was under the impression that a JAD was necessary for OTA ...

Learn something new every night
Sathya Srinivasan
Ranch Hand

Joined: Jan 29, 2002
Posts: 379
JAD is not necessary, but recommended for the following reasons.

1. If you install jut the JAR file, then the app will be treated as 'untrusted' (read security in J2ME for more details).
2. The minimum requirement to make an app 'trusted' is to have a JAD file. A trusted app, much like a trusted applet, has more access.
3. As you mentioned, you can also mention more parameters in the JAD file that would help the device be better prepared for the app.

I have a Sony T610 and I always send only the JAR file (can't even seem to get the JAD file installed!)


Cheers, Sathya Srinivasan - SCJP 1.2, SCWCD 1.2, SCMAD 1.0
Co-Author of Whizlabs SCMAD Certification Exam Simulator and SCMAD Exam Guide Book
Punit Raizada
Ranch Hand

Joined: Mar 20, 2004
Posts: 156
Yup,

Sony Ericsson phones dont keep the JAD file in the phone .. i bet during OTA they download the JAD .. read and verify the signatures and other stuff but dont store it.

PS: Sathya .. your notes are real nice ..
Roseanne Zhang
Ranch Hand

Joined: Nov 14, 2000
Posts: 1953
Originally posted by Sathya Srinivasan:
I have a Sony T610 and I always send only the JAR file (can't even seem to get the JAD file installed!)


That is correct, since Sony T610 does not accept jad file.
Sathya Srinivasan
Ranch Hand

Joined: Jan 29, 2002
Posts: 379
Originally posted by Punit Raizada:
Yup,

PS: Sathya .. your notes are real nice ..


Thanks for the remarks. Glad to be of help.
 
With a little knowledge, a cast iron skillet is non-stick and lasts a lifetime.
 
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