Are there any problems of using Connections other then HTTPConnectoin?

Question

Hi,
I have tried to use datagram connection with the following code:
DatagramConnection c = (DatagramConnection) Connector.open("datagram://localhost:10000");
when i use the midp to test it, it gives out error message like:
javax.microedition.io.ConnectionNotFoundException: The requested protocol does not exist datagram://localhost:10000
Am i missed to setup some things?
P.S. I am using midp and cldc version 1.0.3 and palm emulator

Answer 1

the midp specification (http://java.sun.com/j2me/docs)says that only http-connection is mandatory, kvms and devices can provide the other connection types specified too.
the reason for this is that http is the only protocol of the given, that runs on a certain level of abstarction.
So device manufactors are not bound to a physical protocol such datagram/socket connection. How http transmissions happens depends on the kvm and the device specs.
If you develop for a certain product category, where you know that the devices all implement datagram transmission you can do it, otherwise its recommendet do use only HTTP.
MIDP for Palm does not implement a datagram protocol actually (http://java.sun.com/products/midp4palm/faq.html#Q5)