J2ME & UnicastRemoteObject

Posted on 2002-07-28
Last Modified: 2013-11-23
Hello poeple,

I am new to J2ME and I am experiencing a major Unresolved class error from the JavaCheck tool.

I need to use the UnciastRemoteObject class to my PDA but the JavaCheck tool tells me that this class is unresolved.

I cannot believe that there is no way around this problem.

My project is heavily based on this class and is of great importance to find a solution to that.

Please any help would be greatly appreciated.

Question by:pouli
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LVL 16

Expert Comment

ID: 7184563
there is J2ME[tm] RMI Optional Package
LVL 16

Expert Comment

ID: 7184564
you can probably read something more about it at

hint: is your friend.

Author Comment

ID: 7184932

I saw the links you gave.
what I can infer from what I read is that UnicastRemoteObject is supported by the personal profile.

Althgouh it is optional.

What I cannot understand is why the javaCheck tool tells me that the UnicastRemoteObject is unresolved.

This class is supported by the J2ME RMI profile.


Becasue it is optional this menas that depends form the manufacturer if he includes it or not ?

If it is not included could I just have it as an optional downlaod for the interested peoeple ?


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Author Comment

ID: 7184958
I have just now saw that I have one more important unresolved class the xx.xx.x.Communicator_Skel depends on unresolved class "java.rmi.server.Operation

This class is deprecated and there is no substitue.

I cannot(!) believe that it is so difficult to make a callback to the client.

What I want at the end of the day is the server to call specific methods to the client.

Do I ask for a lot ???

What I do though is to extend the UnicastRemoteObject and implement the _interface class wgich extends the Remote object.

Yesterday I found out that I can make a callback without extending the UnicastRemoteObject but with:


Do you think this will use less classes ?

Have you faced any problem liek that before ??
LVL 16

Expert Comment

ID: 7184970
this is Personal Java which works in enviroments with limited resources. it's very possible that most of the PersonalJava devices does not support RMI at all. you'd better redesign your application to use some other communication protocol.
LVL 16

Accepted Solution

heyhey_ earned 100 total points
ID: 7184998
not sure, but you may need to install the extension before running javaCheck ?

Author Comment

ID: 7185006
I am actaully interested in the Zaurus PDA that is actually a high-end PDA.

It is too costly for me to redesign my application :)

I have to prove to myself that I cannot do anything else before procedding to the solution you said.

It is simply too much work I have to do. I have to redesign the server etc.

Certainly in the next project I will do I will bare in mind this.

It is just my 1st project with J2ME anyway.

I heard that Zaurus java is like having Java 1.1.8
If this is true then all these classes are supported.

I will find out more about Zaurus and tell you.

Author Comment

ID: 7185008
What extension ???
LVL 16

Expert Comment

ID: 7185012
J2ME RMI profile

Author Comment

ID: 7185013
I will have a look

Author Comment

ID: 7185074
I was not able to find a specification file (.spc) that the Javacheck needs to install it.

I downloaded as well the reference implementation files (.java)

I tried to compile them with normal javac through commnad line but it generated some errors.

There is a folder build/share that has 2 files

I think I have to use these files in order to compile them.

Do you know what I am supposed to do ?

Author Comment

ID: 7188138
Hey hey I need your lights.

I found someone with a Zaurus PDA
and we are just right now online trying to make things work

I cannot compile (rmic) with the 1.1.8 version without the default security options.

What I mean is when I make
c:\jdk1.1.8\rmic\rmic Server (for example)

I take a message that says that the default security settings are used.

When I try to run the program I take security exceptions and this is I think because of the default settings.

The question is: How can I compile the classes that extend the UnicastRemoteObject with my security settings? (Possibly I will permit everything for testing)

Thank you in advance.

Author Comment

ID: 7190694
Heyhey problems sovled :)

I found someone who owns a Z and he was willing to help me :)

The Z supports 1.1.8

But it does not support rmiregistry.
It supports though UnicastRemoteObject and it is possible to make a callback to the client from the server.

New problems have arised.

This is called Firewall

I will pos a new question if you think you could help me please have a look.

I will set the title to "RMI Tunelling & Firewalls"

Thank you

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