Thank you for the reply.
Your email was really helpfull, it will solve my problem.
After analysed the source codes of SS part, I roughly got idea how to finish
the collaboration in my project.
>>Yes, I've gone through all the tutorials suggested above and invoked
>>most of the mothods in my application. I mainly use the visad built-in
>>collaboration support so far. Based on RendererControl, all graphics
>>widgets associated with Controls and ScalarMaps worked very well.
>>I found that when a DataReference has been removed in Host, Clients
>>didn't response. After investagation on VisAD, it seems that
>>REFERENCE_REMOVED event was not sent to clients. So I made some changes
>>to VisAD system to make this part work. Although I knew this may bring
>>some trouble later on, but I have no better choice at this moment.
>>To those self-developed graphics widgets (e.g. ComboBox, Button etc.)
>>which neither belongs to Controls nor ScalarMap. I still have no idea
>>how to make them collaborative.
>The VisAD SpreadSheet had some similar requirements. I implemented a
>fairly general way to send messages back and forth between server and
>client, to keep things synchronized that were not already handled by the
>built-in VisAD collaborative display logic.
>Take a look at the VisAD SpreadSheet, in package visad.ss. In
>particular, check out visad/ss/BasicSSCell.java starting at line 283
>(the part labeled "COLLABORATION"). The sendMessage and receiveMessage
>methods handle communication. It should be possible to adapt their
>functionality for your needs, including synchronization of custom
>widgets built with Swing components.