A newer's question.

Hi,all:
    I am a newer to this list,for I am considering to implement the cscw under web.I have several question below,I donot know whether it should be debated:
1.When one use put an object to the server,how to let the other users know the changes immediately?For example,when one create a image,the other uesrs' screen should also show the image.As I know,http does not support the push now.So,how to do that?
2.I have read the WebDAV protocol-06 document,I think it is mainly based on html editor.I think using html has many shortcoming.
Using HTML,when changed a litter,the whole web frame will be refreshed,it caused not only slow,but also incovenient.And,the interface isnot easy to use.Comparing to the windows application,it does not support menu,popupmenu,and many things.I think it is really hard to make the user satisfatied.
well,we can also use the Java and the Activex technology,and I think using Java is more efficient then using HTML.
What do you think of these technologies in WebDAV fields?
3.Is it possible to provide the video confrence services through web?Not using other products such as webphone,can we interegrate the video conference into the web?
Thanks a lot!
Yours
Wang HanMin